MySQL 8.0 Release Notes

Abstract

This document contains release notes for the changes in each release of MySQL 8.0, up through MySQL 8.0.40. For

information about changes in a different MySQL series, see the release notes for that series.

For additional MySQL 8.0 documentation, see the MySQL 8.0 Reference Manual, which includes an overview of

features added in MySQL 8.0 (What Is New in MySQL 8.0), and discussion of upgrade issues that you may encounter

for upgrades from MySQL 5.7 to MySQL 8.0 (Changes in MySQL 8.0).

Before upgrading to MySQL 8.0, review the information in https://dev.mysql.com/doc/refman/8.0/en/upgrading.html

and perform any recommended actions. Perform the upgrade on a test system first to make sure everything works

smoothly, and then on the production system.

Downgrade from MySQL 8.0 to MySQL 5.7, or from a MySQL 8.0 release to a previous MySQL 8.0 release, is not

supported. The only supported alternative is to restore a backup taken before upgrading. It is therefore imperative that

you back up your data before starting the upgrade process.

MySQL platform support evolves over time; please refer to https://www.mysql.com/support/supportedplatforms/

database.html for the latest updates.

Updates to these notes occur as new product features are added, so that everybody can follow the development

process. If a recent version is listed here that you cannot find on the download page (https://dev.mysql.com/

downloads/), the version has not yet been released.

The documentation included in source and binary distributions may not be fully up to date with respect to release note

entries because integration of the documentation occurs at release build time. For the most up-to-date release notes,

please refer to the online documentation instead.

For legal information, see the Legal Notices.

For help with using MySQL, please visit the MySQL Forums, where you can discuss your issues with other MySQL

users.

Document generated on: 2024-08-04 (revision: 28811)

Table of Contents

Preface and Legal Notices ................................................................................................................. 2

Changes in MySQL 8.0.40 (Not yet released, General Availability) ....................................................... 4

Changes in MySQL 8.0.39 (2024-07-23, General Availability) ............................................................... 4

Changes in MySQL 8.0.38 (2024-07-01, General Availability) ............................................................... 4

Changes in MySQL 8.0.37 (2024-04-30, General Availability) ............................................................... 8

Changes in MySQL 8.0.36 (2024-01-16, General Availability) ............................................................. 13

Changes in MySQL 8.0.35 (2023-10-25, General Availability) ............................................................. 17

Changes in MySQL 8.0.34 (2023-07-18, General Availability) ............................................................. 23

Changes in MySQL 8.0.33 (2023-04-18, General Availability) ............................................................. 34

Changes in MySQL 8.0.32 (2023-01-17, General Availability) ............................................................. 42

Changes in MySQL 8.0.31 (2022-10-11, General Availability) ............................................................. 55

Changes in MySQL 8.0.30 (2022-07-26, General Availability) ............................................................. 70

Changes in MySQL 8.0.29 (2022-04-26, General Availability) ............................................................. 86

Changes in MySQL 8.0.28 (2022-01-18, General Availability) ........................................................... 103

Changes in MySQL 8.0.27 (2021-10-19, General Availability) ........................................................... 122

Changes in MySQL 8.0.26 (2021-07-20, General Availability) ........................................................... 143

MySQL 8.0 Release Notes

Changes in MySQL 8.0.25 (2021-05-11, General Availability) ........................................................... 166

Changes in MySQL 8.0.24 (2021-04-20, General Availability) ........................................................... 166

Changes in MySQL 8.0.23 (2021-01-18, General Availability) ........................................................... 182

Changes in MySQL 8.0.22 (2020-10-19, General Availability) ........................................................... 199

Changes in MySQL 8.0.21 (2020-07-13, General Availability) ........................................................... 218

Changes in MySQL 8.0.20 (2020-04-27, General Availability) ........................................................... 240

Changes in MySQL 8.0.19 (2020-01-13, General Availability) ........................................................... 260

Changes in MySQL 8.0.18 (2019-10-14, General Availability) ........................................................... 284

Changes in MySQL 8.0.17 (2019-07-22, General Availability) ........................................................... 304

Changes in MySQL 8.0.16 (2019-04-25, General Availability) ........................................................... 330

Changes in MySQL 8.0.15 (2019-02-01, General Availability) ........................................................... 356

Changes in MySQL 8.0.14 (2019-01-21, General Availability) ........................................................... 356

Changes in MySQL 8.0.13 (2018-10-22, General Availability) ........................................................... 378

Changes in MySQL 8.0.12 (2018-07-27, General Availability) ........................................................... 402

Changes in MySQL 8.0.11 (2018-04-19, General Availability) ........................................................... 418

Changes in MySQL 8.0.5 - 8.0.10 (Skipped version numbers) .......................................................... 442

Changes in MySQL 8.0.4 (2018-01-23, Release Candidate) ............................................................. 442

Changes in MySQL 8.0.3 (2017-09-21, Release Candidate) ............................................................. 477

Changes in MySQL 8.0.2 (2017-07-17, Development Milestone) ....................................................... 499

Changes in MySQL 8.0.1 (2017-04-10, Development Milestone) ....................................................... 525

Changes in MySQL 8.0.0 (2016-09-12, Development Milestone) ....................................................... 568

Index .............................................................................................................................................. 600

Preface and Legal Notices

This document contains release notes for the changes in each release of MySQL 8.0, up through MySQL

8.0.40.

Legal Notices

License Restrictions

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MySQL 8.0 Release Notes

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MySQL 8.0 Release Notes

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Changes in MySQL 8.0.40 (Not yet released, General Availability)

Version 8.0.40 has no release notes, or they have not been published because the product version has not

been released.

Changes in MySQL 8.0.39 (2024-07-23, General Availability)

Bugs Fixed

• InnoDB: In some cases, following the creation of a very large number of tables (8001 or more), the

server could not be restarted successfully. (Bug #36808732)

References: This issue is a regression of: Bug #33398681.

• InnoDB: Improved tablespace file scan performance at startup. (Bug #110402, Bug #35200385)

• Group Replication: Running a CREATE TABLE ... SELECT statement on a source coming from an

asynchronous channel to Group Replication led to errors on the replica. (Bug #36784284)

Changes in MySQL 8.0.38 (2024-07-01, General Availability)

Important

This release is no longer available for download. It was removed due to a critical

issue that could stop the server from restarting following the creation of a very large

number of tables (8001, or more). Please upgrade to MySQL 8.0.39 instead.

• Audit Log Notes

• C API Notes

• Compilation Notes

• Connection Management Notes

• Data Dictionary Notes

• Pluggable Authentication

• Thread Pool Notes

• Bugs Fixed

Audit Log Notes

• Audit log pruning did not function after removing or renaming a file from the audit log. Now pruning

continues in such cases, but with a warning printed in the error log stating that it was not possible to

delete the missing audit log file. (Bug #35902913)

MySQL 8.0 Release Notes

C API Notes

• C API applications stalled while receiving results for server side prepared statements.

Compilation Notes

• Upgraded the bundled googletest and googlemock sources to version 1.14.0. (Bug #36562482)

• Added a missing dependency on GenError. (Bug #36551721)

• It is now possible on Linux systems to build MySQL using a bundled tcmalloc library that is provided

with the source by specifying -DWITH_TCMALLOC=BUNDLED. This is supported on Linux only. (Bug

#36313839)

• The bundled tcmalloc() is now used when building MySQL on Enterprise Linux 8. (Bug #114844, Bug

#35674008)

• Linux aarch64 platform binaries are now built using patchelf --page-size=65536 for compatibility

with systems using either 4k or 64k for the page size. (Bug #114233, Bug #36393794)

Connection Management Notes

• The conn_delay/Waiting in connection_control plugin stage was not reset after a delay

introduced by the connection control plugin which resulted in incorrect monitoring information. (Bug

#35205358)

Data Dictionary Notes

• Attempting to upgrade a MyISAM table containing a mix of regular columns and generated columns from

MySQL 5.7 to 8.0 or later led to table corruption. (Bug #105301, Bug #33503328)

Pluggable Authentication

• The deprecation warning issued when authenticating with the mysql_native_password plugin is now

issued only once. (Bug #35792948)

Thread Pool Notes

• Connecting to a thread group that had no connection handler threads stalled. We fix this by making

sure that connection handler threads terminate only if there is at least one connection thread left. (Bug

#36550125)

Bugs Fixed

• InnoDB: MySQL unexpectedly halted on an UPDATE after an ALTER TABLE operation. (Bug

#36571091)

References: This issue is a regression of: Bug #35183686.

• InnoDB: The log index size calculation now accounts for column order changes. (Bug #36526369)

References: This issue is a regression of: Bug #35183686.

• InnoDB: File system operations performed by InnoDB now consistently fsync the parent directory

when performing directory altering tasks. (Bug #36174938)

MySQL 8.0 Release Notes

• InnoDB: In debug builds, setting the innodb_interpreter_output debug variable would cause the

server to unexpectedly halt. This is now a read-only variable. (Bug #36041032)

• InnoDB: For tables created with an index on a column that was too wide for the redundant row format

(allowed before MySQL 5.7.35), an in-place upgrade silently imported the table but it was not accessible,

which interfered with making backups. Now all operations that involve using the invalid index are

rejected with ER_INDEX_CORRUPT until the index is dropped. An ER_IB_INDEX_PART_TOO_LONG error

is also reported in the error log. (Bug #35869747)

References: See also: Bug #34826861.

• InnoDB: An InnoDB assertion error referencing an invalid column index was triggered when the column

index was valid. (Bug #34800754)

• InnoDB: With an empty XA transaction, shutting the server down after an XA START would cause the

server to halt unexpectedly. (Bug #32416819)

• InnoDB: Shutting down the replication applier or binlog applier while processing an empty XA

transaction caused the system to unexpectedly halt. (Bug #32416819)

• InnoDB: Removed unnecessary heap usage in the Validate_files::check() function.

Our thanks to Huaxiong Song for the contribution. (Bug #115041, Bug #36626203)

• InnoDB: If a partition table was read with innodb_parallel_read_threads=1, read performance

greatly decreased from any table after 256 reads. InnoDB behaved as if it reached the maximum

capacity of parallel read threads despite not using any.

Our thanks to Ke Yu for the contribution. (Bug #114154, Bug #36347408)

• InnoDB: The result from a spatial index containing a column with a spatial reference identifier (SRID)

attribute was empty. In addition, using FORCE INDEX to force a covering index scan on a spatial index

led to an assertion. (Bug #112676, Bug #114200, Bug #35894664, Bug #36361834)

• InnoDB: Fixed performance issues related to querying the data_lock and data_lock_waits tables

when thousands of read-only transactions were present. (Bug #109539, Bug #34951273)

• Replication: If a source contained a stored, generated column populated by a JSON function and

binlog_row_image was set to MINIMAL, any subsequent update or deletion on the underlying column

failed with the following error:

Invalid JSON text in argument 1 to function json_extract: 'The document is empty.'

The replica attempted to re-evaluate the generated column and failed with that error because the

underlying column was unavailable. As of this release, stored, generated columns are not re-evaluated

when the underlying columns are unavailable. (Bug #36515172)

• Replication: Worker jobs now contain information about the relay log file which initiated the transaction,

instead of using the default defined by relay_log. (Bug #36395631)

• Group Replication: Removed a memory leak from /xcom/gcs_xcom_networking.cc. (Bug

#36532199)

• Group Replication: Under certain circumstances, if a primary's host experienced network inactivity of

20 seconds or more, the secondaries could stop unexpectedly. (Bug #36306144)

• Group Replication: Under certain circumstances, if garbage collection occurred just before a relay log

rotation, it could cause the applier to stop applying new transactions on the secondary members.

MySQL 8.0 Release Notes

This was caused by garbage collection incrementing the relay log's last_committed and

sequence_number, creating a gap in the recorded sequence_number after the log rotation. The

applier was unaffected if the gap occurred anywhere else in the relay log.

As of this release, only last_committed is updated during garbage collection. (Bug #36280130, Bug

#36446250)

• JSON: Added missing checks for error handling to NULLIF(), COALESCE(), and the shift (>>) operator.

(Bug #113668, Bug #35513196, Bug #36198403)

References: See also: Bug #31358416.

• MySQL NDB ClusterJ: Running the ClusterJ test suite resulted in an error message saying a number

of threads did not exist. That was due to some wrong handling of threads and connections, which was

corrected by this patch. (Bug #36086735)

• Averages of certain numbers were not always computed correctly. (Bug #36563773)

• The following files in strings contained incorrect license information:

• mb_wc.h

• ctype-uca.cc

• ctype-ucs2.cc

• ctype-utf8.cc

• dtoa.cc

• strxmov.cc

• strxnmov.cc

(Bug #36506181)

• In certain unusual cases, the UpdateXML() function did not process all of its arguments correctly. (Bug

#36479091)

• Explaining a query which used FORCE INDEX on a spatial index containing a column with SRID

attributes led to an unplanned exit. (Bug #36418426)

• When incrementing the reference count for an expression, underlying expressions within this expression

are not looked at. While removing an expression, after decrementing the reference count, even

the underlying expressions were examined, which led to unintentional deletion of the underlying

expressions. This issue manifested in Item_ref::real_item() as well as in an assert in sql/

item.h. We fix this by not looking at the underlying expression unless the current expression contains

the only remaining reference. (Bug #36204344, Bug #36356279)

• Under certain conditions, EXPLAIN FORMAT=JSON FOR CONNECTION sometimes led to an unplanned

exit. (Bug #36189820)

• Under certain conditions, a race condition could result in the amount of RAM used by TABLE_HANDLES

increasing to a maximum of 9GB. (Bug #36170903)

• Some CREATE USER statements were not handled correctly. (Bug #36022885)

MySQL 8.0 Release Notes

• For a SELECT with ORDER BY and LIMIT, the optimizer first chose a full table scan with a very

expensive cost, then performed another check and used the perform_order_index type of path, but

this was not reflected by the cost in the optimizer plan. (Bug #35930969)

• Client connections were not alway terminated correctly during shutdown. (Bug #35854919)

• All internal ACL bitmask variables are now explicitly 32 bits (uint32_t). (Bug #35507223)

• It was not possible to add a functional index on FIND_IN_SET(). (Bug #35352161)

• Running two concurrent OPTIMIZE TABLE statements on the same table with fulltext indexes and

innodb_optimize_fulltext_only enabled sometimes caused the server to exit. (Bug #34929814)

• Removed a memory leak observed while running authentication_kerberos under Valgrind. (Bug

#34482788, Bug #36570929)

• The gen_range() function as implemented by the (deprecated) data masking plugin did not always

return the correct result.

This issue affected the data masking plugin only, and did not affect the data masking component which

supersedes it. (Bug #34163992)

• Fixed an erroneous comment in include/my_command.h.

Our thanks to Sho Nakazono for the contribution. (Bug #114507, Bug #36455468)

• It was possible for a deterministic stored function to return an incorrect result when the function used

JOIN ON inside the return statement. If the query needed to be reprepared due to a table metadata

caused by, for example, FLUSH TABLES between two executions, the ON clause was sometimes lost.

(Bug #114235, Bug #36379879)

• The PROCESSLIST_INFO column of THREADS was not updated when executing a prepared statement.

Thanks to Daniel Lenski and Amazon for the contribution. (Bug #104121, Bug #33057164)

Changes in MySQL 8.0.37 (2024-04-30, General Availability)

• Audit Log Notes

• Character Set Support

• Compilation Notes

• Component Notes

• Optimizer Notes

• Performance Schema Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• MySQL now calls plugin->deinit() with a valid plugin struct as an argument regardless of the

plugin's type.

Our thanks to Martin Alderete for the contribution.

MySQL 8.0 Release Notes

Character Set Support

• When the character_set_server system variable was set using SET PERSIST or SET GLOBAL,

it did not take effect for new client sessions or for a client establishing a connection to the server after

the server was restarted. The only workaround was to set the corresponding command-line option when

starting the server.

To fix this, we now make sure that, at the time of server restart, the configuration data is read in the

correct order so that the variable setting takes effect as expected. (Bug #35529604)

Compilation Notes

• Warnings for unused variables are turned into compilation errors when compiling with -

DMYSQL_MAINTAINER_MODE=1. To avoid this use -DMYSQL_MAINTAINER_MODE=0 to disable such

errors. (Bug #113662, Bug #36198423)

• Improved the cycle timer for the s390x architecture.

Our thanks to Jonathan Albrecht for the contribution. (Bug #112845, Bug #35949958)

Component Notes

• The values for component options set using the --loose prefix were not read when the component was

installed. (Bug #28341329)

Optimizer Notes

• The multi-range read (MRR) optimization did not perform as well as in previous releases. (Bug #113711,

Bug #36220640)

Performance Schema Notes

• User variables assigned decimal values were rounded up in the user_variables_by_thread table.

(Bug #35781732)

• Executing SELECT * from performance_schema.data_locks on a server under heavy load could

cause MySQL to consume too much memory and close unexpectedly.

As of this release, memory used executing such a query is now instrumented with memory/

performance_schema/data_container, enabling you to observe memory consumption. (Bug

#35240825)

• Executing SELECT * from performance_schema.data_locks on a server under heavy load could

cause a deadlock in InnoDB. (Bug #35068461)

References: See also: Bug #35240825.

Functionality Added or Changed

• Important Change; Group Replication: When issued with group_replication_consistency

set to BEFORE_ON_PRIMARY_FAILOVER, the MySQL KILL statement now ignores any consistency

guarantees, with any interrupted transactions now being rolled back.

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated to version 3.0.13. Issues fixed in OpenSSL version 3.0.13 are

described at https://www.openssl.org/news/cl30.txt. (Bug #36261675)

MySQL 8.0 Release Notes

• Packaging: Added support for Fedora 40 and Ubuntu 24.04.

• Microsoft Windows: MySQL Windows binary files (.exe and .dll files) now display additional

information when their properties are viewed. (Bug #36379291)

• The clone plugin version requirements were relaxed to allow cloning between different point releases in

the same series. In other words, only the major and minor version numbers must match when previously

the point release number also had to match.

For example, clone functionality now permits cloning 8.4.0 to 8.4.14 and 8.0.51 to 8.0.37. For 8.0,

previous restrictions still apply to versions older than 8.0.37, so cloning the likes of 8.0.36 to 8.0.42 or

vice-versa is not permitted. (Bug #36293529, WL #15989)

Bugs Fixed

• Important Change: The Robin Hood hashing library has been replaced with unordered_dense. (Bug

#36158022)

• InnoDB; Microsoft Windows: Improved redo log performance on Windows by opening redo log files in

overlapped mode. (Bug #36154818)

References: This issue is a regression of: Bug #12527.

• InnoDB: The log writer calls functions that temporarily release log.writer_mutex; when

innodb_log_writer_threads=OFF, this potentially led to other threads writing to the redo log in

between these times. (Bug #36425219)

• InnoDB: Some FTS operations on tables with FTS indexes led to inconsistent results. For example, if

the server terminated while synchronizing the FTS cache or when synchronization occurred concurrently

with another FTS operation.

Our thanks to Yin Peng and the Tencent team for the contribution. (Bug #36347647)

• InnoDB: When creating an index on a table containing data, valgrind occasionally reported reads of

uninitialized memory from ddl::Builder::bulk_add_row(). (Bug #36342792)

• InnoDB: On Windows, keeping a file open without a shared write lock and attempting to acquire the

fil_shard mutex caused a deadlock with another thread that had acquired the fil_shard mutex and

was attempting to access the same file. (Bug #36159317)

References: See also: Bug #32808809.

• InnoDB: Fixed a potential redo log rotation issue that could emit a "Found existing redo log files, but at

least one is missing" error during recovery. (Bug #36124625)

• InnoDB: Improved os_innodb_umask handling, and made it read-only. (Bug #35932118)

References: This issue is a regression of: Bug #29472125.

• InnoDB: Found and fixed an assertion failure related to full-text indexes. (Bug #35836581)

• InnoDB: Improved buffer handling during the tablespace deletion process, a situation that could have

potentially caused an assertion failure. (Bug #35676106, Bug #36343647)

• InnoDB: If a MySQL table in a system schema had an INSTANT ADD column that was added before

8.0.29 (they are not allowed as of that version), and after MySQL was upgraded to a version greater than

8.0.29, DMLs on these tables would result in the server unexpectedly closing.

Our thanks to Richard Dang for the contribution. (Bug #35625510, Bug #35981565, Bug #36180360)

MySQL 8.0 Release Notes

• InnoDB: The redo log would potentially not log a column order change with instant DDL, which could

cause an incorrect log replay during recovery. (Bug #35183686)

• InnoDB: Results for SHOW ENGINE INNODB STATUS showed an invalid value (NULL) as the first result.

(Bug #113819, Bug #36118112)

References: This issue is a regression of: Bug #34992157.

• InnoDB: With innodb_parallel_read_threads set to a value greater than 1, InnoDB

unnecessarily disabled read-ahead heuristics which resulted in stalls when pages were not already in the

buffer pool. (Bug #113482, Bug #36142806)

• InnoDB: Running a query that used a unique hash index with the TempTable storage engine could take

significantly more time compared to running the query with the MEMORY engine.

Our thanks to xiaoyang chen for the contribution. (Bug #113178, Bug #36037224, Bug #36224958)

• InnoDB: In debug builds, there was an assertion failure in InnoDB's background when a transaction it

wanted to acquire an MDL lock on was no longer active.

This fix is based on a patch from Genze Wu with Alibaba, thank you for the contribution. (Bug #112424,

Bug #35835864)

References: This issue is a regression of: Bug #33700835.

• InnoDB: With innodb_parallel_read_threads set to a value greater than 1, InnoDB would

unnecessarily request asynchronous reads which required more synchronization during I/O completion

and created a bottleneck due to the limited number of available threads (innodb_read_io_threads)

for handling I/O operations. Now this performs synchronous instead of asynchronous reads. (Bug

#112137, Bug #35740866)

• InnoDB: A trx would unexpectedly halt after encountering an incorrect trx->in_innodb value.

Our thanks to Shaohua Wang for the contribution. (Bug #110652, Bug #35277407)

• InnoDB: SELECT ... GROUP BY queries were at least twice as slow with the TempTable engine than

the Memory engine. (Bug #107700, Bug #34338001)

• InnoDB: MySQL no longer ignores the optimizer hint to use a secondary index scan, which instead

forced a clustered (parallel) index scan. (Bug #100597, Bug #112767, Bug #31791868, Bug #35952353)

• Group Replication: Problems arose when members M1 and M2 were in a group, with M1 using u1 as its

recovery user and M2 using u2 as its own recovery user, and both users u1 and u2 existing on M1 and

M2 with all necessary privileges, and when a new member M3 joined the group using u2 as its recovery

user. M3 knew only of user u2, but did not know of user u1, leading START GROUP REPLICATION on

M2 to be rejected since M1 was unable to connect to M2. This also generated a new view_id listing the

group members as M1 and M2, but M1 nevertheless continued trying to connect to M3, with M1 logging

Error in establishing mysql connection and M3 logging Access denied errors for the

connection attempts from M1.

By design, XCom stores the last three known configurations, including references to physical

connections shared among all past and present configurations. This is done to facilitate quick

reconnections by nodes rejoining the group, explicitly or implicitly, and that were already present in any

of those configurations.

A side effect of this was that we might keep attempting to connect to a node that was currently not in

the group. To solve this problem, we inhibit error logging if the node is not in the current configuration, in

MySQL 8.0 Release Notes

order to avoid false negatives which might lead a DBA or an operator to think mistakenly that there is a

problem in the system. (Bug #36210988)

References: See also: Bug #32592027.

• Group Replication: Improved handling of GTID sets. (Bug #36093405)

• Group Replication: Two cases were found in which a member exited the group and moved to the

ERROR state, but did not honor the action specified by group_replication_exit_state_action;

these are listed here:

• When an error occurred while enabling super_read_only

• When member join recovery was not possible, due to missing binary logs and clone groups on group

members

Example: When the value of group_replication_exit_state_action was OFFLINE_MODE and

one of these events took place, offline mode was not enabled as expected. (Bug #36076308)

• Group Replication: After successfully setting a new primary,

group_replication_set_as_primary() in some cases waited indefinitely for the operation to

complete. (Bug #36059098)

• JSON: JOIN and GROUP BY handled some JSON column values differently. (Bug #101048, Bug

#31969607)

• MySQL NDB ClusterJ: The setLimits() method can now be chained to deletePersistentAll()

to limit the number of items to delete. See the description of deletePersistentAll() for details.

(Bug #36049906)

• Updated BuildRequire rules to align with versions now required for CMake and Bison. (Bug

#36343254)

• SET GLOBAL offline_mode=ON did not always perform correctly when issued under high loads. (Bug

#36275182)

References: See also: Bug #36405894.

• Upgraded curl to version 8.6.0. (Bug #36267545)

• mysqldump did not always interpret the server version correctly. (Bug #36248967)

References: See also: Bug #36405879.

• Condition pushdown to a view was rejected with a collation mismatch if the view was created with a

different character set than the character set used when querying the view. (Bug #36246859)

• Use of the deprecated exec_program() command has been replaced by execute_process() to

provide compatibility with CMake 3.28.1 and later. (Bug #36220656)

• Upgraded the protobuf library to version 25.1. (Bug #36108397)

• For building Enterprise Linux RPMs, the build scripts now point to a newer strip command (under

/opt/rh/gcc-toolset-12), and they now check that the corresponding dwz tool is available.

Previously this was only implemented for EL8. (Bug #36090069)

• We now look for gcc-ar and gcc-ranlib when building on Oracle Linux with link-time optimization.

(Bug #36089900)

• The server sometimes terminated unexpectedly in response to a specific query. (Bug #35957627)

MySQL 8.0 Release Notes

• Improved view and trigger definer handling by view and table DDL. (Bug #35942937)

• The server did not always return metadata to the client correctly for certain queries. (Bug #35904044)

• When running queries against a table with a multi-value index, the server sometimes exited

unexpectedly, often while executing a complex SELECT query which used this index. (Bug #35789759)

• Improved code in sql/item_subselect.cc. (Bug #35733778, Bug #35738531, Bug #35779012)

• CREATE USER IF EXISTS was not always logged correctly. (Bug #35530823)

• The server did not disallow subqueries in partition expressions properly. These are invalid, and should

cause a syntax error. (Bug #35476172)

• Some RANK() ... OVER() queries raised an assertion in sql/sql_executor.cc. (Bug #35228083)

• When successive ALTER TABLE ... ALGORITHM=COPY statements were issued within 10 seconds of

one another, the n_rows value became 0. (Bug #35127747)

• Updated the URL used for downloading the Boost C++ libraries. (Bug #113576, Bug #36164514)

• The fix for a previous issue, first addressed in MySQL 8.0.30, was incomplete.

Our thanks to Hao Lu for the contribution. (Bug #113174, Bug #36035044)

References: This issue is a regression of: Bug #110801, Bug #35328028.

• On s390x, we now compile the FMA test with -O2 to avoid overoptimization.

Our thanks to Jonathan Albrecht for the contribution. (Bug #113096, Bug #36016140)

• Although s390x is a big-endian platform, the little-endian ICU data directory was used for compiling.

Our thanks to Jonathan Albrecht for the contribution. (Bug #113095, Bug #36016141)

• Incorrect results were sometimes obtained from a query that used a group by loose index scan. (Bug

#112541, Bug #35854362)

• An assertion failed in debug builds when inserting data with a zero-length column, such as CHAR(0) or

BINARY(0), into a table. Now, a less strict assertion more accurately fails only if it detects that a non-

zero number of bytes copied from a source is identical to the target. (Bug #111450, Bug #35507763)

• A VALUES statement in a correlated lateral or (other) dependent subquery yielded an incorrect result.

(Bug #109252, Bug #110076, Bug #34852090, Bug #35087820)

• IN should return NULL not only if the expression on the left hand side is NULL, but when no match is

found in the list and one of the expressions in the list is NULL as well. In some cases, it was found that

adding rows to a table caused a subsequent prepared SELECT NULL IN (SELECT ...) query to

return a different result when the result should have remained the same. (Bug #94857, Bug #29602835)

Changes in MySQL 8.0.36 (2024-01-16, General Availability)

• Audit Log Notes

• Compilation Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

MySQL 8.0 Release Notes

• Pluggable Authentication

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• In some cases, calling audit_log_read( audit_log_read_bookmark() ) led to an Out of

memory error. (Bug #35957453)

Compilation Notes

• Microsoft Windows: MySQL did not compile correctly using Visual Studio 2022. (Bug #35967676)

• Improved the -DWITH_ZLIB=system check. (Bug #35968195)

• For compiling on Linux, changed the no-error=deprecated-declarations flag to no-

deprecated-declarations for the OpenSSL 3 library.

Our thanks to karry zhang for the contribution. (Bug #112209, Bug #35755328)

Optimizer Notes

• The hashing algorithm employed yielded poor performance when using a HASH field to check for

uniqueness. (Bug #109548, Bug #34959356)

Packaging Notes

• Important Change: The GnuPG build key (A8D3785C) used to sign MySQL downloadable packages

has been updated. The previous GnuPG build key (3A79BD29) expired on 2023-12-14. For information

about verifying the integrity and authenticity of MySQL downloadable packages using GnuPG signature

checking, or to obtain a copy of our public GnuPG build key, see Signature Checking Using GnuPG.

Due to the GnuPG key update, systems configured to use repo.mysql.com may report a signature

verification error when upgrading to MySQL 8.0.36 and higher or to MySQL 8.3.0 and higher using apt

or yum. Use one of the following methods to resolve this issue:

1. Manually reinstall the MySQL APT or YUM repository setup package from https://dev.mysql.com/

downloads/.

2. Download the MySQL GnuPG public key and add it your system GPG keyring.

Performance Schema Notes

• When executing a stored program, the Performance Schema instrumentation caused some unnecessary

overhead.

As of this release, all stored procedure micro instructions (statement/sp/%), except statement/sp/

stmt, are disabled by default. (Bug #27934653)

• The performance of the Performance Schema statement instrumentation has been improved.

Specifically, collecting MESSAGE_TEXT data is now more efficient. (Bug #112621, Bug #35916912)

Pluggable Authentication

• Beginning with this release, the behavior of the AUTHENTICATION_PAM_LOG environment variable used

in debugging the PAM authentication plugin is changed as follows:

MySQL 8.0 Release Notes

• Setting AUTHENTICATION_PAM_LOG to an arbitrary value (except as noted in the next item) no longer

includes passwords in its diagnostic messages.

• To include passwords in the diagnostic messages, set

AUTHENTICATION_PAM_LOG=PAM_LOG_WITH_SECRET_INFO.

For more information, see PAM Authentication Debugging. (Bug #74313, Bug #20042010)

Functionality Added or Changed

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated to version 3.0.12. Issues fixed in OpenSSL version 3.0.12 are

described at https://www.openssl.org/news/cl30.txt. (Bug #36033684)

Bugs Fixed

• Performance; InnoDB: The hashing function used by the InnoDB adaptive hash index became more

expensive as an unintended result of refactoring done in MySQL 8.0.30. (Bug #111538, Bug #35531293)

References: This issue is a regression of: Bug #81814, Bug #16739204, Bug #23584861.

• InnoDB: The hash function used by the adaptive hash index (AHI) was improved to increase

performance. (Bug #35449386)

• InnoDB: If change buffer entries are present during startup, a disabled

innodb_validate_tablespace_paths option will no longer be enforced and instead the MySQL

server will proceed to validate all tablespaces. Otherwise, secondary indexes could end up corrupted.

(Bug #35208990)

• InnoDB: During concurrent DDL and DML operations, DDL could fail if the online log grew too large.

Buffer handling was improved to prevent this issue. (Bug #35115601)

• Replication: An issue with calculating the current number of bytes used for Log_event events in

Performance Schema memory instrumentation made it appear as though the sql/replica_sql thread

on the replica grew endlessly and never decreased in size. (Bug #35546877)

• Replication: Stopping replication while replicating CREATE TABLE AS SELECT caused the server to

exit. (Bug #33934013)

• Group Replication: A forced START GROUP_REPLICATION while a replication channel was in an error

state could lead to an unplanned server exit. (Bug #34724344)

• For building Enterprise Linux 8 RPMs, the build scripts now point to a newer strip command (under

/opt/rh/gcc-toolset-12), and they now check that the corresponding dwz tool is available. (Bug

#36086236)

• In some cases, calling a loadable function installed by an improperly initialized plugin caused an

unplanned shutdown. (Bug #35889261)

• Found and fixed an assertion failure at handler::ha_index_end() in handler.cc. (Bug

#35877600)

• When the MYSQL_FIREWALL plugin failed to initialize properly during server startup, this led to errors in

the server log and sometimes unplanned termination of mysqld. (Bug #35853298)

• Some nested queries with GROUP BY were not handled correctly. (Bug #35846402, Bug #35945822)

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #32918400.

• In limited cases, passing data to the MD5() encryption function could halt the server. (Bug #35764496)

• Some subselects from views were not always handled correctly. (Bug #35738548)

• While performing an operation such as the bulk renaming of many tables, simultaneously executing a

data definition statement similar to CREATE TABLE ... SELECT could stop the server unexpectedly.

(Bug #35735937)

• UPDATE HISTOGRAM did not behave as expected in all cases.

UPDATE HISTOGRAM did not behave as expected in all cases. (Bug #35710404)

• EXPLAIN ANALYZE did not always produce the expected result. (Bug #35710383)

• An error occurred during subquery resolution. (Bug #35710373)

References: This issue is a regression of: Bug #35184353.

• Refreshing of used table information is now postponed to the start of the next execution, just after tables

have been opened, when we know that all table objects are in a proper state. (Bug #35710213, Bug

#36030073)

• Some HAVING queries did not produce expected results. (Bug #35710183)

• Some recursive CTEs did not function as expected. (Bug #35654240)

• Some queries using OVER (PARTITION ...) were not always executed successfully. (Bug

#35627798)

• Some subqueries with ROLLUP were not always handled correctly. (Bug #35621842, Bug #35804794)

• Removed the CPACK_COMPONENT_GROUP_INFO_DISPLAY_NAME configuration option from the

Windows installation MSI interface. Now the INFO_BIN and INFO_SRC files are always installed. (Bug

#35529968)

• Some queries using windowing functions were not always handled correctly. (Bug #35471471)

• In debug builds, a case-altered column name could cause the server to exit. (Bug #35449266)

• MySQL Server installation packages contained two copies of the INFO_SRC file. (Bug #35400142)

• A SELECT statement within a prepared statement unexpectedly returned different results on successive

executions. (Bug #35340987, Bug #35846585, Bug #35846873)

References: This issue is a regression of: Bug #35060385.

• Some SELECT DISTINCT queries were not always handled correctly. (Bug #33725447)

• Removed an assertion failure in sql/field.cc. (Bug #112503, Bug #35846221)

• Sme queries having the form SELECT AVG(...) OVER (PARTITION BY ...) were not always

handled correctly. (Bug #112460, Bug #35710179, Bug #35845413)

• Upgrading MySQL using an official MySQL Yum or SUSE repository always enables the MySQL service.

Now it enables the service only after installing, and preserves (and does not edit) the existing value while

upgrading. (Bug #112382, Bug #35823558)

MySQL 8.0 Release Notes

• For a query with a derived condition pushdown where a column in the condition needs to be replaced,

a matching item could not found, even when known to be present, when the replacement item

was wrapped in a ROLLUP while the matching item was not. (Bug #111665, Bug #35498378, Bug

#35570065, Bug #35826171)

References: This issue is a regression of: Bug #33349994.

• Ordering a nested block where the ORDER BY contained a window function raised an assert in sql/

sql_executor.cc. (Bug #111306, Bug #34856256, Bug #35471522)

• Performing an arithmetic operation on the result over a window function in a stored procedure gave

the correct result the first time the procedure was executed, but returned an incorrect result on all

subsequent invocations. (Bug #110983, Bug #35380604)

References: See also: Bug #110847, Bug #35340987.

• MySQL did not build correctly using the musl version of libc.

Our thanks to Sam James for the contribution. (Bug #110808, Bug #35330950)

• In some cases, selecting from a view leaked a small amount of memory. (Bug #103133, Bug

#32764586)

Changes in MySQL 8.0.35 (2023-10-25, General Availability)

• Audit Log Notes

• Authentication Notes

• C API Notes

• Compilation Notes

• Deprecation and Removal Notes

• SQL Function and Operator Notes

• Packaging Notes

• Security Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• Added the new audit_log_filter_uninstall.sql script to simplify removing MySQL Enterprise

Audit. For information about this plugin, see MySQL Enterprise Audit. (Bug #35611072)

Authentication Notes

• The pluggable FIDO authentication method is deprecated and subject to removal in a future MySQL

release. (WL #15006)

C API Notes

• Earlier distributions, such as MySQL 5.1 and MySQL 5.0, included servers that did not advertise

pluggable authentication. When a newer client using any pluggable authentication method attempted

MySQL 8.0 Release Notes

to connect to one of these older servers, the server emitted a “bad handshake” error message. This

fix now ensures that client-side authentication (specifically, the --default-auth option) works

properly for all servers, including those that do not support pluggable authentication. In addition,

mysql_native_password now replaces caching_sha2_password as the default authentication

method when the server does not support pluggable authentication. (Bug #90994, Bug #28082093)

• The mysql_ssl_set() C API function is deprecated and subject to removal in a future MySQL

release. There are equivalent mysql_options() TLS options for all mysql_ssl_set() parameters.

(WL #11091)

Compilation Notes

• Fixed the WITH_DEVELOPER_ENTITLEMENTS macOS CMake option; it did not activate due to a typo.

(Bug #35374026)

• Fixed a string concatenation warning produced when compiling with Clang 12. (Bug #111614, Bug

#35549962)

• Made additional improvements to WITH_ZLIB functionality.

Thanks to Nikolai Kostrigin for the contribution. (Bug #111549, Bug #35534309)

• Building with WITH_PROTOBUF=system failed with Protobuf 22 or newer due to Protobuf 22 adding the

Abseil dependency. (Bug #111469, Bug #111623, Bug #35546459, Bug #35550389)

• Building with WITH_ZLIB="system" would break the MySQL build as it failed to find ZLIB.

Our thanks to Meng-Hsiu Chiang and the team at Amazon for contributing to this fix. (Bug #111467, Bug

#35511210)

References: This issue is a regression of: Bug #35057542.

• On EL7 aarch64-based platforms, fixed an issue related to how fetching the CPU cache line size

returned 0 that caused the MySQL server to unexpectedly halt. (Bug #110752, Bug #35479763)

References: See also: Bug #107081, Bug #34095278.

• The C++ Standardization Committee's Library Working Group recently resolved an issue (LWG-3865

Sorting a range of pairs) which changes how the comparison operators are defined for std::pair. This

fix updates the equality operator used in two files in sql/auth to align with this change.

Based on a suggestion by the Microsoft Visual Studio team. (Bug #110254, Bug #35137978)

Deprecation and Removal Notes

• Replication: The binlog_transaction_dependency_tracking server system variable is now

deprecated, and subject to removal in a future version of MySQL. Setting or retrieving the value of this

variable now triggers a warning, as does using the equivalent startup option --binlog-transaction-

dependency-tracking. Applications depending on this variable (or option) should begin migrating

away from it as soon as possible. No replacement for this variable or its functionality is planned or

needed. (WL #13964)

• The old and new server system variables are now deprecated, and a warning is now issued whenever

either of these variables is set or read. Expect these variables are to be removed in a future version

of MySQL; applications which rely on them should migrate away from such dependencies as soon as

possible. (WL #8609)

MySQL 8.0 Release Notes

• The --character-set-client-handshake server option, originally intended for use with upgrades

from very old versions of MySQL, is now deprecated, and a warning is issued whenever it is used. You

should expect this option to be removed in a future version of MySQL; applications depending on this

option should begin migration away from it as soon as possible. (WL #13220)

• Two changes in this release affect granting of privileges in MySQL. One of these changes impacts

database grants; the other concerns host names used in grants. These changes are listed here:

1. Database-level grants. The use of the characters % and _ as wildcards in database-level grants

is now deprecated, and you should expect for this wildcard functionality to be removed in a future

MySQL release. The intent is for these characters always to be treated as literals, as they are already

whenever the value of the partial_revokes server system variable is ON.

For example, with partial_revokes set to ON, GRANT SELECT ON db_.* TO user1 allows

user1 to select from any table in a database named db_, but does not allow user1 to select from

tables in databases db1, db2, dbx, dby, and so on. You should expect this always to be the case

once support for wildcards in database names in grants is removed.

2. Host name '%' in grants. The treatment of % by the server as a synonym for localhost when

checking privileges is now also deprecated and thus also subject to removal in a future version of

MySQL.

Currently, privileges granted to 'user1'@'%' are also granted to 'user1'@'localhost'. This

automatic assignment is now deprecated; once the behavior is removed, it will be necessary always

to grant privileges to 'user1'@'localhost' explicitly, using the localhost host name.

Note

In both of the cases listed, no warnings or errors are raised in the user session or

logs, since doing so could very quickly produce a great many such messages.

(WL #14280, WL #15676)

• INFORMATION_SCHEMA.PROCESSLIST is deprecated and subject to removal in a future MySQL

release. As such, the implementation of SHOW PROCESSLIST which uses that table is also deprecated.

It is recommended to use the Performance Schema implementation of SHOW PROCESSLIST instead.

As such, performance_schema_show_processlist is also deprecated and subject to removal in a

future MySQL release. (WL #15915)

• Support for the TLS_AES_128_CCM_8_SHA256 ciphersuite now is deprecated and subject to

removal in a future version of MySQL. Any attempt to set it using either the tls_ciphersuites or

admin_tls_ciphersuites system variable now returns a warning. By default, both system variables

accept these ciphersuites:

• TLS_AES_128_GCM_SHA256

• TLS_AES_256_GCM_SHA384

• TLS_CHACHA20_POLY1305_SHA256

• TLS_AES_128_CCM_SHA256

Several previously supported ciphers now are deprecated and subject to removal in a future version of

MySQL. If the deprecated ciphers are specified using either the ssl_cipher or admin_ssl_cipher

system variable, then a warning now is issued. The following ciphers continue to be supported without

emitting a deprecation warning:

MySQL 8.0 Release Notes

• ECDHE-ECDSA-AES128-GCM-SHA256

• ECDHE-ECDSA-AES256-GCM-SHA384

• ECDHE-RSA-AES128-GCM-SHA256

• ECDHE-RSA-AES256-GCM-SHA384

• ECDHE-ECDSA-CHACHA20-POLY1305

• ECDHE-RSA-CHACHA20-POLY1305

• ECDHE-ECDSA-AES256-CCM

• ECDHE-ECDSA-AES128-CCM

• DHE-RSA-AES128-GCM-SHA256

• DHE-RSA-AES256-GCM-SHA384

• DHE-RSA-AES256-CCM

• DHE-RSA-AES128-CCM

• DHE-RSA-CHACHA20-POLY1305

(WL #15800)

SQL Function and Operator Notes

• The STR_TO_DATE() function did not perform complete range checking on the string to be converted,

so that it was possible to pass to it a string which would yield an invalid date, such as '2021-11-31'.

(Bug #108782, Bug #34704094)

Packaging Notes

• On Windows, the MSI package definition files were updated to work with the Windows Installer XML

(WiX) toolset version 4. Note that they can no longer be used with previous versions of the toolset. (Bug

#35613791)

• The bundled libedit library was upgraded to version 20221030-3.1. (Bug #35489173)

Security Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded

to use curl 8.4.0. Important issues fixed in curl version 8.4.0 are described at https://curl.se/docs/

security.html. (Bug #35897778)

References: See also: Bug #35709229.

Functionality Added or Changed

• Incompatible Change: Upgraded the bundled libfido2 library to libfido2 v1.13.0. This libfido2 version

requires OpenSSL 1.1.1 or higher, which means the authentication_fido and authentication_fido_client

authentication plugins are no longer available on the following platforms: Enterprise Linux 6 and 7,

Solaris 11, and SLES 12. (Bug #35685515)

MySQL 8.0 Release Notes

• Important Change; Group Replication: Version requirements for groups are relaxed beginning with

this release, as follows:

• A server running any MySQL 8.0 release of version 8.0.35 or newer can join the same group.

• A group member running any MySQL 8.0 release newer than 8.0.35 can be downgraded in place to

the previous release.

This change does not affect the requirement that, when selected, the primary must be running the lowest

MySQL version present in the group; this remains true whether this is automatic, or is performed by

executing group_replication_set_as_primary(). (Bug #35397276)

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated to version 3.0.10. Issues fixed in OpenSSL version 3.0.10 are

described at https://www.openssl.org/news/cl30.txt. (Bug #35702863, Bug #35732474)

Bugs Fixed

• Performance: records_in_range performed an excessive number of disk reads for insert operations.

Our thanks to Facebook for the contribution. (Bug #109595, Bug #34976138)

• InnoDB: Fixed processing of single character tokens by a FTS parser plugin.

Our thanks to Shaohua Wang for the contribution. (Bug #35432973)

• InnoDB: On Windows, the redo log file was not flushed even with

innodb_flush_log_at_trx_commit=1. (Bug #112078, Bug #35713721)

• InnoDB: Fixed a potential transaction rollback issue stemming from the ALTER TABLE EXCHANGE

PARTITIONS statement. (Bug #110869, Bug #35352168)

References: This issue is a regression of: Bug #33700835.

• InnoDB: When creating full-text indexes spanning multiple columns, index creation could fail with an

error similar to "ERROR 1062 (23000): Duplicate entry 'NULL-NULL'." (Bug #109242, Bug #33542939,

Bug #34846823)

• InnoDB: The last detected deadlock section of the engine status log was only showing 1024 characters

for the combined thread and query information. Fixing by removing the printed query string limit. (Bug

#80927, Bug #23036096)

• Replication: Memory used by binary log compression was not instrumented. (Bug #35290223)

• Replication: To detect dependencies and conflicts among transactions, MySQL Replication

uses writesets which are extracted from keys that are NOT NULL (primary keys by definition, as

well as unique and foreign keys which are NOT NULL) whenever binlog_format is ROW and

transaction_write_set_extraction is enabled (the default in both cases). In the case of multi-

column unique keys using only the leading parts of column values (see Column Prefix Key Parts),

the writesets were not properly generated, which sometimes led to spurious duplicate key errors; this

was due to the fact that the whole values of referenced key columns were added to the writeset in

such cases, even though the keys themselves referenced only the column prefix. (Bug #111027, Bug

#35404584)

• Following a change made in MySQL 8.0.23, in some cases where GROUP_CONCAT() had previously

returned NULL, it did so no longer. (Bug #35730982)

References: This issue is a regression of: Bug #32053547.

MySQL 8.0 Release Notes

• When no rows matched the WHERE condition of a query, the results of the query as prepared (using

PREPARE) differed from those of the same query when run directly. (Bug #35689804)

• Some queries using INTERSECT were not always processed correctly. (Bug #35504625)

References: See also: Bug #35362424.

• In some cases, the QUOTE() function returned binary data rather than the expected NULL. (Bug

#35499232)

• Previously, executing audit_log_rotate() manually could cause the function to appear

unresponsive when the output performance was low, the workload on the server was heavy, and the

audit_log_strategy system variable had a write strategy of ASYNCHRONOUS or PERFORMANCE. (Bug

#35397216)

• In some cases the QUOTE() function returned NULL even though it had previously been resolved as

non-nullable. (Bug #35381715)

References: See also: Bug #35145246, Bug #35195181.

• A previous fix in MySQL 8.0.30 for a stored program that was not executed correctly following the first

invocation did not cover the case where it contained a SET statement.

Our thanks to Hao Lu for the contribution. (Bug #35328028)

References: This issue is a regression of: Bug #33754993.

• An issue with stored functions was found to be a regression from work done previously to improve

internal functions that are used in copying values between columns. (Bug #35150382)

References: This issue is a regression of: Bug #32742537.

• Some cached queries were not always handled correctly.

Thanks to Nicholas Othieno and Amazon for the contribution. (Bug #35105404, Bug #35511208)

• Updated the Kerberos library bundled with commercial builds to version 1.21.2. (Bug #35001935)

• Some inserts on tables with triggers were not always handled correctly. (Bug #34920120)

References: See also: Bug #35178672, Bug #35195079.

• Some DESCRIBE statements using FORMAT = JSON were not always processed correctly, and

sometimes raised assertions in debug builds. (Bug #34909766)

• Some complex queries using multiple common table expressions were not always handled correctly.

(Bug #34900334)

References: This issue is a regression of: Bug #34377854.

• Some queries with window functions were not pushed down correctly. (Bug #34778435)

• Some complex queries using multiple common table expressions were not always handled correctly.

(Bug #112021, Bug #35284734, Bug #35694546)

References: See also: Bug #111994, Bug #35686058. This issue is a regression of: Bug #34377854.

• For Enterprise Linux, changed the krb5-devel build requirement from commercial to all builds. (Bug

#111596, Bug #35546449)

MySQL 8.0 Release Notes

• CREATE ROLE and DROP ROLE statements were not handled correctly when checking for orphaned

SQL objects. (Bug #111303, Bug #35471453)

• Clone_Snapshot::extend_and_flush_files() always created files of type

OS_CLONE_DATA_FILE. This function uses flush_redo() to handle redo log files, which must be of

type OS_CLONE_LOG_FILE, which could sometimes lead to errors in os_file_set_size().

This problem is now fixed by ensuring that the type is set correctly when creating the new file.

Our thanks to Tencent for the contribution. (Bug #110569, Bug #35240055)

• The low limit heuristic did not work well for ORDER BY DESC due to choosing the wrong index. (Bug

#107626, Bug #34306497)

Changes in MySQL 8.0.34 (2023-07-18, General Availability)

• Account Management Notes

• Audit Log Notes

• Binary Logging

• C API Notes

• Compilation Notes

• Deprecation and Removal Notes

• Performance Schema Notes

• SQL Syntax Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• A new password-validation system variable now permits the configuration and enforcement of a

minimum number of characters that users must change when attempting to replace their own MySQL

account passwords. This new verification setting is a percentage of the total characters in the current

password. For example, if validate_password.changed_characters_percentage has a value

of 50, at least half of the characters in the replacement account password must not be present in the

current password, or the password is rejected.

This new capability is one several that provide DBAs more complete control over password

management. For more information, see Password Management. (WL #15751)

Audit Log Notes

• In MySQL 8.0.33, the audit_log plugin added support for choosing which database to use to store

JSON filter tables. It is now possible to specify an alternative to the default system database, mysql,

when running the plugin installation script. Use the audit_log_database server system variable (or -

D database_name) on the command line together with the alternative database name, for example:

$> mysql -u root -D database_name -p < audit_log_filter_linux_install.sql

For additional information about using audit_log plugin installation scripts, see Installing or

Uninstalling MySQL Enterprise Audit. (Bug #35252268)

MySQL 8.0 Release Notes

• MySQL Enterprise Audit now supports using the scheduler component to configure and execute a

recurring task to flush the in-memory cache. For setup instructions, see Enabling the Audit Log Flush

Task. (WL #15567)

Binary Logging

• Several functions now are added to the libmysqlclient.so shared library that enable developers

to access a MySQL server binary log: mysql_binlog_open(), mysql_binlog_fetch(), and

mysql_binlog_close().

Our thanks to Yura Sorokin for the contribution. (Bug #110658, Bug #35282154)

C API Notes

• In the calling function, len is initialized to 0 and never changed if net->vio is null. This fix adds a

check of net before dereferencing vio.

Our thanks to Meta for the contribution. (Bug #30809590)

• A variable in the async client was uninitialized in certain code paths. It is fixed by always initializing the

variable.

Our thanks to Meta for the contribution. (Bug #30809568)

Compilation Notes

• Microsoft Windows: For Windows, improved MSVC_CPPCHECK support; and check for MSVC warnings

similar to "maintainer" mode. For example, check after all third party configurations are complete. (Bug

#35283401)

References: See also: Bug #34828882.

• Microsoft Windows: For Windows builds, improved WIN_DEBUG_NO_INLINE=1 support; usage would

exceed the library limit of 65535 objects. (Bug #35259704)

• Upgraded the bundled robin-hood-hashing from v3.8.1 to v3.11.5. (Bug #35448980)

• Removed the unused extra/libcbor/doc/ directory as extra/libcbor/doc/source/

requirements.txt inspired bogus pull requests on GitHub. (Bug #35433370)

• Updated the bundled ICU files from version 69.1 to version 73 for the icu-data-files package. (Bug

#35353708)

• ZSTD sources bundled in the source tree were upgraded to ZSTD 1.5.5 from 1.5.0. (Bug #35353698)

• Initialize the internal MEM_ROOT class memory with garbage using the TRASH macro to make easier to

reproduce bugs caused by reading initialized memory allocated from MEM_ROOT. (Bug #35277644)

• We now determine stack direction at runtime rather than at configure time. (Bug #35181008)

• Added the OPTIMIZE_SANITIZER_BUILDS CMake option that adds -O1 -fno-inline to sanitizer

builds. It defaults to ON. (Bug #35158758)

• Changed the minimum Bison version requirement from v2.1 to v3.0.4. For macOS, this may require

installing Bison via a package manager such as Homebrew. (Bug #35154645, Bug #35191333)

• MySQL now sets LANG=C in the environment when executing readelf to avoid problems with non-

ASCII output.

MySQL 8.0 Release Notes

Our thanks to Kento Takeuchi for the contribution. (Bug #111190, Bug #35442825)

• On macOS, MySQL would not compile if rapidjson was installed via Homebrew. The workaround was to

brew unlink rapidjson. (Bug #110736, Bug #35311140)

References: This issue is a regression of: Bug #35006191.

• MySQL would not build with -DWITH_ZLIB=system; it'd complain about not finding the system zlib

library despite finding it. (Bug #110727, Bug #110745, Bug #35307674, Bug #35312227)

Deprecation and Removal Notes

• Important Change: Since MySQL provides other means of performing database dumps and backups

with the same or additional functionality, including mysqldump and MySQL Shell Utilities, the

mysqlpump client utility program has become redundant, and is now deprecated. Invocation of this

program now produces a warning. You should keep in mind that mysqlpump is subject to removal in

a future version of MySQL, and move applications depending on it to another solution, such as those

mentioned previously. (WL #15652)

• Replication: The sync_relay_log_info server system variable is deprecated in this release, and

getting or setting this variable or its equivalent startup option --sync-relay-log-info now raises a

warning.

Expect this variable to be removed in a future version of MySQL; applications which make use of it

should be rewritten not to depend on it before this happens. (Bug #35367005, WL #13968)

• Replication: The binlog_format server system variable is now deprecated, and subject to removal

in a future version of MySQL. The functionality associated with this variable, that of changing the binary

logging format, is also deprecated.

The implication of this change is that, when binlog_format is removed, only row-based binary

logging, already the default in MySQL 8.0, will be supported by the MySQL server. For this reason, new

installations should use only row-based binary logging, and existing ones using the statement-based or

mixed logging format should be migrated to the row-based format. See Replication Formats, for more

information.

The system variables log_bin_trust_function_creators and

log_statements_unsafe_for_binlog, being useful only in the context of statement-based logging,

are now also deprecated, and are thus also subject to removal in a future release of MySQL.

Setting or selecting the values of any of the variables just mentioned now raises a warning. (WL #13966,

WL #15669)

• Group Replication: The group_replication_recovery_complete_at server system variable is

now deprecated, and setting it produces a warning. You should expect its removal in a future release of

MySQL. (WL #15460)

• The mysql_native_password authentication plugin now is deprecated and subject to removal

in a future version of MySQL. CREATE USER, ALTER USER, and SET PASSWORD operations now

insert a deprecation warning into the server error log if an account attempts to authenticate using

mysql_native_password as an authentication method. (Bug #35336317)

• Previously, if the audit_log plugin was installed without the accompanying audit tables and functions

needed for rule-based filtering, the plugin operated in legacy filtering mode. Now, legacy filtering mode is

deprecated. New deprecation warnings are emitted for legacy audit log filtering system variables. These

deprecated variables are either read-only or dynamic.

MySQL 8.0 Release Notes

(Read-only) audit_log_policy now writes a warning message to the MySQL server error log during

server startup when the value is not ALL (default value).

(Dynamic) audit_log_include_accounts, audit_log_exclude_accounts,

audit_log_statement_policy, and audit_log_connection_policy. Dynamic variables print a

warning message based on usage:

• Passing in a non-NULL value to audit_log_include_accounts or

audit_log_exclude_accounts during MySQL server startup now writes a warning message to the

server error log.

• Passing in a non-default value to audit_log_statement_policy or

audit_log_connection_policy during MySQL server startup now writes a warning message to

the server error log. ALL is the default value for both variables.

• Changing an existing value using SET syntax during a MySQL client session now writes a warning

message to the client log.

• Persisting a variable using SET PERSIST syntax during a MySQL client session now writes a warning

message to the client log.

(WL #11248)

• MySQL enables control of FIPS mode on the server side and the client side using a system variable

and client option. Application programs can use the MYSQL_OPT_SSL_FIPS_MODE option to

mysql_options() to enable FIPS mode on the client. Alternatively, it is possible to handle FIPS mode

directly through OpenSSL configuration files rather than using the current server-side system variable

and client-side options. When MySQL is compiled using OpenSSL 3.0, and an OpenSSL library and

FIPS Object Module are available at runtime, the server reads the OpenSSL configuration file and

respects the preference to use a FIPS provider, if one is set. OpenSSL 3.0 is certified for use with FIPS.

To favor the OpenSSL alternative, the ssl_fips_mode server system variable, --ssl-fips-mode

client option, and the MYSQL_OPT_SSL_FIPS_MODE option now are deprecated and subject to removal

in a future version of MySQL. A deprecation warning prints to standard error output when an application

uses the MYSQL_OPT_SSL_FIPS_MODE option or when a client user specifies the --ssl-fips-mode

option on the command line, through option files, or both.

Prior to being deprecated, the ssl_fips_mode server-side system variable was dynamically

settable. It is now a read-only variable (accepts SET PERSIST_ONLY, but not SET PERSIST or SET

GLOBAL). When specified on the command line or in the mysqld-auto.cnf option file (with SET

PERSIST_ONLY) a deprecation warning prints to the server error log. (WL #15631)

• The mysql_ssl_rsa_setup program originally provided a simple way for community users to

generate certificates manually, if OpenSSL was installed on the system. Now, mysql_ssl_rsa_setup

is deprecated because MySQL Community Edition no longer supports using yaSSL as the SSL library,

and source distributions no longer include yaSSL. Instead, use MySQL server to generate missing SSL

and RSA files automatically at startup (see Automatic SSL and RSA File Generation). (WL #15668)

• The keyring_file and keyring_encrypted_file plugins now are deprecated.

These keyring plugins are superseded by the component_keyring_file and

component_keyring_encrypted_file components. For a concise comparison of keyring

components and plugins, see Keyring Components Versus Keyring Plugins. (WL #15659)

• Previously, the MySQL server processed a version-specific comment without regard as to whether

any whitespace followed the MySQL version number contained within it. For example, the comments

MySQL 8.0 Release Notes

/*!80034KEY_BLOCK_SIZE=1024*/ and /*!80034 KEY_BLOCK_SIZE=1024*/ were handled

identically. Beginning with this release, when the next character following the version number in

such a comment is neither a whitespace character nor the end of the comment, the server issues a

warning: Immediately starting the version comment after the version number

is deprecated and may change behavior in a future release. Please insert a

whitespace character after the version number.

You should expect the whitespace requirement for version-specific comments to become strictly

enforced in a future version of MySQL.

See Comments, for more information. (WL #15686)

• The MySQL client library currently supports performing an automatic reconnection to the server if it

finds that the connection is down and an application attempts to send a statement to the server to be

executed. Now, this feature is deprecated and subject to removal in a future release of MySQL.

The related MYSQL_OPT_RECONNECT option is still available but it is also deprecated. C API functions

mysql_get_option() and mysql_options() now write a deprecation warning to the standard error

output when an application specifies MYSQL_OPT_RECONNECT. (WL #15766)

Performance Schema Notes

• The type used for the Performance Schema clone_status table's gtid_executed column has been

changed from VARCHAR(4096) to LONGTEXT. (Bug #109171, Bug #34828542)

SQL Syntax Notes

• CURRENT_USER() can now be used as a default value for VARCHAR and TEXT columns in CREATE

TABLE and ALTER TABLE ... ADD COLUMN statements.

The functions SESSION_USER(), USER(), and SYSTEM_USER() are also supported in all of the cases

just mentioned. By way of example, the following sequence of statements now works similarly to what is

shown here, with the precise output dependent on your environment:

mysql> SELECT CURRENT_USER();

+-------------------+

| CURRENT_USER() |

+-------------------+

| sakila@localhost |

+-------------------+

1 row in set (0.00 sec)

mysql> CREATE TABLE t (

> c1 VARCHAR(288) DEFAULT (USER()),

> c2 VARCHAR(288) DEFAULT (CURRENT_USER()),

> c3 VARCHAR(288) DEFAULT (SESSION_USER()),

> c4 VARCHAR(288) DEFAULT (SYSTEM_USER())

> );

Query OK, 0 rows affected (0.04 sec)

mysql> INSERT INTO t VALUES ROW();

Query OK, 1 row affected (0.01 sec)

mysql> TABLE t;

+-------------------+-------------------+-------------------+-------------------+

| c1 | c2 | c3 | c4 |

+-------------------+-------------------+-------------------+-------------------+

+-------------------+-------------------+-------------------+-------------------+

1 row in set (0.00 sec)

MySQL 8.0 Release Notes

When used in this way, these functions are also included in the output of SHOW CREATE TABLE and

SHOW COLUMNS, and referenced in the COLUMN_DEFAULT column of the Information Schema COLUMNS

table where applicable.

If you need to insure that values having the maximum possible length can be stored in such a column,

you should make sure that the column can accommodate at least 288 characters (255 for the user name

and 32 for the host name, plus 1 for the separator @). For this reason—while it is possible to use one

of these functions as the default for a CHAR column, it is not recommended due to the risk of errors or

truncation of values. (Bug #17809, Bug #11745618)

Functionality Added or Changed

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated from OpenSSL 1.1.1 to OpenSSL 3.0. The exact version is now

3.0.9. More information on changes from 1.1.1 to 3.0 can be found at https://www.openssl.org/docs/

man3.0/man7/migration_guide.html. (Bug #35475140, WL #15614)

• Packaging: Beginning with this release, binary archive packages previously named using -el7-

x86_64.tar and -el7-x86_64.tar.gz are now named using -linux-glibc2.17-x86_64.tar

and -linux-glibc2.17-x86_64.tar.gz, respectively. For example, if you used mysql-8.0.33-

el7-x86_64.tar to install or upgrade to MySQL 8.0.33, you should use mysql-8.0.34-linux-

glibc2.17-x86_64.tar for installing or upgrading to MySQL 8.0.34.

The naming change reflects the fact that these binaries are intended to be compatible with any Linux

system using glibc2.17 or newer; this includes Enterprise Linux 7, EL8, and EL9.

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 8.1.2. (Bug #35329529)

Bugs Fixed

• Important Change: The default value of the connection_memory_chunk_size server system

variable, when introduced in MySQL 8.0.28, was mistakenly set at 8912. This fix changes the default to

8192, which is the value originally intended. (Bug #35218020)

• NDB Cluster: The fix for a previous issue introduced a slight possibility of unequal string values

comparing as equal, if any Unicode 9.0 collations were in use, and the collation hash methods calculated

identical hash keys for two unequal strings. (Bug #35168702)

References: See also: Bug #27522732. This issue is a regression of: Bug #30884622.

• InnoDB: Possible congestion due to purging a large number of system threads has been fixed. (Bug

#35289390, Bug #110685)

• InnoDB: ddl::Aligned_buffer now uses the standard memory allocator and not kernel memory

management. (Bug #35194732, Bug #110411)

• InnoDB: An upgrade from MySQL 5.7 to MySQL 8.0.32 might fail due to deprecated configuration

parameters innodb_log_file_size or innodb_log_files_in_group. The workaround is to start

MySQL 8.0.32 with --innodb-redo-log-capacity=206158430208. (Bug #35155280)

• InnoDB: Performance regression due to hash function changes in MySQL 8.0.30 have been fixed. (Bug

#34870256)

• InnoDB: The rules for aggregating entries in the redo log have been fixed. (Bug #34752625, Bug

#108944)

MySQL 8.0 Release Notes

• InnoDB: Several errors due to tablespace deletion and the buffer pool have been fixed. (Bug

#34330475, Bug #107689)

• Packaging; Group Replication: The group replication plugin from the Generic Linux packages did not

load on some platforms that lacked a compatible version of tirpc. (Bug #35323208)

• Replication: Changes in session_track_gtids were not always propagated correctly. (Bug

#35401212)

• Replication: By design, all DDL operations (including binary log operations such as purging the binary

log) acquire a shared lock on the BACKUP_LOCK object, which helps to prevent simultaneous backup

and DDL operations. For binary log operations, we checked whether any locks existed on BACKUP_LOCK

but did not check the types of any such locks. This caused problems due to the fact that binary log

operations should be prevented only when an exclusive lock is held on the BACKUP_LOCK object, that is,

only when a backup is actually in progress, and backups should be prevented when purging the binary

log.

Now in such cases, instead of checking for locks held on the BACKUP_LOCK object, we acquire a shared

lock on BACKUP_LOCK while purging the binary log. (Bug #35342521)

• Replication: In all cases except one, when mysqlbinlog encountered an error while reading an event,

it wrote an error message and returned a nonzero exit code, the exception being for the active binary log

file (or any binary log where the format_description_log_event had the LOG_EVENT_BINLOG_IN_USE_F

flag set), in which case it did not write a message, and returned exit code 0, thus hiding the error.

Now mysqlbinlog suppresses only those errors which are related to truncated events, and when

doing so, prints a comment rather than an error message. This fix also improves the help text for the --

force-if-open option. (Bug #35083373)

• Replication: Compressed binary log event handling was improved. (Bug #33666652)

• Replication: A transaction consisting of events each smaller than 1 GiB, but whose total size was larger

than 1 GiB, and where compression did not make it smaller than 1 GiB, was still written to the binary

log as one event bigger than 1 GiB. This made the binary log unusable; in effect, it was corrupted since

neither the server nor other tools such as mysqlbinlog could read it.

Now, when the compressed data grows larger than 1 GiB, we fall back to processing the transaction

without any compression. (Bug #33588473)

• Group Replication: In a group replication setup, when there was a source of transactions other than the

applier channel, the following sequence of events was possible:

1. Several transactions being applied locally were already certified, and so were associated with

a ticket, which we refer to as Ticket 2, but had not yet been committed. These could be local or

nonlocal transactions.

2. A view is created with Ticket 3, and must wait on transactions from Ticket 2.

3. The view change (VC1) entered the GR applier channel applier and waited for the ticket to change to

4. Another group change, and another view change (VC2), occurred while the transactions from Ticket

2 were still completing.

This gave rise to the following issue: There was a window wherein the last transaction from Ticket 2 had

already marked itself as being executed but had not yet popped the ticket; VC2 popped the ticket instead

MySQL 8.0 Release Notes

but never notified any of the participants. This meant that VC1 continued to wait indefinitely for the ticket

to change, and with the additional effect that the worker could not be killed.

We fix this by checking for the need to break each second so that this loop is responsive to changes in

the loop condition; we also register a new stage, so that the loop is more responsive to kill signals. (Bug

#35392640)

References: See also: Bug #35206392, Bug #35374425.

• Group Replication: Removed a memory leak discovered in

Network_provider_manager::open_xcom_connection(). (Bug #34991101)

• Group Replication: When a group action was sent to the group and the connection was killed on the

coordinator, group members were in different states, with members which received the coordinated

action waiting for the member that executed it, and the member which started execution having nothing

to process, which caused problems with coordination of the group.

Now in such cases, we prevent this issue from occurring by causing group actions to wait until all

members have completed the action. (Bug #34815537)

• Group Replication: Cleanup of resources used by OpenSSL connections created indirectly by group

replication was not carried out as expected at all times. We fix this by adding cleanup functionality that

can be called at any time such connections are created by group replication. (Bug #34727136)

• JSON: When the result of JSON_VALUE() was an empty string and was assigned to a user variable, the

user variable could in some cases be set to NULL instead, as shown here:

mysql> SELECT JSON_VALUE('{"fname": "Joe", "lname": ""}', '$.lname') INTO @myvar;

Query OK, 1 row affected (0.01 sec)

mysql> SELECT @myvar = '', @myvar IS NULL;

+-------------+----------------+

| @myvar = '' | @myvar IS NULL |

+-------------+----------------+

| NULL | 1 |

+-------------+----------------+

1 row in set (0.00 sec)

With this fix, the query just shown now returns (1, 0), as expected. (Bug #35206138)

• JSON: Some JSON schemas were not always processed correctly by JSON_SCHEMA_VALID(). (Bug

#109296, Bug #34867398)

• In rare cases, MySQL server could exit rather than emit an error message as expected. (Bug

#35442407)

• The internal resource-group enhancement added in MySQL 8.0.31 and refactored in MySQL 8.0.32 is

now reverted. (Bug #35434219)

References: Reverted patches: Bug #34702833.

• An in-place upgrade from MySQL 5.7 to MySQL 8.0, without a server restart, could result in unexpected

errors when executing queries on tables. This fix eliminates the need to restart the server between the

upgrade and queries. (Bug #35410528)

• A fix in MySQL 8.0.33 made a change for ORDER BY items already resolved so as not to resolve them

again (as is usually the case when a derived table is merged), but this did not handle the case in which

an ORDER BY item was itself a reference. (Bug #35410465)

References: This issue is a regression of: Bug #34890862.

MySQL 8.0 Release Notes

• Changes in session_track_gtids were not always handled correctly. (Bug #35401212)

• Some pointers were not always released following statement execution. (Bug #35395965)

• Some instances of subqueries within stored routines were not always handled correctly. (Bug

#35377192)

• Fortified parsing of the network packet data sent by the server to the client. (Bug #35374491)

• Encryption enhancements now strengthen compliance and remove the use of deprecated APIs. (Bug

#35339886)

• When a column reference given by table name and column name was looked up in the function

find_item_in_list(), we ignored that the item searched for might not have a table name, as it was

not yet resolved. We fix this by making an explicit check for a null table name in the sought-after item.

(Bug #35338776)

• Deprecated the lz4_decompress and zlib_decompress command-line utilities that exist to support

the deprecated mysqlpump command-line utility. (Bug #35328235)

• Queries using LIKE '%...%' ran more poorly than in previous versions of MySQL. (Bug #35296563)

• In Bounded_queue::push(), when Key_generator::make_sortkey() returns UINT_MAX (error),

then no key has been produced; now when this occurs, we no longer update the internal queue.

As part of this fix, push() now returns true on error. (Bug #35237721)

• The authentication_oci plugin is fixed to allow federated and provisioned users to connect to a

DB System as a mapped Proxy User using an ephemeral key-pair generated through the OCI CLI. (Bug

#35232697)

• Some queries using common table expressions were not always processed correctly. (Bug #35231475)

• The internal function compare_pair_for_nulls() did not always set an explicit return value. (Bug

#35217471)

• Removed the clang-tidy checks that clash with the MySQL coding style. (Bug #35208735)

• Some subqueries using EXISTS in both the inner and outer parts of the query were not handled

correctly. (Bug #35201901)

• Rotated audit log files now always reset the ID value of the bookmark to zero, rather than continuing the

value from the previous file. (Bug #35200070)

• Errors were not always propagated correctly when evaluating items to be sorted by filesort. (Bug

#35195181)

References: See also: Bug #35145246.

• The fix for a previous issue with ROLLUP led to a premature server exit in debug builds. (Bug

#35168639)

References: This issue is a regression of: Bug #33830659.

• Simplified the implementation of Item_func_make_set::val_str() to make sure that we never try

to reuse any of the input arguments, always using the local string buffer instead. (Bug #35154335, Bug

#35158340)

• When transforming subqueries to a join with derived tables, with the containing query being grouped, we

created an extra derived table in which to do the grouping. This process moved the initial select list items

MySQL 8.0 Release Notes

from the containing query into the extra derived table, replacing all of the original select list items (other

than subqueries, which get their own derived tables) with columns from the extra derived table.

This logic did not handle DEFAULT correctly due to the manner in which default values were modelled

internally. This fix adds support for DEFAULT(expression) in queries undergoing the transform

previously mentioned. This fix also solves an issue with item names in metadata whereby two

occurrences of the same column in the select list were given the same item name as a result of this

same transform. (Bug #35150085, Bug #35101169)

• A query of the form SELECT * FROM t1 WHERE (SELECT a FROM t2 WHERE t2.a=t1.a +

ABS(t2.b)) > 0 should be rejected with Subquery returns more than 1 row, but when the

subquery_to_derived optimization was enabled, the transform was erroneously applied and the

query returned an incorrect result. (Bug #35101630)

• Handling of certain potentially conflicting GRANT statements has been improved. (Bug #35089304)

• A query using both MEMBER OF() and ORDER BY DESC returned only a partial result set following the

creation of a multi-valued index on a JSON column. This is similar to an issue fixed in MySQL 8.0.30, but

with the addition of the ORDER BY DESC clause to the prblematic query. (Bug #35012146)

References: See also: Bug #106621, Bug #33917625.

• The debug server asserted on certain operations involving DECIMAL values. (Bug #34973932)

• All instances of adding and replacing expressions in the select list when transforming subqueries to use

derived tables and joins have been changed so that their reference counts are maintained properly. (Bug

#34927110)

• Index Merge (see Index Merge Optimization) should favor ROR-union plans (that is, using RowID

Ordered Retrieval) over sort-union plans if they have similar costs, since sort-union requires additionally

sorting of the rows by row ID whereas ROR-union does not.

For each part of a WHERE clause containing an OR condition, the range optimizer gets the best range

scan possible and uses all these range scans to build an index merge scan (that is, a sort-union scan). If

it finds that all the best range scans are also ROR-scans, the range optimizer always proposes a ROR-

union scan because it is always cheaper than a sort-union scan. Problems arose when the best range

scan for any one part of an OR condition is not a ROR-scan, in which case, the range optimizer always

chose sort-union. This was true even in cases, where it might be advantageous to choose a ROR-scan

(even though it might not be the best range scan to handle one part of the OR condition), since this

would eleminate any need to sort the rows by row ID.

Now, in such cases, when determining the best range scan, the range optimizer also detects whether

there is any possible ROR-scan, and uses this information to see whether each part of the OR condition

has at least one possible ROR-scan. If so, we rerun the range optimizer to obtain the best ROR-scan for

handling each part of the OR condition, and to make a ROR-union path. We then compare this cost with

the cost of a sort-union when proposing the final plan. (Bug #34826692, Bug #35302794)

• Selecting from a view sometimes raised the error Illegal mix of collations ... for

operation '=' when the collation used in the table or tables from which the view definition selected

did not match the current session value of collation_connection. (Bug #34801210)

• Valid MySQL commands (use and status) and C API functions (mysql_refresh, mysql_stat,

mysql_dump_debug_info, mysql_ping, mysql_set_server_option, mysql_list_processes,

and mysql_reset_connection) could write an error message to the audit log, even though running

the command or calling the function emitted no such error. (Bug #33966181)

MySQL 8.0 Release Notes

• Increased the maximum fixed array size to 8192 instead of 512. This fixes an issue with mysqladmin

extended status requests, which can exceed 512 entries.

Our thanks to Meta for the contribution. (Bug #30810617)

• The mysqldump --column-statistics option attempted to select from

information_schema.column_statistics against MySQL versions before 8.0.2, but this now

generates the warning column statistics not supported by the server and sets the

option to false.

Our thanks to Meta for the contribution. (Bug #28782417)

• The function used by MySQL to get the length of a directory name was enhanced. (Bug #28047376)

• Executing a query with an implicit aggregation should return exactly one row, unless the query has a

HAVING clause that filters out the row, but a query with a HAVING clause which evaluated to FALSE

sometimes ignored this, and returned a row regardless. (Bug #14272020)

• The presence of an unused window function in a query, along with an ORDER BY that could have been

eliminated, led to an unplanned server exit. (Bug #111585, Bug #35168639, Bug #35204224, Bug

#35545377)

References: This issue is a regression of: Bug #35118579.

• ORDER BY RANDOM_BYTES() had no effect on query output. (Bug #111252, Bug #35148945, Bug

#35457136)

• Fixed an issue which could occur when loading user-defined functions. (Bug #110576, Bug #35242734)

• Concurrent execution of FLUSH STATUS, COM_CHANGE_USER, and SELECT FROM I_S.PROCESSLIST

could result in a deadlock. A similar issue was observed for concurrent execution of COM_STATISTICS,

COM_CHANGE_USER, and SHOW PROCESSLIST.

Our thanks to Dmitry Lenev for the contribution. (Bug #110494, Bug #35218030)

• The mysqldump utility could generate invalid INSERT statements for generated columns. (Bug

#110462, Bug #35208605)

• During optimization, range-select tree creation uses logic which differs based on the left-hand side of the

IN() predicate. For a field item, each value on the right-hand side is added to an OR tree to create the

necessary expression. In the case of a row item comparison (example: WHERE (a,b) IN ((n1,m1),

(n2, m2), ...)), an expression in disjunctive normal form (DNF) is needed. A DNF expression is

created by adding an AND tree with column values to an OR tree for each set of RHS values, but instead

the OR tree was added to the AND tree causing the tree merge to require exponential time due to O(n

)

runtime complexity. (Bug #108963, Bug #34758905)

• When using SELECT to create a table and the statement has an expression of type GEOMETRY, MySQL

could generate an empty string as the column value by default. To resolve this issue, MySQL no longer

generates default values for columns of type GEOMETRY under these circumstances. Our thanks to

Tencent for the contribution. (Bug #107996, Bug #34426943)

• For index skip scans, the first range read set an end-of-range value to indicate the end of the first range,

but the next range read did not clear the stale end-of-range value and applies this stale value to the

current range. Since the indicated end-of-range boundary had already been crossed in the previous

range read, this caused the reads to stop, causing multiple rows to be missed in the result.

We fix this by making sure in such cases that the old end-of-range value is cleared. (Bug #107460, Bug

#34235624, Bug #34982949)

MySQL 8.0 Release Notes

Changes in MySQL 8.0.33 (2023-04-18, General Availability)

• Audit Log Notes

• Compilation Notes

• Component Notes

• Deprecation and Removal Notes

• MySQL Enterprise Notes

• Performance Schema Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• MySQL Enterprise Audit previously used tables in the mysql system database for persistent storage of

filter and user account data. For enhanced flexibility, the new audit_log_database server system

variable now permits specifying other databases in the global schema namespace at server startup. The

mysql system database is the default setting for table storage. (WL #15500)

Compilation Notes

• Microsoft Windows: Added MSVC Code Analysis support for Visual Studio 2017 and higher. This adds

a new MSVC_CPPCHECK (defaults to OFF) CMake option that either enables or disables this analysis

on the current directory and its subdirectories. (Bug #34828882)

• Downgraded curl deprecation warnings to -Wno-error for curl versions greater than 7.86 when MySQL is

built with a GNU compiler or clang. (Bug #35111625)

• On macOS, added -framework CoreFoundation and -framework SystemConfiguration when linking the

curl interface to link with shared system libraries as needed. (Bug #35104962)

• Replaced the MY_INCLUDE_SYSTEM_DIRECTORIES macro with library interfaces. (Bug #35018072,

Bug #35028089, Bug #35072295)

• Improved CMake code to support alternative linkers. (Bug #34963568)

• Removed the deprecated Docs/mysql.info file from the build system. (Bug #34960126)

• Added a top-level .clang-tidy file and associated .clang.tidy files in the strings/ and mysys/

directories. Also enabled compdb support to enable clang-tidy usage on header files. (Bug #34917075)

• Removed several unmaintained or unused C++ source files for functionality such as uca-dump and

uctypedump. (Bug #34898978)

• Added a CMake build option to enable colorized compiler output for GCC and Clang when compiling on

the command line. To enable, pass -DFORCE_COLORED_OUTPUT=1 to CMake. (Bug #34897192)

• On Windows, also install .pdb files for associated .dll files if they are found for 3rd-party libraries. (Bug

#34863555)

• Enterprise Linux 8 and Enterprise Linux 9 builds now use GCC 12 instead of GCC 11. (Bug #34829151)

• Building with -static-libgcc -static-libstdc++ now also builds the bundled protobuf with static libraries, as

required.

MySQL 8.0 Release Notes

Thanks to Alex Xing for the contribution. (Bug #110216, Bug #35123848)

Component Notes

• INSTALL COMPONENT now includes the SET clause, which sets the values of component system

variables while installing one or more components. The new clause reduces the inconvenience and

limitations associated with the other ways of assigning variable values. For usage information, see

INSTALL COMPONENT Statement. (WL #10916)

Deprecation and Removal Notes

• User-defined collations (see Adding a Collation to a Character Set) are now deprecated. Either of the

following now causes a warning to be written to the log:

• Any occurrence of COLLATE followed by the name of a user-defined collation in an SQL statement

• Use of the name of a user-defined collation as the value of collation_server,

collation_database, or collation_connection

You should expect support for user-defined collations to be removed in a future version of MySQL. (WL

#14277)

MySQL Enterprise Notes

• MySQL Enterprise Edition now provides data masking and de-identification capabilities based on

components, rather than being based on a plugin library that was introduced in MySQL 8.0.13. The

component implementation provides dedicated privileges to manage dictionaries and extends the list of

specific types to include:

• Canada Social Insurance Number

• United Kingdom National Insurance Number

• International Bank Account Number

• Universally Unique Identifier (UUID)

An improved table-based dictionary registry replaces the file-based dictionary used by the plugin. For

a summary of the differences between the component and plugin implementations, see Data-Masking

Components Versus the Data-Masking Plugin. Existing plugin users should uninstall the server-side

plugin and drop its loadable functions before installing the new MySQL Enterprise Data Masking and De-

Identification components. (Bug #33851601, WL #12641)

Performance Schema Notes

• The Performance Schema Server Telemetry Traces service is added in this release. An interface which

provides plugins and components a way to retrieve notifications related to SQL statements' lifetime.

For more information on this interface, see the Server telemetry traces service section in the MySQL

Source Code documentation.

The following were added:

• Status variable Telemetry_traces_supported. Whether server telemetry traces is supported.

(Boolean)

MySQL 8.0 Release Notes

• TELEMETRY_ACTIVE column was added to the threads table. Indicates whether the thread has an

active telemetry session attached.

(WL #15059)

Functionality Added or Changed

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated to version 1.1.1t. Issues fixed in OpenSSL version 1.1.1t are

described at https://www.openssl.org/news/cl111.txt. (Bug #35092429)

• Replication: As part of ongoing work to change old terminology used in MySQL products, the

terms “master”, “slave”, and “MTS” have been replaced in error messages relating to MySQL

Replication by “source”, “replica”, and “MTA”, respectively. This includes all error messages listed in

messages_to_clients.txt and messages_to_error_log.txt relating to replication; the present

task does not perform this replacement for messages used in other contexts.

See the MySQL 8.0 Error Message Reference, for more information. (Bug #108422, Bug #34594819,

WL #14191)

• Replication: mysqlbinlog --start-position now accepts values up to 18446744073709551615,

unless the --read-from-remote-server or --read-from-remote-source option is also used, in

which case the maximum is 4294967295. (Bug #77818, Bug #21498994)

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.88.1. (Bug #34828111)

• The use of a generated column with DEFAULT(col_name) to specify the default value for a named

column is not permitted and now emits an error message. (Bug #34463652, Bug #34369580)

• The new TELEMETRY_LOG_ADMIN privilege now enables telemetry log configuration. This privilege is

defined by the telemetry_log plugin, which is deployed exclusively through MySQL HeatWave on

AWS. (Bug #111395, Bug #35494180)

• It is now possible to return the Statement ID to the client for successfully executed statements. To

enable this per session, add statement_id to the value of session_track_system_variables, or

set session_track_system_variables to the special value * (asterisk). (WL #15418)

Bugs Fixed

• NDB Cluster: Occasional temporary errors which could occur when opening a table from the NDB

dictionary while repeatedly performing concurrent schema operations were not retried. (Bug #34843889)

• NDB Cluster: During iteration, ordered index scans retain a cursor position within each concurrently

scanned ordered index fragment. Ordered index fragments are modified and balanced as a result of

committing DML transactions, which can require scan cursors to be moved within the tree. When running

with query threads configured (AutomaticThreadConfig set to 1), multiple threads can access the

same index fragment tree structure, and the scans of multiple threads can have their cursors present in

the same structure.

The current issue arose due to an assumption in the logic for moving scan cursors when committing

DML operations that all scan cursors belonged to the LDM thread owning the index fragment, which did

not allow for the possibility that such fragments might belong to query threads. (Bug #33379702)

References: See also: Bug #32257063.

• InnoDB: Dead code removal. (Bug #35036850, Bug #109873)

MySQL 8.0 Release Notes

• InnoDB: Error messages related to innodb_doublewrite moved to the error log. (Bug #34883045,

Bug #109330)

• InnoDB: Prevent online DDL operations from accessing out-of-bounds memory. (Bug #34750489, Bug

#108925)

• InnoDB: ALTER TABLE ... AUTO_INCREMENT could be set to less than MAX + 1 and not forced to

MAX + 1. (Bug #33419246, Bug #105092)

• InnoDB: Innodb_data_pending_fsyncs could show extremely high inaccurate values because of a

variable overflow. (Bug #30133150)

• Partitioning: Some IN() queries on partitioned tables were not always handled correctly. (Bug

#34801284)

References: This issue is a regression of: Bug #32311183.

• Partitioning: Queries using the INDEX_MERGE optimizer hint was not handled correctly in all cases.

(Bug #34797257)

• Replication: XA transactions whose XIDs contained null bytes could not be recovered. (Bug

#34918985)

• Replication: When binlog_order_commits was set equal to 1, for any two transactions and for

any sub-step of the commit phase, the transaction that was written to the binary log first did not always

execute the sub-step first, as expected. (Bug #34703698)

• Replication: Some binary log events were not always handled correctly. (Bug #34617506)

• Replication: The binary log recovery process did not report all possible error states. (Bug #33658850)

• Replication: Following CHANGE REPLICATION SOURCE TO

SOURCE_CONNECTION_AUTO_FAILOVER=1, failover generated a number of misleading warnings in the

log that implied there were problems when in fact conditions were those expected for such a failover.

These log messages have been updated accordingly. (Bug #32135376)

• Replication: When a transaction failed, as a side effect, extraneous error messages relating the

replication data repositories were written to the log. Now in such cases, we suppress such error

messages, which are not directly related to the issue of the failed transaction or its cause. (Bug

#19820134)

• Replication: Setting binlog_order_commits to OFF could lead to a missed GTID in the next binary

log file's Previous_gtids event.

Our thanks to Yewei Xu and the Tencent team for the contribution. (Bug #109485, Bug #34930969)

• Replication: Corrected the SQL statements suggested in the error message text for

ER_RPL_REPLICA_ERROR_RUNNING_QUERY.

Our thanks to Dan McCombs for the contribution. (Bug #109154, Bug #34822612)

• Replication: A hash scan builds a hash of changes, scans the target table or index, and applies any

matching change for the current entry. In the build phase, it uses only the before image, and skips

any after image. Problems arose in some cases because generated columns were computed for the

(skipped) after image, leading to replication errors. This is fixed by not computing generated columns

any longer for seek-only calls such as hash scans.

Our thanks to dc huang for the contribution. (Bug #107366, Bug #34198907)

MySQL 8.0 Release Notes

• Replication: In certain rare cases, it was possible to set gtid_mode=OFF for one session while another

session, after WAIT_FOR_EXECUTED_GTID_SET() was issued by a user in this second session, was

still waiting for the next GTID set from the first session. This could result in the second session waiting

indefinitely for the function to return. (Bug #99921, Bug #31505993)

• Group Replication: Accessing the Performance Schema

replication_group_communication_information and replication_group_member_stats

tables in parallel sometimes caused subsequent group replication operations to hang. (Bug #34870181)

• Group Replication: In certain cases, the group replication secondary node unexpectedly shut down

while purging the relay log. (Bug #34397106)

• Group Replication: When shutting down the Group Replication plugin, the order in which the

associated events were reported the error log sometimes led to confusion. To remove any doubts, we

now make sure that Plugin group_replication reported: 'Plugin 'group_replication'

has been stopped. is in fact the last log message relating to the shutdown, written only when

all other events associated with shutting down the plugin have been logged. (Bug #109345, Bug

#34887491)

• Microsoft Windows: The authentication_fido_client plugin stopped responding during

the authentication process if it was unable to find a FIDO device on the Windows client host. (Bug

#34918044)

• In certain cases, CONVERT(utf8mb3_column USING UTF16) was rejected with the error Cannot

convert string '\x--...' from binary to utf16. (Bug #35129361)

• When joining two tables on a string column, and the column from one of the tables has an additional

predicate comparing it with a temporal literal, constant propagation in some cases incorrectly caused the

join condition to be modified such that it used temporal rather than string semantics when comparing the

strings. This caused incorrect results to be returned from the join. (Bug #35115909)

• Error messages returned after calling the mysql_reset_connection() C API function in a prepared

statement did not identify the function name properly. (Bug #35107280)

• Fixed a regression in a previous fix for an issue with windowing functions.

Our thanks to Dmitry Lenev for the contribution. (Bug #35061924)

References: This issue is a regression of: Bug #34572136.

• When replacing subqueries in transforms, the internal flag showing whether a given query block contains

any subqueries (PROP_SUBQUERY) was not updated afterwards. (Bug #35060385)

• A client setting the character set to an impermissible client character set (ucs2, utf16, utf16le,

or utf32) could cause unexpected behavior when the client used an authentication plugin. (Bug

#35054579)

• EXPLAIN ANALYZE displayed 0 when the average number of rows was less than 1. To fix this, we now

format numbers in the output of EXPLAIN ANALYZE and EXPLAIN FORMAT=TREE such that numbers in

the range 0.001-999999.5 are printed as decimal numbers, and numbers outside this range are printed

using engineering notation (for example: 1.23e+9, 934e-6). In addition, trailing zeroes are no longer

printed, and numbers less than 1e-12 are printed as 0.

This helps ensure consistent precision regardless of the number's value and improve readability, while

producing minimal rounding errors. (Bug #34990948)

• The NTILE() function did not work correctly in all cases. (Bug #34986665)

MySQL 8.0 Release Notes

• Some joins on views did not perform correctly. (Bug #34985359)

• Transforming a correlated scalar subquery to a derived table led to a wrong result for InnoDB tables

when the subquery included duplicate predicates. An example of a query which could be affected by this

issue is shown here:

SELECT * FROM t1

WHERE (

SELECT t2.a FROM t2

WHERE t2.a = t1.a AND t2.a = t1.a

) > 0;

(Bug #34973220)

• Fixed an assert in sql/item_strfunc.cc that could potentially lead to issues with the SPACE()

function. (Bug #34962821)

• Using ROW_COUNT() as the length argument to LPAD() or RPAD() did not perform as expected. (Bug

#34961236)

• A query with a window function having an expression with a CASE function in its ORDER BY clause could

lead to a server exit. (Bug #34933045)

• The fix for a previous issue introduced an assertion in debug builds when optimizing a HAVING clause.

(Bug #34923792)

References: This issue is a regression of: Bug #33725415.

• When using mysqld_multi, the system that obscures "--password" usage as "--password=*****" would

also match "--password-history" and "--password-require-current" definitions as "--password", but now

explicitly checks for "--password=" instead. (Bug #34918740)

• In some cases, calling the mysql_bind_param() C API function could cause the server to become

unresponsive. (Bug #34869076)

• The authentication_oci_client plugin was unable to open a valid configuration file if any of

its entries contained an equals sign character separated by spaces (for example, key_file = /

home/user/.oci/oci_api_key.pem). Now, both 'key=value' and 'key = value' entry formats are

supported. (Bug #34864078)

• Incorrect results were returned when the result of an INTERSECT or EXCEPT operation was joined with

another table. This issue affected these operations in such cases when used with either DISTINCT or

ALL. (Bug #34843764)

• When preparing a view query, the operation used the system character set (instead of the character set

stored in data dictionary) and then reported an invalid character-string error. (Bug #34800905)

• Prepared statements that operate on derived tables, including views, could stop unexpectedly due to

problems with the code for reopening tables after an error. (Bug #34798403)

• Removed an assertion raised in certain cases by the RANDOM_BYTES() function in debug builds. (Bug

#34781507)

• There was an issue in how persisted variables were set on startup, causing certain variables not to get

properly set to their persisted value. (Bug #34751419)

• The MAKETIME() function did not perform correctly in all cases. (Bug #34745241)

• Some functions with multiple arguments did not produce the expected results. (Bug #34741801)

MySQL 8.0 Release Notes

• A table reference in an ORDER BY outside the parenthesized query block in which the table was used,

and which query block had no LIMIT or ORDER BY of its own, raised an error. (Bug #34704011)

References: This issue is a regression of: Bug #103954, Bug #32980249.

• A left join with an impossible condition as part of an ON clause was not optimized as in MySQL 5.7,

so that in MySQL 8.0, the query executed more quickly without the impossible condition than with it.

An example of such a query, impossible condition included, is SELECT * FROM t1 JOIN t2 ON

t1.c1=t2.c1 AND 1=2. (Bug #34668756)

• When a user defined function was part of a derived table that was merged into the outer query block, or

was part of a subquery converted to a semi-join, knowledge of whether this UDF was deterministic (or

not) was lost during processing. (Bug #34666531)

• With JSON logging enabled and an event subclass specified in the audit log filter definition, an empty

item ("" : { }) was appended to the end of the logged event. (Bug #34659904)

• Some subqueries did not execute properly. (Bug #34616553)

• After the asymmetric_encrypt() component function in a SELECT query encountered a NULL field to

decrypt, it could return NULL values for other non-NULL encrypted fields. (Bug #34598912)

• The server did not always shut down cleanly after uninstalling the audit log plugin. (Bug #34594035)

• Certain antijoins were not handled correctly by the server. (Bug #34370673)

References: This issue is a regression of: Bug #30573446.

• When the MySQL 5.7 Optimizer has 2 choices for an index to filter rows, one primary and one

secondary, it picks a range scan on the secondary index because the range scan uses more key parts.

MySQL 8.0 did not use this logic, instead choosing the primary index to filter rows with WHERE clause

filtering. Primary key use is not suitable in such cases due to the presence of LIMIT, and due to the

nature of data distribution. The secondary index was not considered while resolving order by due to

constant elimination. This resulted in much different query plans in MySQL 5.7 and MySQL 8.0 for the

same query.

We solve this issue in MySQL 8.0 by skipping the constant key parts of the index during order-by

evaluation only if the query is constant-optimized, which can be done at this time, but not during LIMIT

analysis. (Bug #34291261)

• The MySQL data dictionary caches failed lookups of se_private_id values (IDs which are not found),

which speeds up execution of code specific to InnoDB, relying on the fact that InnoDB does not reuse

these IDs. This assumption does not necessarily hold for other storage engines, most notably NDB,

where this problem was resolved previously by not using this cache.

We extend the previous fix made for NDB so that the cache lookup is now employed only when the table

uses the InnoDB storage engine. (Bug #34145006)

References: See also: Bug #33824058.

• Unexpected results were seen in some queries using DENSE_RANK(), possibly with the addition of WITH

ROLLUP. (Bug #34099408)

• Fixed an assert raised in sql/sql_tmp_table.cc following work done previously to reimplement

ROLLUP processing. (Bug #33830659)

References: This issue is a regression of: Bug #30969045.

MySQL 8.0 Release Notes

• Some CTEs that did not use any tables were not always handled correctly. (Bug #33725542)

References: This issue is a regression of: Bug #27062031.

• Accessing rows from a window frame of a window function call present only in the query's ORDER BY list

raised an error. (Bug #33069747)

• PERCENT_RANK() used with ORDER BY column did not return the correct result. (Bug #33064174)

References: This issue is a regression of: Bug #27484133.

• The --exclude-tables and --include-tables mysqlpump options did not handle views. (Bug

#21303549)

• Changed the MySQL systemd service unit configuration from After=network-online.target to

Wants=network-online.target to ensure that all configured network devices are available and

have an IP address assigned before the service is started. (Bug #109996, Bug #35068274)

• AVG(...) OVER (ROWS BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING) did not return the

correct result. (Bug #109725, Bug #35013880)

References: This issue is a regression of: Bug #108008, Bug #34431996.

• A query of the form SELECT 1 FROM t1 WHERE NOT EXISTS (VALUES ROW(1), ROW(2))

caused an assert in debug builds when the subquery_to_derived optimizer switch was enabled.

(Bug #109723, Bug #35014318)

References: See also: Bug #108910, Bug #34746261.

• mysqlimport did not escape reserved word table names when used with the --delete option. (Bug

#109711, Bug #34999015)

• When cloning a condition to push down to a derived table, characters in strings representing conditions

were converted to utfmb4 correctly only for values less than 128 (the ASCII subset), and code points

outside the ASCII subset were converted to invalid characters, causing the resulting character strings

to become invalid. For derived tables without UNION, this led to problems when a column name from

the derived table used characters outside the ASCII subset, and was used in the WHERE condition. For

derived tables with UNION, it created problems when a character outside the ASCII subset was present

in a WHERE condition.

We fix these issues by initializing the string used for representing the condition in such cases to the

connection character set. (Bug #109699, Bug #34996488)

• Using --single-transaction with mysqldump version 8.0.32 required either the RELOAD or

FLUSH_TABLES privilege. This requirement now applies only when both gtid_mode=ON (default

OFF) and with --set-gtid-purged = ON|AUTO (default AUTO). (Bug #109685, Bug #109701, Bug

#34993824, Bug #34998910, Bug #35020512)

References: This issue is a regression of: Bug #105761, Bug #33630199.

• Fixed a number of issues present in the internal documentation for the scramble generator algorithm in

sha256_scramble_generator.cc and sha2_password_common.cc.

Our thanks to Niklas Keller for the contribution. (Bug #109576, Bug #34967141)

• CREATE USER IF NOT EXISTS added a password history entry even when the user already existed

and the password was not updated. This caused a subsequent ALTER USER statement to be rejected.

(Bug #109415, Bug #34906592)

MySQL 8.0 Release Notes

• Many joins using eq_ref access did not perform as well as in previous versions. This issue was first

reported in MySQL 8.0.29. (Bug #109361, Bug #34891365)

• A hash outer join sometimes incorrectly matched NULL with a decimal zero or an empty string that used

a non-padding collation, leading to erroneous results. (Bug #109211, Bug #34837464)

References: This issue is a regression of: Bug #33794977.

• An object used internally by ALTER INSTANCE RELOAD TLS was not freed until the number of readers

reached 0, under the assumption is that the number of readers should reach 0 fairly frequently. The

read lock held during an SSL handshake is generally an expensive operation, with network calls,

so when roundtrips between the client and the server took excessively long, the lock was held for a

relatively long amount of time. This meant that, when changing the value of this object and there were a

sufficient number of incoming SSL connections being made, the number of readers might not reach 0 in

a reasonable length of time, leaving the thread holding the lock using 100% of the CPU until the lock was

released.

We fix this by adding a wait after setting the pointer to this object to a new value, but before releasing the

old object.

Our thanks to Sinisa Milivojevic for the contribution. (Bug #107567, Bug #34284186)

• If mysqldump or mysqlpump could not convert a field's default value to UTF-8 (for instance, if the field

was of type BINARY and the default value did not coincide with valid UTF-8), the operation produced

results that were not valid to import. Further, using the --hex-blob option did not resolve the issue.

We now convert the default value to the system character set. If this fails, the server sends the value as

hexadecimal instead to make it more human-readable. (Bug #104840, Bug #33322551)

• A connection using the C API (libmysqlclient) client library could fail with the FUTURE crypto policy.

(Bug #104778, Bug #33316709)

• While cloning a temporary table for a common table expression which used shared materialization, the

cloned temp table was not marked as using hash deduplication, leading to wrong results. We now set

the hash field for the cloned temporary table correctly, and update the hidden field count to take this into

account. (Bug #102251, Bug #32383712)

References: See also: Bug #103052, Bug #32659629.

• CREATE EVENT and ALTER EVENT assumed that all values passed to them (other than in a DO clause)

resolved as scalars without actually checking the values. This led to assertions when any such values

actually rows.

We now perform an explicit check for the number of columns when resolving such items, and report an

error when one produces a row and not a scalar value. (Bug #57552, Bug #11764690)

• A view reference whose underlying field is a constant is not marked as constant when the reference

is part of an inner table of an outer join. It was found that, when pushing a condition down to a derived

table, the reference was stripped off and only the underlying field was cloned, which made it a constant,

and led to wrong results.

To fix this problem, we ensure that we do not push such a condition down to the derived table by adding

a check to see first whether the table used by the condition matches the derived table or is a constant

expression; only when it is one or the other of these do we actually push the condition down. (Bug

#34661, Bug #11747971)

Changes in MySQL 8.0.32 (2023-01-17, General Availability)

MySQL 8.0 Release Notes

• Authentication Notes

• C API Notes

• Compilation Notes

• Deprecation and Removal Notes

• Generated Invisible Primary Keys (GIPKs)

• Keyring Notes

• Pluggable Authentication

• Spatial Data Support

• SQL Syntax Notes

• Thread Pool Notes

• Functionality Added or Changed

• Bugs Fixed

Authentication Notes

• The server could return LDAP_OPERATIONS_ERROR for LDAP authentication failures, rather than only

for actual LDAP server errors such as when an AD domain is not accessible. Now, the server returns

LDAP_AUTHENTICATION_ERROR, a MySQL-specific error code, to indicate authentication errors. (Bug

#100333, Bug #31680279)

C API Notes

• The sha256_password_auth_client_nonblocking() function always returned an error, even

when the public key was available. (See the MySQL Server Doxygen documentation, available at https://

dev.mysql.com/doc/index-other.html.) Our thanks to Facebook for the several fixes in this patch. (Bug

#34556764)

Compilation Notes

• Microsoft Windows: The authentication_ldap_sasl server plugin is no longer built for Windows

as only the client is supported for SASL-based LDAP authentication. (Bug #34448155)

• On Windows, compiling MySQL server using VS 2022 would emit an error about two projects named

"parser-t" if tests and the NDB storage engine were enabled. The tests were renamed to avoid conflict on

case-insensitive operating systems. (Bug #34790413)

• On MacOS, silenced deprecation warnings generated by Xcode 14; this includes suggestions to use

snprintf(3) instead of sprintf(3), and warnings about possible loss of precision from 64 to 32 bit integers.

(Bug #34776172)

• Removed the boost library usage from the plugins. (Bug #34694419)

• Removed all 3rd party files named 'Makefile' as they were not used. (Bug #34648199)

• Added clang 15 support. (Bug #34638573)

• Located and removed unused code; located it using fastcov. (Bug #34583577)

MySQL 8.0 Release Notes

• Improved code related to building the ndbcluster plugin by fixing warnings generated with 'gcc 11.2.0

RelWithDebInfo on Ubuntu 22.04' and 'gcc 8.3.1 on el6'. (Bug #34384889)

• Now use full file paths for the Bison and Flex source files to help simplify debugging and gcov reports.

(Bug #109022, Bug #34776151)

• Building MySQL would fail if the building user lacked access to the mysqld temporary directory. Now --

no-defaults is used when creating the INFO_BIN file. (Bug #108947, Bug #34756282)

Deprecation and Removal Notes

• Use of the dollar sign ($) as the first character of an unquoted identifier is now deprecated, raises a

warning (ER_WARN_DEPRECATED_SYNTAX_NO_REPLACEMENT), and is subject to removal in a future

release.

This affects statements using such an identifier for the name of any database, table, view, column,

stored program, or alias. Identifiers beginning with a dollar sign are still permitted only when they are

quoted—that is, delimited by single or double quote marks (' or "), or by backtick characters (`),

depending on the server SQL mode. Example:

mysql> TABLE $t; # Unquoted, produces warning

+------+

| a |

+------+

| 1 |

| 2 |

+------+

2 rows in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS\G

*************************** 1. row ***************************

Level: Warning

Code: 1681

Message: '$ as the first character of an unquoted identifier' is deprecated and

will be removed in a future release.

1 row in set (0.00 sec)

mysql> TABLE `$t`; # Quoted, no warning

+------+

| a |

+------+

| 1 |

| 2 |

+------+

2 rows in set (0.00 sec)

User variables are not affected by this change. For example, the statement SELECT 1 INTO @$x does

not produce a warning.

See Schema Object Names, for more information. (Bug #34785775, WL #15422)

References: See also: Bug #34684193.

• The CLIENT_NO_SCHEMA flag is deprecated. Client programs that specify CLIENT_NO_SCHEMA

as the client_flag argument to mysql_real_connect() can now omit the flag and the db

argument to have the connection set the database value to the current (or default) database. The

libmysqlclient library now prints a warning on standard error when mysql_real_connect()

is called with CLIENT_NO_SCHEMA. In addition, the server adds a deprecation warning for every non-

prepared query executed, if the connection has CLIENT_NO_SCHEMA. (WL #13128)

MySQL 8.0 Release Notes

• Previously, legacy compression-control parameters were deprecated and replaced with new

configuration parameters for greater control over the use of compression in connections to the server.

The new and deprecated parameters are:

• The --compression-algorithms client option enables deprecation of the legacy --compress

client option and the Compression status variable.

• The MYSQL_OPT_COMPRESSION_ALGORITHMS C API option enables deprecation of the legacy

MYSQL_OPT_COMPRESS C API option.

• The MASTER_COMPRESSION_ALGORITHMS option for the CHANGE MASTER TO statement enables

deprecation of the legacy slave_compressed_protocol system variable.

The deprecated parameters will be removed in a future MySQL version.

Now, the following client programs print a deprecation warning to standard error when a client user

invokes one of the programs with --compress (or -C, if applicable): mysqlpump, mysqlcheck,

mysql, mysqladmin, mysqlbinlog, mysqldump, mysqlimport, mysqlshow, mysqlslap,

mysql_upgrade, and mysqltest.

The mysqlbackup --compress option has different capabilities and is not deprecated. (WL #13292)

Generated Invisible Primary Keys (GIPKs)

• Replication: It is now possible to cause a replica to add a generated invisible primary key to

any InnoDB table that otherwise, as replicated, has no primary key. This is implemented by

adding GENERATE as a possible value for the CHANGE REPLICATION SOURCE TO statement's

REQUIRE_TABLE_PRIMARY_KEY_CHECK option.

REQUIRE_TABLE_PRIMARY_KEY_CHECK = GENERATE can be used on a per-channel basis. Suppose

the replica is configured with two replication channels, named ch1 and ch2, and you execute the

statements shown here:

STOP REPLICA;

SET @@sql_require_primary_key = ON;

CHANGE REPLICA SOURCE TO

REQUIRE_TABLE_PRIMARY_KEY_CHECK = GENERATE

FOR CHANNEL ch1;

START REPLICA;

The effect of these statements is that the replica now adds an invisible primary key for tables whose

creation is replicated by channel ch1, but does not do so for any keyless table that is created in the

context of ch2.

A replica ignores any setting for sql_generate_invisible_primary_key that has been made on

the source, and this variable is not replicated. (This behavior is unchanged from previous releases.)

REQUIRE_TABLE_PRIMARY_KEY_CHECK = GENERATE is not compatible with MySQL Group

Replication, where ON, OFF, and STREAM are the only supported values for this option.

See CHANGE REPLICATION SOURCE TO Statement, and Generated Invisible Primary Keys, for

further information. (WL #15419)

MySQL 8.0 Release Notes

Keyring Notes

• Host names of endpoints specified in component_keyring_oci configuration files, and obtained from

the Oracle Cloud Infrastructure Console or by querying the Oracle Cloud Infrastructure API, now can

retain the https:// prefix that previously had to be removed when generating a MySQL configuration

for the Oracle Cloud Infrastructure Vault keyring component. (Bug #34636297)

Pluggable Authentication

• On Windows, the client-side Kerberos authentication plugin now supports GSSAPI through the

MIT Kerberos library. It is possible to choose between SSPI and GSSAPI at runtime using a new

plugin option supported by the authentication_kerberos_client authentication plugin on

Windows. Client users invoke mysql or mysqldump with the --plugin-authentication-

kerberos-client-mode command-line option to set the mode to GSSAPI. The default mode of the

authentication_kerberos_client plugin is SSPI, previously the only authentication method on

Windows.

For more information, see Connection Commands for Windows Clients in GSSAPI Mode. (WL #15336)

Spatial Data Support

• The MySQL ST_Transform() function now supports all Cartesian projections, with the exceptions of

EPSG 1042 (Krovak Modified), EPSG 1043 (Krovak Modified (North Orientated)), EPSG 9816 (Tunisia

Mining Grid), and EPSG 9826 (Lambert Conic Conformal (West Orientated)). (Bug #27272733, Bug

#34495023, WL #15164)

SQL Syntax Notes

• Important Change: Previously, MySQL supported the use of “full” as the name of a table, column,

view, stored procedure, or stored function, as well as for the alias of a table, view, or column. Beginning

with this release, using “full” (regardless of letter case) in this fashion as an unquoted identifier is now

deprecated, and raises a warning. This is to align more closely with the SQL standard, in which FULL is

reserved as a keyword.

For example, the following CREATE TABLE and DROP TABLE statements now raise warnings, as shown

here:

mysql> CREATE TABLE full (c1 INT, c2 INT);

Query OK, 0 rows affected, 1 warning (0.03 sec)

mysql> SHOW WARNINGS\G

*************************** 1. row ***************************

Level: Warning

Code: 4119

Message: Using FULL as unquoted identifier is deprecated, please use quotes or

rename the identifier.

1 row in set (0.00 sec)

mysql> DROP TABLE full;

Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> SHOW WARNINGS\G

*************************** 1. row ***************************

Level: Warning

Code: 4119

Message: Using FULL as unquoted identifier is deprecated, please use quotes or

rename the identifier.

1 row in set (0.00 sec)

MySQL 8.0 Release Notes

To execute the statements without the warnings, encase the table name in each of them with backtick

characters (`), like this:

mysql> CREATE TABLE `full` (c1 INT, c2 INT);

Query OK, 0 rows affected (0.03 sec)

mysql> DROP TABLE `full`;

Query OK, 0 rows affected (0.02 sec)

The use of FULL in the right hand side of a value assignment is not affected by this change. For

example, the SET statement shown here remains valid:

mysql> SHOW VARIABLES LIKE '%metadata%';

+---------------------------------------+---------+

| Variable_name | Value |

+---------------------------------------+---------+

| binlog_row_metadata | MINIMAL |

| innodb_stats_on_metadata | OFF |

| performance_schema_max_metadata_locks | -1 |

| resultset_metadata | FULL |

+---------------------------------------+---------+

4 rows in set (0.00 sec)

mysql> SET @@global.binlog_row_metadata=FULL;

Query OK, 0 rows affected (0.00 sec)

mysql> SHOW VARIABLES LIKE '%metadata%';

+---------------------------------------+-------+

| Variable_name | Value |

+---------------------------------------+-------+

| binlog_row_metadata | FULL |

| innodb_stats_on_metadata | OFF |

| performance_schema_max_metadata_locks | -1 |

| resultset_metadata | FULL |

+---------------------------------------+-------+

4 rows in set (0.00 sec)

For more information, see Keywords and Reserved Words. (WL #15241)

• It is now possible to set the default format for the output of any EXPLAIN statement which obtains a

query execution plan, and which has no FORMAT option, using the explain_format system variable

added in this release. Like the FORMAT option, this variable can take any of the values TRADITIONAL,

JSON, or TREE. DEFAULT is also supported as a synonym for TRADITIONAL. (DEFAULT is not supported

with the FORMAT option for EXPLAIN.) Suppose the value of explain_format is TREE; in this case,

the output from any such EXPLAIN statement uses the tree-based format, as though FORMAT=TREE had

been specified as part of the EXPLAIN statement.

Any value set for explain_format is overridden by a FORMAT option. This means that, if

explain_format is set to TREE, supplying FORMAT=JSON when invoking EXPLAIN causes the value

of explain_format to be ignored, and the result is displayed using the JSON format.

explain_format also affects the behavior of EXPLAIN ANALYZE; since this statement supports only

the TREE format, if the value of explain_format is not TREE, this means that any EXPLAIN ANALYZE

MySQL 8.0 Release Notes

statement that does not specify the TREE format explicitly raises the error This version of MySQL

doesn't yet support 'EXPLAIN ANALYZE with format format'.

The new system variable has both global and session scope, can be persisted, and can be set from the

command line (as --explain-format) or in a my.cnf option file.

See the description of explain_format. See also Obtaining Execution Plan Information, and Obtaining

Information with EXPLAIN ANALYZE, for further information and examples. (WL #15040)

References: See also: Bug #33629360.

Thread Pool Notes

• Whenever a connection was terminated due to inactivity, the thread pool plugin printed only a generic

message about connections timing out; this often made analysis of such timeouts more difficult than

necessary. A new INFO_LEVEL message makes it clear that a connection has been terminated due to

inactivity in the thread pool, as well as which timeout value was used to make this determination. (Bug

#34767607)

• Two columns added to the Performance Schema tp_thread_state table in this release make it

possible to identify a thread's type, and to map threads in this table to those in the Performance Schema

threads table. The type of thread is now shown in the tp_thread_state table's TP_THREAD_TYPE

column, and the thread's unique ID in the THREAD_ID column. For more information, see The

tp_thread_state Table. (Bug #34020058)

Functionality Added or Changed

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library

for MySQL Server has been updated to version 1.1.1s. Issues fixed in OpenSSL version 1.1.1s are

described at https://www.openssl.org/news/cl111.txt. (Bug #34828308)

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.86.0. (Bug #34828111)

• The internal resource-group enhancement added in MySQL 8.0.31 is refactored, but it continues to

support the Resource_group_supported status variable. (Bug #34702833, Bug #34699751)

References: Reverted patches: Bug #34264356.

Bugs Fixed

• Important Change: The implementation of the max_join_size system variable, although documented

as a maximum number of rows or disk seeks, did not check the number of rows or disk seeks directly,

but instead treated max_join_size as the maximum estimated cost to permit. While cost and row

count are correlated, they are not the same, and this could lead to unexpected results when some large

queries were allowed to proceed.

In this release, we change how max_join_size is used, so that it now actually limits the maximum

number of row accesses in base tables. If the estimate indicates that a greater number of rows must

be read from the base tables, an error is raised. This makes the actual behavior better reflect what is

documented. (Bug #83885, Bug #25118903)

• InnoDB: Undetectable problems after upgrade from 8.0.28, crash and corruption.

Any new row inserted after upgrade will have all columns added with ALGORITHM=INSTANT

materialized and have version=0.

MySQL 8.0 Release Notes

In the new implementation, a column added with ALGORITHM=INSTANT will fail if the maximum possible

size of a row exceeds the row size limit. So new rows with materialized ALGORITHM=INSTANT columns

will always be within row size limit. (Bug #34558510)

• InnoDB: No more garbled UTF characters in SHOW ENGINE INNODB STATUS (Bug #34486877, Bug

#108111)

• InnoDB: Alter handler adjusted so that adding more than 1024 columns with ALGORITHM=INSTANT no

longer causes a crash. (Bug #34378513, Bug #107854)

• InnoDB: After a column added with ALGORITHM=INSTANT, an online rebuild DDL no longer crashes.

(Bug #33788578, Bug #106279)

• InnoDB: Several adaptive hash index (AHI) code optimizations and improvements were implemented,

addressing various issues including potential race conditions. (Bug #33601434)

• Replication: When SOURCE_HEARTBEAT_PERIOD was set to a very small value (such as 1

microsecond) on the server using CHANGE REPLICATION SOURCE TO, and the mysqlbinlog client

program was started with --read-from-remote-server and --stop-never=1, it was possible for

the binary log dump thread to send an EOF packet to the client before all events had been sent. (Bug

#34860923)

• Replication: Removed an assert from sql/rpl_group_replication.cc which triggered a false

error in testing. (Bug #34619134)

• Replication: After MySQL was started with --server-id=0, trying to change the server ID by using

SET PERSIST server_id=N (where N is an integer greater than zero) and restarting the server had

the following results:

• SELECT @@server_id returned N.

• Any replication SQL statement such as START REPLICA was rejected with

ER_SLAVE_CONFIGURATION.

To fix this problem, we now ensure that such checks use the value of the server variable rather than the

value passed to the startup option. (Bug #34412816)

• Replication: When replicating compressed binary log events generated by the NDB binary log injector,

relay log positions were not updated in the multithreaded applier, thus causing replication to hang. (Bug

#33889030)

References: See also: Bug #33784241.

• Replication: Issuing STOP REPLICA SQL_THREAD while the SQL thread was handling a transaction

caused replication to stop immediately, instead of waiting 60 seconds for the event group to complete

before shutting down the SQL thread as expected.

The root cause of this issue was due to the internal variable storing the last event start time not being

reset after the SQL thread was restarted.

We fix this by resetting the variable holding the last event start time whenever the SQL thread is started.

(Bug #33646899)

• Replication: While their wording might imply otherwise, the log messages Setting

super_read_only=ON (ER_GRP_RPL_SUPER_READ_ON) and Setting super_read_only=OFF

(ER_GRP_RPL_SUPER_READ_OFF) were written only after the operations were attempted, and not

beforehand, or while the operations were ongoing. This sometimes led to confusion when setting the

MySQL 8.0 Release Notes

variable was rejected, and this was logged prior to the set attempt itself being logged. To keep this from

happening, these messages are now logged just prior to attempting the operation. (Bug #108843, Bug

#34728079)

• Replication: The relay_log_space_limit system variable is a 64-bit value, but its valid maximum

was specified internally as that of a 32-bit value. (Bug #106323, Bug #33799840)

• Replication: Eliminated an unnecessary update of the gtid_executed table which was performed

when rotating the binary logs. (Bug #106116, Bug #33759477)

• Group Replication: The WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE column of the MySQL

Performance Schema's replication_group_communication_information table reflects

the runtime value of a Paxos Single Leader setup in a group, letting users know what the value of

group_replication_paxos_single_leader must be on joining members.

A group that was bootstrapped with single-leader enabled but with its protocol version downgraded

to one that did not support it reported WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE

equal to 0, as expected, but attempting to join an instance to the group using

group_replication_paxos_single_leader = 0 was not possible.

To solve this problem, we change the behaviour and make the value of

group_replication_paxos_single_leader consistent with the communication version that the

group is running. Since this variable was introduced in MySQL 8.0.27, it is not known or used in any

previous version, and so we now enforce the following rules:

• When a node tries to join a group that is running MySQL 8.0.26 or earlier and we are version 8.0.27 or

later, we reject the attempt with an error stating that group_replication_paxos_single_leader

must be OFF before joining the group

• When we try to use group_replication_set_communication_protocol() to set a

version less than 8.0.27 and we are of version 8.0.27 or later, we reject the function call if

group_replication_paxos_single_leader is not OFF.

In addition, we also change the value checked to determine whether changing the group leader is

allowed after running group_replication_set_communication_protocol(). Previously, this

was the runtime value of group_replication_paxos_single_leader, which takes effect only after

a group reboot. Instead, when we run group_replication_set_communication_protocol(),

we now use the value shown by the replication_group_communication_information table's

WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE column, described previously. (Bug #34555045, Bug

#34828311)

• Group Replication: In a 3 node cluster, all nodes were killed due to running out of memory.

Subsequently, after all nodes were restarted successfully, attempting to bring the cluster back online

caused the node that had been the primary to hang.

For more information, see Rebooting a Cluster from a Major Outage. (Bug #108339, Bug #34564856)

• Group Replication: When a group was run with group_replication_consistency = AFTER

and a secondary failed due to external conditions such as an unstable network, the secondary could

sometimes encounter the error Transaction 'GTID' does not exist on Group Replication

consistency manager while receiving remote transaction prepare.

The root cause of this issue was that the primary might log out of order the View_change_log_event

with which the secondary rejoined; when the secondary used the primary as the group donor, this could

cause the secondary to catch up with the group improperly and, eventually, generate incorrect GTIDs for

the group transactions. The group replication primary ensures that the View_change_log_event is

MySQL 8.0 Release Notes

logged after all preceding transactions, but there was a window during which transactions ordered after

the View_change_log_event on the group global order could be logged before the event.

To solve this issue, we now make sure that transactions ordered before a view are always logged before

the View_change_log_event, and that transactions ordered after a view are always logged after

this event. This is now done by the binary log ticket manager, which guarantees the order in which

transactions in the binary log group commit are committed. (Bug #104980, Bug #33405699)

References: See also: Bug #34746357.

• Microsoft Windows: When compiling MySQL on Windows platforms, the CMake -

DWITH_WIN_JEMALLOC option was not always handled correctly. (Bug #108341, Bug #34698376)

• JSON: While saving the result of JSON_ARRAYAGG() or JSON_OBJECTAGG() in a column, the data

type information was lost due to the result being an item of type SUM_FUNC_ITEM. To fix this, we remove

the type check and this way retain the original type information. (Bug #108326, Bug #34548259)

• Some remote connections to the server were not handled correctly. This issue arose as the result of a

previous fix for an issue with require_secure_transport. (Bug #34857411)

References: This issue is a regression of: Bug #34094706.

• Some query plans were not stable due to nondeterministic sorting of Key_use_array in

sql_optimizer.cc; now we sort it with std::stable_sort() instead of std::sort(). (Bug

#34823952)

References: This issue is a regression of: Bug #25965593.

• Binary packages that include OpenLDAP rather than linking to the system OpenLDAP library were

upgraded to use version 2.5.13. (Bug #34815046)

• In some cases, an unexpected packet sent by the server to a MySQL client program during

authentication could result in an infinite loop. (Bug #34805922)

• GIS data was not always handled correctly in windowing functions. (Bug #34778646)

• A thread remained bound to the CPU of a dropped resource group even after it was assigned to the user

default resource group (USR_default). USR_default has 0 CPU priority and no CPU affinity, so with

this fix, the thread now is able to run any CPU with USR_default. (Bug #34748973)

• With JSON logging enabled, calling the audit_log_rotate() function did not rotate the file as

expected. A rotated file name consists of the timestamp from the last event logged into the file. When the

file is empty, last timestamp is the same as the timestamp in the already created file. To fix this issue,

the function now uses the current time to name the file if the file is empty. (Bug #34733508)

• Some queries having multiple lateral derived tables did not produce the expected result. (Bug

#34716246)

• The bundled zlib library has been upgraded to zlib 1.2.13; zlib 1.2.13 is now the minimum zlib version

supported. (Bug #34711762, Bug #34711758)

• Certain INTERSECT queries were not handled correctly. (Bug #34642435)

• Using the MAX_EXECUTION_TIME optimizer hint with a value greater than the stated maximum kept

an upgrade to MySQL 8.0.30 from completing; this caused the server to report a warning which was

interpreted by the upgrade process as an unrecoverable error. (Bug #34607401)

• In certain cases, evaluation of window functions was not performed correctly. (Bug #34572136)

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #32644631, Bug #32802301.

• Some CTEs were not processed correctly. (Bug #34572040, Bug #34634469)

References: This issue is a regression of: Bug #33856374.

• Values returned from functions or operators that convert a value to FLOAT (CAST(... AS FLOAT),

CONVERT(..., FLOAT), JSON_VALUE(... RETURNING FLOAT)) may have extra precision in their

internal representation, since they are stored in double precision internally. This sometimes caused

unexpected results when checking such values for equality, such as SELECT DISTINCT returning

duplicates and comparison operators incorrectly reporting two equal values as unequal.

We fix this problem by stripping off the extra double precision from the values before returning them, and

by making any conversion from float to string in these conversion operators use float format instead of

double format. (Bug #34554755)

• Removed an assertion in query_expression::assert_not_fully_clean(). (Bug #34526104)

• Upgrading from MySQL 5.7 to MySQL 8.0 with a very large number of tables in a single database

caused the server to consume excessive memory. It was found that, during the process of checking

whether tables could be upgraded, we fetched all the data dictionary Table objects upfront, processing

each and fetching its name, then performed CHECK TABLE ... FOR UPGRADE on the list. Fetching all

objects beforehand was not necessary in this case, and contributed greatly to memory consumption.

To correct this problem, we now fetch one Table object at a time in such cases, performing any

required checks, fetching its name, and releasing the object, before proceeding with the next one. (Bug

#34526001)

• When creating natural join columns, a hidden column added as part of a materialized derived table

is used in constructing the join condition, which is later used to check whether the join eligible for

pushdown to derived tables. The current issue arose when this column was not retrieved from the

derived table due to it being hidden; this occurred even when the condition pushdown optimization was

not enabled. We solve this problem by rejecting all hidden columns added internally, and not merely for

hidden columns added for functional indexes. (Bug #34523627)

• Types were not derived consistently from user variables. This could be seen, for example, by executing

the following statements repeatedly:

CREATE TABLE t AS SELECT @max_error_count UNION SELECT 'a';

SHOW CREATE TABLE t;

In this particular case, the output of the SHOW CREATE TABLE statement showed

`@max_error_count` text the first time, and `@max_error_count` mediumblob in successive

iterations. (The second is correct.) (Bug #34523475)

• Following work done in MySQL 8.0.23 to improve host resolution for user accounts, the time needed for

CREATE USER to complete increased significantly, particularly when running many such statements in

close succession.

Prior to upgrading to this release, you can work around this issue when issuing many such statements

in succession by preceding them with a single CREATE USER 'fakeuser' ACCOUNT LOCK (you

can use any user name that does not conflict with existing ones for this). When finished, you can (and

should) clean up by issuing the following statements:

DROP USER 'fakeuser';

FLUSH PRIVILEGES;

MySQL 8.0 Release Notes

For more information, see Access Control, Stage 1: Connection Verification. (Bug #34449016)

• The data_masking server-side plugin could emit a runtime error and halt unexpectedly. (Bug

#34445632)

• Stack overruns could be erroneously reported when using the thread pool under heavy load. The race

condition causing this in the thread pool has been avoided with an additional thread group ID check.

(Bug #34414959)

• Some multiply nested queries were not performed correctly. (Bug #34377854)

• When merging a derived table, a nested join condition is added to the derived table and the underlying

tables are added to this join nest. In addition, the join condition is associated with the derived table.

Evaluation for range access is skipped if the table is an inner table of an outer join or if the table is an

inner table and the join is not a semijoin. For a derived table, the underlying base table was treated as

being of the latter kind, range analysis was skipped, and the range access method was thus unavailable.

To fix this problem, we now evaluate for range access when the embedding table is a derived table, and

ensure that the join condition associated with the derived table is used for the range optimization. (Bug

#34347116)

• A LOAD DATA INFILE statement issued with a subquery could cause the server to return an incorrect

warning (Subquery returns more than 1 row). (Bug #34336033)

• Improved handling of resource allocation for internal temporary tables. (Bug #34174001)

• A specific column added after a drop using the INSTANT algorithm could cause a data error and a server

exit. (Bug #34122122)

• A query such as SELECT 1 AS one FROM t WHERE 1=(SELECT 1 UNION SELECT 2) is

transformed to this:

SELECT 1 AS one

FROM t

JOIN ( SELECT 1 AS col1 UNION SELECT 2) derived

WHERE 1 = derived.col1;

The optimizer in this case pushed down 1 = derived.col1 into the union, removing the contribution

from SELECT 2, which led to an erroneous result. We now no longer push the condition down in such

cases. (Bug #33910786)

• Some parenthesized query expressions with either or both of ORDER BY and LIMIT were not always

handled correctly. (Bug #33725530)

• Reimplemented retention of item trees having multiple references, by using a reference count in every

Item object. Also removed old code no longer needed due to this change. (Bug #33725415)

• An assert occurred in InnoDB during upgrade of the data dictionary when the definition of the

innodb_ddl_log table changed, even when such changes were effectively null operations, such

as updating utf8 and utf8_bin in table and column definitions to utf8mb3 and utf8mb3_bin,

respectively. (Bug #33688509)

References: This issue is a regression of: Bug #33787300.

• Data and GTIDs backed up by mysqldump were inconsistent when the options --single-

transaction and --set-gtid-purged=ON were both used. This was because, between the start of

the transaction by mysqldump and the fetching of GTID_EXECUTED, GTIDs on the server could have

MySQL 8.0 Release Notes

increased already. With this fix, a FLUSH TABLES WITH READ LOCK is performed before fetching

GTID_EXECUTED, to ensure that its value is consistent with the snapshot taken by mysqldump.

Our thanks to Marcelo Altmann for the contribution.

Limitation: This fix adds a requirement for the RELOAD privilege when using --single-transaction

to execute FLUSH TABLES WITH READ LOCK; the MySQL team is investigating a solution. (Bug

#33630199, Bug #105761)

• SET PERSIST accepted dot-separated names of variables registered by components as well as MyISAM

multiple key cache variables, but RESET PERSIST rejected the same names with a syntax error. To

fix this discrepancy, we add support in this to RESET PERSIST for variable names containing a dot

character (.). (Bug #33417357)

• Some grouped queries were not always handled correctly. (Bug #33294005, Bug #33349994)

• When multifactor authentication used the auth_socket authentication plugin for the first factor, the

server executed the wrong code during the second-factor authentication workflow and returned an error

message. The second factor could be any authentication plugin. (Bug #33192223)

• Use of a wild card as a column identifier in an INSERT statement was allowed by the parser even though

the syntax is not supported, which led to an assert in debug builds and a silent rejection of the statement

in release builds. This construction has been removed as a possibility from the grammar, and is now

handled strictly as a syntax error. (Bug #33142665)

References: This issue is a regression of: Bug #30528450.

• In prepared statements, some types of subqueries could cause a server exit. (Bug #33100586)

• Some floating-point literals were not always handled correctly. (Bug #32824429)

• A DELETE statement with a table alias could result in an intermittent server exit. (Bug #32762229)

• Moved INFO_SRC and INFO_BIN from the mysql-common package to the mysql-community-

server-core package, the same package as mysqld and more consistent with RPM packaging. (Bug

#32752147)

• Some queries making use of MATCH() within a HAVING clause were not handled correctly. (Bug

#32616816, Bug #32934558, Bug #34782389)

• A CREATE VIEW statement that contained a subquery sometimes led to an assertion in debug builds.

(Bug #108783, Bug #34703610)

• The deduction of data types for dynamic parameters passed as parameters to a user-defined SQL

function was correct only for a single parameter; with more than one parameter, no such deduction was

performed for the second and following parameters, with the result that their types were always reported

erroneously to clients as MYSQL_TYPE_INVALID. (Bug #108545, Bug #34629157)

• The internal function clone_os_copy_file_to_buf() did not advance the buffer position in the

event of a partial read.

Our thanks to Laurynas Biveinis for the contribution. (Bug #108317, Bug #34543194)

• Views that access system views could encounter an access-denied error during normal use if the

pushdown condition included expressions that used native functions from the system view. (Bug

#108202, Bug #34515868)

• When using window functions, the current row could reevaluate itself based on the wrong record in some

cases. (Bug #108008, Bug #34431996)

MySQL 8.0 Release Notes

• A condition pushdown into a UNION of queries having LIKE clauses did not preserve the correct

character set, leading to an (erroneous) empty result.

We solve this problem in two parts:

1. By refactoring resolution of LIKE expressions, in which character set determination and propagation

were previously performed in two separate blocks of the code that were not always consistent with

one another.

2. By adding, in the internal parse_expression() function, a character set prefix to any literal

character string that is cloned.

(Bug #107787, Bug #34359297, Bug #34589153)

• The audit_log server-side plugin always logged an entire multiple query, rather than logging only the

specific part of the query that was executed. Changing when the query length is set resolves the issue.

(Bug #107390, Bug #34207811)

• Following an upgrade to MySQL 8.0.27 a specific query started consuming comparatively high amounts

of memory whenever it was run within a stored procedure. (Bug #107327, Bug #34190122)

• When a mysqld startup option was used with the maximum- prefix, the upper bound for the

corresponding system variable was set but its current value was not checked against or adjusted

according to the new limit and thus could in some cases be greater than the stated maximum. We fix this

by adjusting the current value if it is larger than the new user defined maximum value. (Bug #99029, Bug

#31072098)

• The mysql_stmt_close() C API function could stop responding after a prepared statement was

canceled using KILL QUERY. (Bug #84470, Bug #25584097)

Changes in MySQL 8.0.31 (2022-10-11, General Availability)

• Audit Log Notes

• Compilation Notes

• Component Notes

• Deprecation and Removal Notes

• Keyring Notes

• Optimizer Notes

• Performance Schema Notes

• SQL Syntax Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• The audit_log_rotate() function simplifies audit log file rotation. Previously, audit log file rotation

required renaming the file manually and setting audit_log_flush = ON to close the file and open a

new log file with the original name. The audit_log_rotate() function renames the current file and

creates a new one. Manually renaming the audit log file is no longer necessary.

MySQL 8.0 Release Notes

The audit_log_flush variable is deprecated as of MySQL 8.0.31; expect support for it to be removed

in a future version of MySQL. (WL #15249)

Compilation Notes

• Microsoft Windows: Fixed all C++ deprecation warnings by not using deprecated C++ STL features.

(Bug #33985941)

• Renamed internal Performance Schema functions from _utf8* to _utf8mb4* as they've used utf8mb4

since v8.0.11. (Bug #34351301)

References: See also: Bug #27407745.

• Fixed linker flags for clang/ubsan to workaround a LLVM/Clang related integer issue as described in

LLVM bug #16404. (Bug #34311325)

• Updated helper scripts to use 'utf8mb3' for charsets/collations instead of 'utf8' for future compatibility.

Renamed functions and data structures used to handle utf8mb3 character sets and collations to help

clarify their utf8mb3 usage. (Bug #34263480, Bug #34025412)

• Cleaned up CMake code, and simplified INFO_BIN and INFO_SRC. (Bug #34139084)

Component Notes

• New component services now enable server components and plugins to query within the local server.

The new MySQL command services are similar to C API functions in libmysql, except they do not

expose protocol internals to the client. For information about these services, see the MySQL Server

Doxygen documentation, available at https://dev.mysql.com/doc/index-other.html. Search for:

• s_mysql_mysql_command_factory

• s_mysql_mysql_command_options

• s_mysql_mysql_command_query

• s_mysql_mysql_command_query_result

• s_mysql_mysql_command_field_info

• s_mysql_mysql_command_error_info

(WL #14293)

Deprecation and Removal Notes

• The keyring_oci plugin is deprecated and subject to removal in a future release of MySQL. Instead,

consider using the component_keyring_oci component for storing keyring data (see Using the

Oracle Cloud Infrastructure Vault Keyring Component). (WL #14943)

Keyring Notes

• MySQL Keyring previously implemented Oracle Cloud Infrastructure Vault Keyring keystore capabilities

using a server plugin, but now is transitioning to use the MySQL component infrastructure. The new

keyring component has similarities to the existing keyring_oci plugin, but is configured differently and

can access keys that were created using the keyring_oci plugin when a similar set of configuration

MySQL 8.0 Release Notes

options are used to initialize the new component. For configuration details, see Using the Oracle Cloud

Infrastructure Vault Keyring Component.

component_keyring_oci is not loaded using the --early-plugin-load server option during

startup or configured during startup or at runtime using system variables:

• During startup, the server determines which keyring component to load using a manifest file, and

the loaded component consults its own configuration file when it initializes. See Keyring Component

Installation.

• At runtime, the ALTER INSTANCE RELOAD KEYRING statement enables reconfiguring an installed

keyring component after changes to its configuration file. See ALTER INSTANCE Statement.

If a keyring component is installed, the Performance Schema keyring_component_status table

provides status information about it. See The keyring_component_status Table. (WL #14943)

Optimizer Notes

• Important Change: The MySQL Optimizer's internal management of set operations has been improved,

with the following effects:

• Bodies of parenthesized query expressions can now be nested to in combination with UNION. For

example, the query shown here, previously rejected with error ER_NOT_SUPPORTED_YET, is now

allowed:

(

(SELECT a, b, c FROM t ORDER BY a LIMIT 3) ORDER BY b LIMIT 2

) ORDER BY c LIMIT 1;

• When collapsing parenthesized expression bodies, MySQL now follows the semantics specified in

the SQL standard, so that a higher outer limit cannot override an inner lower one. This means that the

expression (SELECT ... LIMIT 3) LIMIT 5 can return at most three rows.

• UNION DISTINCT and UNION ALL can now be nested in arbitrary combinations.

The maximum nesting level supported in all the cases just listed is 63; this follows any simplifications or

merging performed by the parser. See Parenthesized Query Expressions, for more information. (Bug

#103954, WL #11350)

• An outer reference in a derived table pointing to a table in a JOIN operation that was not available for

the subquery to be reported (incorrectly) as valid, whereas such a reference without a derived table was

correctly reported as invalid.

In a related issue, an outer reference to a derived table placed inside the VALUES clause of an INSERT

statement was not recognized as valid, whereas a similar reference without a derived table was so

recognized. Now such a reference to a derived table is accepted within VALUES.

In both cases, we fix the problem by making sure that the correct name resolution context is used for the

outer reference. (Bug #32678303, Bug #34131822)

Performance Schema Notes

• The Performance and sys schemas now expose metrics for the global and session memory limits

introduced in MySQL 8.0.28.

The following columns were added to tables of the Performance Schema:

MySQL 8.0 Release Notes

• SETUP_INSTRUMENTS:

• FLAGS

• THREADS:

• CONTROLLED_MEMORY

• MAX_CONTROLLED_MEMORY

• TOTAL_MEMORY

• MAX_TOTAL_MEMORY

• EVENTS_STATEMENTS_CURRENT, EVENTS_STATEMENTS_HISTORY, and

EVENTS_STATEMENTS_HISTORY_LONG:

• MAX_CONTROLLED_MEMORY

• MAX_TOTAL_MEMORY

• Statement Summary Tables:

• MAX_CONTROLLED_MEMORY

• MAX_TOTAL_MEMORY

• Performance Schema Connection Tables:

• MAX_SESSION_CONTROLLED_MEMORY

• MAX_SESSION_TOTAL_MEMORY

• PREPARED_STATEMENTS_INSTANCES:

• MAX_CONTROLLED_MEMORY

• MAX_TOTAL_MEMORY

The following columns were added to the sys schema STATEMENT_ANALYSIS and X

$STATEMENT_ANALYSIS views:

• MAX_CONTROLLED_MEMORY

• MAX_TOTAL_MEMORY

The PROPERTIES column of the SETUP_INSTRUMENTS table was updated with the

controlled_by_default flag.

You can also add, or remove, non-global memory instruments to the set of controlled-memory

instruments by setting the value of the FLAGS column of SETUP_INSTRUMENTS.For example:

SQL> UPDATE PERFORMANCE_SCHEMA.SETUP_INTRUMENTS SET FLAGS="controlled"

WHERE NAME='memory/sql/NET::buff';

(WL #14432)

MySQL 8.0 Release Notes

SQL Syntax Notes

• It is now possible to set a column histogram to a user-specified JSON value. This can be useful when

sampling leaves out important values. This also means that a secondary (replica) MySQL server can

assume the work of sampling the data and building the histogram, which can then be used on the

primary (source) without impacting its performance.

This capability is provided through an extension to ANALYZE TABLE ... UPDATE HISTOGRAM. The

following statement sets the histogram for column col_name of table tbl_name to the histogram's

JSON representation json_data:

ANALYZE TABLE tbl_name

UPDATE HISTOGRAM ON col_name

USING DATA 'json_data'

You can confirm afterwards this by checking the value of the HISTOGRAM column of the Information

Schema COLUMN_STATISTICS table.

See Histogram Statistics Analysis, for more information and examples.

Our thanks to Kaiwang Chen for this contribution to MySQL. (Bug #104040, Bug #33012389, WL

#15123)

• In this release MySQL adds support for the SQL standard INTERSECT and EXCEPT table operators.

query_a INTERSECT query_b includes only rows appearing in both result sets.

query_a EXCEPT query_b returns any rows from the result set of query_a which are not in the

result of query_b.

INTERSECT and EXCEPT both support DISTINCT and ALL, with DISTINCT the default in both cases.

(This is the same as for UNION).

INTERSECT groups before EXCEPT or UNION, so TABLE r EXCEPT TABLE s INTERSECT TABLE t

is evaluated as TABLE r EXCEPT (TABLE s INTERSECT TABLE t).

See INTERSECT Clause, and EXCEPT Clause, for additional information and examples. (Bug #1309,

Bug #31336, Bug #11747209, Bug #11744757, WL #349)

Functionality Added or Changed

• Important Change; Replication: The Rewriter plugin rewrites SQL queries according to a table of

rewriter rules. Previously, all queries were subject to rewrites, including those from any user regardless

of privileges, as well as internal system queries like those performed by the replication applier thread, by

bootstrapping the MySQL Server, and by storage engines. This MySQL release provides a mechanism

for allowing the plugin to skip rewrites for certain queries, such as those executed by system threads,

and those from designated users.

We do this by implementing a new privilege SKIP_QUERY_REWRITE, which

indicates a user whose queries are not rewritten. A new system variable

rewriter_enabled_for_threads_without_privilege_checks controls whether rewrites are

skipped for threads executing with privilege checks disabled. Such threads include upgrade threads,

initialisation threads, and replication threads which have PRIVILEGE_CHECKS_USER as NULL. To

preserve backward compatibility, the default setting for this variable is variable is ON, although the

recommended setting is OFF.

MySQL 8.0 Release Notes

Both SKIP_QUERY_REWRITE and

rewriter_enabled_for_threads_without_privilege_checks are available only if the

Rewriter plugin is installed.

For more information, see The Rewriter Query Rewrite Plugin. (WL #14527)

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL

library for MySQL Server has been updated to version 1.1.1q. Issues fixed in OpenSSL version

1.1.1q are described at https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/

vulnerabilities.html. (Bug #34414695)

• InnoDB: Two new status variables are provided for monitoring online buffer pool resizing

operations. The Innodb_buffer_pool_resize_status_code status variable

reports a status code indicating the stage of an online buffer pool resizing operation. The

Innodb_buffer_pool_resize_status_progress status variable reports a percentage value

indicating the progress of each stage.

For more information, see Configuring InnoDB Buffer Pool Size. (WL #15175)

• Replication: When replication filtering is in use, a replica no longer raises replication errors related

to privilege checks or require_row_format validation for events which are filtered out. Previously,

all privileges were checked in the applier, with some being checked before applying filters and others

not until after; with this release, privilege checks are now deferred until after all replication filters have

been applied. In addition, prior to this release, checks for require_row_format equal to 1 took place

on both the receiver and the applier; now the applier alone performs this check, before any filters are

evaluated.

This makes it possible to filter out any transactions that fail validation, using existing replication filters,

and for the replica to accept only that part of the database to which a given user has been granted

access, as long as updates to this part of the database are replicated only in row-based format. Another

instance in which this might be desirable is when migrating to MySQL Database Service from on-

premise or cloud services which use administration tables to which the inbound replication user does not

have access.

Privilege checks protect against updating critical tables on the replica. Checking require_row_format

protects against replicating unsafe operations; this is used in conjunction with privilege checks, because

the guaranteed absence of unsafe operations removes the need for some session context initialization

and cleanup actions, which in turn removes the need to grant privileges for those operations.

Other behavior changes associated with this work are noted in the following list:

• The receiver thread no longer errors out when an event that violates require row format validation

is received; the applier thread no longer errors out when an event that violates require row format

validation is handled and subsequently filtered out due to replication filters.

MySQL 8.0 Release Notes

• The applier thread no longer errors out for Query log events that are filtered out due to lack of

privileges for setting any of the system variables listed here:

• pseudo_thread_id

• sql_require_primary_key

• default_table_encryption

This is because setting the variable and checking whether the applier is authorized to set it are now

performed only after filtering takes place. If an event is filtered out, the applier does not try to set the

variable, and thus never fails a check whether it has the necessary privileges to do so.

• The applier thread no longer errors out on privilege checks when an Execute_load_query event

is handled and ends up being filtered out due to replication filters. This is also the case when an

Append_block or Begin_load_query event is applied, and a subsequent Execute_load_query

event is handled and then filtered out.

• The applier thread no longer errors out on privilege checks or require_row_format checks for

Delete_file events. These events are not filterable, because they do not contain the table name or

database name, so we assume they are filtered out. We assume this to be safe because Delete_file

events do not alter database state.

• The applier thread no longer creates or deletes files in the filesystem during the handling

of Append_block or Delete_file events, when there is a user account configured by

PRIVILEGE_CHECKS_USER and it does not have the FILE privilege, nor if require_row_format is

enabled.

• For a replication event altered by --replicate-rewrite-db, any privilege checks apply to the

rewritten database.

See How Servers Evaluate Replication Filtering Rules, and Replica Errors During Replication, for more

information. (Bug #33704306, Bug #33733677, WL #15032)

• The new Resource_group_supported status variable is added to indicate whether a server supports

the resource group feature. (Bug #34264356)

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.85.0. (Bug #34138733, Bug #34614578)

• The new thread_pool_transaction_delay system variable permits specifying a delay period, in

milliseconds, before worker threads start executing a new transaction. The maximum value is 300000 (5

minutes).

A transaction delay can be used in cases where parallel transactions affect the performance of other

operations due to resource contention. For example, if parallel transactions affect index creation or

an online buffer pool resizing operation, you can configure a transaction delay to reduce resource

contention while those operations are running. (WL #15277)

• The new thread_pool_query_threads_per_group system variable lets you increase the number

of query threads in a thread group, from the default of a single query thread. When you are using the

high concurrency thread pool algorithm (thread_pool_algorithm=1), consider increasing the value

if you experience slower response times due to long-running transactions. It cannot exceed the value of

thread_pool_max_transactions_limit. (WL #15330)

MySQL 8.0 Release Notes

• Thread pool plugin features previously only available with MySQL Database Service, are now available

in MySQL Enterprise Edition.

• The thread_pool_max_transactions_limit variable defines the maximum number of

transactions permitted by the thread pool plugin. Defining a transaction limit binds a thread to a

transaction until it commits, which helps stabilize throughput during high concurrency.

• The thread_pool_dedicated_listeners variable dedicates a listener thread in each thread

group to listen for incoming statements from connections assigned to the group. This variable is only

useful when a transaction limit is defined by thread_pool_max_transactions_limit. Having an

additional dedicated listener thread in each thread group consumes more resources and affects thread

pool performance. thread_pool_dedicated_listeners should therefore be used cautiously.

• The TP_CONNECTION_ADMIN privilege enables a user to access the server with a privileged

connection. When the limit defined by thread_pool_max_transactions_limit has been

reached, new connections cannot access the server. A privileged connection ignores the limit defined

by thread_pool_max_transactions_limit and permits connecting to the server to increase the

transaction limit, remove the limit, or kill running transactions.

(WL #15293)

• The new field WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE in the Performance Schema table

replication_group_communication_information shows whether the replication group supports

the use of a single consensus leader, even if group_replication_paxos_single_leader

is currently set to OFF on the queried member. The field is set to 1 if the group was started with

group_replication_paxos_single_leader set to ON, and its communication protocol version is

MySQL 8.0.27 or above. (WL #15203)

• Activating MySQL Server’s offline mode, which is done by changing the value of the offline_mode

system variable to ON, now requires the CONNECTION_ADMIN privilege in addition to the

SYSTEM_VARIABLES_ADMIN privilege (or the deprecated SUPER privilege, which covers both these

privileges). Sessions whose users have the CONNECTION_ADMIN privilege remain connected when

offline mode is activated, and users with that privilege can make new connections to an offline server

instance. The new requirement means that administrators who can activate offline mode cannot

inadvertently lock themselves out by doing so. (WL #13400)

• Added the read-only build_id system variable. On Linux systems, a 160-bit SHA1 signature is

generated at compile time; this value, converted to a hexadecimal string, provides a unique identifier for

the build. This value is written in the server log at startup.

This variable is not supported on platforms other than Linux. (WL #15161)

• Added Ubuntu 22.10 support.

Bugs Fixed

• Incompatible Change: The service pfs_plugin_table, deprecated since MySQL 8.0.14, is removed

in this release.

Plugins or components using this service must be updated to use pfs_plugin_table_v1 and

pfs_plugin_column_* instead. (Bug #34361827)

• Important Change; Replication: Query log events filtered by the default database whenever --

replicate-do-db or --replicate-ignore-db was used included XA START, XA END, XA

COMMIT, and XA ROLLBACK (but not XA PREPARE or XA COMMIT ONE_PHASE), regardless of the

binary log format.

MySQL 8.0 Release Notes

This can lead to one of the issues listed here:

• When XA START or XA END was filtered out, the sequence of XA statements within the first part of the

transaction were rendered invalid, which made the replica stop with an error.

• When XA START and XA END were preserved while XA COMMIT or XA ROLLBACK was filtered out,

then a transaction could remain in the prepared state indefinitely on the replica.

To prevent either of these problems from occurring, we no longer filter XA START, XA END, XA COMMIT,

or XA ROLLBACK statements by the default database with --replicate-do-db or --replica-

ignore-db. (Bug #106201, Bug #33764808)

• InnoDB: After upgrading to a release that supports row versions for columns added or dropped using

ALGORITHM-INSTANT, a failure occurred during an instant ADD COLUMN operation on a table with a

nullable column and an instantly added column. (Bug #34488482)

• InnoDB: Adding a virtual column and dropping a column in the same ALTER TABLE statement raised an

invalid debug assertion failure. (Bug #34467592)

• InnoDB: The physical position of columns were not set correctly after dropping a column and renaming

an existing column to the name of the dropped column. (Bug #34463089)

• InnoDB: A Valgrind error detected in mtr_t::start() was corrected. (Bug #34327575)

• InnoDB: A DDL operation on a corrupted partitioned table raised an assertion failure. (Bug #34293555)

• InnoDB: An index block latch order violation during histogram sampling blocked concurrent inserts and

could cause a deadlock failure. (Bug #34282448, Bug #34174927, Bug #107299)

• InnoDB: An ALTER TABLE operation executed while a data load operation was in progress raised an

assertion failure. (Bug #34267618)

• InnoDB: InnoDB memory leaks during MySQL server initialization, identified by Address Sanitizer

(ASAN) builds, were fixed. (Bug #34156050)

• InnoDB: During recovery, a tablespace object associated with encrypted undo tablespace pages that

were fetched from disk did not contain the encryption keys required to decrypt the pages, resulting in a

failure. (Bug #34148143)

• InnoDB: In debug builds, a descending b-tree scan raised a debug assertion failure. (Bug #34144951)

• InnoDB: The innodb_redo_log_consumer_advance() function failed to handle an invalid

argument. (Bug #34052884)

• InnoDB: A column added using ALGORITHM=INSTANT was visible in read views created before the

DDL operation that added the column. (Bug #33937504)

• InnoDB: A failure occurred while upgrading a MySQL instance with a MySQL 5.6 data directory

containing user-created table with a particular table ID. Assignment of that table ID resulted in

assignment of conflicting data dictionary table IDs while upgrading from MySQL 5.7 to MySQL 8.0.

Thanks to Rahul Malik for the contribution. (Bug #33919635)

• InnoDB: A buffer block containing intrinsic temporary table page was relocated during page traversal,

causing an assertion failure. (Bug #33715694)

• InnoDB: Dropping a table with a discarded tablespace caused an assertion failure. (Bug #33232978)

MySQL 8.0 Release Notes

• InnoDB: Page I/O reads not completed before shutdown reached the flush phase caused an assertion

failure in cases where pages had change buffer merges to be completed after the I/O read. (Bug

#33192496)

• InnoDB: An index latch order violation in dict_table_x_lock_indexes() caused an assertion

failure. (Bug #32912868)

• InnoDB: A TRUNCATE TABLE operation failed to free an acquired mutex in specific cases. (Bug

#107858, Bug #34380370)

• InnoDB: In debug builds, importing a tablespace without a .cfg file for table with an instantly added or

dropped column raised an assertion failure. (Bug #107517, Bug #34307874)

• InnoDB: A potential memory leak in the trx_undo_prev_version_build() function was corrected.

Thanks to Alex Xing for the contribution. (Bug #106952, Bug #34051207)

• InnoDB: A debug assertion failure occurred while redoing a space deletion during recovery. (Bug

#103482, Bug #32819101)

• InnoDB: An InnoDB startup message that specified the number of object pools was removed to avoid

confusion with the number of buffer pool instances. (Bug #80248, Bug #22653060)

• Partitioning: A partitioned table was not repartitioned as expected when an ALTER TABLE statement

acted to change the character set of any of its columns. The root cause of this was that, when

determining whether a change in character set could be done as an in-place alter operation, we did not

consider whether any columns affected by the character set change were part of the table's partitioning

expression. Since such a change might lead to a repartitioning of the table, it could not be done in place.

Now when a change in character set is planned, we also check whether this affects any columns that are

part of a partitioning expression; if not, then we can perform the operation in place. (Bug #106884, Bug

#34031693)

• Replication: Corrected an internal error in replication information handling. (Bug #34214416)

• Replication: When a single event caused multiple updates to the same row of a table on a replica, the

change could not be applied if the replica had a primary key on the table that did not exist in the source.

The hash-based row lookup algorithm now operates in this situation even if a primary key is present in

the replica’s table. (Bug #34114296)

• Replication: When a single statement generated multiple write events for different tables on a replica,

extra auto-increment columns in the replica’s tables were only cleaned up for the last event generated.

They were not cleaned up at all if the last event did not involve a table with an extra auto-increment

column. The cleanup process now always takes place for multiple write events. (Bug #34095290)

• Replication: A misleading error was returned to the client if the

group_replication_force_members system variable was set, and the wait for the view change

timed out. The error, and associated errors, have been updated so they do not suggest that the values

given for the system variable were incorrect. (Bug #34091087)

• Replication: The FILTER_RULE column in the Performance Schema table

replication_applier_filters showed incorrect data for filters whose rule did not exist. The table

now displays the empty string in this situation. (Bug #33885484)

MySQL 8.0 Release Notes

• Replication: It was possible in some rare instances of flushing or synchronization errors for the server

to attempt an update of the endpoint of the binary log using invalid values for both the file and position

within the file, leading to undefined behavior.

To solve this issue, we now call the internal function update_binlog_end_pos(binlog_file,

pos) only when both the file and position parameters are known to be valid. (Bug #33818238)

• Replication: Operations using the SID of a invalid GTID log event sometimes led to undefined behavior.

We solve this issue by ensuring that the SID is always initialized, even when it belongs to an invalid

GTID log event. (Bug #33784022)

• Replication: Calculation of the maximum length of status variables (MAX_SIZE_LOG_EVENT_STATUS)

was not performed correctly.

Issues corrected in this fix are listed here:

• sql_require_primary_key and default_table_encryption require 2 bytes (one for type ID,

one for the variable)

• The maximum length of time_zone was calculated as 255 instead of

MAX_TIME_ZONE_NAME_LENGTH

• An additional byte (each) is required to save the length of the user variable, the number of database

IDs stored in binlog_accessed_db_names, and the type of microseconds

In addition, master_data_written, which was not actually used, has been removed. (Bug

#33713071)

• Replication: On 32-bit platforms, setting binlog_expire_logs_seconds to 2147483648 (2

) or

more had the effect of causing all binary logs to be purged before the specified time had elapsed. (Bug

#33670457)

• Replication: If a group configuration change is in progress, new members cannot join. The error

message issued in this scenario now states what operation is in progress, such as a primary election,

a swap between single primary mode and multi-primary mode, or a change of group communication

protocol. (Bug #32766981)

• Replication: When the binary log sender thread waited for updates with heartbeats enabled, it

sometimes missed update signals, so that changes were not replicated until the next signal was issued

and noticed by the thread.

Our thanks to Facebook for the contribution. (Bug #104491, Bug #33176377)

• Group Replication: The START REPLICA and STOP REPLICA statements were permitted for the

Group Replication applier channel (group_replication_applier), but stopping and starting the

channel manually can leave online members of the replication group incapable of committing remote

transactions. These statements can no longer be used for the channel when Group Replication is

running. (Bug #34231291)

• Group Replication: A deadlock could occur when Group Replication was started on a server instance,

but errors such as incompatible configuration caused the member to leave immediately. The service

registry now manages the registration and deregistration of services by an alternative process that

avoids the issue. (Bug #34194893)

• Group Replication: In an InnoDB ClusterSet, in the event of a commit order deadlock and subsequent

retry, Group Replication could roll back a transaction during certification with an error stating that the

MySQL 8.0 Release Notes

GTID for the transaction had already been used. The error is now only returned if the GTID has been

used on the server instance as well as in the group. (Bug #34157846)

• Group Replication: After checking a transaction commit has no conflicts and is in the correct order,

Group Replication reports back to the committing session. When the event scheduler thread was started,

Group Replication was not able to find the committing session, resulting in the member entering ERROR

state and leaving the group. The procedure to locate the committing session was extended to find

daemon threads, as used to start the event scheduler thread. Thanks to Lou Shuai for the contribution.

(Bug #107635, Bug #34312482)

• Calling many stored procedures from the same connection led the server to consume an ever-increasing

amount of virtual memory. (Bug #35110491)

• When the system variable replication_optimize_for_static_plugin_config was enabled to

improve performance for semisynchronous replication, the RAPID plugin could not be used in the server

due to issues with notification handling. The issue has now been fixed. (Bug #34549470)

• Strings containing many leading zeros were incorrectly marked as overflowing when converting them to

decimal, causing the value returned to be the maximum decimal value for the given precision and scale.

We fix this by replacing all leading zeros in such cases with a single 0, prior to conversion. (Bug

#34479194)

• Differences between the WSAPoll function on Windows and the poll() function on Unix-like systems

caused thread pool code on Windows to consider invalid file descriptors or sockets as ready for I/O. (Bug

#34478731)

• If a MySQL instance at MySQL 8.0.27 or above joined a replication group running at MySQL

8.0.26, the member action mysql_start_failover_channels_if_primary was

removed to match the member actions configuration for to the rest of the group. However, if

the instances were upgraded to run at MySQL 8.0.27 or above, the member action was not

reinstated unless group_replication_reset_member_actions() was issued on a

server that then bootstrapped the group. Joining members now check if the member action

mysql_start_failover_channels_if_primary is available to them, and add it to their member

actions configuration if it is. (Bug #34464526)

• A constant expression used in the SELECT list of a query was not always handled correctly by the server.

(Bug #34418412)

• Added a missing error check in Json_table_column::fill_column(). (Bug #34416304)

• Some string functions accepting multiple arguments did not process all of the arguments properly. (Bug

#34393009)

• Columns of type YEAR created for temporary tables holding UNION results were not always guaranteed

to be of the correct length. (Bug #34370933)

• If a view (v1) accessed another view (v2), and if v2 was recreated, then SHOW COLUMNS FROM v1

reported an invalid view error. This issue could occur only when the user was granted global privileges

with roles, but not table-level privileges. It is fixed by checking for global privileges if table-level privileges

are absent. (Bug #34341533)

• Queries on the Performance Schema table replication_group_member_actions could fail due to

conflicts between threads. The issue has now been fixed. (Bug #34337673)

• Added a missing error check after an item evaluation when reading const tables. (Bug #34327798)

MySQL 8.0 Release Notes

• Reparsing and cloning of derived tables was not always handled correctly in certain cases. (Bug

#34317258, Bug #34408241)

• Pushing a condition down to a derived table with set operations when multiple query blocks were present

was not always handled correctly. (Bug #34306361)

• A startup failure during RSA key creation resulted in empty or incomplete keys. Keys are now generated

in a fail-safe manner. (Bug #34274914)

• When comparing two string values with explicit COLLATE clauses, these should have the same collation,

else the comparison should be rejected, but this was not always enforced.

For more information, see Collation Coercibility in Expressions. (Bug #34274525)

• A CREATE USER operation read from binary log failed to execute on a replica server due to an

unexpected syntax error. (Bug #34178823)

• A precision mismatch could sometimes occur in a CAST to FLOAT operation on an integer value, when

using SQL_SMALL_RESULT as opposed to SQL_BIG_RESULT (see SELECT Statement).

For SQL_BIG_RESULT, the value was truncated according to the inherent precision of an IEEE 32 bit

floating point value, which is the correct behavior. With SQL_SMALL_RESULT, the precision from the

original integer value was preserved; this happened because the value was copied to a temporary table

which supported only double precision values, and these values were later copied back to the client.

We fix this by distinguishing the type of floating point value when copying such values to a temporary

table, so that double precision values are stored as type double and single precision values are stored

as type float. (Bug #34167787)

• Executed codespell on the majority of source code, and fixed the reported spelling errors in the code

comments. (Bug #34163323)

• In certain cases, when checking an internal function pointer before it was called, the wrong pointer was

validated. (Bug #34134738)

• Both the access path and the iterator for eq_ref access had a use_order member for determining

whether to use an ordered index scan. Since eq_ref always returns at most one row, ordering it is not

necessary; thus, use_order serves no purpose here, and has been removed from the access path and

the corresponding iterator. (Bug #34122706)

• Improved the ADD_GDB_INDEX CMake option to also function when loading unit tests. (Bug #34117732)

References: See also: Bug #29925009.

• Removed GNU 'gold' linker support, including the associated USE_LD_GOLD CMake option. (Bug

#34094324)

• Manually created directories in a MySQL 5.7 data directory (treated as schema directories in MySQL

5.7) with special characters in the directory name or schemas and tables created with special characters

in their name using a `#mysql50#` prefix caused DDL failures after upgrading to MySQL 8.0. In

MYSQL 8.0, the special characters are replaced with question mark characters (?) when the object

names are added to the data dictionary. The name mismatch caused DDL operations on the affected

objects to fail. Upgrade now stops with an error if invalid schema and table names are encountered.

In MySQL 5.7, you can update invalid schema and table names to a valid encoding using mysqlcheck.

To identify invalid names, run:

mysqlcheck --check-upgrade --all-databases

MySQL 8.0 Release Notes

To fix invalid names, run:

mysqlcheck --fix-db-names --fix-table-names --all-databases

In MySQL 5.7, directory names that have special characters can also be updated to use valid encoding

using the following SQL syntax:

ALTER DATABASE `directory_name` UPGRADE DATA DIRECTORY NAME;

(Bug #34066605)

• Conditions using the null-safe equals operator (<=>) can now considered by the executor as equijoin

conditions. Predicates using such conditions are not considered as equijoin predicates, but rather as

extra predicates to evaluate following the join. (Bug #34063499)

• Support was added for compiling the MySQL Enterprise Encryption component with OpenSSL 3. (Bug

#34043029)

• Executed codespell on the source code and fixed the reported spelling errors in the code comments.

(Bug #34006439)

• When one or more arguments to GREATEST() were temporal values, the order in which they were

passed to the function could affect the result. (Bug #33996054)

• A SELECT with a LEFT JOIN on a derived table containing a nested subquery as part of a WHERE

clause with an IN predicate returned incorrect results. (Bug #33971286)

• Calls to ERR_clear_error() in the vio_ssl_write() and ssl_handshake_loop() functions

caused errors when compiling with OpenSSL 3.0. (Bug #33967647)

• The server did not always process nested views as expected. (Bug #33876690)

• mysqlpump might not be given the correct permissions to use derived tables (tables that are generated

by a query FROM clause), causing the dump process to stop if these were present. Derived tables are

now handled separately and privileges are set for them. (Bug #33866103)

• Repeated execution of a stored routine having as a subquery a SELECT containing multiple AND, OR, or

XOR conditions led to excessive consumption and possibly eventual exhaustion of virtual memory. (Bug

#33852530)

• EXPLAIN ANALYZE provides information about the estimated cost and elapsed time for each iterator in

the query plan. We expect these numbers to be cumulative, so that the cost (or time) for a given iterator

includes the cost of any iterators on which this iterator depends. For example, the estimated cost of

joining table t1 with table t2, using a table scan of t1 followed by a primary key lookup on t2, should

be no less than the cost of scanning t1 plus the cost of the cardinality lookups on t2.

For some queries involving materialization or temporary tables, these numbers were not cumulative.

In addition, cost estimates were incorrect when materializing the result of a UNION operation and

subsequently performing a table scan on the temporary (materialized) table. (Bug #33834146, Bug

#34302461)

• Coercion of collations for comparisons of two string values was dependent upon the order of the

operands. Given one string using the utf8mb4 character set and one using utf8mb3, the comparison

was carried out using the utf8mb4 collation when the left operand was utf8mb4, and utf8mb3 when

the left operand was utf8mb3.

The root of the problem was with the special handling used for coercion of ASCII strings; since both

strings were literals, they were scanned for ASCII and non-ASCII characters, and the repertoire property

MySQL 8.0 Release Notes

set according to this. This meant that it was possible for one string to be treated as ASCII while the other

string was not; when the utf8mb4 string was considered ASCII and thus compatible with the utf8mb3

string it was (wrongly) converted prior to the comparison.

We fix this by using the internal MY_CS_PUREASCII property rather than MY_REPERTOIRE_ASCII;

MY_CS_PUREASCII is derived strictly from the character set, and not the actual string, which makes

determination of collation deterministic. Now in such cases, neither string is identified as ASCII, which

leads to conversion of the utf8mb3 to utf8mb4 before the comparison is performed, as expected. (Bug

#33801312)

• The scope of the connect_timeout limit was extended to full-packet reads. (Bug #33723597)

References: See also: Bug #34574013.

• New validation was added to ensure that the Event Scheduler restarts automatically on the server as

expected. (Bug #33711304)

References: See also: Bug #33539082.

• When a prepared statement was executed with no cursor, it could return the wrong result if the previous

execution used a cursor. This issue is fixed by creating and saving two query result objects, one for use

with a cursor and one for use without a cursor. The objects are created on demand, so if a prepared

statement is never used with cursors, the cursor-specific query result object is never created. (Bug

#33535746)

• A prepared statement with parameters could fail to update a row, but the same statement with the same

data did update the row when issued as a query. The fix for the problem is to assign a default data type

to the parameters, although this can be inefficient because there is no context available for data type

propagation and a character string type is given implicitly. In this case, the best practice is to wrap such

parameter declarations in CAST clauses that supply the desired data types. (Bug #33521861)

• For a table using the FEDERATED storage engine, if consecutive queries on the local server had a

delay between them that exceeded the remote server’s wait timeout (wait_timeout setting), a packet

error was returned on the local server. The timeout error from the remote server is now handled correctly

by the local server, and it reconnects and executes the statement again. (Bug #33500956)

• Handled an unexpected condition which could arise during join optimization. (Bug #31401468)

References: See also: Bug #34350945.

• Following execution of SET @@character_set_client = @@character_set_system, optimizer

hints were not parsed correctly. (Bug #107820, Bug #34370403)

• A query performing a full-text search in boolean mode on a column of a MyISAM table led to an assertion

in debug builds when the column was not of a string type. This was due to the fact that MyISAM allows

MATCH columns without indexes in boolean mode, and therefore also allows integer columns, which are

subject to constant propagation. Such queries on tables using any storage engine other than MyISAM

were not affected by this issue.

This is fixed by disabling constant propagation on the MATCH clause when the column is not of a

string type, so that we can safely assume that it contains only column references. (Bug #107638, Bug

#34311472)

• Corrected errors in comments in my_time.cc. Our thanks to Dimitry Kudryavtsev for the contribution.

(Bug #107633, Bug #34308417)

• Following changes to connection error handling in MySQL 8.0.24, if an error such as exceeding

max_allowed_packet caused the mysql client to disconnect from the server, the error was not reset

MySQL 8.0 Release Notes

afterwards to indicate the disconnect. On subsequent queries, the original error was returned, and

automatic reconnection did not take place because the mysql client did not have a disconnection error.

The error is now reset to indicate disconnection and allow clients to reconnect. (Bug #107605, Bug

#34303841)

• Following a bug fix in MySQL 8.0.29, if the password was provided in an option file, the mysql client did

not prompt for a password if the -p option was specified at login. The client now always prompts for a

password when the -p option is specified and uses the specified password, even if an alternative was

populated from an option file. (Bug #107205, Bug #34134984)

• The alternative for the deprecated --ssl=off server option to disable the use of encrypted connections

was not working as documented, or as presented in the deprecation warning. Setting the tls_version

system variable to the empty value (tls_version='') now works correctly for this purpose. (Bug

#106459, Bug #33858646)

• An aggregate query on a BIT column returned a value that was formatted as a bit string, but also had

the BINARY flag added automatically. New validation now checks for and skips setting the BINARY flag

for BIT results. (Bug #106241, Bug #33781442)

• SHOW SLAVE STATUS and SHOW SLAVE HOSTS used more CPU following the introduction of SHOW

REPLICA STATUS and SHOW REPLICA HOSTS than previously. (Bug #105924, Bug #33684069)

• When a NO_SKIP_SCAN hint referred to a specific index not to be used for a table skip scan, all other

possible indexes were also ignored, and, thus, a skip scan was not used for any indexes on the table.

This occurred because processing was not performed for all possible keys for a skip scan if the

NO_SKIP_SCAN hint was not applicable to all indexes. (Bug #104670, Bug #33251616)

• Queries using WHERE column IN (list) took an increasingly excess amount of CPU time as the list

of values grew in length. (Bug #102037, Bug #32311183)

Changes in MySQL 8.0.30 (2022-07-26, General Availability)

• Character Set Support

• Compilation Notes

• Deprecation and Removal Notes

• Generated Invisible Primary Keys (GIPKs)

• Keyring Notes

• Performance Schema Notes

• Pluggable Authentication

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• XA Transaction Notes

• Functionality Added or Changed

• Bugs Fixed

MySQL 8.0 Release Notes

Character Set Support

• Important Change: A previous change renamed character sets having deprecated names prefixed with

utf8_ to use utf8mb3_ instead. In this release, we rename the utf8_ collations as well, using the

utf8mb3_ prefix; this is to make the collation names consistent with those of the character sets, not

to rely any longer on the deprecated collation names, and to clarify the distinction between utf8mb3

and utf8mb4. The names using the utf8mb3_ prefix are now used exclusively for these collations

in the output of SHOW statements such as SHOW CREATE TABLE, as well as in the values displayed

in the columns of Information Schema tables including the COLLATIONS and COLUMNS tables. (Bug

#33787300)

References: See also: Bug #30624990.

• Important Change: When more than one language had the same collation definition, MySQL

implemented collations for only one of the languages. This meant that some languages were covered

only by utf8mb4 Unicode 9.0 collations that are specific to other languages. This release fixes such

MySQL 8.0 Release Notes

issues by adding language-specific collations for those languages that were previously covered only by

language-specific collations for other languages. The new collations are listed here:

• Norwegian

• (Bokmål) utf8mb4_nb_0900_ai_ci

• (Bokmål) utf8mb4_nb_0900_as_cs

• (Nynorsk) utf8mb4_nn_0900_ai_ci

• (Nynorsk) utf8mb4_nn_0900_as_cs

• Serbian with Latin characters:

• utf8mb4_sr_latn_0900_ai_ci

• utf8mb4_sr_latn_0900_as_cs

• Bosnian with Latin characters:

• utf8mb4_bs_0900_ai_ci

• utf8mb4_bs_0900_as_cs

• Bulgarian:

• utf8mb4_bg_0900_ai_ci

• utf8mb4_bg_0900_as_cs

• Galician:

• utf8mb4_gl_0900_ai_ci

• utf8mb4_gl_0900_as_cs

• Mongolian with Cyrillic letters:

• utf8mb4_mn_cyrl_0900_ai_ci

• utf8mb4_mn_cyrl_0900_as_cs

For more information, see Language-Specific Collations. (Bug #31885256, WL #14307)

Compilation Notes

• On Enterprise Linux, fixed ADD_LINUX_RPM_FLAGS so that the initial values of CMAKE_C_FLAGS

and CMAKE_CXX_FLAGS are used before modifying them. (Bug #34131794)

References: This issue is a regression of: Bug #33730302.

• Added a new SHOW_SUPPRESSED_COMPILER_WARNINGS CMake option. Enable it to show

suppressed compiler warnings, and do so without failing with -Werror. It defaults to OFF. (Bug

#34046748)

• Added macOS/ARM support. (Bug #34017614)

MySQL 8.0 Release Notes

• On Windows, deprecation warnings (C4996) were globally disabled with the /wd4996 command-

line option; now deprecation warnings are disabled on the localized level where appropriate. (Bug

#33975638)

• On Windows, improved the generated INFO_BIN and INFO_SRC files. (Bug #33972317, Bug

#34052301)

• Improved GCC 8 support to include -lstdc++fs in order to use std::filesystem. (Bug #33939798)

Deprecation and Removal Notes

• Replication: Setting the replica_parallel_workers system variable (or the equivalent server

option --replica-parallel-workers) to 0 is now deprecated, and doing so now raises a warning.

To achieve the same result (that is, use single threading) without the warning, set

replica_parallel_workers=1 instead. (WL #13956)

• The --skip-host-cache server option is now deprecated, and subject to removal in a future release.

Use a statement such as SET GLOBAL host_cache_size = 0, or set host_cache_size in the

my.cnf file, instead. (WL #14359)

• The --old-style-user-limits option causes the server to enforce user limits as they were prior

to MySQL 5.0.3, and is intended for backwards compatibility with very old releases. This option is now

deprecated, and using it now raises a warning. You should expect this option to be removed in a future

release of MySQL, and so you are advised to begin now to remove any dependency your MySQL

applications might have on this option. (WL #13228)

Generated Invisible Primary Keys (GIPKs)

• MySQL 8.0.30 now supports GIPK mode, which causes a generated invisible primary key (GIPK) to be

added to any InnoDB table that is created without an explicit primary key. This enhancement applies to

InnoDB tables only.

The definition of the generated key column added to an InnoDB table by GIPK mode is shown here:

my_row_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT INVISIBLE PRIMARY KEY

The name of the generated primary key is always my_row_id; you cannot, while GIPK mode is in effect,

use this as a column name in a CREATE TABLE statement that creates a new InnoDB table unless it

includes an explicit primary key.

GIPKs are not enabled by default. To enable them, set the

sql_generate_invisible_primary_key server system variable (also introduced in this release) to

ON. This setting has no effect on replication applier threads; this means that a replica never generates a

primary key for a replicated table that was not created on the source with a primary key.

You cannot alter a generated invisible primary key while GIPKs are in effect, with one exception: You

can toggle the visibility of the GIPK using ALTER TABLE tbl CHANGE COLUMN my_row_id SET

VISIBLE and ALTER TABLE tbl CHANGE COLUMN my_row_id SET INVISIBLE.

By default, generated invisible primary keys can be seen in the output of SHOW CREATE

TABLE and SHOW INDEX; they are also visible in MySQL Information Schema tables such

as the COLUMNS and STATISTICS tables. You can make them hidden instead by setting

show_gipk_in_create_table_and_information_schema to OFF.

MySQL 8.0 Release Notes

You can exclude generated invisible primary keys from the output of mysqldump using the --skip-

generated-invisible-primary-key option added in this release. mysqlpump also now supports a

--skip-generated-invisible-primary-key option which excludes GIPKs from its output.

For more information and examples, see Generated Invisible Primary Keys. For general information on

invisible column support in MySQL, see Invisible Columns. (Bug #34092605, WL #13784)

Keyring Notes

• The keyring_aws plugin has been updated to use the latest AWS Encryption SDK for C (version

1.9.186).

The keyring_aws_region variable supports the additional AWS regions supported by the new SDK.

Refer to the variable description for a list of supported AWS regions. (WL #14547)

Performance Schema Notes

• InnoDB: In the Performance Schema instrumentation for InnoDB read-write locks, lock acquisition

failures and successes for TRY (no-wait) operations were instrumented incorrectly. (Bug #34131395)

• Group Replication: Performance Schema now provides instrumentation for performance monitoring of

Group Replication memory usage.

See Monitoring Group Replication Memory Usage with Performance Schema Memory Instrumentation.

(WL #14726)

Pluggable Authentication

• The SASL LDAP plugin failed to properly parse Kerberos Key Distribution Center (KDC) host information

read from the Kerberos configuration file, resulting in SASL authentication error. (Bug #31862170)

Security Notes

• It is now possible to compile the MySQL server package (mysqld + libmysql + client tools) using

OpenSSL 3.0 on supported platforms, which should not change the behavior of the server or client

programs. For additional information, see https://wiki.openssl.org/index.php/OpenSSL_3.0. (WL #14683)

Spatial Data Support

• Previously, the ST_TRANSFORM() function added in MySQL 8.0.13 did not support Cartesian Spatial

Reference Systems. Beginning with this release, support is provided by this function for the Popular

Visualisation Pseudo Mercator (EPSG 1024) projection method, used for WGS 84 Pseudo-Mercator

(SRID 3857). (WL #11961)

SQL Syntax Notes

• It is now possible to determine whether a REVOKE statement which cannot be executed raises an error

or a warning. This is implemented with the addition of two new statement options, listed here with brief

descriptions:

• IF EXISTS causes REVOKE to raise a warning rather than an error as long as the target user or role

does not exist.

• IGNORE UNKNOWN USER causes REVOKE to raise a warning instead of an error if the target user or

role is not known, but the statement would otherwise succeed.

MySQL 8.0 Release Notes

For a single target user or role and a given privilege or role to be removed, using the IF EXISTS and

IGNORE UNKNOWN USER options together in the same REVOKE statement means that the statement

succeeds (albeit doing nothing, and with a warning), even if both the target user or role and the privilege

or role to be removed are unknown, as long as the statement is otherwise valid. In the case of multiple

targets, multiple privileges or roles to be removed, or both, the statement succeeds, performing those

removals which are valid, and issuing warnings for those which are not.

For more information, see REVOKE Statement. (Bug #102232, Bug #32495441, WL #14690)

XA Transaction Notes

• Replication; Group Replication: Previously, recovery was not guaranteed when a server node in a

replication topology unexpectedly halted while executing XA PREPARE, XA COMMIT, or XA ROLLBACK.

To address this problem, MySQL now maintains consistent XA transaction state across a topology using

either MySQL “classic” Replication or MySQL Group Replication when a server node is lost from the

topology and then regained. This also means that XA transaction state is now propagated so that nodes

do not diverge while doing work within a given transaction in the event that a server node halts, recovers,

and rejoins the topology.

For any multi-server replication topology (including one using Group Replication), the XA transaction

state propagates consistently, so that all servers remain in the same state at all times. For any such

topology of any size (including a single server, as long as binary logging is enabled), it is now possible

to recover any server to a consistent state after it has halted unexpectedly and been made to rejoin the

topology after dropping out.

This enhancement is implemented for the case of a single server by adding support for a two-phase

XA prepare between the storage engine and the server's internal transaction coordinator (ITC), with

the state of the prepare retained by both. This means that the ITC can purge its internal logs safely,

without the risk of losing state, should the server halt following the purge. In the single-node case,

imposing order of execution between the storage engine and the binary log prevents externalization

of GTIDs before the corresponding changes become visible to the storage engine; in a topology

comprising multiple servers, this keeps the transaction state from being broadcast to the topology before

it is guaranteed to be locally consistent and persistent. In all cases, the state of the XA transaction is

extracted from the last binary log file to be written and synchronized with the transaction state obtained

from the storage engine.

A known issue in this release can be encountered when the same transaction XID has been used

to execute XA transactions sequentially. If there a disruption in operation occurs while the server is

processing XA COMMIT ... ONE PHASE using this same XID, after the transaction has been prepared

in the storage engine, the state between the binary log and the storage engine can no longer be reliably

synchronized.

For more information, see XA Transactions. (WL #11300)

Functionality Added or Changed

• Important Change: Binary packages that include curl rather than linking to the system curl library have

been upgraded to use curl 7.83.1. (Bug #34138733)

• Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL

library for MySQL Server has been updated to version 1.1.1o. Issues fixed in OpenSSL version

1.1.1o are described at https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/

vulnerabilities.html. (Bug #34133985)

MySQL 8.0 Release Notes

• Important Change: The fido2 library included with MySQL, used with the authentication_fido

plugin, has been upgraded to version 1.8.0. (Previously, version 1.5.0 was included with MySQL.)

For more information, see FIDO Pluggable Authentication. (WL #15111)

• InnoDB: The innodb_doublewrite system variable, which enables or disables the doublewrite

buffer, has two new settings, DETECT_ONLY and DETECT_AND_RECOVER. With the DETECT_ONLY

setting, database page content is not written to the doublewrite buffer, and recovery does not use

the doublewrite buffer to fix incomplete page writes. This lightweight setting is intended for detecting

incomplete page writes only. The DETECT_AND_RECOVER setting is equivalent to the existing ON setting.

For more information, see Doublewrite Buffer.

Thanks to Facebook for the contribution. (Bug #32727919, Bug #103211, WL #14719)

• InnoDB: InnoDB now supports dynamic configuration of redo log capacity. The

innodb_redo_log_capacity system variable can be set at runtime to increase or decrease the total

amount of disk space occupied by redo log files.

With this change, the number of redo log files and their default location has also changed. From MySQL

8.0.30, InnoDB maintains 32 redo log files in the #innodb_redo directory in the data directory.

Previously, InnoDB created two redo log files in the data directory by default, and the number and size

of redo log files were controlled by the innodb_log_files_in_group and innodb_log_file_size

variables. These two variables are now deprecated.

When the innodb_redo_log_capacity setting is defined, innodb_log_files_in_group and

innodb_log_file_size settings are ignored; otherwise, those settings are used to compute the

innodb_redo_log_capacity setting (innodb_log_files_in_group * innodb_log_file_size

= innodb_redo_log_capacity). If none of those variables are set, redo log capacity is set to the

innodb_redo_log_capacity default value, which is 104857600 bytes (100MB).

Several status variables are provided for monitoring the redo log and redo log capacity resize operations.

As is generally required for any upgrade, this change requires a clean shutdown before upgrading.

For more information about this feature, see Redo Log. (WL #12527)

• Added Ubuntu 22.04 support. (Bug #34123545)

• The order of the columns in the primary key definition for a few tables in the mysql schema has been

changed, so that the columns containing the host name and user name are together in sequence at the

start of the primary key. ACL queries on these tables are performed using only the host name and user

name, and if those columns are not together in sequence, a full table scan must be performed to identify

the relevant record. Placing the host name and user name together means that index lookup can be

used, which improves performance for CREATE USER, DROP USER, and RENAME USER statements, and

for ACL checks for multiple users with multiple privileges.

The changed tables are mysql.db, mysql.tables_priv, mysql.columns_priv and

mysql.procs_priv. When you upgrade to MySQL 8.0.30 or later, these tables are modified in the

second step of the MySQL upgrade process. Use the --upgrade=FORCE option when performing

logical upgrades using a backup or export utility such as mysqldump or mysqlpump, which ensures

that the table structures are checked and rebuilt with the new column order. (Bug #33644645, Bug

#33637244, WL #14965)

• The myisam_repair_threads system variable and myisamchk --parallel-recover option were

removed. (Bug #31052408, WL #14938)

MySQL 8.0 Release Notes

• A new mysqldump option --mysqld-long-query-time lets you set a custom value of the

long_query_time system variable for mysqldump’s session. Use the new option to increase the

elapsed time allowed for mysqldump’s queries before they are written to the slow query log file, in order

to avoid unnecessary logging. Thanks to Facebook for the contribution. (Bug #96369, Bug #96369, Bug

#30110717, WL #13447)

• Error log components can now be loaded implicitly at startup before the InnoDB storage engine is

available. This new method of loading error log components loads and enables the components defined

by the log_error_services variable.

Previously, error log components had to be installed first using INSTALL COMPONENT and were

only loaded after InnoDB was fully available, as the list of components to load was read from the

mysql.components table, which is an InnoDB table.

Implicit load of error log components has these advantages:

• Log components are loaded early in the startup sequence, making logged information available

sooner.

• It helps avoid loss of buffered log information should a failure occur during startup.

• Loading log components using INSTALL COMPONENT is not required, simplifying error log

configuration.

For more information about this feature, see Error Log Configuration.

If you have previously installed loadable log components using INSTALL COMPONENT and you list those

components in a log_error_services setting that is read at startup (from an option file, for example),

your configuration should be updated to avoid startup warnings. For more information, see Error Log

Configuration Methods. (WL #14793)

• MySQL Enterprise Audit’s audit log file can now be extended with optional data fields to show the query

time, the number of bytes sent and received, the number of rows returned to the client, and the number

of rows examined. This data is available in the slow query log for qualifying queries, and in the context of

the audit log it similarly helps to detect outliers for activity analysis. It is delivered to the audit log through

new component services that you set up as an audit log filtering function. The extended data fields can

only be added when the audit log is in JSON format (audit_log_format=JSON), which is not the

default setting. (WL #14921)

• MySQL Server’s AES_ENCRYPT() and AES_DECRYPT() functions now support the use of a key

derivation function (KDF) to create a cryptographically strong secret key from information such as a

password or a passphrase that you pass to the function. The derived key is used to encrypt and decrypt

the data, and it remains in the MySQL Server instance and is not accessible to users. Using a KDF is

highly recommended, as it provides better security than specifying your own premade key or deriving it

by a simpler method when you use the function. The functions support HKDF (available from OpenSSL

1.1.0), for which you can specify an optional salt and context-specific information to include in the keying

material, and PBKDF2 (available from OpenSSL 1.0.2), for which you can specify an optional salt and

set the number of iterations used to produce the key. (WL #12669, WL #15188)

• A new system status variable Tls_library_version shows the runtime version of the OpenSSL

library that is in use for the MySQL instance. The version of OpenSSL affects features such as support

for TLSv1.3. (WL #13407)

• From MySQL 8.0.30, MySQL Enterprise Encryption’s functions are provided by a component, rather than

being installed from the openssl_udf shared library. The new functions provided by the component

use only the generally preferred RSA algorithm, not the DSA algorithm or the Diffie-Hellman key

MySQL 8.0 Release Notes

exchange method, and they follow current best practice on minimum key size. The component functions

also add support for SHA3 for digests (provided that OpenSSL 1.1.1 is in use), and do not require

digests for signatures, although they support them.

If you upgrade to MySQL 8.0.30 from an earlier release where the functions are installed manually from

the openssl_udf shared library file, the functions you created remain available and are supported.

However, these legacy functions are deprecated from this release, and it is recommended that you

install the component instead. The component functions are backward compatible, so RSA public

and private keys, encrypted data, and signatures that were produced by the legacy functions can

be used with the component functions. For the component functions to support decryption and

verification for content produced by the legacy functions, you must set the new system variable

enterprise_encryption.rsa_support_legacy_padding to ON (the default is OFF).

The component functions generate public and private RSA keys in PKCS #8 format. They

allow a minimum key size of 2048 bits, which is a suitable minimum RSA key length for current

best practice. You can set a maximum key size up to 16384 bits using the system variable

enterprise_encryption.maximum_rsa_key_size, which defaults to a maximum key size of 4096

bits. (WL #15024)

• Connections whose users have the CONNECTION_ADMIN privilege are not terminated when MySQL

Server is set to offline mode, which is done by changing the value of the offline_mode system

variable to ON. Previously, checking for connections that had the CONNECTION_ADMIN privilege could

cause a race condition because it involved accessing other threads. Now, a flag for each thread caches

whether or not the user for the thread has the CONNECTION_ADMIN privilege. The flag is updated if

the user privilege changes. When offline mode is activated for the server, this flag is checked for each

thread, rather than the security context of another thread. This change makes the operation threadsafe.

In addition, when offline mode is activated, connections whose users have the SYSTEM_USER privilege

are now only terminated if the user that runs the operation also has the SYSTEM_USER privilege. Users

that only have the SYSTEM_VARIABLES_ADMIN privilege, and do not have the SYSTEM_USER privilege,

can set the offline_mode system variable to ON to activate offline mode. However, when they run

the operation, any sessions whose users have the SYSTEM_USER privilege remain connected, in

addition to any sessions whose users have the CONNECTION_ADMIN privilege. This only applies to

existing connections at the time of the operation; users with the SYSTEM_USER privilege but without the

CONNECTION_ADMIN privilege cannot make new connections to a system in offline mode. (WL #14317)

Bugs Fixed

• InnoDB: A TRUNCATE TABLE operation failed to remove data dictionary entries for columns that were

dropped using ALGORITHM=INSTANT.

Thanks to Marcelo Altmann for the contribution. (Bug #34302445)

• InnoDB: An incorrect nullable column calculation on tables with instantly added columns caused data to

be interpreted incorrectly. (Bug #34243694)

• InnoDB: After upgrading to MySQL 8.0.29, a failure occurred when attempting to access a table with an

instantly added column. (Bug #34233264)

• InnoDB: Only the physical position of instantly added columns was logged, which was not sufficient for

index recovery. The logical position of columns was also required. (Bug #34181432)

• InnoDB: The field_phy_pos debug variable in the InnoDB sources was not updated for child tables

during a cascading update operation. (Bug #34181419)

MySQL 8.0 Release Notes

• InnoDB: Some instances of the rec_get_instant_row_version_old() function in the InnoDB

sources did not check for row versioning. (Bug #34173616)

• InnoDB: The read_2_bytes() function in the InnoDB sources, which reads bytes from the log buffer,

returned a null pointer. (Bug #34173425)

• InnoDB: In a specific locking scenario, an implicit lock was not converted to an explicit lock as expected,

triggering a lock_rec_has_expl(LOCK_X | LOCK_REC_NOT_GAP, block, heap_no, trx)

debug assertion failure. (Bug #34123159)

• InnoDB: A check that determines if a table has instantly added columns was performed for each

column, which affected the performance of ADD and DROP COLUMN operations on tables with numerous

columns. The check is now performed once per table. (Bug #34112147)

• InnoDB: A workload that generated a large number of lock requests and numerous timeouts caused

a long semaphore wait failure. To address this issue, optimizations were implemented to reduce the

number of exclusive global lock system latches. (Bug #34097862)

• InnoDB: The m_flush_bit in the redo log block header, which was set for the first block of multiple

blocks written in a single log write call, provided no benefit and has been removed. (Bug #34091444)

• InnoDB: Fixed clang-tidy and cppcheck warnings, which included the removal of unused code and

unnecessary checks. (Bug #33957087)

• InnoDB: Recovery of a redo log file mini-transaction (mtr) caused a debug assertion failure on a

MySQL Server instance with a small innodb_log_buffer_size setting.

Thanks to Mengchu Shi for the contribution. (Bug #33945602)

• InnoDB: Compiling with the WITH_VALGRIND source configuration option produced Wunused-

variable warnings. (Bug #33899862)

• InnoDB: Multiple issues with the lock-free hash table (ut_lock_free_hash_t) were addressed. (Bug

#33830934)

• InnoDB: A query on a generated column with a secondary index caused a failure. The field number

representing the position of the generated column was not valid. (Bug #33825077)

• InnoDB: Memory consumption was greater than expected when updating and inserting rows with multi-

valued index columns. The memory allocated for multi-valued columns for each row update was held

until the file handle was released. (Bug #33766482)

• InnoDB: The UT_LOCATION_HERE structure in the InnoDB sources was not used consistently. (Bug

#33436161)

• InnoDB: A table object needed to retrieve an array of values from a multi-valued index column when

computing the value of a generated column was unavailable. (Bug #32725063)

• InnoDB: A 4GB tablespace file size limit on Windows 32-bit systems has been removed. The limit was

due to an incorrect calculation performed while extending the tablespace. (Bug #28934351)

• InnoDB: Hash and random generator functions in the InnoDB sources were improved. (Bug #16739204,

Bug #23584861)

• InnoDB: A DROP TABLE operation on a table with a discarded tablespace caused an unnecessary

assertion failure. (Bug #107207, Bug #34135187)

• InnoDB: A query on a table with a JSON column returned only a partial result set after adding a multi-

valued index. (Bug #106621, Bug #33917625)

MySQL 8.0 Release Notes

• InnoDB: Purging a record with multiple binary large object values raised an insertion failure due to a

mini-transaction (mtr) conflict. (Bug #105592, Bug #33574272)

• InnoDB: Enabling the adaptive hash index (AHI) on a high-concurrency instance caused temporary AHI

search latch contention while the hash index was being built.

Thanks to Zhou Xinjing from CDB Team at Tencent for the patch. (Bug #100512, Bug #31750840)

• Packaging: The SASL LDAP clientside plugin was missing from the MySQL Community packages for

Windows.

• Replication: When a table definition diverged between the source and the replica because the replica

had an extra primary key, updates and deletes on the replica would fail if that table had an index that

was present both on the source and the replica. Primary keys for an InnoDB table are automatically

included in all indexes, and the replication applier needs values for all parts of the key to be included in

an event in order to search the index. Previously, the applier checked that all the user-defined key parts

were present, but the check did not cover hidden primary keys that were automatically included. The

applier now validates that both user-defined and automatically included key parts are present in an event

before using the index to search the data. (Bug #34122738)

• Replication: The write sets extracted by MySQL Replication from transactions when the

transaction_write_set_extraction system variable is enabled (which is the default) are

extracted from primary keys, unique keys, and foreign keys. They are used to detect dependencies and

conflicts between transactions. Previously, write sets involving multi-column foreign keys were incorrectly

identifying each column as a separate foreign key. The issue has now been fixed and foreign key write

sets include all referenced key columns. (Bug #34095747, Bug #34144531)

• Replication: When row-based replication was in use, a replica could sometimes override the SQL mode

value that was sent by the source, in an attempt to avoid issues with additional columns on the slave. In

extreme cases this could lead to data divergence. The problem has been corrected so the replica now

preserves the source’s SQL mode wherever possible. (Bug #33945038)

• Replication: MySQL’s semisynchronous replication did not respect the value of the

net_read_timeout system variable and forced a read timeout of one millisecond. This could result

in the function experiencing partial reads of acknowledgment messages and packets arriving out

of order, while other connections in the MySQL system were functioning correctly. The value of the

net_read_timeout system variable is now applied to connections for semisynchronous replication.

(Bug #101056, Bug #31976209)

• Replication: When the --replicate-same-server-id option was used to make the replica not skip

events that have its own server ID, if the log file was rotated, replication stopped with an error. The log

rotation event now checks and applies the current value of the option. (Bug #89375, Bug #27492990)

• Group Replication: The COUNT_TRANSACTIONS_REMOTE_IN_APPLIER_QUEUE column in

the Performance Schema table replication_group_member_stats could persistently show

transactions related to view change events (View_change_log_event) that had already been

applied. These events are queued in the Group Replication applier channel but applied in the Group

Replication recovery channel, causing a race condition that could result in the counter decrement

being lost. The increment of the count now takes place at a more suitable point, and the counter for

COUNT_TRANSACTIONS_REMOTE_IN_APPLIER_QUEUE is also now set to zero when the applier is not

busy. (Bug #33602354, Bug #33674059)

• Group Replication: A deadlock could occur in Group Replication when a member was interacting with

the service infrastructure, such as a joining member checking for incompatible configuration and then

leaving the group due to it. The issue has now been fixed. (Bug #32688091)

MySQL 8.0 Release Notes

• Group Replication: The message logged when a member tries to rejoin a Group Replication

topology when there is an old incarnation of the same server still present has been upgraded from an

informational note to a warning message. (Bug #32651024)

• API: Applications that previously used the MySQL client library to perform an automatic reconnection to

the server received the following mysql_query error after the server was upgraded:

[4031] The client was disconnected by the server because of inactivity. See wait_timeout and

interactive_timeout for configuring this behavior. (Bug #105229, Bug #34007830)

• Pushing a condition down to a derived table was not handled correctly in all cases. (Bug #34311090)

• After pushing down a condition to a derived table having a set operation, while folding an always true

boolean condition, the rewrite was not correct due to not setting abort_on_null to true for the cloned

condition when making a copy during condition pushdown to a derived table with a set operation. (Bug

#34298238)

• A missing error return when processing an invalid ORDER BY expression in a view definition led to an

assert in debug builds. (Bug #34239456)

• MySQL Server would not compile with the latest version of Visual Studio 2022. (Bug #34231639)

• While attempting to clone a system variable during condition pushdown, the server sometimes could not

determine the correct context of the cloned expression.

To prevent this, we disallow condition pushdown to derived tables when they use system variables, or if

the underlying expressions in the derived table contain system variables. (Bug #34205559)

• Added Enterprise Linux 9 (EL9) support. (Bug #34190004)

• On macOS 11, MySQL Server did not have the correct entitlement to generate a core dump in the event

of an unexpected server halt. A build option WITH_DEVELOPER_ENTITLEMENTS has been added to

allow a build to generate core dumps. (Bug #34163987)

• Improved error handling for '-DWITH_LIBEVENT=system' and '-DWITH_EDITLINE=system' on systems

missing libevent-devel or libedit-devel. (Bug #34131334, Bug #34123545)

• The fix for Bug #33830493 in MySQL 8.0.29 addressed the situation where if a MySQL instance stopped

unexpectedly or was restarted shortly after a SET PERSIST statement was used to record system

variable settings, the configuration file mysqld-auto.cnf could be left empty, in which case the server

restart could not proceed. The persisted system variables are now written to a backup file, which is only

renamed to mysqld-auto.cnf after the success of the write has been verified, leaving the original

mysqld-auto.cnf file still available. On a restart, if a backup file with valid contents is found, the

server reads from that file. Otherwise the mysqld-auto.cnf file is used and the backup file is deleted.

The file was not flushed to disk by this fix, so it was still possible for the issue to occur. This patch adds

those operations. (Bug #34122866)

• Fixed the -DENABLE_GCOV CMake option. (Bug #34113243)

• The SENSITIVE_VARIABLES_OBSERVER privilege, introduced in MySQL 8.0.29, is now granted to

users with the SYSTEM_VARIABLES_ADMIN privilege during upgrade. Previously, the privilege was not

granted to any database user during upgrade. (Bug #34068378)

• A select from a view that used left joins did not return any results. (Bug #34060289)

• Under certain circumstances TRUNCATE performance_schema.accounts caused duplicated counts

in global_status.

MySQL 8.0 Release Notes

This occurred if some hosts were not instrumented. For example, if

performance_schema_hosts_size was set to a low value.

Our thanks to Yuxiang Jiang and the Tencent team for the contribution. (Bug #34057013, Bug #106939)

• It was possible under certain conditions for EXPLAIN ANALYZE to attempt access of an iterator that did

not exist. (Bug #34051681)

References: This issue is a regression of: Bug #33905399.

• Support was added for compiling the keyring_oci plugin with OpenSSL 3. (Bug #34043013)

• Corrected two issues found with EXPLAIN ANALYZE:

• Timings displayed as actual time were not cumulative.

• For a materialized table, the output now show the number of rows materialized, rather than the

number of rows read from the materialized table.

(Bug #34025798, Bug #34135465)

References: See also: Bug #33834146, Bug #34678179.

• Events recorded in the Performance Schema tables for thread creation and deletion were retained until

server shutdown, instead of being removed when the client connection ended. Thread creation and

deletion now takes place after the Performance Schema instrumentation is created for the user session,

so it is cleaned up when the session ends. (Bug #34019988)

• Upgraded the bundled zlib library to zlib 1.2.12. Also made zlib 1.2.12 the minimum zlib version

supported, and removed WITH_ZLIB from the WITH_SYSTEM_LIBS CMake option. (Bug #34015600)

• The CONNECTION_ID() function, since it returns a session ID which remains constant for the lifetime of

the session, was treated as a constant function. This caused issues when CONNECTION_ID() was used

inside a trigger attached to a table which might be reused by other sessions. We fix this by making the

function const for execution, and returning the actual session ID when the function is evaluated. (Bug

#34009876)

• Executed codespell on the source code and fixed the reported spelling errors in the code comments.

(Bug #34006439)

• The MySQL Enterprise Encryption openssl_udf function library plugin was reimplemented to use

OpenSSL 3 APIs. (Bug #33992115)

• FEDERATED storage engine code was revised to address NULL pointer and variable access issues. (Bug

#33962357)

• Histograms in MySQL returned a selectivity estimate of 0 for values that outside buckets. This meant

that values might be missing from the histogram because they were missed during sampling, or because

the histogram had grown stale. To prevent this, we introduce a constant lower bound of 0.001 on the

selectivity estimates produced by histograms. This choice of lower bound corresponds to the selectivity

of a value or range that we are likely to miss during sampling.

Using a constant lower bound rather than a statistical estimate for the selectivity of a missing value has

the advantage of simplicity and predictability, and provides some protection against underestimating the

selectivity due to stale histograms and within-bucket heuristics.

For more information about histograms in MySQL, see Optimizer Statistics. (Bug #33935417)

MySQL 8.0 Release Notes

• For certain queries using a common table expression (CTE), EXPLAIN ANALYZE did not provide any

profiling data for the CTE even when the CTE was known to be executed. This happened when the

following conditions were met:

• The CTE was referenced more than once in the query plan.

• The first reference to the CTE (in the order of the output of EXPLAIN FORMAT=TREE) was never

executed.

• At least one of the subsequent references was executed at least once.

The problem was that the CTE plan was always printed when encountering the first reference to the

CTE; if that reference was never executed, the CTE was not materialized there; and thus there was no

profiling data to print.

The fix for this issue ensures that we print the CTE plan when it is first executed, that is, the point at

which it is materialized. The output then includes profiling data. If the CTE is never executed, we print

the plan at the last reference, when there is no profiling data. (Bug #33905399)

• The output from the command mysqld --verbose --help previously showed plugin load options as

ON even when they were off by default, or turned off using an option. The output now shows the current

value for the plugin. (Bug #33870892)

• The Server now bundles curl (7.83.1) and only uses it when alternative SSL systems are used, such as

openssl11 on EL7. (Bug #33859507, Bug #34154806)

• Debug MySQL binaries can now be built using -0g and -fno-inline. (Bug #33855533)

• The FIREWALL_EXEMPT privilege, introduced in MySQL 8.0.27, is now granted to users with the

SYSTEM_USER during upgrade. Previously, the privilege was not granted to any database user during

upgrade. (Bug #33854409)

• A correlated subquery did not use a functional index as expected. This occurred when an outer column

reference used inside the subquery was not considered as constant for subquery execution, which

allowed consideration of the functional index to be skipped.

We fix this problem by making sure to consider the outer column reference as constant while executing

the subquery. (Bug #33851055)

• Added alternate OpenSSL system package support by passing in openssl11 on EL7 or openssl3 on EL8

to the WITH_SSL Cmake option. Authentication plugins, such as LDAP and Kerberos, are disabled as

they do not support these alternative versions of OpenSSL. (Bug #33835934)

• Prepared statements with subqueries that accessed no tables, but the subquery evaluation raised an

error, triggered an assert failure in debug builds. (Bug #33773799)

• Some stored functions were not executed correctly following the first invocation. (Bug #33754993)

• When performing a query using a recursive common table expression (CTE) with a removal of a query

expression after constant predicate elimination, it is expected that when the reference count of table

objects for the CTE temporary table reaches zero, it should be possible once again to recreate the table,

but in certain cases one of the table references was not properly recorded as attached to the CTE. (Bug

#33725503)

References: See also: Bug #32962511.

• Added a missing error return to the parser. (Bug #33725502)

MySQL 8.0 Release Notes

• A number of issues with pushdown of conditions making use of outer references, relating to work done

in MySQL 8.0.22 to implement condition pushdown for materialized derived tables, have been identified

and resolved. (Bug #33725403, Bug #33725500, Bug #33725508, Bug #33725534, Bug #33725545)

• The plan generated for a SELECT using a common table expression involves table materialization and

an index scan on the materialized table. Because the temptable engine does not yet support all index

scan methods, such queries might not always execute correctly.

With other MySQL engines, the materialization access path has special handling when the access path

is not considered basic; for temptable, an index scan was not considered basic, which led to undefined

behavior.

We fix this issue by considering the index scan access path basic, and thus avoiding use of any index

scan access methods on temptable tables. (Bug #33700735)

• The Data_free column in the INFORMATION_SCHEMA.FILES table was not updated after adding a

new data file to the InnoDB system tablespace. (Bug #33508534)

• If a plugin attempted to register a system variable with a name that duplicated that of an existing system

variable, the existing static system variable might be overwritten, and uninstalling the plugin might leave

pointers to the freed memory. The issues have now been fixed. (Bug #33451101)

• SHOW TABLES and SELECT * FROM INFORMATION_SCHEMA.TABLES did not return any results from

the Performance Schema if the user had access privileges on individual Performance Schema tables,

only. (Bug #33283709)

• Calling a function relating to the data_masking plugin without first installing the plugin led to an

unplanned server shutdown. Functions relating to this plugin are initialized by calling init functions

which in turn access the UDF metadata service, but this is valid only when the data masking plugin is

installed. We fix this problem by adding a check to verify that the plugin is installed before initializing

such functions, and to return an appropriate error message if the plugin providing them is not installed.

(Bug #33234046)

• Under certain conditions, the server did not handle the expiration of max_execution_time or the

execution of a KILL statement correctly. (Bug #33218625)

• mysqlslap, which uses multiple threads to connect to the server, could not run with a user account

that used FIDO authentication. The issue has been fixed by an update to the FIDO library allowing the

authentication to be performed on multiple threads. (Bug #33067183)

• If an incorrect value was set for the binlog_checksum system variable during a session, a

COM_BINLOG_DUMP command made in the same session to request a binary log stream from a source

failed. The server now validates the specified checksum value before starting the checksum algorithm

setup process. (Bug #32442749)

• For slow query logging, the Slow_queries status variable was not implemented unless the slow query

log was enabled, contrary to the documentation. (Bug #28268680, Bug #91496)

• New parameters (examined_row_count, affected_row_count, and return_row_count) were

added to the audit plugin. Our thanks to J D for the contribution. (Bug #110628, Bug #35267239)

• A prepared statement could accept an empty string as a valid float value, which represents a regression

from 8.0.27 behavior. This fix explicitly checks that the length of an interpreted string is non-empty and

fully interpreted as a (float) number. In addition, new verification now ensures that:

• All numeric values are supported with empty strings and strings that are all spaces.

• Regular numeric values are supported, as well as numeric values with leading and trailing spaces.

MySQL 8.0 Release Notes

(Bug #107399, Bug #34213338)

References: This issue is a regression of: Bug #32213576.

• Upgrading to MySQL 8.0.29 led to issues with existing spatial indexes (see Creating Spatial Indexes).

The root cause of the problem was a change in how geographic area computations were performed

by the included Boost library, which was upgraded to version 1.77.0 in MySQL 8.0.29. We fix this by

ensuring that we accommodate the new method whenever such computations are performed. (Bug

#107320, Bug #34184111)

References: This issue is a regression of: Bug #33353637.

• When pushing a condition down to derived table for prepared statements, we clone a condition which

also includes parameters when a derived table contains unions. When a statement needed to be

reprepared during execution—for example, when the signedness of the value specified did not match

that of the actual datatype—the parameter was not cloned correctly resulting in errors. This occurred

because the value specified for the parameter was used to print the string for reparsing, instead of a

literal ? placeholder character.

Now in such cases we set a flag QT_NO_DATA_EXPANSION for printing parameters for reparsing which,

when enabled, causes the ? placeholder to be printed, rather than the actual value. (Bug #107230, Bug

#34148712)

• On MacOS, improved Boost library detection logic for Homebrew as a potentially incompatible system's

Boost version could get used even with -DWITH_BOOST set. (Bug #107151, Bug #34121866)

References: This issue is a regression of: Bug #33769505.

• On RHEL 7.x, fetching the CPU cache line size returned 0 on s390x RHEL 7.x which caused

rpl_commit_order_queue and integrals_lockfree_queue to fail.

Our thanks to Namrata Bhave for the contribution. (Bug #107081, Bug #34095278)

• When the mysql client was unable to reconnect to the server following an unexpected server halt,

the process of building the completion hash allocated memory that was not freed. The reconnection

operation now does not build the completion hash if the client fails to reconnect, and the memory

concerned is freed if the client is disconnected. (Bug #106864, Bug #34019571)

• Added a cycle timer for the s390x architecture.

Our thanks to Namrata Bhave for the contribution. (Bug #106824, Bug #33997819)

• In certain cases, incorrect results could result from execution of a semijoin with materialization, when

the WHERE clause of the subquery contained an equality. In some cases, such as when one side of such

an equality was an IN or NOT IN subquery, the equality was neither pushed down to the materialized

subquery, nor evaluated as part of the semijoin. This also caused issues with some inner hash joins.

(Bug #106710, Bug #106718, Bug #33952115, Bug #33957233)

References: See also: Bug #84705, Bug #25466100.

• Comparator functions for queries like (<date column> <non-date column>) IN ((val1,

val2), (val3, val4), …) could return the wrong results. (Bug #106567, Bug #33897969)

• Fixed an assert definition in SetOsLimitMaxOpenFiles; our thanks to hongyuan li for the contribution.

(Bug #106555, Bug #33893197)

MySQL 8.0 Release Notes

• Previously, it was assumed that, when the same non-nullable expression was used as both the first

and second arguments to LIKE, the result was always true, and so could be optimized away. This

assumption turns out not to be valid, due to the fact that LIKE treats the backslash (\) as an escape

character, even when ESCAPE is not specified. This led to different results when the condition was

used in the SELECT list as opposed to the WHERE clause. To fix the problem, we no longer perform this

optimization with LIKE, with or without an ESCAPE clause. (Bug #106444, Bug #33852756)

• In some cases, when arguments other than global transaction IDs (such as column values) were passed

to GTID_SUBSET(), the function returned values other than the expected NULL. (Bug #106298, Bug

#33793942)

• A problem with evaluation of general quantified comparison predicates occurred when the left-hand side

of the predicate was NULL. In such cases, the value of the subquery evaluation from the last current row

is saved, so that it does not need re-evaluation, but the cached value (result_for_null_param) was

not cleared between executions, so that the next execution could re-use the result from the previous

execution. One consequence of this was that, when a subquery execution first caused zero rows to

match from the subquery—which for an ALL predicate should return TRUE—a subsequent execution

causing at least one row to match also returned TRUE, even though FALSE was expected.

To solve this issue, we now make sure to clear result_for_null_param while cleaning up the

subquery predicate following execution. (Bug #106164, Bug #33755139)

• Test cases executed with the --async-client option and shutdown commands caused mysqltest

to halt unexpectedly. (Bug #105797, Bug #33643149)

• MySQL supports the use of equiheight histograms to improve selectivity estimates. Each bucket in an

equiheight histogram for a column should contain roughly the same number of values (rows); keeping

the buckets small helps minimize any error.

When constructing an equiheight histogram, too many values were sometime placed in the same

bucket, which could result in substantial errors in selectivity estimation. We fix this by introducing a new

equiheight construction algorithm that guarantees low error, and adapts to the distribution of the data

to make efficient use of its buckets. In addition, a new estimator for the number of distinct values in

histogram buckets provides improved worst-case error guarantees.

See The INFORMATION_SCHEMA COLUMN_STATISTICS Table, and Optimizer Statistics, for more

information. (Bug #104789, Bug #33302021)

• Deprecation warnings returned to client programs were sent to stdout rather than stderr, which in

the case of mysqldump could mean that the dump file no longer worked because the warnings were

included in it. The issue has now been fixed and the warnings are sent to stderr. (Bug #104769, Bug

#33733529)

• Extended support for chained SSL certificates. (Bug #54158, Bug #27491518)

Changes in MySQL 8.0.29 (2022-04-26, General Availability)

Important

This release is no longer available for download. It was removed due to a critical

issue that could cause data in InnoDB tables having added columns to be

interpreted incorrectly. Please upgrade to MySQL 8.0.30 instead.

• Authentication Notes

• Character Set Support

MySQL 8.0 Release Notes

• Compilation Notes

• Deprecation and Removal Notes

• SQL Function and Operator Notes

• Optimizer Notes

• Performance Schema Notes

• Security Notes

• SQL Syntax Notes

• Test Suite Notes

• XA Transaction Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Authentication Notes

• The maximum size of FIDO authenticator data was increased. (Bug #33655192)

Character Set Support

• Important Note: The server now uses utf8mb3 rather than utf8 in the following cases:

• In the output of SHOW SQL statements (SHOW CREATE TABLE, SHOW CREATE VIEW, SHOW CREATE

DATABASE)

• When reporting invalid strings.

(Bug #33385252, Bug #33395007)

• The server now uses utf8mb3 in place of the alias utf8 for character set names when populating

data dictionary tables from built-in character sets. This affects the display of character set and related

information in the MySQL Information Schema tables listed here:

• CHARACTER_SETS

• COLLATIONS

• COLUMNS

• COLLATION_CHARACTER_SET_APPLICABILITY

• PARAMETERS

• ROUTINES

• SCHEMATA

This change also affects the output of the SQL SHOW CHARACTER SET, SHOW COLLATION, SHOW

CREATE DATABASE, and SHOW CREATE TABLE statements. (Bug #30624990)

MySQL 8.0 Release Notes

Compilation Notes

• InnoDB: After addressing the associated issues, the C4100, C4127, C4245 and C4389 MSVC++ level 4

compiler warnings were re-enabled. (Bug #33437498, Bug #33571677)

• GCC 11 is now a supported compiler for building MySQL on EL7 or EL8. This compiler is available in

the devtoolset-11 (EL7) or gcc-toolset-11 (EL8) package. It is also recommended to use GCC

11 when building third-party applications that are based on the libmysqlclient C API library. (Bug

#33730302)

• The server could not be compiled with Bison 3.8.1 or newer. (Bug #33488047)

Deprecation and Removal Notes

• Important Change: Previously, MySQL allowed arbitrary delimiters and an arbitrary number of them in

TIME, DATE, DATETIME, and TIMESTAMP literals, as well as an arbitrary number of whitespaces before,

after, and between the date and time values in DATETIME and TIMESTAMP literals. This behavior is now

deprecated, and you should expect it to be removed in a future version of MySQL. With this release, the

use of any nonstandard or excess delimiter or whitespace characters now triggers a warning of the form

Delimiter 'char' in position pos in datetime value 'value' at row rownum is

superfluous and is deprecated, followed by Please remove, or in cases in which a suitable

replacement can be suggested, Prefer the standard 'replacementchar'.

A deprecation warning is returned only for the first nonstandard delimiter or whitespace character

encountered in the literal value. An example is shown here:

mysql> SELECT DATE"2020/02/20";

+------------------+

| DATE"2020/02/20" |

+------------------+

| 2020-02-20 |

+------------------+

1 row in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS\G

*************************** 1. row ***************************

Level: Warning

Code: 4095

Message: Delimiter '/' in position 4 in datetime value '2020/02/20' at row 1 is

deprecated. Prefer the standard '-'.

1 row in set (0.00 sec)

Such warnings are not elevated to errors in strict mode.

For more information and examples, see String and Numeric Literals in Date and Time Context. (WL

#13601)

• Replication: The replica_parallel_type system variable is now deprecated; whenever this

variable is read or set, or the equivalent option is set in my.cnf, the server now issues a deprecation

warning, as shown here:

mysql> SELECT @@replica_parallel_type; SHOW WARNINGS\G

+-------------------------+

| @@replica_parallel_type |

+-------------------------+

| LOGICAL_CLOCK |

+-------------------------+

1 row in set, 1 warning (0.00 sec)

*************************** 1. row ***************************

MySQL 8.0 Release Notes

Level: Warning

Code: 1287

Message: '@@replica_parallel_type' is deprecated and will be removed in a future

release.

1 row in set (0.00 sec)

You should expect this variable and the equivalent server option --replica-parallel-type to be

removed in a future MySQL release.

• The myisam_repair_threads system variable and myisamchk --parallel-recover option are

deprecated; expect support for both to be removed in a future release of MySQL.

Values other than 1 (the default) for myisam_repair_threads produce a warning. (WL #14937)

• The server system variables query_prealloc_size and transaction_prealloc_size are now

deprecated, and setting either or both of these no longer has any effect in the MySQL server. Expect

them to be removed in a future MySQL release.

For more information, see the descriptions of these variables in the documentation (Server System

Variables). (WL #13720)

References: See also: Bug #26940369.

• The --abort-slave-event-count and --disconnect-slave-event-count options for mysqld,

previously used in testing, and not normally required in a production setting, have been deprecated.

Expect them to be removed in a future version of MySQL. (WL #14526)

SQL Function and Operator Notes

• Aggregate functions based on expressions comparing values with a NULL were not ignoring the NULL

correctly. (Bug #33624777, Bug #105762)

• When an aggregation function is evaluated during optimization, it is presumed that the WHERE

condition has already been evaluated; thus, it can be removed. Before the removal, the optimizer

verifies whether the WHERE condition has any table-independent conditions by making a call to

make_cond_for_table(). When a condition was considered expensive (for example, it used a stored

procedure), it was incorrectly assumed that there was a table-independent condition. We fix this by

excluding expensive conditions in the call to make_cond_for_table().

In addition, a constant condition which was expensive to evaluate, such as f() = 1 where function

f() did not use any tables, often led to incorrect results. In most cases, if a condition is constant

for execution, it is evaluated when optimizing the WHERE condition, skipping it if it is considered too

expensive. The present issue arose due to skipping the condition while optimizing an implicitly grouped

query. To avoid this, we now evaluate such conditions prior to aggregation. (Bug #33305617)

• Columns used by the DEFAULT() function were not marked internally as READ when fixing its

arguments. (Bug #33142135)

Optimizer Notes

• If the column of a table being loaded using LOAD DATA was used in the WHERE clause of a subquery

used inside a SET statement, the column was reported as unknown. (Bug #33714885)

• Aggregated queries that performed an index lookup (eq_ref) could in some cases return wrong results.

This was seen when the execution plan used streaming aggregation instead of aggregation in temporary

tables.

We fix this by disabling eq_ref caching below aggregate nodes. (Bug #33491183)

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #100614, Bug #31790217.

• The derived materialized table condition pushdown optimization can now be used with most unions.

This means that an outer WHERE condition can now be pushed down to every query block of the query

expression of the materialized derived table or view.

Suppose we create tables t1 and t2, and then the view v based on these two tables, using the SQL

statements shown here:

CREATE TABLE t1 (

id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,

c1 INT,

KEY i1 (c1)

);

CREATE TABLE t2 (

id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,

c1 INT,

KEY i1 (c1)

);

CREATE OR REPLACE VIEW v AS

SELECT id, c1 FROM t1

UNION ALL

SELECT id, c1 FROM t2;

Now, when the query SELECT * FROM v WHERE c1 = 12 is executed, the condition c1 = 12 is

pushed down to both query blocks of view v, as shown here in the output of EXPLAIN:

mysql> EXPLAIN FORMAT=TREE SELECT * FROM v WHERE c1 = 12\G

*************************** 1. row ***************************

EXPLAIN: -> Table scan on v (cost=1.26..2.52 rows=2)

-> Union materialize (cost=2.16..3.42 rows=2)

-> Covering index lookup on t1 using i1 (c1=12) (cost=0.35 rows=1)

-> Covering index lookup on t2 using i1 (c1=12) (cost=0.35 rows=1)

1 row in set (0.00 sec)

This can now be done for most UNION queries. For exceptions, and additional information, see Derived

Condition Pushdown Optimization. (Bug #24012, Bug #36802, Bug #106006, Bug #11746156, Bug

#11748590, Bug #13650627, Bug #30587347, Bug #33318096, Bug #33738597, WL #13730)

Performance Schema Notes

• New Performance Schema instrumentation collects information about whether a query was processed

on the PRIMARY or SECONDARY engine, where the PRIMARY engine is InnoDB and the SECONDARY

engine is HeatWave. This instrumentation is intended for use with MySQL Database Service with

HeatWave.

Two new Performance Schema table columns were added:

• An EXECUTION_ENGINE column that indicates whether a query was processed on the PRIMARY

or SECONDARY engine was added to the Performance Schema statement event tables (see

Performance Schema Statement Event Tables), and to the performance_scema.threads and

performance_scema.processlist tables.

• A COUNT_SECONDARY column that indicates the number of times a query was processed on the

SECONDARY engine was added to the Performance Schema statement summary tables (see

Statement Summary Tables).

MySQL 8.0 Release Notes

An execution_engine column was also added to the sys.processlist and sys.x$processlist

views in the MySQL sys Schema. (WL #14346)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL

Server has been updated to version 1.1.1n from 1.1.1l. Issues fixed in OpenSSL are described at

https://www.openssl.org/news/cl111.txt and at http://www.openssl.org/news/vulnerabilities.html. (Bug

#33840722, Bug #33970835)

SQL Syntax Notes

• An IF NOT EXISTS option is now supported for the statements CREATE FUNCTION, CREATE

PROCEDURE, and CREATE TRIGGER.

For CREATE FUNCTION, when used to create a stored function, and for CREATE PROCEDURE, this

option prevents an error from occurring if there is already a routine having the same name. For CREATE

FUNCTION, when used to create a loadable function, the option prevents an error in the event there

already exists a loadable function having that name. For CREATE TRIGGER, the option prevents an

error from occurring if there is already a trigger with the same name, on the same table, and in the same

schema. This is intended to improve ease of use for these statements in scripting, rapid (re)deployment,

replication, and other instances of potential repeated use.

This enhancement makes the syntax of these statements more consistent with that of CREATE

DATABASE, CREATE TABLE, CREATE USER, and CREATE EVENT, all of which already support IF

NOT EXISTS. This also provides a complement to the IF EXISTS option already supported by DROP

PROCEDURE, DROP FUNCTION, and DROP TRIGGER.

For more information, see Stored Objects, as well as Function Name Resolution. See also Replication of

CREATE TABLE ... SELECT Statements. (Bug #15287, Bug #11745440, WL #14722)

References: See also: Bug #33301931.

Test Suite Notes

• Null pointers now are checked to reduce heap-use-after-free errors under Valgrind with the --

async-client option. (Bug #33702755)

XA Transaction Notes

• Group Replication: Group replication in some scenarios faced problems because it was not possible

to commit an XA transaction prepared on another connection. To address such issues, MySQL now

supports detached XA transactions; once prepared, an XA transaction is no longer connected to the

current session. This happens as part of executing XA PREPARE. The prepared XA transaction can be

committed or rolled back by another connection, and the current session can then initiate another XA or

local transaction without waiting for the prepared XA transaction to complete.

Support for this feature can be disabled, and the classic behavior reinstated, by setting the

xa_detach_on_prepare system variable introduced in this release to OFF. The default is ON, which is

recommended, especially in a replication setting.

You should be aware that, when detached XA transaction support is enabled

(xa_detach_on_prepare = ON), it is not possible to use temporary tables within XA transactions.

MySQL 8.0 Release Notes

For more information, see XA Transaction States, as well as Server Instance Configuration. (Bug

#100163, Bug #31599926, WL #14700)

X Plugin Notes

• A difference in format between Unix socket lock files for classic MySQL protocol and X Protocol meant

that the server could not start if the file for the other protocol was present. For the benefit of instances

where it is not possible to remove the file manually, such as MySQL Database Service instances, the

protocols now use the same format for the file. (Bug #31468581)

Functionality Added or Changed

• InnoDB: To improve code quality and facilitate debugging, instances of #define in the InnoDB sources

were replaced by constexpr specifiers or inline functions. (WL #14680)

• InnoDB: InnoDB now supports ALTER TABLE ... DROP COLUMN operations using

ALGORITHM=INSTANT.

Operations that support ALGORITHM=INSTANT only modify metadata in the data dictionary. Table data

is unaffected, making the operations instantaneous. If not specified explicitly, ALGORITHM=INSTANT is

used by default by DDL operations that support it.

Prior to MySQL 8.0.29, an instantly added column could only be added as the last column of the table.

From MySQL 8.0.29, an instantly added column can be added to any position in the table.

Instantly added or dropped columns create a new row version. Up to 64 row versions are permitted. A

new TOTAL_ROW_VERSIONS column was added to the INFORMATION_SCHEMA.INNODB_TABLES table

to track the number of row versions.

For more information about DDL operations that support ALGORITHM=INSTANT, see Online DDL

Operations. (WL #13899)

• Replication: Automatic purging of binary log files by the server is now controlled using the

binlog_expire_logs_auto_purge system variable introduced in this release. By default, automatic

purging is enabled (binlog_expire_logs_auto_purge set to ON); to disable it, set the value of this

variable to OFF.

The interval to wait before purging is controlled by binlog_expire_logs_seconds and

expire_logs_days. Setting both of these system variables to 0 stops automatic purging from taking

place, even when binlog_expire_logs_auto_purge is set to ON. (WL #14930)

• Microsoft Windows: Added jemalloc support on Windows, and enabled it for official MySQL binaries.

The new WITH_WIN_JEMALLOC CMake option accepts a directory containing jemalloc.dll that's

copied to the same directory as mysqld.exe and/or mysqld-debug.exe and utilizes it for memory

management operations. Standard memory functions are used if jemalloc.dll is not found or does

not export the required functions. An INFORMATION level log message records whether or not jemalloc

is found and used. (WL #14633)

• The new clone_delay_after_data_drop variable permits specifying a delay period immediately

after removing existing data on the recipient MySQL Server instance at the start of a remote cloning

operation. The delay is intended to provide enough time for the file system on the recipient host to free

space before data is cloned from the donor MySQL Server instance. Certain file systems free space

asynchronously in a background process. On these file systems, cloning data too soon after dropping

existing data can result in clone operation failures due to insufficient space. The maximum delay period

is 3600 seconds (1 hour). The default setting is 0 (no delay). (Bug #32826134, WL #14857)

MySQL 8.0 Release Notes

• The group_replication_set_as_primary function appoints a specified group member as the new

primary and overrides the election process. Previously, the function waited for all active transactions on

the existing primary to end, including incoming transactions after the function was used, before making

the current primary read only and changing to the new primary. There was no upper limit to the wait time.

An optional timeout parameter is now available to let you set a timeout for running transactions. You

can set a timeout from 0 seconds (immediately) up to 3600 seconds (60 minutes) for transactions that

are running when you use the function. There is no default setting for the timeout, so if you do not set

it the former behavior of the function still applies, with no upper limit to the wait time. When the timeout

expires, for any transactions that did not yet reach their commit phase, the client session is disconnected

so that the transaction does not proceed. Transactions that reached their commit phase are allowed to

complete. When you set a timeout, it also prevents new transactions starting on the primary from that

point on. Explicitly defined transactions (with a START TRANSACTION or BEGIN statement) are subject

to the timeout, disconnection, and incoming transaction blocking even if they do not modify any data. To

allow inspection of the primary while the function is operating, single statements that do not modify data,

as listed in Permitted Queries Under Consistency Rules, are permitted to proceed. (WL #14585)

• MySQL Server now has the capability to securely store persisted system variable values containing

sensitive data such as private keys or passwords, and restrict viewing of the values. No MySQL Server

system variables are currently marked as sensitive, but the new capability allows system variables

containing sensitive data to be persisted securely in the future. A keyring component must be enabled on

the MySQL Server instance to support secure storage for persisted system variable values, rather than a

keyring plugin, which do not support the function.

In the operating system file where persisted system variables are stored, the names and values of

sensitive system variables are stored in an encrypted format, along with a generated file key to decrypt

them. The generated file key is in turn encrypted using a master key that is stored in a keyring. After

upgrading to MySQL 8.0.29, the format of the mysqld-auto.cnf option file remains the same

until the first time a SET PERSIST or SET PERSIST ONLY statement is issued, and at that point it is

changed to a new format, even if the system variable involved is not sensitive. In the new format, the

option file cannot be read by older releases of MySQL Server.

The new system variable persist_sensitive_variables_in_plaintext controls whether

the server is permitted to store the values of sensitive system variables in an unencrypted format,

if keyring component support is not available at the time when SET PERSIST is used to set the

value. The default setting, ON, encrypts the values if keyring component support is available, and

persists them unencrypted (with a warning) if it is not. This setting also allows the server to start if

encrypted system variable values cannot be decrypted, in which case their defaults are used. When

persist_sensitive_variables_in_plaintext is set to OFF, which is the most secure setting,

sensitive system variable values cannot be persisted if keyring component support is unavailable, and

the server does not start if encrypted system variable values cannot be decrypted.

The values of sensitive system variables are also protected when they are handled. If a

SET statement is issued for a sensitive system variable, the query is rewritten to replace the

value with “redacted” before it is logged to the general log and audit log. The new privilege

SENSITIVE_VARIABLES_OBSERVER allows a holder to view the values of sensitive system

variables in the Performance Schema tables global_variables, session_variables,

variables_by_thread, and persisted_variables, to issue SELECT statements to return their

values, and to track changes to them in session trackers for connections. Users without this privilege

cannot view those system variable values. (WL #13469)

• The keyring_okv keyring plugin, which uses the Key Management Interoperability Protocol (KMIP) to

communicate securely, is used with MySQL’s keyring service to store keyring data in a KMIP-compatible

back end keyring storage product such as Oracle Key Vault, Gemalto SafeNet KeySecure Appliance,

Townsend Alliance Key Manager, and Entrust KeyControl. The plugin now allows you to specify more

MySQL 8.0 Release Notes

than one standby server to provide backup connections to the back end keyring storage product if the

primary server is unavailable. You can add up to 64 standby servers by editing the okvclient.ora

file to specify the IP addresses and port numbers of the servers as a comma-separated list in the value

of the STANDBY_SERVER variable. The plugin iterates over the standby servers until it can establish a

connection, with a 20-second wait for each connection attempt. You should therefore ensure that the

list of standby servers is kept short, accurate, and up to date, and servers that are no longer valid are

removed, as they can significantly affect the keyring_okv plugin’s connection time and therefore the

server startup time. (WL #14363)

• Isolation of access to system variables is now better enforced in the server code that parses, resolves,

and executes SQL statements accessing or updating such variables. (WL #14529)

• MySQL Server now supports SSL session reuse by default with a timeout setting to control how long the

server maintains a session cache that establishes the period during which a client is permitted to request

session reuse for new connections. All MySQL client programs support session reuse. For server-side

and client-side configuration information, see Reusing SSL Sessions.

In addition, C applications now can use the C API capabilities to enable session reuse for encrypted

connections (see SSL Session Reuse). (WL #13075)

Bugs Fixed

• InnoDB: A failure occurred when attempting to purge undo records for a table with an instantly added

column. (Bug #33924532)

• InnoDB: High-priority transactions were not permitted to stop waiting when interrupted or to timeout

while waiting for a lock, preventing deadlocks from being resolved. In cases where the blocking

transaction is also high-priority, high-priority transactions are now permitted to stop waiting when

interrupted or timeout when exceeding the lock wait timeout period. If a blocking transaction is not high-

priority, high-priority transactions wait for the blocking transaction to release its locks. (Bug #33856332)

• InnoDB: The AIO synchronization queue used on Windows was removed. The synchronous file I/O

read-write function (SyncFileIO::execute) was revised to handle files opened for both normal and

overlapped I/O, as it does on Linux. (Bug #33840645)

• InnoDB: Table version metadata was not reset after truncating all partitions of a table with an instantly

added column. (Bug #33822729)

• InnoDB: The srv_error_monitor_thread() function, which prints warnings about semaphore

waits, failed to handle a long semaphore wait as expected. To address this issue, a blocking call was

moved to a more appropriate location. Related monitor thread code was simplified and improved, and

missing shutdown signals were added for several server threads.

Enabling and disabling of the standard monitor by InnoDB is now performed independently of the user-

settable innodb_status_output variable. This change addresses an issue in which the monitor was

enabled by InnoDB in a particular scenario but not set back to its previous value. Thanks to Yuhui Wang

for the contribution. (Bug #33789526, Bug #93878)

• InnoDB: Valgrind testing identified an off-by-one error in rec_convert_dtuple_to_rec_old() in

the InnoDB sources. (Bug #33784672)

• InnoDB: The UNIV_DEBUG variant of the mem_heap_alloc() function in the InnoDB sources was

modified to improve Valgrind error detection. (Bug #33783709)

• InnoDB: A fast shutdown did not wait for all active I/O operations to finish before closing all files. (Bug

#33768584)

MySQL 8.0 Release Notes

• InnoDB: A Clang warning reported an incorrectly placed @return command. (Bug #33734011)

• InnoDB: Values of the new record locks array (m_prebuilt->new_rec_locks[]) were not properly

synchronized when switching between partitions, causing an assertion failure due to locks being freed or

not freed as expected. (Bug #33724166)

• InnoDB: A race condition in the function that updates the double write buffer when a write request is

completed caused a long semaphore wait error. (Bug #33712370)

• InnoDB: A function wrongly assumed that changing a record in an indexed column always requires

creating a new record in the secondary index, resulting in an lock-related assertion failure. To address

this and other similar cases, the lock_rec_convert_impl_to_expl() function that converts an

implicit record lock to an explicit record lock is now used only when an implicit record lock is actually

held. (Bug #33657235)

• InnoDB: A number of Doxygen issues in the InnoDB sources were addressed. (Bug #33603036)

• InnoDB: A missing null pointer check for an index instance caused a failure. (Bug #33600109)

• InnoDB: Starting the server after an incremental backup failed with an error indicating that page tracking

was unusable. (Bug #33521528)

• InnoDB: An assertion failure was raised during InnoDB recovery. The failure was due to a server exit

that occurred after pages were freed in a local mini-transaction before the free list and index list could be

reset. The free list and index list, which spanned the freed pages, were traversed during recovery. (Bug

#33454557)

• InnoDB: The btr_insert_into_right_sibling() B-tree function, which is inserts a tuple into the

right sibling page when the cursor is at the end of a page, caused an ACID violation due to an incorrect

lock function call. (Bug #33405696)

• InnoDB: When using COMPACT or REDUNDANT row format, it was possible to create a table that

exceeded the maximum row size, which could eventually result in 'Row size too large' errors when

inserting data. BLOB prefixes were not included in the record size check performed during the CREATE

TABLE operation. (Bug #33399379)

• InnoDB: A function that retrieves the master encryption key (get_master_key()) tried to acquire the

master key ID mutex (master_key_id_mutex), which was not yet initialized. (Bug #33067891)

• InnoDB: A redundant and costly check was removed from the

lock_sec_rec_read_check_and_lock lock system function, which is used to place a lock on a

secondary index record. (Bug #33059387)

• InnoDB: The TempTable storage engine did not properly handle a file-full error. (Bug #32929392)

• InnoDB: A DDL log error encountered during an ALTER TABLE ... ALGORITHM=COPY operation

was not handled, causing a failure during a subsequent ALTER TABLE ... ALGORITHM=INPLACE

operation. (Bug #32716838)

• InnoDB: Purge threads processed undo records of an encrypted table for which the tablespace was not

loaded, causing a failure. (Bug #32586721)

• InnoDB: A thread posted an asynchronous I/O operation and closed itself, resulting in an operating

system file operation error. (Bug #30567295)

• InnoDB: Incorrect AUTO_INCREMENT values were generated when the maximum integer column value

was exceeded. The error was due to the maximum column value not being considered. The previous

valid AUTO_INCREMENT value should have been returned in this case, causing a duplicate key error.

(Bug #87926, Bug #26906787)

MySQL 8.0 Release Notes

• InnoDB: Transaction lock priority was modified so that a transaction holding a shared lock and waiting

to upgrade to an exclusive lock is prioritized ahead of a another transaction waiting for an exclusive lock

on the same row. In other words, the transaction that already holds a shared lock is granted an exclusive

lock first. Some other transaction holding a shared lock on the same row can still prevent an exclusive

lock from being a granted in this scenario.

The lock_rec_find_set_bit and lock_rec_has_expl functions in the transaction lock system

sources were optimized. (Bug #21356, Bug #11745929)

• Partitioning: In some cases, establishing a connection to MySQL server could fail if the .ibd file for a

partition was missing. (Bug #33459653)

• Partitioning: Following work done in MySQL 8.0.17 to cause all NOT IN and NOT EXISTS subqueries

to be transformed into antijoins, the inner part of a nested outer join produced by this transformation was

not considered while pruning table partitions. (Bug #33060953)

• Replication: In a replication group with group_replication_consistency=AFTER set, if a new

primary was elected and then the previous primary was restarted, the new primary left the group with an

error message. The handling of delayed view changes and transaction prepares has been adjusted to

prevent this situation. (Bug #33755920)

• Replication: A deadlock caused when the network provider was being stopped could cause STOP

GROUP_REPLICATION to wait indefinitely on some group members. (Bug #33044886)

• Group Replication: Group Replication checked too late in the auto-rejoin process that a rejoining

member was the only type of instance allowed to enter a group while in an error state. The issue has

now been fixed. (Bug #33615493)

• Group Replication: Group Replication could log a warning message about a member joining while a

group configuration operation was running, in situations where there was no joining member, just a view

change. The message is now only logged when appropriate. (Bug #33378364)

• Group Replication: Group Replication now logs operating system errors returned when there is a

problem connecting to the local XCom instance, so it is easier to resolve issues such as a firewall

blocking the connection. (Bug #33189767, Bug #104523)

• Group Replication: To help prevent a primary election from hanging, Group Replication stops waiting

for a confirmation from any members that leave the group during the election. If all the members for

which confirmation was pending leave, Group Replication declares that the primary election completed

successfully. Previously, if the primary member was one of the members that left, a primary change was

incorrectly stated as having happened when that had not been able to take place. Now, if the primary

member leaves during an election, Group Replication declares the primary election as an unsuccessful

election with no primary change. (Bug #33059773)

• Microsoft Windows: On Windows, added WinFlexBison support. (Bug #33788290)

• On EL6/EL7, a mysql-community-server-debug installation was not obsoleted by installing commercial

packages. (Bug #33956760)

• MySQL Server would not build EL7 on ARM when building against shared libraries that are copied by

the cmake build system, such as a non-system OpenSSL. Now --page-size is set as reported by getconf.

(Bug #33904267)

• An anonymous user with the PROCESS privilege could not select rows from the processlist table.

(Bug #33869388)

• The range optimizer did not take into account the session memory limit. (Bug #33869004)

MySQL 8.0 Release Notes

• When sorting subqueries, the same filesort operation may be executed many times, with different input,

and so the longest add-on column may change between executions, but the buffer for this column was

not reallocated when necessary. Now, when the previously allocated buffer is sufficiently large, we reuse

it, otherwise we allocate a new one. (Bug #33865094)

• An invalid result was obtained from a common table expression that was materialized and used in

multiple query blocks, where, in the first query block that used the CTE, there were multiple possible

key definitions, which caused the internal function JOIN::finalize_derived_keys() to move the

definition of the key used into position zero, and the second query block using the CTE manipulated an

index that occupied the same position as the original position for the key chosen for the first query block.

This happened as an unintended side effect of work done in MySQL 8.0.22 to prepare DML statements

once only.

For more information, see WITH (Common Table Expressions). (Bug #33856374)

• Improved error handling when executing stored procedures and stored functions. (Bug #33851256)

• A trigger that selected from a view did not always yield the expected result. (Bug #33847722)

• Computations performed while loading time zone information require negative values of my_time_t.

Normally, that type's minimum value is zero, corresponding to the start of the UNIX Epoch (1970-01-01

00:00:00, with no time zone offset), which is reflected in the constant MYTIME_MIN_VALUE. This

minimum value did not work correctly for setting up the TIME_ZONE_INFO data structures in all cases,

since some time zone offsets are negative. This fix permits negative values for my_time_t while

populating the time zone information database cache. (Bug #33837691)

• If a MySQL instance stopped unexpectedly or was restarted shortly after a SET PERSIST statement was

used to record system variable settings, the configuration file mysqld-auto.cnf could be left empty,

in which case the server restart could not proceed. The persisted system variables are now written to

a backup file, which is only renamed to mysqld-auto.cnf after the success of the write has been

verified, leaving the original mysqld-auto.cnf file still available. On a restart, if a backup file with valid

contents is found, the server reads from that file. Otherwise the mysqld-auto.cnf file is used and the

backup file is deleted. (Bug #33830493)

• filesort did not always check the lengths of string values properly when calculating sort keys. (Bug

#33830073)

References: This issue is a regression of: Bug #29739778.

• A primary key comprising the GROUP_ID and MEMBER_ID columns was added to the

mysql.firewall_membership table. (Bug #33824544)

• A fix made in MySQL 8.0.20 for an inconsistency in the rows matched value when updating an

updatable view having WITH CHECK OPTION handled this issue for an update of a single table only. In

this release, we fix the issue for multi-table UPDATE statements as well. (Bug #33815426)

References: See also: Bug #30158954.

• The linked ProtoBuf library for MySQL Server has been updated to version 3.19.4. Issues fixed in

the new Protobuf version are described at https://github.com/protocolbuffers/protobuf/releases. (Bug

#33813846)

• It was possible to insert invalid characters into a utf32 column. (Bug #33810558)

• Reinstalling the MySQL Enterprise Firewall plugin caused a failure. The failure was due to a call to

update a previously persisted firewall system variable before the plugin was fully initialized. (Bug

#33809478)

MySQL 8.0 Release Notes

• Hash joins using VARCHAR or DECIMAL join columns returned an excessive number of rows. An example

using VARCHAR is shown here:

# Create and populate table

CREATE TABLE t(a VARCHAR(10), b VARCHAR(10));

INSERT INTO t VALUES ('x', 'xx'), ('xx', 'x');

# No indexes, so uses a hash join

SELECT * FROM t AS t1, t AS t2 WHERE t1.a = t2.a AND t1.b = t2.b;

Prior to the fix, the query just shown returned four rows; now it returns two rows as expected. (Bug

#33794977)

• The INFORMATION_SCHEMA.KEY_COLUMN_USAGE table did not list invisible key columns. (Bug

#33781534)

• The server did not perform proper cleanup after accessing a view created from a view. (Bug #33777821)

• In a grouped query using WITH ROLLUP and a window function which ordered on an aggregate already

present in the SELECT list, an extra (and unnecessary) aggregate was added as a hidden column when

resolving the window's ordering clause. (Bug #33769911)

• The data masking mask_ssn() function returned a 'String argument width too large' error

for a valid non-constant value (data read from a database row as opposed to a hard-coded value).

Additionally, validation was not performed for zero-length constant and non-constant values (empty

strings) or for constant values that are too small. These issues were addressed for all data masking

functions that string inputs with length boundaries. (Bug #33759276)

• ROLLUP was not handled correctly in some cases with ORDER BY and a window function. (Bug

#33753245)

• Corrected a number of issues in Doxygen comments. (Bug #33734001, Bug #33734035, Bug

#33734062, Bug #33734075, Bug #33734104, Bug #33734117, Bug #33734129, Bug #33734143, Bug

#33734155, Bug #33734181, Bug #33734188, Bug #33734206)

• Statements that cannot be parsed (due, for example, to syntax errors) are no longer written to the slow

query log. (Bug #33732907)

• The message describing MySQL Enterprise Thread Pool’s initial configuration is now issued as a

SYSTEM message rather than informational, so that it is visible at the default logging level. (Bug

#33729821)

• A pre-locking optimization related to session tracking caused recursive locking in some scenarios. (Bug

#33728209)

• A union involving an IN subquery was not always handled properly when it also used an ORDER BY

clause. (Bug #33725507)

• The mysqlpump client utility could stop unexpectedly when a password prompt was requested using

command line options. If an error is encountered during this process an appropriate error message is

now returned before the client exits. (Bug #33688141)

• Implemented standard package policy to ship separate debuginfo RPMs for the following platforms:

SLES/openSUSE, and community EL6 and EL7. Commercial versions of EL6 and EL7 are now built with

the RelWithDebInfo build type instead of Debug, which greatly decreases their size. (Bug #33663811,

Bug #33684418, Bug #33664929)

• It was not possible to run mysqld with the trace log enabled. (Bug #33653824)

MySQL 8.0 Release Notes

• When the --fido-register-factor option was used at startup for FIDO device registration, the

mysql client could use incorrect syntax in the ALTER USER statement, resulting in a failure. The issue

has now been fixed. (Bug #33650498)

• When searching a SET column value, a user variable passed as the first argument to FIND_IN_SET()

did not produce the same result as a constant value used in the same manner.

Example: Consider the table t1 created and populated as shown here:

CREATE TABLE t1 (c1 SET('a', 'b', 'c', 'd'));

INSERT INTO t1 (c1) VALUES ('a, c, d'), ('c');

The values shown for var and str should be the same in both rows of the output from the following

query, but were not:

SET @a = 'c';

SELECT FIND_IN_SET(@a, c1) AS var, FIND_IN_SET('c', c1) AS str FROM t1;

Now we make sure in such cases to return the position of the match within the set used for the column

definition whether the value sought is a constant or a column value. (Bug #33635637)

• A SET PASSWORD operation using an authentication method that does support it produced a warning

instead of an expected error. (Bug #33635445)

• If the plugin directory was not specified at MySQL Server startup, and a user attempted FIDO device

registration, the mysql client stopped unexpectedly. The situation is now handled and an appropriate

error is reported. (Bug #33631144)

• A change made in MySQL 8.0.27 moved the EXPLAIN output for composite access paths including

filter and sort from inside the table path to the MATERIALIZE access path, but did not include

INDEX_RANGE_SCAN among the composite access paths. This could in some cases result in undefined

behavior. (Bug #33611545)

References: This issue is a regression of: Bug #32788576.

• It was not possible to revoke the DROP privilege on the Performance Schema. (Bug #33578113)

• The internal CreateIteratorFromAccessPath() function has been rewritten so that it is no longer

employs recursion; this is expected to reduce stack usage significantly when executing queries. (Bug

#33569770)

• The mysql client could stop unexpectedly when attempting FIDO device registration with a challenge-

response error. The issue has now been fixed. (Bug #33568944)

• An INFORMATION_SCHEMA.FILES or INFORMATION_SCHEMA.TABLES query executed by prepared

statement or stored function returned stale data. Cached data was reported after the data had changed.

(Bug #33538106, Bug #105450)

• A query returned an incorrect result when it met all of the following conditions:

• The result set contained a column with a nondeterministic element.

• The column did not refer to a table.

• There was implicit grouping.

• The query plan used aggregation from a temporary table. This temporary table was empty.

MySQL 8.0 Release Notes

Given an empty table t with column c1, the statement INSERT INTO t SELECT MAX(t.c1),

RAND(0) AS x FROM t provides an example of such a query; by inserting into the same table, we

ensure that the query plan aggregates from a temporary table. The temporary table has a column for c1,

and the (single) result row picks c1 from the first row of the temporary table. If the temporary table was

empty, there was no first row, and c1 became 0; this led to the insertion of (NULL, 0) rather than, for

example, (NULL, 0.155) into t.

We fix this by not storing such columns in the temporary table. (Bug #33535379)

References: See also: Bug #32384355.

• Following changes in password handling in MySQL 8.0.27, if the mysql client was interrupted with Ctrl +

C, a password prompt could be issued requiring the user’s password in order to action the interrupt. The

password is now recorded when it is provided in response to a prompt (as well as when it is provided on

the command line at startup), so it can be used automatically by the new connection that is established

for the interrupt. (Bug #33514253)

• The internal keyread flag indicates reading only index entries and not full rows. When this flag was set

for an index merge scan during initialization, it was subsequently reset when initializing the individual

range scans picked as part of the index merge scan, which indicated reading rows instead of index

entries. We fix this by setting the indexes chosen as covering indexes while reading the index entries.

(Bug #33499071)

• Data copying stalled when cloning page-compressed tables where the compressed data size on the

donor host was equivalent to the available disk space on the recipient host. The holes punched on the

recipient host were smaller than the page size, resulting in disk fragmentation that limited the amount of

space available for cloned data. The process for handling page-compressed tables on the recipient host

was modified to reduce fragmentation and improve data copying speed.

To improve the rate of flushing, the clone plugin now uses the fsync flush method when flushing page-

compressed tables on file systems that support hole punching. (Bug #33482747)

• It was possible, when creating a view, for a subquery to be evaluated during resolution when it was

deemed constant. (Bug #33438883)

• Nominally, in EXPLAIN FORMAT=TREE output, we write a number of rows only as an integer. For a

result of zero, it was difficult to determine whether this was 0.49 or 0.00001, so we add enough precision

to get one leading digit in such cases. (Bug #33426283)

• VALUES in some instances did not function as specified. (Bug #33414289)

• In debug builds, certain combinations of user variables of type MYSQL_TYPE_DOUBLE hit an assert when

used in the context of CAST() or CONVERT(). (Bug #33406728)

• When setting up multiple equalities, the optimizer added an outer reference when it was not required.

(Bug #33394701)

• The minimum supported version of the Boost library for MySQL builds has now been raised to 1.77.0.

(Bug #33353637)

References: See also: Bug #33052171.

• Redundant init and checkout_access_maps function code was removed from the

Security_context class. (Bug #33339129, Bug #104915)

• The sys schema view schema_unused_indexes did not update correctly.

100

MySQL 8.0 Release Notes

schema_unused_indexes retrieves unused index information from

table_io_waits_summary_by_index_usage, returning no data if the index was used to query a

row which is not present in the table.

As of this release, schema_unused_indexes is updated even if the row is not found. (Bug #33302400)

• Some queries using common table expressions were not handled correctly by EXPLAIN. (Bug

#33300271)

• The server did not obtain index statistics correctly for certain complex queries. (Bug #33270516)

• Under certain circumstances, when executing TRUNCATE TABLE

performance_schema.status_by_thread; a race condition could occur.

Our thanks to Facebook for their contribution to this fix. (Bug #33165726)

• A page cleaner thread timed out as it waited for an exclusive lock on an index page held by a full-text

index creation operation on a large table. (Bug #33101844)

• For an InnoDB table, a secondary index is extended to include the table's primary key; that is, all

columns that are part of the primary key are marked as being part of all secondary indexes. An exception

to this is when a secondary index is defined as unique, server does not use the primary key extension.

This could lead to problems while setting up the read sets for dynamic range scan. We fix this issue by

making sure in the case of a unique seconary index to include all primary key parts in the read set. (Bug

#33101025)

References: This issue is a regression of: Bug #30417361.

• An existing foreign key constraint that referenced a non-existing table could result in a connection error

after the table was created or renamed. (Bug #33054071)

• While creating a value list for an empty VALUES during execution of an INSERT statement, a hidden

element was added, which subsequently led to an assertion in debug builds. To fix the problem, we now

skip any hidden elements when the VALUES list is created.

See INSERT ... ON DUPLICATE KEY UPDATE Statement, for more information. (Bug #32774799)

• Aliases to SELECT list items in ORDER BY which were part of expressions were not resolved in the

same way as standalone aliases, so that ORDER BY alias was resolved correctly, but ORDER BY

function(alias) was not. (Bug #32695670)

• An offline keyring migration from an empty or non-existing keyring source (specified by

keyring_file_data) appeared to complete successfully, without warning. The keyring migration

process now checks for errors when fetching keys. If no keys are found at the specified keyring source, a

warning message is written to the error log indicating that the keyring has no keys. (Bug #32327411)

• When removing a condition which was always true, a subquery referring to a view was removed even

though the subquery was itself referred to elsewhere in the query. (Bug #31946448)

References: See also: Bug #31216115.

• An EXPLAIN statement, if used with multiple-table UPDATE statements that contained derived tables,

could cause the server to exit. (Bug #31884434)

• A memory leak occurred if mysqldump was used on more than one table with the --order-by-

primary option. The memory allocated for sorting each table’s rows is now freed after every table,

rather than only once. (Bug #30042589, Bug #96178)

101

MySQL 8.0 Release Notes

• mysqld_safe log message textual errors were corrected. Thanks to Bin Wang at China Mobile for the

contribution. (Bug #106590, Bug #33903639)

• Equivalent queries could return different results because the execution paths differed slightly. For

example, Item::val_int_from_string() and Item_string::val_int() should use the same

algorithm for string to integer conversion. (Bug #106517, Bug #33881339)

• Updated CMake rules to handle the deprecated PermissionsStartOnly systemd option. The

alternative executable prefix was added in systemd 231 (July 2016) while PermissionsStartOnly was

deprecated in systemd 240 (Dec 2018). The preferred executable prefix is now used where available.

(Bug #106468, Bug #33862323)

• Following work done in MySQL 8.0.22 to implement condition pushdown for materialized derived tables,

an implicitly grouped query with an aggregation function in some cases returned an empty set instead of

NULL. (Bug #106414, Bug #33838439)

• A prepared and executed query like 'SELECT ?' with a DATE, TIME, DATETIME, or TIMESTAMP as

the bound argument could return the wrong column type. The issue is fixed by restoring the previous

logic that reprepared such queries to give each dynamic parameter its literal value. (Bug #106352, Bug

#33813951)

References: This issue is a regression of: Bug #32915973.

•

A null-safe comparison (≪=>) did not evaluate correctly for a TIMESTAMP column in a trigger. (Bug

#106286, Bug #33790919)

References: This issue is a regression of: Bug #32942327.

• When writing DECIMAL values to the hash join buffer, the values were first normalized. This

normalization could in some cases unintentionally alter the values, which made the values fall into the

wrong hash bucket and caused incorrect results to be returned from the join.

The problem was that the normalization removed leading zeros in a manner which caused some values

to lose some of their least significant digits. We fix this by calculating the desired precision and passing

the calculated value instead of changing the original value. (Bug #106272, Bug #33787914)

• A query having a WHERE condition of the form c NOT BETWEEN NULL AND COALESCE(a, b),

having DATETIME columns a, b, and c, with columns a and c created as NOT NULL, did not return

correct results. Further investigation showed that, in such cases, when the second or third argument to

BETWEEN was NULL, the comparison results were inverted, causing it to evaluate as NULL for FALSE,

and FALSE for NULL. (Bug #106267, Bug #33788832)

• A NULL-safe comparison between 0 (FALSE) and NULL could return TRUE, even though the

implementation responsible for evaluating an object of this type can never result in NULL and should

always return FALSE. (Bug #105773, Bug #33630225)

• The QUICK_RANGE constructor used the main thread memory root for allocating keys, rather than the

same memory root as used for allocating the QUICK_RANGE object itself. This resulted in unexpectedly

high memory usage when executing multiple queries using a range check for the query plan. (Bug

#105331, Bug #33516707)

References: See also: Bug #28805105, Bug #28857990.

• SELECT DISTINCT on a VARCHAR column returned 2 distinct values when the column contained an

empty string and a string consisting of a single whitespace character when the TempTable storage

engine was used (internal_tmp_mem_storage_engine = TempTable). This behavior was

102

MySQL 8.0 Release Notes

incorrect when using a utf8_bin collation with PAD SPACE; trailing spaces should have been ignored

when selecting distinct values.

For temporary tables created using the TempTable storage engine, the two strings were hashed to

different values, since the TempTable hashing function always hashed zero-length data to 0. (In the

case just described, the empty string was hashed to 0 while the space character from the other string

was used to generate a nonzero hash value.)

This is now fixed by removing any special handling for zero-length data in the TempTable storage

engine's hashing function.

Our thanks to Brian Yue for the contribution. (Bug #105316, Bug #33506241)

• SELECT COUNT(*) using a multi-valued index reported the wrong number of rows. (Bug #104898, Bug

#33334928)

• The test program main.ssl-big failed with Too many connections.

Our thanks to Facebook for the contribution. (Bug #104377, Bug #33139204, Bug #33165693)

• The two types of histograms supported by MySQL, singleton and equi-height, previously stored their

collections of buckets in a map and a set, respectively. This release changes both histogram types such

that they now store buckets in dynamic arrays instead, which reduces space overhead and speeds up

selectivity estimation due to reduced indirection when performing binary search on the buckets.

Because both types of histograms are constructed by inserting buckets in sorted order, and buckets are

serialized to JSON in sorted order, there is no additional work involved in switching to a dynamic array.

(Bug #104109, Bug #33045204)

• An invalid conversion between signed and unsigned variables led to incorrect result from a query of

the form SELECT ALL t1.c1,t2.c1 FROM t1,t2 WHERE t1.c1 > t2.c1. (Bug #102025, Bug

#32302724)

• As of this release, the Performance Schema is collation-aware (Bug #98545, Bug #30881109)

• An assert error could occur when inserting data larger than 32 bytes in the ROLE column of

setup_actors. As of this release, the ROLE column is increased from CHAR(32) to CHAR(96). (Bug

#74678, Bug #19947842)

Changes in MySQL 8.0.28 (2022-01-18, General Availability)

• Audit Log Notes

• C API Notes

• Character Set Support

• Compilation Notes

• Data Type Notes

• Deprecation and Removal Notes

• Event Scheduler Notes

• Full-Text Search Notes

• SQL Function and Operator Notes

103

MySQL 8.0 Release Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• The new audit_log_disable system variable permits disabling audit logging for all connecting and

connected sessions. See Disabling Audit Logging. (WL #14699)

C API Notes

• Building C API client programs on Windows using Clang as the compiler returned various compiler

warnings, including an unused variable warning. (Bug #33520805, Bug #33520861)

Character Set Support

• Incompatible Change: CONVERT(string USING charset) did not compute the correct maximum

length for its return value, which should be the same as that calculated for CAST(string AS

charset). This meant that some conversions of strings from BINARY to nonbinary character sets which

should have been rejected as invalid returned values instead.

Prior to upgrading, applications that may rely on the previous CONVERT() behavior should be checked

and updated as necessary. In particular, for indexes on generated columns using CONVERT() with

invalid values, you should correct such values, drop the index, then re-create it before upgrading

to this release. In some cases, it may be simpler to rebuild the table using ALTER TABLE table

FORCE, rather than dropping and re-creating the index. See SQL Changes, for more information. (Bug

#33199145)

• The output from EXPLAIN FORMAT=TREE hex-encoded ranges for multi-valued indexes, even when

the data type was not a binary one. In addition, ranges using string types were also printed with hex-

encoded values, when they had a binary collation. The latter issue also affected regular indexes, but

was more visible with multi-valued indexes, since these always use utf8mb4_0900_bin collation.

Now, hex-encoding is used only for string types having a binary character set. Strings with non-binary

character sets are now printed in EXPLAIN FORMAT=TREE output as plain text, with escaping for any

special characters. (Bug #33343948)

• For some functions, the resolved character set was not always the same as the character set of the first

argument. (Bug #32668730, Bug #33238711)

Compilation Notes

• InnoDB: Compilation issues associated with the following MSVC++ level 4 compiler warnings were

addressed: C4201, C4701, C4702, C4703, C4706. The compiler warnings, which were previously

disabled, are now enabled. (Bug #33464699)

• InnoDB: MSVC++ level 4 compiler warnings were enabled. (Bug #33437498)

• InnoDB: An access violation occurred when building a debug version of MySQL using Visual Studio

2019 version 16.10 or version 16.11. The violation was due to an STL iterator bug. (Bug #33223243)

104

MySQL 8.0 Release Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.80.0. (Bug #33576431)

Data Type Notes

• This release fixes the following two issues relating to date and time values:

• Inserting a CHAR value such as '12:00:00' into a DATE, DATETIME, or TIMESTAMP column

raised the wrong error. In the case of a DATE column, this error was similar to Data truncation:

Incorrect date value: '2012-00-00' for column 'd' at row 1. This occurred for both

the binary and text protocols.

• Inserting a value with an offset into a DATE or TIME column using the binary protocol gave a wrong

result. For example, when the connection time zone was set to GMT-5, inserting '2021-10-10

00:00:00.123+01:00' into a TIME column yielded '18:00:00'; that is, the value was converted

to the connection time zone (this should be done only with respect to DATETIME columns).

We fix these by recognizing and adjusting for time zone offsets whenever a TIMESTAMP value with a

time zone offset is inserted into a TIME or DATE column. (Bug #33616957, Bug #33649009)

References: See also: Bug #33539844.

• A fix in MySQL 8.0.27 for a previous issue changed the resolved type of a boolean expression from

signed INT to unsigned BIGINT in order to simplify type handling, but what appeared then as a

harmless metadata change turned out to cause problems for some of the MySQL Connectors.

We now revert the metadata change and provide a different fix for the original problem, by adjusting the

max_length for the negation of an integer to at least two characters. (Bug #33516898)

References: This issue is a regression of: Bug #33117410.

• Sorts of some column types, including JSON and TEXT, sometimes exhausted the sort buffer if its size

was not at least 15 times that of the largest row in the sort. Now the sort buffer need only be only 15

times as large as the largest sort key. (Bug #103325, Bug #105532, Bug #32738705, Bug #33501541)

References: This issue is a regression of: Bug #30400985, Bug #30804356.

Deprecation and Removal Notes

• Support for the TLS v1.0 and TLS v1.1 connection protocols is removed as of MySQL 8.0.28. The

protocols were deprecated from MySQL 8.0.26. For background, refer to the IETF memo Deprecating

TLS v1.0 and TLSv 1.1. Make connections using the more-secure TLSv1.2 and TLSv1.3 protocols.

TLSv1.3 requires that both the MySQL Server software and the client application were compiled with

OpenSSL 1.1.1 or higher.

From MySQL 8.0.28, client programs, including MySQL Shell, that support a --tls-version option

for specifying TLS protocols for connections to the MySQL server cannot make a TLS/SSL connection

with the protocol set to TLSv1 or TLSv1.1. If a client attempts to connect using these protocols, for TCP

connections, the connection fails, and an error is returned to the client. For socket connections, if --

ssl-mode is set to REQUIRED, the connection fails, otherwise the connection is made but with TLS/

SSL disabled.

On the server side, the following settings are changed from MySQL 8.0.28:

• Permitted values for tls_version and admin_tls_version no longer include TLSv1 or TLSv1.1.

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MySQL 8.0 Release Notes

• Permitted values for group_replication_recovery_tls_version no longer include TLSv1 or

TLSv1.1.

• For asynchronous replication, replicas can no longer set the protocol for connections to the source

server (SOURCE_TLS_VERSION option for CHANGE REPLICATION SOURCE TO) to TLSv1 or

TLSv1.1.

(WL #14775)

• The shortcuts ASCII for CHARACTER SET latin1 and UNICODE for CHARACTER SET ucs2 are now

deprecated, and you should expect their removal in a future version of MySQL. Using either of these

now raises a warning; use CHARACTER SET instead. (WL #13146)

• The character sets listed here, along with all of their collations, are now deprecated, and subject to

removal in a subsequent release of MySQL:

• ucs2

• macroman and macce

• dec

• hp8

The use of any of these character sets or their collations in SQL statements or elsewhere in the MySQL

server now produces a deprecation warning.

You should use utf8mb4 instead of any of the character sets just listed. See also The ucs2 Character

Set (UCS-2 Unicode Encoding), West European Character Sets, and Central European Character Sets.

(WL #13594, WL #13595, WL #13596, WL #13597)

Event Scheduler Notes

• As a previous convenience, the server automatically restarted the Event Scheduler as needed when the

super_read_only system variable was disabled. Now this same convenience is applied independently

when the read_only system variable is disabled. Prior to this update, disabling read_only could also

disable super_read_only if needed, but because the code was separate, the Event Scheduler was

not restarted. (Bug #33539082)

Full-Text Search Notes

• Due to the fact that, as implemented, MATCH() does not act as a function of its arguments, but rather

as a function of the row ID of the current row in the underlying scan of the base table, a query using a

rollup column as the argument to this function tended to perform poorly, and with unreliable results. This

being the case, the use of a rollup column with MATCH() is no longer permitted whenever the following

conditions are true:

• MATCH() appears in the SELECT list, GROUP BY clause, HAVING clause, or ORDER BY clause.

• The query uses GROUP BY ... WITH ROLLUP.

• A grouping column is used as the argument to MATCH().

Any such queries are now rejected with ER_FULLTEXT_WITH_ROLLUP. (The use of MATCH() with a

rollup column in the WHERE clause is not affected by this change, and is still permitted.)

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MySQL 8.0 Release Notes

For more information, see Full-Text Search Functions. (Bug #32565923, Bug #32996762, WL #14697)

SQL Function and Operator Notes

• Important Change: When using prepared statements, the DATE_ADD() and DATE_SUB() functions

returned DATETIME values, even when calculations involved combinations of YEAR, MONTH, or DAY parts

only (that is, no time parts).

Previous to implementing single preparation of prepared statements in MySQL 8.0.22, TIME values

were returned in such cases; before this was done, values used as arguments and their types were

used to determine the result type of certain temporal functions at resolution time, such as DATE_ADD(),

DATE_SUB(), and ADDTIME(). Afterwards, user variable references and dynamic parameters are

considered constant for the lifetime of one execution only, requiring that the return type be determined

in another fashion, in this case from the function type. For example, the default resolved type for

DATE_ADD() was deemed to be DATETIME if the first argument was a dynamic parameter, since

DATETIME accomodates all temporal values and thus an implicit reprepare can be avoided.

The change just described represents a regression; the problem is better solved by deriving a more

precise resolved data type, and performing a reprepare only if that does not match the actual value of

the parameter. (Such functionality was already in use in the MySQL server for numeric parameters.) This

solution is implemented by this fix.

We now parse string and numeric values when temporal values are expected. When a valid temporal

value is found, the value is converted. This fix also improves determination of resolved data types for

temporal functions.

With this fix, the DATE_ADD() and DATE_SUB() functions (and their synonyms functions ADDDATE()

and SUBDATE()) resolve types as follows:

• If the first argument is a dynamic parameter, its resolved type is DATE if the second argument is an

interval that contains some combination of YEAR, MONTH, or DAY values only; otherwise, its type is

DATETIME.

• If the first argument is resolved as DATETIME, the resolved type of the function is also DATETIME.

• If the first argument is a DATE, the resolved type of the function is also DATE, unless the interval

argument uses HOUR, MINUTE, or SECOND, in which case it is DATETIME.

• If the first argument is a TIME value, the resolved type is also TIME, unless the interval argument uses

any of YEAR, MONTH, or DAY, in which case the resolved type of the function is DATETIME.

If none of the preceding conditions are met, the function is resolved as VARCHAR (as in MySQL 8.0.21

and earlier).

The ADDTIME() and SUBTIME() functions now resolve types as follows:

• If the first argument is a dynamic parameter, the resolved type is TIME, rather than DATETIME.

• Otherwise, the resolved type of the function is derived from the resolved type of the first argument.

In addition, for DATE_ADD() and DATE_SUB(), if the resolved type of the first argument is DATE, and

a DATETIME value is provided, the statement is reprepared so that the function has the resolved type

DATETIME. Behavior is unchanged when a TIME value is provided.

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MySQL 8.0 Release Notes

For ADDTIME() and SUBTIME(), there are no forced reprepares. (Bug #103781, Bug #32915973, Bug

#33477883, Bug #33539844)

• Previously, loadable functions and stored functions shared the same namespace and could not have the

same name. A subsequent implementation change eliminated the reason to share the same namespace

and permitted a stored function to be created with the same name as an existing loadable function. To

invoke the stored function, it is necessary to qualify it with a schema name. The server now generates a

warning if the stored function name collides with an existing loadable function name. (Bug #33301931)

• Queries making use of the MBRContains() function did not employ all available spatial indexes. (Bug

#32975221)

References: This issue is a regression of: Bug #29770705.

• The FORMAT() function returned a formatted number without showing the thousands separator and

grouping between separators when either the es_ES or es_MX locale was specified. (Bug #31374305)

• The result length of the GROUP_CONCAT() function was wrong when the value of

group_concat_max_len was increased. With a small group_concat_max_len value, the result was

correct. This issue was caused by arithmetic overflow.

Our thanks to Hope Lee for the contribution. (Bug #105380, Bug #33521497)

Optimizer Notes

• For a query, a range scan can be picked first and the optimizer decide that the same range scan can be

used to skip ordering. In some cases, when the requested order is not the same as the index order, a

reverse index scan is required. If the requested ordering is on the key part that is not already used by the

range scan, we update the number of used key parts for the range scan to reflect the change. The issue

occurred because the key part information was not also updated, and when it was necessary to access

key part information based on the number of key parts used.

We also now note when a reverse scan uses extended key parts, and set the correct flags for evaluation

accordingly. (Bug #33615893)

References: This issue is a regression of: Bug #33037007.

• In both optimizer trace and EXPLAIN FORMAT=TREE output, date ranges were printed as binary. Now in

such cases we print temporal values as quoted strings. (Bug #33335079)

• When a condition was pushed down, the result of evaluating assignments to user variables in the

SELECT list of the subquery were sometimes affected. For this reason, we now prevent condition

pushdown for statements with assignments to user variables.

Our thanks to Casa Zhang and the Tencent team for the contribution. (Bug #104918, Bug #33341080)

• When the join buffer was set to certain arbitrary sizes, the number of chunk files created for hash joins

was too small. This meant that each file contained more rows than could fit in the join buffer, so that

the probe chunks needed to be read multiple times. This was caused by using integer division when

computing how many chunk files are needed; we fix this by using floating-point division instead.

Our thanks to Øystein Grøvlen for the contribution. (Bug #104186, Bug #33073354)

• A query using aggregation on a BIT type could return different results depending on the indexes or

join type employed. This was due to the fact that a DML statement using such an aggregation caches

the BIT values using an integer type, and later looks up and converts to a string format for output. The

108

MySQL 8.0 Release Notes

current issue arose because this lookup treated the BIT value as an integer, resulting in an incorrect

string value.

This is fixed by adding a new internal class for cached BIT values which can convert bit values to string

formats correctly.

Our thanks to Hope Lee for the contribution. (Bug #100859, Bug #31894023)

• When a DML statement containing an outer DISTINCT query with a subquery inside a HAVING clause,

the inner subquery attempts to use a column reference for a column from the outer DISTINCT query,

but this should be allowed only if the subquery is used somewhere outside of the HAVING, or if the outer

SELECT does not use grouping. The current issue came about because such a query was allowed to run

even though neither of these conditions were met.

To fix this, the column reference check is expanded to detect an invalid column reference of this sort,

and to return an error if it does.

Our thanks to Song Zhibai for the contribution. (Bug #97742, Bug #30617496)

Packaging Notes

• The GnuPG build key used to sign MySQL downloadable packages has been updated. The previous

GnuPG build key is set to expire on 2022-02-16. For information about verifying the integrity and

authenticity of MySQL downloadable packages using GnuPG signature checking, or to obtain a copy of

our public GnuPG build key, see Signature Checking Using GnuPG.

Due to the GnuPG key update, systems configured to use repo.mysql.com may report a signature

verification error when upgrading to MySQL 5.7.37 and higher or to MySQL 8.0.28 and higher using apt

or yum. Use one of the following methods to resolve this issue:

1. Manually reinstall the MySQL APT or YUM repository setup package from https://dev.mysql.com/

downloads/.

2. Download the MySQL GnuPG public key and add it your system GPG keyring.

• For MySQL APT repository instructions, see Appendix A: Adding and Configuring the MySQL APT

Repository Manually.

• For MySQL YUM repository instructions, see Upgrading MySQL with the MySQL Yum Repository.

(Bug #33587308)

• The bundled libedit library was upgraded to version 20210910-3.1. (Bug #33568767)

Performance Schema Notes

• A new statement metric, CPU_TIME, is now available, enabling you to measure the CPU time spent on a

query.

The following changes were made to support this:

• A timer, THREAD_CPU, was added to the Performance Schema PERFORMANCE_TIMERS table.

• A consumer, events_statements_cpu was added to the Performance Schema

setup_consumers table.

events_statements_cpu is disabled by default.

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MySQL 8.0 Release Notes

• A Performance Schema command option, performance-schema-consumer-events-

statements-cpu to enable or disable the consumer, events_statements_cpu.

See Performance Schema Command Options for more information.

• The following columns were added:

• CPU_TIME column was added to the following Performance Schema tables:

• events_statements_current

• events_statements_history

• events_statements_history_long

CPU_TIME is the time spent on CPU for the current thread, expressed in picoseconds.

• SUM_CPU_TIME column was added to the following Performance Schema tables:

• events_statements_summary_by_thread_by_event_name

• events_statements_summary_by_account_by_event_name

• events_statements_summary_by_user_by_event_name

• events_statements_summary_by_host_by_event_name

• events_statements_summary_global_by_event_name

• events_statements_summary_by_digest

• events_statements_summary_by_program

• prepared_statements_instances

SUM_CPU_TIME is the CPU time spent on the current thread, expressed in picoseconds, for the

corresponding aggregations.

• CPU_LATENCY column was added to the following sys schema tables:

• statement_analysis

• user_summary_by_statement_type

• user_summary_by_statement_latency

• host_summary_by_statement_type

• host_summary_by_statement_latency

• processlist

• session

CPU latency is the CPU time spent on the current thread, expressed in human-readable form.

• CPU_LATENCY column was added to the following sys schema x$ tables:

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MySQL 8.0 Release Notes

• x$statement_analysis

• x$user_summary_by_statement_type

• x$host_summary_by_statement_type

• x$processlist

• x$session

• x$user_summary_by_statement_latency

• x$host_summary_by_statement_latency

CPU latency is the CPU time spent on the current thread, expressed in picoseconds.

Our thanks to Facebook for their contribution to this fix. (Bug #32202060, Bug #101764, WL #14779)

Functionality Added or Changed

• Important Change: The number of distinct windows which can appear in a given SELECT is now limited

to 127. The number of distinct windows is the sum of the named windows and the implicit windows

specified as part of any window function's OVER clause.

In order to use a large number of windows, it may be necessary to increase the value of the

thread_stack server system variable. (Bug #33279604)

• InnoDB: InnoDB now supports ALTER TABLE ... RENAME COLUMN operations using

ALGORITHM=INSTANT.

Operations that support ALGORITHM=INSTANT only modify metadata in the data dictionary. Table data

is unaffected, making the operations instantaneous. If not specified explicitly, ALGORITHM=INSTANT is

used by default by DDL operations that support it.

For more information about this and other DDL operations that support ALGORITHM=INSTANT, see

Online DDL Operations. (WL #14785)

• It is theoretically possible for a user with sufficient permissions using MySQL Enterprise Audit to

mistakenly create an “abort” item in the audit log filter that prevents themselves and other administrators

from accessing the system. From MySQL 8.0.28, the AUDIT_ABORT_EXEMPT privilege is available

to permit a user account’s queries to always be executed even if an “abort” item would block them.

Accounts with this privilege can therefore be used to regain access to a system following an audit

misconfiguration. The query is still logged in the audit log, but instead of being rejected, it is permitted

due to the privilege.

Accounts created in MySQL 8.0.28 or later with the SYSTEM_USER privilege have the

AUDIT_ABORT_EXEMPT privilege assigned automatically when they are created. The

AUDIT_ABORT_EXEMPT privilege is also assigned to existing accounts with the SYSTEM_USER privilege

when you carry out an upgrade procedure with MySQL 8.0.28 or later, if no existing accounts have that

privilege assigned. (WL #14670)

• The tmp_table_size variable now defines the maximum size of individual in-memory internal

temporary tables created by the TempTable storage engine. An appropriate size limit prevents individual

queries from consuming an inordinate amount global TempTable resources. See Internal Temporary

Table Storage Engine. (WL #14647)

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MySQL 8.0 Release Notes

• The innodb_open_files variable, which defines the number of files InnoDB can have open at one

time, can now be set at runtime using a SELECT innodb_set_open_files_limit(N) statement.

The statement executes a stored procedure that sets the new limit.

To prevent non-LRU manged files from consuming the entire innodb_open_files limit, non-LRU

managed files are now limited to 90 percent of the innodb_open_files limit, which reserves 10

percent of the innodb_open_files limit for LRU managed files.

The innodb_open_files limit now includes temporary tablespace files, which were not counted

toward the limit previously. (WL #14591)

• The functions FROM_UNIXTIME(), UNIX_TIMESTAMP(), and CONVERT_TZ() now handle 64-bit

values on platforms that support them, including 64-bit versions of Linux, MacOS, and Windows.

On compatible platforms, FROM_UNIXTIME() now accepts a maximum argument of

32536771199.999999 seconds, corresponding to '3001-01-18 23:59:59.999999' UTC (including

the optional fraction of up to 6 digits). If the argument is larger than this, the function returns NULL.

On compatible platforms, UNIX_TIMESTAMP() now accepts a maximum value of '3001-01-18

23:59:59.999999' UTC, corresponding to 32536771199.999999 seconds since the Unix Epoch. If the

argument is larger than this, the function returns 0.

In addition, on compatible platforms, CONVERT_TZ() now performs time zone conversion beyond 2038,

up to '3001-01-18 23:59:59.999999' UTC. If the datetime argument exceeds this value, the

argument is returned unchanged. This “no-op” behavior is the same as previously with values beyond

'2038-01-19 03:14:07.999999' UTC.

The behavior of these 3 functions on 32-bit platforms is unchanged.

The behavior of the TIMESTAMP type is also unaffected by this change; its maximum allowed value

remains '2038-01-19 03:14:07.999999' UTC, regardless of platform. For dates futureward of this,

use the MySQL DATETIME type instead. (WL #14630)

• This release introduces monitoring and limiting of memory allocation on a global and per-user

basis. You can now observe the total memory consumed by all user connections by checking the

value of the Global_connection_memory status variable, which must be enabled by setting

global_connection_memory_tracking = 1.

The total includes memory used by system processes, or by the MySQL root user, although these users

are not subject to disconnection due to memory usage.

Memory used by the InnoDB buffer pool is not included in the total.

You can control indirectly how often the status variable is updated by adjusting

connection_memory_chunk_size; Global_connection_memory is updated only when the total

memory usage varies by more than this amount.

You can specify limits on resource consumption per user connection by setting

connection_memory_limit; any user whose memory usage exceeds this amount

cannot issue additional queries. You can also impose a global memory limit by setting

global_connection_memory_limit. Whenever Global_connection_memory exceeds the

global limit, no regular users can issue new queries requiring memory usage. System users such as

MySQL root are not bound by these limits. (WL #13458)

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MySQL 8.0 Release Notes

Bugs Fixed

• InnoDB: The minimum I/O buffer size calculated during an index creation operation did not align with the

I/O block size, permitting a record to exceed the buffer boundary. (Bug #33570629)

• InnoDB: The sync_array_detect_deadlock algorithm used by the semaphore deadlock checker

in debug builds was simplified in terms of code and time complexity, and an implementation of the

algorithm was introduced for use in release builds. (Bug #33538505)

• InnoDB: The ut::make_unique library function in the InnoDB sources now permits specifying the

type of field allocated. (Bug #33538461)

• InnoDB: A Performance Schema instrumentation was added for tracking redo log buffer memory

allocations. (Bug #33527660)

• InnoDB: Warnings printed to the error log for long semaphore waits did not provide information about

the latch owner. (Bug #33509386)

• InnoDB: A latch release and reacquisition mechanism was introduced to reduce the amount of time

that threads spend in critical sections protected by a global lock system latch. (Bug #33502610, Bug

#33563523)

• InnoDB: A hole punch operation on Windows caused a failure. The operation was performed as an

overlapped (asynchronous) operation, which requires a OVERLAPPED structure containing a handle to an

event object. The OVERLAPPED structure was not provided. (Bug #33496778)

• InnoDB: The ut_time() infrastructure in the InnoDB sources was replaced with a type-checked

standard library implementation. (Bug #33460092)

• InnoDB: Numerous Trying to access missing tablespace errors were printed to the error log

following a restore operation. (Bug #33437625)

• InnoDB: Performance Schema aware ut::make_unique and ut::make_shared

memory management library functions were added to the InnoDB sources. Similar functions

(ut::make_unique_aligned and ut::make_shared_aligned) were added for types with

extended alignment. (Bug #33420694)

• InnoDB: The buf_validate() function in the InnoDB sources was optimized, improving performance

on debug builds.

Thanks to Hobert Lu for the contribution. (Bug #33417058, Bug #104967)

• InnoDB: On a NUMA-enabled system, the page size of memory chunks allocated to the buffer pool

did not align with the system page size in certain scenarios, causing in the following error: Failed to

set NUMA memory policy of buffer pool page frames to MPOL_INTERLEAVE. (Bug

#33406701)

References: This issue is a regression of: Bug #32714144.

• InnoDB: Two instances of std::unique_ptr with mem_heap in the InnoDB sources now use the

Scoped_heap() wrapper, which uses a stateless function object instead of a pointer to a function. (Bug

#33405520)

• InnoDB: The m_end_range flag in the prebuilt struct, which is set to true when the end of the range

is exceeded while populating the prefetch cache, was not set to false when the prefetch cache was reset

(initialized). As a result, in cases where the end of the range is not exceeded and the handler is reused,

the m_end_range flag could be set incorrectly the next time the prefect cache is used. (Bug #33384537)

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MySQL 8.0 Release Notes

• InnoDB: Column metadata in the data dictionary was not updated when a new table ID was assigned to

a table after discarding the table's tablespace during a table import operation. (Bug #33319149)

• InnoDB: Setting the innodb_interpreter debug-only system variable to NULL caused a failure. (Bug

#33316661)

• InnoDB: Full-text index creation file management was improved. (Bug #33270893)

• InnoDB: An update operation that inserted a new row into a temporary table used for aggregation

caused the temporary table to be moved to disk and the update operation to be retried on the new on-

disk temporary table. A BLOB pointer in the record data prepared before the temporary table was moved

to disk was rendered stale, causing a failure. (Bug #33242407)

• InnoDB: Memory allocation is now performed by a new standards-compliant custom memory allocator

which is compatible with Performance Schema. (Bug #33159210)

• InnoDB: A race condition between threads attempting to deinitialize and initialize statistics for the same

table raised and assertion failure. (Bug #33135425)

• InnoDB: An innodb_flush_log_at_trx_commit setting other than 1 or a long running transaction

could have resulted in an inconsistent rate of redo log flushing. (Bug #33128461)

• InnoDB: Allocation of large pages is now handled by a library designed to handle this. In cases where

the large page allocation mechanism cannot be used, a fallback mechanism allocates regular aligned

pages. Fallback can occur when large page address space is exhausted, when large page support

is disabled by the underlying hardware or operating system architecture, or when large page support

in MySQL is disabled explicitly (--large-pages=0). Occurrences of ut_allocator functions for

allocation and deallocation of large pages have been replaced by the new library functions. (Bug

#33119009, Bug #33118309, Bug #33149501, Bug #32135935)

• InnoDB: Handling of regular 4K page-aligned allocations is now performed by a self-contained library

which is compatible with Performance Schema. (Bug #33118362)

• InnoDB: Functions belonging to a new InnoDB library responsible for dynamic storage management of

suitably aligned types has replaced the functions previously used for this purpose. (Bug #33110341)

• InnoDB: Dynamic allocation of suitably aligned types is now handled by a library which is compatible

with Performance Schema. (Bug #33110312)

• InnoDB: While a purge thread was freeing LOB pages at end of a purge batch, a required index data

structure was freed, causing a failure. (Bug #32918325)

• InnoDB: Inconsistencies in Performance Schema instrumentation logic for dynamic memory

management functions (ut_* functions) were addressed. (Bug #32715466)

• InnoDB: InnoDB dynamic allocation routine limitations prevented dynamic allocation of an array of

constructible types. The limitations have been addressed, permitting allocation of default constructible

types, non-default constructible types, and types that are both default and non-default constructible. (Bug

#32714047)

• InnoDB: When using READ COMMITTED or READ UNCOMMITTED, certain queries executed on a table

inside of a trigger or function prevented concurrent transactions on the same table. The acquired locks

were too restrictive. (Bug #32636792)

• InnoDB: Hole punch functionality was not working as expected for tablespace pages that were

encrypted and compressed, for most pages on Windows, and for Windows volumes that do not

implement Microsoft volume management functions. (Bug #32136255)

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MySQL 8.0 Release Notes

• InnoDB: Replacing the ut_time() infrastructure with a type-checked standard library (std)

implementation in MySQL 8.0.28 caused a performance regression. The regression was due the time

library used by std clocks, which generates system calls. Low resolution clocks are now used instead.

(Bug #107763, Bug #34352870)

References: This issue is a regression of: Bug #33460092.

• Packaging: Added an icu-data-files RPM that was separated from the server package. This is a

package of ICU data files needed by MySQL regular expressions. (Bug #35162346)

• Partitioning: Creating a table with nondeterministic functions in generated column expressions

should not be possible, but this was not enforced in all cases; a series of one or more ALTER TABLE

statements could be employed to arrive at a partitioned table with one or more such generated columns.

When attempting to execute the CREATE TABLE statement obtained by running SHOW CREATE TABLE

against this table, MySQL rejected the statement with a misleading error message referring to the

partitioning expression rather than to the problematic column, despite the fact that the partitioning

expression itself was legal.

This was caused by the result of a check for any unsafe expressions defined for a generated column

(in the internal variable thd->safe_to_cache_query), which was later checked again without being

cleared while parsing the partition expression, leading to an error even when the partition expression

did not refer to the problematic generated column expression. Now in such cases, we reset thd-

>safe_to_cache_query before parsing the partition function.

The issue of allowing the use of certain nondeterminstic functions (AES_ENCRYPT(), AES_DECRYPT(),

RANDOM_BYTES()) in generated columns is handled separately. (Bug #29268656)

References: See also: Bug #32592320.

• Partitioning: A query using an index other than the primary key of a partitioned table sometimes

resulted in excessive CPU load. (Bug #104576, Bug #33238010)

• Replication: A PURGE BINARY LOGS statement could be issued while the instance was locked for

backup, which contravened the rules of the backup lock by removing files from the server. The statement

now cannot be used while a LOCK INSTANCE FOR BACKUP statement is in effect. (Bug #33437026)

• Replication: Replication stopped with an error when reading a table map event if the name of the table

or database was over 64 bytes – the limit is 64 characters, so the use of multi-byte characters could

cause this situation. The replica now no longer checks the size of the table and database names, and

supports the transmission of longer names. (Bug #33305975, Bug #104798)

• Replication: A lock conflict could occur if the Performance Schema table

replication_applier_status_by_worker was queried while a STOP REPLICA command was in

progress. The issue has now been resolved. (Bug #33290947)

• Replication: From MySQL 8.0.26, new versions of the plugins that implement semisynchronous

replication are supplied to replace the terms “master” and “slave” with “source” and “replica”.

Following this, the UNINSTALL PLUGIN statement incorrectly allowed the old versions of the plugins,

rpl_semi_sync_master and rpl_semi_sync_slave, to be uninstalled when replication channels

were currently using them. The issue has now been fixed. (Bug #33270401)

• Replication: When the PAD_CHAR_TO_FULL_LENGTH SQL mode was enabled on a replica server,

trailing spaces could be added to a replication channel’s name in the replication metadata repository

tables, resulting in errors in replication operations that identified the channel using that data. The issue

has now been fixed in MySQL 8.0 by using VARCHAR for character columns, and in MySQL 5.7 by

disabling the SQL mode when reading from those tables. Thanks to Brian Yue for the contribution. (Bug

#33213841)

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MySQL 8.0 Release Notes

• Replication: If a replica was disconnecting while a SHOW REPLICAS statement was being issued, the

server was able to access deleted data. (Bug #33206343, Bug #104566)

• Replication: If a replica server with the system variable replica_preserve_commit_order = 1 set

was used under intensive load for a long period, the instance could run out of commit order sequence

tickets. Incorrect behavior after the maximum value was exceeded caused the applier to hang and the

applier worker threads to wait indefinitely on the commit order queue. The commit order sequence ticket

generator now wraps around correctly. Thanks to Zhai Weixiang for the contribution. (Bug #32891221,

Bug #103636)

• Replication: The replication receiver thread stopped with an error if the replication source server sent a

heartbeat event containing a binary log file position that was above the 4GB offset, due to the large size

of the binary log file. A new heartbeat event (Heartbeat_log_event_v2, log event type 41) that handles

the larger value correctly has been added for use in this situation. (Bug #29913991)

• Group Replication: Group Replication could stop unexpectedly during the auto-rejoin procedure while

the Performance Schema replication group member statistics table was being checked. The concurrency

of the operations is now handled correctly. (Bug #33609089)

• Group Replication: Group Replication's selection process for a group member to be the donor for

distributed recovery involves the use of the standard random selector defined for the operating system.

If this random device was not available and an exception was thrown, the member's joining process

stopped. Group Replication now takes this possibility into account and uses a fallback random selector if

the one on the operating system returns an error. (Bug #33596124)

• Group Replication: The STOP GROUP_REPLICATION statement stops asynchronous replication

channels on the group member, but it does not implicitly commit transactions that are in progress on

them like STOP REPLICA does. This is because on a Group Replication group member, an additional

transaction committed during the shutdown operation would leave the member inconsistent with the

group and cause an issue with rejoining. The server is left in a read-only state after the operation is

completed. This situation leads to failed commits for transactions that are in progress while stopping

Group Replication, so to avoid these, the STOP GROUP_REPLICATION statement now cannot be issued

while a GTID is assigned as the value of the gtid_next system variable. (Bug #33412483)

• Group Replication: An expelled group member using the Group Replication auto-rejoin procedure

reported its state as RECOVERING too early on, while it was still collecting information from other group

members and before the compatibility checks were complete. The state change is now carried out while

the view is being installed, which is the point where the rejoining member is actually accepted as a group

member. (Bug #33380840)

• Group Replication: Disabling the Group Replication plugin in a MySQL source distribution using the

CMake option DWITH_GROUP_REPLICATION=0 did not disable applications and tests related to Group

Replication, which caused them to build incorrectly. (Bug #33308513)

• Group Replication: In Group Replication, if a SET gtid_next statement is used on a group member

to set the GTID for the next transaction, it is possible for the same GTID to be used for a transaction that

starts concurrently on another member. If both transactions reach the commit stage, the second one in

the total order is rolled back, resolving the situation. However, when the transaction consistency level

for Group Replication (the group_replication_consistency system variable) was set to BEFORE

or BEFORE_AND_AFTER, members could reach a deadlock with one holding ownership of a GTID in the

gtid_owned set, and another waiting for ownership to be released before committing the transaction.

The wait function now only considers the GTIDs for committed transactions and not the GTIDs that are

owned but not committed, except where a session owns a GTID that is concurrently committed, in which

case the executing session errors out. (Bug #33051454, Bug #104096)

• Group Replication: The group communication engine for Group Replication (XCom, a Paxos variant)

now logs more information in the situation where the existing group members have difficulty in

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MySQL 8.0 Release Notes

communicating with a joining member, for example due to network issues. This can result in the group

remembering an old incarnation of the joining member and not allowing it to attempt to join again. (Bug

#32873315)

• Group Replication: Group Replication's Group Communication System (GCS) now differentiates in its

records of expelled members between those that had successfully joined the group, and those that never

did manage to join the group. (Bug #32630484)

• Group Replication: A race condition occurred if the Group Replication group member statistics in

the Performance Schema were queried when Group Replication was being started or stopped. (Bug

#32392468)

• Microsoft Windows: On Windows, added missing debug and test suite binaries for MySQL Server

(commercial) and MySQL NDB Cluster (commercial and community). (Bug #32713189)

• JSON: When the first argument passed to JSON_TABLE() was a row instead of a single JSON value,

an assertion was raised while trying to evaluate the row expression. We fix this by raising an error during

function resolution if the first argument is a row, so that the row expression itself is never evaluated. (Bug

#33414235)

• Using LPAD() or RPAD() in the expression for a generated column led to corrupted indexes on the

parent table. (Bug #33661337)

References: See also: Bug #32668730, Bug #33238711.

• In some cases where warnings were issued, rows were missing from the results of aggregation using a

temporary table. (Bug #33603911)

• For openSUSE 15, added the libtirpc rpcgen build requirement in mysql.spec to now use TI-RPC. (Bug

#33582982)

• An UPDATE statement acting on multiple tables sometimes adds elements to a list each time it is

executed. Elements were never removed from this list, which increased the memory footprint for each

execution of the statement. We fix this by clearing the element list following execution. (Bug #33574408)

• The size of the HOST column of the Performance Schema processlist table is increased from

VARCHAR(255) to VARCHAR(261). (Bug #33570218)

• A keyring migration failure due to an OpenSSL error raised an assertion. The SSL error state was not

flushed from the thread's OpenSSL error queue. (Bug #33546207)

• A process listing function call caused a failure. (Bug #33511690)

• The commercial Debian server packages contained two testing plugins

(component_test_page_track_component.so and component_test_global_priv_registration.so); they

were moved to the separate and optional testing package. (Bug #33504443)

• For Fedora, increased the release package version number from 1 to 10; this to help eliminate

potential installation related problems with native Fedora dnf/yum packages of the same version. (Bug

#33504443)

• Increased compat level to 11 for Debian-based packages as the previous level of 9 is deprecated; and

replaced calls to dh_systemd_enable + dh_systemd_start with dh_installsystemd to satisfy requirements

for compatibility level 10+. (Bug #33458752)

• A delete operation involving a full-text search query caused a failure. (Bug #33455243)

• An improperly handled error caused a startup failure when using the keyring_okv plugin. (Bug

#33449117)

117

MySQL 8.0 Release Notes

• For Debian, added a mysql-community-server dependency to the mysql-community-server-

debug package so as to pull in all required packages needed by the debug build. (Bug #33426737)

• For virtual generated columns of type DECIMAL, we now always store some data, so that we avoid

undefined behavior when trying to convert the field buffer to a decimal value. (Bug #33424846)

• MySQL now supports pushing a condition down to a derived table when an expression from the

underlying derived table contains a variable set by a stored procedure. (Bug #33423394)

• tls_version and admin_tls_version settings are now validated server startup. (Bug #33390209)

• The admin_tls_version variable accepted an invalid value. (Bug #33389818)

• If two or more deprecated system variables were persisted using a SET PERSIST statement, when

the server was restarted, a deprecation warning was only logged for the first of the deprecated system

variables. (Bug #33388488)

• For an index range scan whose key parts are equal, the range is now shown as an equality. For

example, a = 3 is now displayed, instead of 3 <= a <= 3 previous to this change. (Bug #33351123)

• Replaced /var/run references with /run as /var/run usage is deprecated for tmpfiles.d

configuration files. The symlink from /var/run to /run remains to keep current setups functional. (Bug

#33351110, Bug #33588618)

• Executing SHOW PROCESSLIST or accessing INFORMATION_SCHEMA.PROCESSLIST on a server with

a specific configuration caused a failure. (Bug #33341623)

• Added a mapping from ICU error code U_FILE_ACCESS_ERROR to the new MySQL error code

ER_REGEXP_MISSING_FILE. (Bug #33326003)

• A failed keyring function argument validation check caused a failure. (Bug #33319782)

• The index range scan iterator did not always increment the number of rows examined as expected. (Bug

#33305632)

• Enabling the create_admin_listener_thread system variable on the command line could cause a

server exit during startup under specific error conditions. (Bug #33300587)

• The SUBSTR() function did not always correctly handle errors raised when trying to evaluate its

arguments. (Bug #33290160)

• International Components for Unicode version 67 introduced a new implementation for \X (match a

grapheme cluster), which requires locale data not currently included with MySQL.

This means that, when using the version of ICU bundled with MySQL, a query using \X raises

the error ER_REGEXP_MISSING_RESOURCE; when using ICU supplied by the system, we report

ER_WARN_REGEXP_USING_DEFAULT as a Note. (Bug #33290090)

• A full-text search query on a table stored in the BLACKHOLE storage engine where the chosen query plan

used a full-text index scan caused an error instead of returning an empty result set. (Bug #33250020)

• The LOCK_TIME returned by the performance schema was under evaluated, missing time spent in rows

locks, and time spent when locking multiple tables. As of this release, LOCK_TIME accounts for:

• all the time waited on SQL TABLES

• all the time waited on DATA locks

LOCK_TIME is now reported consistently in the slow log and the performance schema. (Bug #33236909)

118

MySQL 8.0 Release Notes

• A new option \T for the mysql client prompt prints an asterisk (*) if the current session is inside a

transaction block. You can use the option with the --prompt command-line option, in a MySQL option

file, or with the MYSQL_PS1 environment variable. Thanks to Murakami Kohei for the contribution. (Bug

#33214862, Bug #104598)

• Constant subqueries in RANGE INTERVAL expressions were not always handled correctly. (Bug

#33197418)

• Decimal expressions which evaluated as NULL were not always handled correctly. (Bug #33169048)

• A user account that was granted a MySQL role with a global SELECT privilege was denied access to

the mysql database. The user account's global privileges were not checked when the role was granted.

(Bug #33159353, Bug #104423)

• When setting up an Item_ref to a SELECT alias, its cached properties are copied (including whether

it is part of a ROLLUP expression or not). However, these might not yet be correctly computed, so the

computation should to be done first or the values could be wrong. Having the wrong value could cause

certain expressions to be materialized in an intermediate step when they should not (because they

contain ROLLUP expressions that are not ready for computation, but having the wrong value is unknown

at this point). The issue is fixed by forcing cached values to be recomputed when an item is designated

as a rollup item. (Bug #33149402, Bug #104394)

• An invalid comment string detected while upgrading a table from MySQL 5.7 to MySQL 8.0 caused the

upgrade to fail with errors that did not provide sufficient contextual information. (Bug #33148961)

• It was possible in some cases to create a generated column of type SERIAL, which is not allowed.

See Numeric Data Type Syntax, and CREATE TABLE and Generated Columns, for more information

(Bug #33141966)

• Statements which commit a transaction implicitly or explicitly are not allowed inside a trigger

or a stored function. Both CREATE TRIGGER and CREATE FUNCTION should report an error

(ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG) in this case, but did not correctly handle DROP

TABLESPACE. (Bug #33141958)

• A SHOW TABLE STATUS operation raised an assertion failure when run on a table defined with a very

large AVG_ROW_LENGTH value. (Bug #33114368)

• When calculating the maximum number of rows likely to be read from a scan, the intermediate result

was a double that could become greater than the maximum allowed value for a 64-bit unsigned integer.

This triggered undefined behavior when converting the intermediate double value to an integer, which in

some cases could lead to assert failures.

We fix this by clamping the result in the range [1, UINT64_MAX]. (Bug #33066458)

• Queries using both UNION and LIMIT 0 triggered an assert failure in debug builds. (Bug #33066455)

References: This issue is a regression of: Bug #32302724.

• Renaming an event using ALTER EVENT ... RENAME TO did not delete the Performance Schema

instrumentation for the original event. (Bug #33059358)

• An SSL handshake assertion was raised on debug builds when using the thread pool plugin. (Bug

#33012398)

• Some prepared statements using either GROUP BY WITH ROLLUP or one or more window functions

could be executed successfully only once. (Bug #33007266)

119

MySQL 8.0 Release Notes

• An error occurred for statements of the form INSERT INTO view VALUE(tuple) AS

row_alias(id_list). When executing such statements, the server calls the internal function

Sql_cmd_insert_base::prepare_values_table() in order to prepare the derived table created

as a VALUES alias; this function populates Sql_cmd_insert_base.values_field_list with

Item_field objects pointing to the columns of the underlying table. When inserting into a view

rather than a table, an expected real_item() transform, needed to map from an Item_view_ref

referencing the view column to an Item_field representing the corresponding column in the

underlying table, was not performed. (Bug #32858783)

• Some multiply-nested subselects were not handled correctly, and could lead to an unplanned shutdown

of the server. (Bug #32547812)

• Inspection of a session thread object during a SHOW PROCESSLIST operation and a concurrent change

to the thread's security context resulted in a race condition. (Bug #32320541, Bug #102052)

• In cases where there are no operations to be performed on the result of a UNION, the rows are streamed

without storing them in a temporary table, although a placeholder for the temporary table still exists

in the query block. Since this table is not instantiated, a check for estimates of the cost of reading

the rows from the table while calculating the access cost and optimizing for range based access had

unpredictable results.

We fix this by skipping retrieval of such row estimates in the case of an uninstantiated temporary table.

(Bug #32255904)

• A multi-table DELETE statement using common table expressions was not always handled correctly.

(Bug #32238558)

References: This issue is a regression of: Bug #98330, Bug #30796015.

• If a CR_UNKNOWN_ERROR was to be sent to a client, an exception could occur. (Bug #31933415)

• SSL-related code was revised to avoid a potential memory leak. (Bug #31933295)

• In some cases, multiple-table UPDATE statements could block concurrent access. (Bug #31731752)

• Keyring system variables that use an internal slot for complex settings no longer accept a setting of

DEFAULT. (Bug #30879700)

• The Timestamp column in the mysql.tables_priv and myql.columns_priv grant tables was

set to a zero timestamp value ("0000-00-00 00:00:00") for GRANT and REVOKE operations,

preventing a logical restore of the grant tables. As of MySQL 8.0.28, a valid start time value is written to

the Timestamp column.

If you have existing grant table records with zero timestamp values that are preventing a logical restore

of the grant tables, a workaround is to update records in the grant tables or in the dump files, replacing

zero timestamp values with CURRENT_TIMESTAMP.

Thanks to Venkatesh Prasad Venugopal for the contribution. (Bug #30863899, Bug #98495)

• Producing a per-table dump using mysqldump in MySQL 5.7 and 8.0 requires a longer execution time

compared to MySQL 5.6. This is because the information_schema.files table, which is queried

for information on log file groups by mysqldump, contains information about InnoDB data files as well as

NDB data files from MySQL 5.7. In MySQL 8.0, the issue has been fixed by rewriting the query to select

only the appropriate data files. In MySQL 5.7, Information Schema tables do not have indexes, so a full

table scan is still required. (Bug #29210990, Bug #93875)

• Keyring memory management was improved. (Bug #25042167)

120

MySQL 8.0 Release Notes

• Incorrect values for FORCE INDEX FOR GROUP BY could be set while saving and restoring the

presence of FORCE INDEX hints within tables. (Bug #105694, Bug #33604416)

• If a query with the sql_buffer_result system variable enabled returned just one row, and an attempt

was made to insert the result into a table, then an error in setting the output from the temporary table

could produce a data exception. (Bug #105351, Bug #33515752)

References: This issue is a regression of: Bug #33152269.

• Resetting of the active slice was not performed in WindowIterator::Read() at the end the end of the

input result set for windowing. This led to reading wrong values on reaching the ORDER BY sort, since

the number of the active slice was still set to 1—that is, to the items being read from the input table—

while the ORDER BY sorting stage needs to read the values after computation of any window functions.

For this, it needs the active slice to be that of the last window's output table.

We fix this by moving the resetting of the slice to the output slice immediately following the read, so that

it is already set correctly when returning at the end of the input set and moving on to the ordering.

Our thanks to Casa Zhang and the Tencent team for the contribution. (Bug #105045, Bug #33399696)

• Code inspection revealed use of strncpy() in the internal function set_parse_error_message()

without making sure that the last byte of the buffer being copied into was a null byte. We fix this by using

snprintf() instead of strncpy(); this ensures that the result is valid even if it is truncated. (Bug

#104856, Bug #33321787)

• When executing prepared statements that activated a trigger created with the DEFINER clause (or a

stored function), invoker privileges were used for checking table access instead of definer privileges.

This, in turn, could cause privilege checks on tables used by the trigger or stored function to fail. (Bug

#104168, Bug #33064461)

• When a singleton histogram is constructed, its cumulative frequency is calculated by adding

frequencies of previous buckets with the current bucket; because a floating-point value was used for

the accumulator, this sometimes led to accumulated float errors, with the final cumulative frequency

fractionally greater than 1.0.

This fix accumulates the frequency with an integer type instead, to avoid intermediate floating-point

errors.

Our thanks to Casa Zhang and the Tencent team for the contribution. (Bug #104108, Bug #33045336)

• With index_condition_pushdown=ON and transaction_isolation='READ-COMMITTED', locks

on secondary indexes were not released until the transaction was either committed or rolled back, even

though the secondary indexes were unmatched. (Bug #102722, Bug #32554667)

• Multi-valued indexes were not used for queries executed from within stored functions. (Bug #102359,

Bug #32427727)

References: See also: Bug #104700, Bug #33268466.

• An error occurred for an SQL statement having the form shown here:

INSERT INTO target_table

SELECT aggregate_expression, non_aggregate_expression

FROM empty_table;

This happened when the query plan used aggregation from a temporary table, and when

non_aggregate_expression was constant during one execution of the query, but could vary

between executions. Such an expression might, for example, include a function such as NOW() or

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MySQL 8.0 Release Notes

USER(). This resulted in the temporary table getting a column for non_aggregate_expression,

which is unnecessary, since all rows have the same value. In addition, if there were no rows, there was

no legal value to insert into target_table, which is what actually triggered the error.

We fix this by not using a temporary table column when non_aggregate_expression is const for

the current execution. (Bug #102252, Bug #32384355, Bug #33546083)

• When executing a prepared statement that included values passed in as strings, MySQL attempted to

parse them as integers and could return an error unrelated to the input value.

After a recent change, dynamic parameter handling was refactored so that the derived data type for

parameters was determined based on context. For example, in a comparison such as int_col = ?,

the parameter was given the same type as the (integer) column it was compared to. To preserve

compatibility with existing MySQL applications, if a decimal or float value was supplied as parameter, the

statement was automatically reprepared with new type assigned to the parameter based on the actual

value. This handling preserved compatibility for numeric parameters.

However, if a string parameter was supplied, it was still interpreted as an integer (the resolved data type)

and this behavior was not compatible with older MySQL versions that detected the actual type of the

value. The consequences being that if int_col = ? is executed with the parameter value '1.7', only

the integer part of the string was used, making the effective comparison int_col = 1.

To fix the issue, now when a string parameter is supplied, the parameter is analyzed to determine if it is

an integer, a decimal, or a float value and the actual data type of the parameter is updated accordingly.

Later, the actual type is compared to the resolved type and if it is incompatible, the statement is

reprepared with the new actual type. So, the previous statement now evaluates as int_col = 1.7 and

the comparison evaluates using decimal numbers. (Bug #101806, Bug #32213576, Bug #103364, Bug

#32787037)

Changes in MySQL 8.0.27 (2021-10-19, General Availability)

• Audit Log Notes

• Authentication Notes

• Character Set Support

• Compilation Notes

• Connection Management Notes

• Data Type Notes

• Deprecation and Removal Notes

• Storage Engine Notes

• Firewall Notes

• SQL Function and Operator Notes

• Keyring Notes

• Optimizer Notes

• Performance Schema Notes

• Pluggable Authentication

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MySQL 8.0 Release Notes

• Security Notes

• Server Administration

• Spatial Data Support

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• A CREATE USER statement BY 'auth_string' clause was written to the audit log and general query

log as an AS 'auth_string' clause. (Bug #33184550)

Authentication Notes

• Previously, MySQL user accounts authenticated to the server using a single authentication method.

MySQL now supports multifactor authentication (MFA), which makes it possible to create accounts that

have up to three authentication methods. MFA support entails these changes:

• CREATE USER and ALTER USER syntax has been extended to permit specification of multiple

authentication methods.

• The authentication_policy system variable enables MFA policy to be established by controlling

how many factors can be used and the types of authentication permitted for each factor. This places

constraints on how the authentication-related clauses of CREATE USER and ALTER USER statements

may be used.

• Client programs have new --password1, --password2, and --password3 command-

line options for specifying multiple passwords. For applications that use the C API, the new

MYSQL_OPT_USER_PASSWORD option for the mysql_options4() C API function enables the same

capability.

In addition, MySQL Enterprise Edition now supports authentication to MySQL Server using devices such

as smart cards, security keys, and biometric readers. This authentication method is based on the Fast

Identity Online (FIDO) standard, and uses a pair of plugins, authentication_fido on the server side

and authentication_fido_client on the client side. The server-side FIDO authentication plugin is

included only in MySQL Enterprise Edition distributions.

Multifactor authentication can use existing MySQL authentication methods, the new FIDO authentication

method, or a combination of both. For more information, see Multifactor Authentication, and FIDO

Pluggable Authentication. (Bug #33159968, WL #14183)

• In cases where an authentication plugin performed no hashing of the authentication string, CREATE

USER statements with a BY 'auth_string' clause failed with an error. (Bug #33125289)

Character Set Support

• Regular expression functions now report an error when an expression or pattern cannot be converted to

a character set which is suitable for the ICU regular expression engine.

In addition, error checking in several geometry functions has been improved. (Bug #33290245)

• The gen_dictionary() function now takes latin1 as the character set of its argument, and returns

the same character set. (Bug #30389649)

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MySQL 8.0 Release Notes

• Otherwise identical strings, using, respectively, the ASCII (collation ascii_general_ci) and UCS2

(collation ucs2_general_ci) character sets did not match as expected in join conditions. (Bug

#104571, Bug #33204161)

References: See also: Bug #24847620, Bug #30746908, Bug #32244631, Bug #32501472.

• Given the default collation c1 of a character set cs, and a different collation c2 (that is, not equal to

c1), then the statement CREATE DATABASE d COLLATE c2 CHARACTER SET cs created a new

database with the default collation set to c1 instead of c2. (Bug #104504, Bug #33183590)

Compilation Notes

• InnoDB: A workaround was implemented for a Clang issue that causes a build failure on Windows

(Bugzilla – Bug 51538). (Bug #33217633)

• MySQL now can be compiled using C++17. The following minimum version requirements apply for

compiler support:

• GCC 7.1 or Clang 5 (Linux)

• XCode 10 (macOS)

• GCC 10 (Solaris)

• Visual Studio 2019 Update 4 (Windows)

In particular, on Solaris, GCC is now the only supported compiler. The code has been cleaned up to

remove adaptations and workarounds for Sun Studio, Oracle Studio, and SunPro. (Bug #32907274, Bug

#103757, Bug #32907475, Bug #32992125, Bug #32992242, Bug #33004840, Bug #33086882)

Connection Management Notes

• Previously, if the server restricted a client to the sandbox mode used to handle client connections

for accounts with expired passwords, the client could use the SET statement. This is no longer

permitted. For more information about sandbox mode, see Server Handling of Expired Passwords. (Bug

#16369085, WL #13214)

Data Type Notes

• YEAR values were not always interpreted correctly. (Bug #33142669)

References: This issue is a regression of: Bug #31994744.

Deprecation and Removal Notes

• Important Change: The default_authentication_plugin variable is deprecated as of MySQL

8.0.27; expect support for it to be removed in a future version of MySQL.

The default_authentication_plugin variable is still used in MySQL 8.0.27, but in conjunction

with and at a lower precedence than the new authentication_policy system variable, which is

introduced in MySQL 8.0.27 with the multifactor authentication feature. For details, see The Default

Authentication Plugin. (Bug #27515356, WL #14138)

• Important Change: The BINARY operator is now deprecated, and subject to removal in a future release

of MySQL. Use of BINARY now causes a warning. Use CAST(... AS BINARY) instead. (WL #13619)

124

MySQL 8.0 Release Notes

Storage Engine Notes

• The BLACKHOLE storage engine maximum key length has been increased from 1000 to 3072 bytes (the

same as InnoDB). Thanks to Adam Cable for the contribution. (Bug #32788749, Bug #103371)

Firewall Notes

• The new FIREWALL_EXEMPT privilege exempts a user from firewall restrictions. This is useful, for

example, for any database administrator who configures the firewall, to avoid the possibility of a

misconfiguration causing even the administrator to be locked out and unable to execute statements. See

MySQL Enterprise Firewall. (WL #14517)

SQL Function and Operator Notes

• The SPACE() function did not handle certain large or unsigned values correctly. (Bug #33180446)

• Function arguments were not always evaluated correctly during resolution of functions defined within

views. (Bug #33142010)

References: This issue is a regression of: Bug #29904087.

• Bit functions in window expressions assert that the runtime size of a bit mask is not bigger than its

resolve time size. We found several violations of this rule, listed here:

• ENCRYPT() sometimes computed the maximum size of the result incorrectly.

• CONVERT(), CONCAT(), CONCAT_WS(), EXPORT_SET(), INSERT(), REPLACE(), and

WEIGHT_STRING() did not compute the maximum result length properly for the binary character set.

• During resolution of REPLACE(str, from_str, to_str) we assumed that the entire length of

from_str would be replaced for each match in str, but since from_str may be only 1 character

long, it is possible for str to be replaced with multiple copies of to_str.

• COMPRESS() computed the maximum result length in an arbitrary fashion. Now we use

compressBound from the zlib library instead.

(Bug #32922688, Bug #33117410, Bug #33275424)

References: See also: Bug #33516898.

Keyring Notes

• Diagnostics for keyring_hashicorp plugin configuration issues have been improved. (Bug

#32075854)

Optimizer Notes

• EXPLAIN FORMAT=TREE now shows more precise information than displayed previously about scans

generated by the range optimizer. In particular, sub-iterators are now displayed explicitly, and are

properly timed with EXPLAIN ANALYZE; index range scans now show the actual ranges being scanned.

Descriptions in the output are also more user-friendly than before; for example, index_for_group_by

shown for a query using DISTINCT is replaced by index skip scan for deduplication.

In addition, a roundoff error causing inaccuracies in row count estimation for read over range intersection

scans has been corrected, and optimizer traces for index range scans now correctly displays implicit key

parts from InnoDB primary keys when they are used. (Bug #33037007, Bug #33062448)

125

MySQL 8.0 Release Notes

• When transforming EXISTS to a semijoin, and when the query contained a view reference, the query

was not processed correctly. (Bug #32813550)

References: This issue is a regression of: Bug #30671329.

• In the case of a lateral derived table, if the creation of the cache invalidator was delayed, the table

materialization was emitted without the invalidator, which kept rematerialization from occurring during

execution and led to wrong results.

The pending cache invalidator was emitted only when the index of the lateral table was less than that

of the last table in the table list being considered. When the table index of the pending invalidator was

equal to the last table of the join slice, the cache invalidator was skipped and the materialization was

emitted without the invalidator.

We fix this by creating the pending cache invalidator if the table index of the pending invalidator is less

than or equal to that of the last table in the table list of the current join slice. (Bug #32407774)

Performance Schema Notes

• To assist monitoring and troubleshooting, the Performance Schema instrumentation is now used to

export names of instrumented threads to the operating system. This enables utilities that display thread

names, such as debuggers and the Unix ps command, to display distinct mysqld thread names rather

than “mysqld”. This feature is supported only on Linux, macOS, and Windows. For more information, see

The setup_instruments Table. (WL #14587)

Pluggable Authentication

• Microsoft Windows: The Kerberos authentication method added in MySQL 8.0.26 for MySQL server

and client hosts running Linux is now supported on the client side for Windows. This enables MySQL

client applications running on Windows to connect to MySQL accounts on Linux server hosts that

authenticate using Kerberos. For details, see Kerberos Pluggable Authentication. (WL #14605)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.1.1l. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl111.txt and at http://www.openssl.org/news/vulnerabilities.html. (Bug

#33273138, Bug #33309871)

Server Administration

• Setting the session value of the following system variables is now a restricted operation and the session

user must have privileges sufficient to set restricted session variables:

• low_priority_updates

• max_delayed_threads

• max_error_count

• min_examined_row_limit

• preload_buffer_size

• select_into_buffer_size

• select_into_disk_sync_delay

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MySQL 8.0 Release Notes

• show_old_temporals

For information about the privileges required to set restricted session variables, see System Variable

Privileges. (WL #14695)

Spatial Data Support

• The ST_SymDifference() and ST_Intersection() functions now permit the geometry arguments

to have a geographic spatial reference system (SRS). Previously, ST_SymDifference() and

ST_Intersection() supported only geometry arguments in a Cartesian SRS. See Spatial Operator

Functions. (WL #10996, WL #14273)

Functionality Added or Changed

• Important Change; Group Replication: The system variable

group_replication_components_stop_timeout specifies the time that Group Replication waits

for each of its modules to complete ongoing processes while shutting down. The component timeout

applies after a STOP GROUP_REPLICATION statement is issued, which happens automatically during

server restart or auto-rejoin. The timeout is used to resolve situations in which Group Replication

components cannot be stopped normally, which might happen if the member is expelled from the group

while it is in an error state, or while a process such as MySQL Enterprise Backup holds a global lock on

tables on the member. In such situations, the member cannot stop the applier thread or complete the

distributed recovery process to rejoin. The STOP GROUP_REPLICATION statement does not complete

until either the situation is resolved (for example, by the lock being released), or the component timeout

expires and the modules are shut down regardless of their status.

Previously, the timeout value defaulted to 31536000 seconds (365 days), which did not help in situations

such as those just described. The new default value is 300 seconds, so that Group Replication

components are stopped after 5 minutes if the situation is not resolved before that time, allowing the

member to be restarted and to rejoin. (WL #14245)

References: See also: Bug #31460690, Bug #31648211, Bug #32309647.

• Replication: When GTID-based replication is in use on a replica server, the replication applier and

receiver threads still track and have some dependencies on binary log file names and file positions,

as used for the alternative binary log file position based replication. A new option for the CHANGE

REPLICATION SOURCE TO statement, GTID_ONLY, removes the persistence of file names and file

positions from the replication metadata repositories. For replication channels with this setting, in-memory

file positions are still tracked, and file positions can still be observed for debugging purposes in error

messages and through interfaces such as SHOW REPLICA STATUS statements (where they are shown

as being invalid if they are out of date). However, the writes and reads required to persist and check

the file positions are avoided in situations where GTID-based replication does not actually require them,

including the transaction queuing and application process. The GTID_ONLY setting also means that the

replication metadata is flushed less frequently.

The GTID_ONLY option is disabled by default for asynchronous replication channels, but it is enabled

by default for group replication channels, and it cannot be disabled for them. To set GTID_ONLY =

1 for a replication channel, GTIDs must be in use on the server (gtid_mode = ON), and row-based

binary logging must be in use on the source (statement-based replication is not supported). The

CHANGE REPLICATION SOURCE TO options REQUIRE_ROW_FORMAT and SOURCE_AUTO_POSITION

must each be set to 1 for the replication channel. When GTID_ONLY is set to 1, the replica uses

replica_parallel_workers=1 if that system variable is set to zero for the server, so it is always

technically a multi-threaded applier. This is because a multi-threaded applier uses saved positions rather

than the replication metadata repositories to locate the start of a transaction that it needs to reapply.

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MySQL 8.0 Release Notes

Thanks to Facebook for offering a contribution related to this issue. (Bug #94360, Bug #29364334, WL

#7491)

• Replication: Multithreading is now enabled by default for replica servers. A multithreaded applier has a

number of applier threads that execute transactions in parallel. This behavior can avoid many cases of

unwanted replication lag that can cause temporary divergence between the source and replicas.

The following default server settings are used to produce the multithreading behavior:

• replica_parallel_workers=4. This setting enables multithreading and creates four applier

threads on the replica, plus a coordinator thread to manage them. If you are using multiple replication

channels, each channel has this number of threads. Four applier threads provide a base level of

parallelism, and you can change the setting to specify up to 1024 applier threads.

• replica_preserve_commit_order=1. This setting ensures that transactions are externalized on

the replica in the same order as they appear in the replica's relay log, so the replica never enters a

state that the master was not in, and there are no gaps in the sequence of transactions that have been

executed from the relay log.

• replica_parallel_type=LOGICAL_CLOCK. This setting specifies that transactions that are part of

the same binary log group commit on a replication source server are applied in parallel on a replica. It

is required when replica_preserve_commit_order=1 is set.

To override the new defaults and disable multithreading for a replica server, specify

replica_parallel_workers=0. This setting disables parallel execution and gives the

replica a single applier thread and no coordinator thread. When you apply this setting, the

replica_parallel_type and replica_preserve_commit_order options have no effect and are

ignored. (WL #10475)

• Group Replication: The asynchronous connection failover mechanism for MySQL replication

now enables a replica that is part of a managed replication group to automatically reconnect to

the sender if the current receiver (the primary of the group) fails. The new feature works with

Group Replication, on a group configured in single-primary mode, where the group’s primary is a

replica that has a replication channel with SOURCE_CONNECTION_AUTO_FAILOVER set to ON. The

feature operates by default on a group in this situation, although you can disable it for the group by

disabling the new member action mysql_start_failover_channels_if_primary, using the

group_replication_disable_member_action() function. The feature is designed for a group of

senders and a group of receivers to keep synchronized with each other even when some members are

temporarily unavailable. It also synchronizes a group of receivers with one or more senders that are not

part of a managed group. A replica that is not part of a replication group cannot use this feature.

To configure this feature, the replication channel and the replication user account and password

for the channel must be set up on all the member servers in the replication group, and on any new

joining members. You can do this using the CHANGE REPLICATION SOURCE TO statement, or if the

new servers are provisioned using MySQL’s clone functionality, this all happens automatically. The

SOURCE_CONNECTION_AUTO_FAILOVER setting for the channel is broadcast to group members from

the primary when they join, and also if it is changed. The source list is broadcast to all members when

they join or when it is updated. If the primary goes offline or into an error state, the new primary that is

selected for the group has the source list and the channel configuration already in place, and establishes

a replacement asynchronous replication connection with the source.

A new function asynchronous_connection_failover_reset() is also provided for administrators

to remove all settings relating to the asynchronous connection failover mechanism. Use this function to

clean up a server that is no longer being used in a managed group. (WL #14020)

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MySQL 8.0 Release Notes

• Group Replication: The group communication engine for Group Replication (XCom, a Paxos variant)

defaults to using every member of the group as a leader. When the Group Replication communication

protocol version is set to 8.0.27 or later, the group communication engine can now use a single leader

to drive consensus when the group is in single-primary mode. Operating with a single consensus leader

improves performance and resilience in single-primary mode, particularly when some of the group’s

secondary members are currently unreachable.

The single consensus leader is colocated with the group’s primary, and changes when a new primary

is elected. The Performance Schema table replication_group_communication_information

shows the preferred and actual consensus leader, or leaders if all members are used as a leader, the

communication protocol version, and the write concurrency.

To enable the new behavior, set the system variable group_replication_paxos_single_leader

to ON (the default is OFF). When Group Replication is running in multi-primary mode, or with earlier

communication protocol versions, or when group_replication_paxos_single_leader is set to

OFF, the group communication engine operates using every member of the group as a leader.

Note that when you manually upgrade the members of a replication group to a new MySQL

Server release, the group's communication protocol version is not automatically upgraded

to match. If you no longer need to support members at earlier releases, you can use the

group_replication_set_communication_protocol() function to set the communication

protocol version to the new MySQL Server version to which you have upgraded the members. MySQL

InnoDB Cluster manages the communication protocol version automatically for replication groups

created using that function. (WL #9149)

• Group Replication: In previous releases, Group Replication secured group communication connections

and distributed recovery connections between members using its own implementation of the security

protocols, including TLS/SSL and the use of an allowlist for incoming Group Communication System

(GCS) connections. Replication groups can now use the MySQL Server's own connection security

in place of the Group Replication implementation. Using the MySQL protocol means that standard

methods of user authentication can be used for granting (or revoking) access to the group in place of the

allowlist, and that the latest functionality of the server's protocol is always available on release. Network

namespaces are supported for Group Replication when the MySQL communication stack is used.

To use the MySQL Server's implementation of the connection security management

in place of the Group Replication implementation, set the new system variable

group_replication_communication_stack to MYSQL. In addition, the network address set by

group_replication_local_address for each group member must be changed to one of the IP

addresses and ports which MySQL Server is listening on, as specified by bind_address. If a network

namespace is used, this must be configured using the CHANGE REPLICATION SOURCE TO statement

in the group_replication_recovery channel.

Authentication is carried out using the existing replication user account that Group Replication uses

for distributed recovery, as set using CHANGE REPLICATION SOURCE TO, and this user must

be given the new GROUP_REPLICATION_STREAM privilege. The TLS/SSL configuration for the

connection is taken from Group Replication's existing settings for securing distributed recovery, plus

the group_replication_ssl_mode system variable that specifies whether TLS/ SSL is enabled or

disabled for group communications. These settings must be configured if they are not already in place.

All these settings must be the same on all group members to avoid communication issues.

As part of this work, the default value for the performance_schema_max_cond_classes system

variable is increased from 100 to 150.

See Group Replication Requirements For The MySQL Communication Stack for more details. (WL

#9852)

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MySQL 8.0 Release Notes

• Programs that encounter issues while processing include or includedir directives in option files

now produce error messages that are more informative about the cause of the errors. (Bug #32798288,

Bug #103397)

• The default value for the thread_stack system variable has been increased to 1048576 on all

supported platforms. (Bug #103912, Bug #32965326)

References: See also: Bug #32934187.

• A default time zone can now be set for a server by using the server option --default-time-zone

while starting a MySQL Server Docker container. Before, the container failed to start if the option was

used. (WL #14703)

• For online DDL operations, storage is usually the bottleneck. To address this issue, CPU utilization

and index building has been improved. Indexes can now be built simultaneously instead of serially.

Memory management has also been tightened to respect memory configuration limits set by the user.

See Configuring Parallel Threads for Online DDL Operations.

The new innodb_ddl_threads variable defines the maximum number of parallel threads for the sort

and build phases of index creation.

The new innodb_ddl_buffer_size variable defines the maximum buffer size for DDL operations.

The default setting is 1048576 bytes (approximately 1 MB). Defining a buffer size limit avoids potential

out of memory errors for online DDL operations that create or rebuild secondary indexes. See Online

DDL Memory Management. (WL #14283)

• The clone plugin now permits concurrent DDL operations on the donor MySQL Server instance while

a cloning operation is in progress. Previously, a backup lock was held during the cloning operation,

preventing concurrent DDL on the donor. To revert to the previous behavior of blocking concurrent

DDL on the donor during a clone operation, enable the clone_block_ddl variable. See Cloning and

Concurrent DDL. (WL #9683)

• Setting a session value for the internal_tmp_mem_storage_engine variable now requires the

SESSION_VARIABLES_ADMIN or SYSTEM_VARIABLES_ADMIN privilege. (WL #14728)

Bugs Fixed

• Incompatible Change: For all SELECT statements on a view, the query digest was based on the view

definition. As a result, different queries had the same digest and aggregated together in the Performance

Schema table events_statements_summary_by_digest, so statistics in that table were not usable

for distinguishing distinct SELECT statements.

The query digest for each SELECT statement on a view now is based on the SELECT,

not the view definition. This enables distinguishing distinct SELECT statements in the

events_statements_summary_by_digest table. However, tools that use query digests may need

some adjustment to account for this change. For example, MySQL Enterprise Firewall and query rewrite

plugins rely on query digests and existing rules for them that are associated with views may need to be

updated. (Bug #27540213, Bug #89559, Bug #31761802)

• Important Change: EXPLAIN FORMAT=TREE now shows whether an index scan uses a covering

index, and thus does not need to look up other columns from the table/clustered index. For example,

if idx1 is a covering index, the old output Index scan on t1 using idx1 is now shown as

Covering index scan on t1 using idx1. Previously, this information was shown only for

FORMAT=TRADITIONAL and FORMAT=JSON.

This fix also improves the wording used for full-text search to align with this change. For example, the

old output Indexed full text search on t1 (which was the same in both the covering and non-

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MySQL 8.0 Release Notes

covering cases) is now Full-text index search on t1 when there is no covering index, and

Full-text covering index search on t1 when a covering index is used. (Bug #32825235)

• InnoDB: An excessive number of notes were written to the error log when the innodb_open_files

limit was temporarily exceeded. (Bug #33343690)

• InnoDB: An in-place DDL operation failed to flush all modified pages. (Bug #33290335, Bug #33238133)

• InnoDB: A parallel scan returned an incorrect partition ID when loading data into HeatWave from a

subpartitioned InnoDB table. (Bug #33276021)

• InnoDB: The unused os_event::event_iter field in the InnoDB sources was removed to reduce

memory use in the os_event structure.

Our thanks to Facebook for the contribution. (Bug #33252468)

• InnoDB: The srv_purge_thread and srv_worker_thread threads were duplicated in the

performance_schema.threads table.

Thanks to Kaige Ye for the contribution. (Bug #33209066, Bug #104575)

• InnoDB: Truncation of an undo tablespace during use by an active transaction raised an assertion

failure. The transaction was prematurely marked as complete, permitting the truncation operation. (Bug

#33162828)

• InnoDB: When loading data into HeatWave from a partitioned table with concurrent DML modifying the

primary key, the partition ID reported in the load callback was found to be incorrect for some records.

(Bug #33139692)

• InnoDB: Instances of MY_ATTRIBUTE((noreturn)) and MY_ATTRIBUTE((unused)) in the

InnoDB sources were replaced by C++17 [[noreturn]] and [[maybe_unused]] attributes. (Bug

#33112971)

• InnoDB: Each buffer pool block includes a block->lock_hash_val field. Caching of this value was

determined to be unnecessary, as it introduced unnecessary coupling of the buffer and lock system and

unnecessary memory usage. (Bug #33072415)

• InnoDB: A query that performed an index merge with retrieval ordered by row ID raised an assertion

failure. The record buffer set up for the index merge could not be used due to the scanned table

containing a primary key with a BLOB component. A record buffer cannot be used for reading BLOBs,

which are stored outside of the record. The BLOB primary key was not detected when the record

buffer was set up, as the primary key column was not yet in the read set. Retrievals ordered by row ID

temporarily add the primary key at a later stage when needed. To address this issue, a record buffer

is no longer requested for row-ordered retrievals if the primary key has a BLOB component. (Bug

#33067554)

• InnoDB: Deleting or updating a row from a parent table initiated a cascading SET NULL operation

on the child table that set a virtual column value to NULL. The virtual column value should have been

derived from the base column value.

Thanks to Yin Peng at Tencent for the contribution. (Bug #33053297)

• InnoDB: On a system that was nearing disk capacity, an InnoDB recovery operation involving

application of file extension redo log records (MLOG_FILE_EXTEND) could cause a failure. (Bug

#33002492)

• InnoDB: Conflicting explicit locks granted on the same record raised an assertion failure. (Bug

#33000142)

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MySQL 8.0 Release Notes

• InnoDB: Freeing the first page of LOB at the end of purge batch raised an assertion failure. The failure

was due an invalid root page number. (Bug #32958624)

• InnoDB: To facilitate failure reporting and resolution, the ib::fatal() function in the InnoDB sources

was revised to include the caller's location. (Bug #32957311)

• InnoDB: Recovery on the clone recipient server failed with the following error: Error reading

encryption for innodb_undo_007. The encryption key was not written to encrypted spaces

created during the page copy phase of the clone operation. (Bug #32950216)

• InnoDB: To avoid generating unwanted warning messages, the fil_space_acquire() function in the

InnoDB sources was replaced by the fil_space_acquire_silent() function where possible. Both

functions are used by background threads to acquire a tablespace. (Bug #32944543)

• InnoDB: InnoDB CRC32 checksum algorithm implementations have now been optimized for use with

ARM and x86/x64 architectures. (Bug #32887066)

• InnoDB: Startup on an instance with thousands of tables took an excessive amount of time due a large

amount of traffic on the error logging subsystem. (Bug #32846656)

• InnoDB: The INFORMATION_SCHEMA.FILES view did not show the current path of the

temporary tablespace file, and the file name shown was different from the one defined by the

innodb_temp_data_file_path variable. (Bug #32840635, Bug #103553)

• InnoDB: On Windows, keeping a file open without a shared write lock while attempting to acquire the

fil_shard mutex caused a deadlock with another thread that had acquired the fil_shard mutex and

was attempting to access the same file. (Bug #32808809)

• InnoDB: Starting a MySQL Server instance using the same InnoDB data files as an another running

MySQL Server instance resulted in an initialization failure. (Bug #32777654, Bug #103338)

• InnoDB: The InnoDB recovery process did not recognize that page compression had been applied

to data that was being recovered, causing the tablespace data file to increase in size during the redo

log apply phase, which could lead to a recovery failure for systems approaching a disk-full state. (Bug

#32771259)

• InnoDB: An assert that traversed a list of file segments which were not full to calculate the number of

used pages for comparison with the number of used pages tracked by a field in the file segment inode

failed sporadically. (Bug #31685095)

• InnoDB: A transaction failed to roll back when the server was restarted after failure occurred during an

online DDL operation. Table locks could not be resurrected for the uncommitted transaction and the data

dictionary table object could not be loaded for the affected table.

Thanks to Shaohua Wang for the contribution. (Bug #31131530, Bug #99174)

• InnoDB: A query that used a temporary table for aggregation exhausted the memory available to

the TempTable storage engine, causing an update operation to fail with a table is full error. (Bug

#31117893, Bug #99100)

• Replication: The replication applier (SQL) thread overrode retryable errors (such as deadlocks and wait

timeouts) from storage engines with a key not found error, causing replication to stop without retrying

the transaction. These errors are no longer overridden. (Bug #33107663)

• Replication: When the Group Replication distributed recovery process synchronized a joining member

with the donor, the Performance Schema table replication_group_member_stats table was

not updated with the current number of transactions queued on the group_replication_applier

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MySQL 8.0 Release Notes

channel (the COUNT_TRANSACTIONS_REMOTE_IN_APPLIER_QUEUE field.) The count is now tracked

while new transactions are arriving during distributed recovery, although it remains zero until the

joiner has certified the transactions that were received in the first phase of distributed recovery. (Bug

#33067441)

• Replication: For multithreaded replicas (replicas on which replica_parallel_workers

is set to a value greater than 0), if replica_parallel_workers is set to 1, the setting for

replica_preserve_commit_order is now ignored. When there is a single applier, transactions are

always executed and committed in the same order as in the replica's relay log; ignoring the process to

preserve the commit order avoids potential performance degradation. (Bug #33048169)

• Replication: An assertion was raised if a replica MySQL Server instance with unpopulated time zones

attempted to replicate a statement that set a time zone value that was unknown to the replica. Replicas

now handle this situation correctly. (Bug #32986721)

• Replication: The error messages issued by MySQL Replication when GTIDs required for auto-

positioning have been purged could be incorrectly assigned or scrambled in some situations. (Bug

#32965864)

• Replication: If a group member was elected as the primary right before or while it was shutting down,

the shutdown process hung while waiting on the primary election process, which was attempting to make

the server leave the group since the election had failed due to the shutdown. The error handling process

for primary elections now takes this into account, and does not take any further actions if the member is

already leaving the group. (Bug #32884709)

• Replication: Querying the Performance Schema table

replication_asynchronous_connection_failover could return an error if a row was deleted

during the query process. In this situation, the row count is now returned as zero, and the query can be

retried. (Bug #32701593)

• Replication: In some situations, a replica that used connection compression was not able to re-establish

a lost connection to the source server. The issue has now been fixed. (Bug #32494609)

• Group Replication: During the Group Replication auto-rejoin procedure, a group member sets its status

to RECOVERING. If the group member does not manage to rejoin, it should change the status to ERROR,

but if a view change occurred in the meantime, it was possible for the status to remain in RECOVERING.

The member status is now set to ERROR after an unsuccessful auto-rejoin procedure, regardless of any

ongoing or stuck view changes. (Bug #33276418)

• Group Replication: Garbage collection for certification information has been moved from the Group

Replication Group Communication System (GCS) thread to a background thread, so that sending and

receiving of messages are not blocked while garbage collection is in progress. (Bug #33190276)

• Group Replication: When group_replication_consistency is

BEFORE_ON_PRIMARY_FAILOVER, in the event of a primary failover, client connections are held until

the new primary has the same state as the previous primary. Some monitoring and administration

statements are exempt from this hold, so that the new primary can be inspected during the failover

process.

Previously, DO statements had a blanket exemption from this hold, but now only DO statements that do

not use tables or loadable functions are exempt; this is the same as for SELECT. (Bug #33130768)

• Group Replication: MySQL Server incorrectly permitted reads from Performance Schema tables

relating to Group Replication while Group Replication was stopping or restarting, and the data concerned

should not have been used. The server now checks whether Group Replication is in OFFLINE status or

uninitialized before executing the query. (Bug #33085494)

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MySQL 8.0 Release Notes

• Group Replication: When group_replication_consistency is set to

BEFORE_ON_PRIMARY_FAILOVER, in the event of a primary failover, client connections are held until

the new primary has the same state as the previous primary. Some monitoring and administration

statements are exempt from this hold, so that the new primary can be inspected during the failover

process. Previously, SHOW statements had a blanket exemption from the hold (with the exception of

SHOW CREATE USER), but now only SHOW statements that do not depend on data (only on status or

configuration) are exempt. See Configuring Transaction Consistency Guarantees, for a complete listing

of exempt SHOW statements. (Bug #33082509)

• Group Replication: A deadlock could occur when a statement referencing Access Control Lists (ACLs),

such as CREATE USER, was executed on the primary of a Group Replication group, and a member

joined the group immediately afterwards before the transaction commit was confirmed by the other group

members. The distributed recovery process needs a read lock on the ACL cache which is locked by

the ACL statement. This situation blocked Group Replication's Group Communication System (GCS)

thread until the ACL statement timed out, making the primary unreachable and possibly preventing the

new member from joining. The ACL cache lock is now no longer required for the distributed recovery

process, although the lock in the situation described is only released after the view change is complete

and the ACL statement is committed. Any new connections or statements that require the ACL cache

lock, including a member join when Group Replication uses the MySQL communication stack, must

therefore wait on this or fail and retry. (Bug #33025231)

• Group Replication: If the thread that runs the Group Replication applier module is stopped, the

group cannot function properly because it cannot exchange group transactions and messages.

Previously, a member in this situation remained in ONLINE status and ignored the internal errors.

The member now changes to ERROR status if the thread is stopped, and takes the action specified by

group_replication_exit_state_action. (Bug #32934479)

• Group Replication: In MySQL 8.0.22 and later, a replication source server writes a TRUNCATE TABLE

statement to the binary log to notify replicas to empty a MEMORY table the first time it is used after a

server restart. Previously, the thread where the statement was logged was not registered with the

global thread manager, so Group Replication was not able to acknowledge it. The issue has now been

corrected. (Bug #32355801)

• JSON: Made additional improvements in JSON function error handling to those made in MySQL 8.0.23.

(Bug #32864910)

References: See also: Bug #31856260.

• JSON: JSON_TABLE() allowed duplicate column names when the names differed in case only,

although column names are case-insensitive in MySQL.

Now this function compares column names in case-insensitive fashion. (Bug #102824, Bug #32591074)

• Added Ubuntu 21.10 packages. (Bug #33501583, Bug #105274)

• The MySQL client library could contribute to a memory leak if MySQL was linked against OpenSSL

1.0.1, as is the case for builds on EL6. (Bug #33335046)

• Implicitly grouped queries sometimes calculate aggregates during optimization when their values can be

easily retrieved from indexes. When a predicate referenced a column that was declared with a NO PAD

collation, that predicate might be evaluated using PAD SPACE semantics, and so return wrong results.

This was because an internal function that checked for insignificant trailing spaces made the assumption

that all nonbinary collations had PAD SPACE semantics, which was true of MySQL 5.7, but is not the

case for MySQL 8.0, which has added many collations having NO PAD semantics, including the default

collation (utf8mb4_0900_ai_ci).

We fix this by explicitly checking the padding attribute of the collation in such cases. (Bug #33282123)

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MySQL 8.0 Release Notes

• A query containing a common table expression with a MATCH() AGAINST() clause executed on a table

defined without a full-text index raised an assertion failure. (Bug #33264864)

• Several Performance Schema tables contained default timestamp values of 0 (zero) which conflicted

with the default sql_mode values NO_ZERO_IN_DATE and NO_ZERO_DATE.

For example, attempting to create a new table based on such a Performance Schema table resulted

in an error similar to the following: ERROR 1067 (42000): Invalid default value for

'FIRST_SEEN'

Default timestamp values have been removed from the following tables:

• performance_schema.events_errors_summary_by_account_by_error

• performance_schema.events_errors_summary_by_host_by_error

• performance_schema.events_errors_summary_by_thread_by_error

• performance_schema.events_errors_summary_by_user_by_error

• performance_schema.events_errors_summary_global_by_error

• performance_schema.events_statements_summary_by_digest

• performance_schema.host_cache

• performance_schema.replication_applier_filters

• performance_schema.replication_applier_global_filters

(Bug #33240123, Bug #104643)

• A failed write to the NOTIFY_SOCKET environment variable caused a failure. The

ER_SYSTEMD_NOTIFY_WRITE_FAILED error associated with the failed write has two parameters, but

only one parameter was passed to the error logging routine. (Bug #33239183)

• An incorrectly type-casted variable was used when setting the --ssl-fips-mode option. (Bug

#33223230)

• The following threads were not present in the performance_schema.threads table:

• buf_resize_thread

• fts_optimize_thread

Thanks to Kaige Ye for the contribution.

Thanks to Kaige Ye for the contribution. (Bug #33214130, Bug #104582, Bug #33214136, Bug #104583)

• A recursive call to an internal save function led to an unexpected error. (Bug #33198164)

• The internal mysqld_list_fields() function failed to remove temporary tables created to evaluate

JSON table functions. (Bug #33177686)

• The code to produce minimal TAR packages added debug symbols to the packages, which caused

larger (roughly by 10x) builds. Now DEB/RPM compiler flags are on by default for debug symbol builds,

and off by default for minimal sized release builds. (Bug #33151629, Bug #104402)

• Some multi-table DELETE statements were found to leak memory. (Bug #33151275)

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MySQL 8.0 Release Notes

References: See also: Bug #18684036.

• The return value for a copy function internal to the server was not handled as expected. (Bug

#33142669)

References: This issue is a regression of: Bug #31982292.

• Empty range frames were not always handled correctly. (Bug #33142418)

References: This issue is a regression of: Bug #90300, Bug #27808099.

• In debug builds, the ALTER TABLE statement could produce an error if it added a new virtual column

with the same name as one of the columns later referred to by a foreign key. This fix now ignores a

virtual column if the name is duplicated and instead uses existing, non-virtual column names to check

conditions. (Bug #33114045)

• An assert condition to ensure that execution of a stored program instruction is started when there are no

errors did not work properly for a CASE statement in a loop. (Bug #33079184)

• In debug builds, ANALYZE TABLE with the UPDATE HISTOGRAM clause could return a non-success

value to the caller, instead of a success value, after successfully clearing the diagnostics area. (Bug

#33079073)

• The mecab_charset system status variable now reports its value as utf8mb4 rather than utf8, which

is deprecated. (Bug #33078623)

• In debug builds, MySQL Enterprise Encryption UDFs did not set the nullable flag when returning NULL.

(Bug #33077931)

• The range optimizer was sometimes called when a plan lock was in force. This caused issues since the

range optimizer can call itself, but a plan lock does not allow for recursion. (Bug #33076462)

References: This issue is a regression of: Bug #18684036.

• CAST() and DEFAULT(), when used inside stored routines, were not always handled correctly. (Bug

#33075828)

• String functions that use temporary string buffers during evaluation could lead to unexpected shutdowns.

(Bug #33073951)

• The error message emitted after a host name failed to resolve to an IP address did not include a

meaningful errno value. Now, (-2) indicating EAI_NONAME is returned in the message instead of (0).

(Bug #33064143)

• A statement such as CREATE TABLE t SELECT 1 created an InnoDB table that was written

incorrectly to the binary log if the value of binlog_format was set to ROW and sql_mode was in

ANSI mode. As a result, replication of the statement failed with an error on the replica. Applying the

mysqlbinlog utility to such a binary log could also fail.

The atomic CREATE...SELECT was implemented by adding a new clause to CREATE TABLE called

START TRANSACTION. However, this clause was not added when ANSI mode was enabled. This in turn

caused the execution of an ordinary implicitly committed CREATE TABLE in the middle of the transaction

and produced an error in GTID mode if the transaction had an assigned GTID. The issue is fixed by

removing the SQL mode dependency from the new clause. (Bug #33064062, Bug #104153)

• A log file containing a malformed ISO8601 timestamp was processed incorrectly. (Bug #33060440)

136

MySQL 8.0 Release Notes

• String conversion warnings that previously referred to utf8 now reference utf8mb3 instead. (Bug

#33059330)

• When building MySQL from source on Unix platforms, .bz2 files are now used for Boost archive

downloads rather than .tar.gz files. (Bug #33052171)

• For Enterprise Linux 8 (and Fedora), fixed the debuginfo RPMS packages by disabling

REPRODUCIBLE_BUILD in fprofile.cmake. (Bug #33037380)

• For a query with rollup, when setting an expression as nullable because it had a grouping column,

we missed setting all expressions within that expression as nullable, doing so only for the topmost

expression. This meant that, during evaluation, a NULL generated by rollup was not always propagated

correctly. To fix this, we now set all the expressions having a grouping column as nullable when the

query uses rollup. (Bug #33036184)

• During execution of EXPLAIN, when crossing into a different query block through a streaming or

materialization node, this node was counted as the root, rather than the actual root node. (Bug

#33030136)

• Fixed an undefined conversion from double to int64 in sql/join_optimizer/cost_model.cc.

(Bug #33024410)

• The internal function find_in_group_list() did not match up match up all items correctly during

ROLLUP processing. We fix this by adding casts to GROUP BY expressions. (Bug #33022742, Bug

#33123934)

References: This issue is a regression of: Bug #30969045.

• A missing test for success of a memory allocation in the MySQL client library could lead to a client exit.

(Bug #33019026)

• An audit log function call from a prepared statement caused an error. (Bug #33016004)

• Avoid adding column names prefixed with !hidden! to ensure that new names do not collide with

names used by existing hidden columns for functional indexes. Generated hidden column names now

have the following new form that extends the use of functional indexes into environments that do not

support names generated by MD5():

!hidden!index_name!key_part_number!counter

The counter value of a generated name is zero unless a column with that name already exists in the

table. In this case, the value is incremented until the name becomes unique. (Bug #32983024)

• Removed an unnecessary hard-coded dependency on the range optimizer from sql_help.cc. (Bug

#32976042)

• Insufficient buffer space allocation during window function execution could cause an assertion to be

raised. (Bug #32975889)

• When finding the list of tables under a hash join, we did not take into account those that were also

hidden under ZERO_ROWS iterators. This could lead to NULL row flags not being set correctly, which

also caused problems when weedout wanted to save row IDs for them. (Bug #32975168)

• The gen_dictionary(), gen_range(), and gen_rnd_pan() data masking functions each could

generate the same value if executed in close temporal proximity multiple times. (Bug #32970772)

• Creation and deletion of temporary tables used in resolution of common table expressions and having

table references created within subqueries were not always managed correctly. (Bug #32962511)

137

MySQL 8.0 Release Notes

• When the -–binary-as-hex option is enabled for the mysql client, empty strings are now printed as

0x instead of NULL. (Bug #32961656, Bug #103906)

• The resolver usually terminates the analysis and exits after encountering an error in a statement. In the

case of duplicate column analysis, the resolver continued to the end of the column list, possibly adding

multiple error messages to the diagnostics object. (Bug #32960158)

• When a scalar subquery returned multiple rows, the resulting error was not always handled correctly.

(Bug #32956779)

• Changing the server SQL mode after creating a table containing generated columns could cause

spurious messages to be written to the error log. (Bug #32954466)

• Manifest file reading could fail on Windows. (Bug #32950322)

• Evaluation of the values in an IN() list did not stop immediately on error, which led to assert failures.

We fix this by stopping evaluation in such cases as soon as an error has been raised. (Bug #32942328)

• If an error was raised while evaluating a comparison of two non-nullable values as strings, the result of

the comparison was set to NULL, even though the result was non-nullable according to the comparison

operator metadata. The error was correctly returned to the user, but an assertion was raised by this

inconsistency when running in debug mode.

This is fixed by causing Arg_comparator not to set its owner to NULL when the owner is not nullable.

(Bug #32942327)

• An unset variable referenced in an SQL script executed during an upgrade operation caused a failure.

(Bug #32939819)

• Improper error propagation in filesort operations could raise an assertion. (Bug #32932969)

• In the internal WalkAndReplace() function, errors from set_cmp_func() were not correctly

propagated. (Bug #32918927, Bug #33007298)

References: This issue is a regression of: Bug #32548377.

• A deadlock could occur if a RESET REPLICA ALL statement was used while the channel configuration

was being read. (Bug #32906709)

• A potential race condition in accessing the persisted variables cache has been eliminated. (Bug

#32901419)

• The constant propagation performed by the MySQL optimizer could in some cases replace references

to a column that was not nullable with a nullable expression. When this occurred, the parent item of the

replaced column reference could sometimes have the wrong nullability, leading assert failures later,

during execution, when a non-nullable item unexpectedly returned NULL.

We fix this by skipping constant propagation in cases where a non-nullable column reference is replaced

by a nullable expression. (Bug #32895824)

References: This issue is a regression of: Bug #32371039.

• A column name provided in a query could differ in collation details, or because the name was provided

as an expression alias in the query, and still match a column name in the dictionary. The query output

contained the column name specified in the query (for example, aaa) rather than the column name from

the dictionary (for example, AAA). (Bug #32892045)

• When the server SQL mode is other than strict mode, certain string functions return NULL to indicate

that the result is too large for the result buffer, which could lead to in inconsistent behaviour such as

138

MySQL 8.0 Release Notes

incorrectly sorted output. In addition, the functions LAST_INSERT_ID() and CAST(... AS CHAR) did

not maintain nullability properly for all cases. (Bug #32864958)

• Hidden items added as part of an ORDER BY, windowing function, or a reference to a view were not

always handled correctly in implicitly grouped queries. (Bug #32863279, Bug #33079592)

• Type resolution for negation did not set the proper precision when converting the type from integer to

decimal. This is fixed by assigning the same precision as the argument. (Bug #32863037)

References: This issue is a regression of: Bug #31348202.

• Improper error propagation for failed CREATE TABLE ... SELECT statements caused rollback not to

occur. (Bug #32855882)

• When used in a subquery, a VALUES having more than one ROW() was not always handled correctly.

(Bug #32851684)

• The error packet that MySQL Server sends to a client program when the wait timeout expires

(ER_CLIENT_INTERACTION_TIMEOUT) used an incorrect sequence number of 2 instead of 0 in the

packet header when protocol compression was used. (Bug #32835205, Bug #103412)

• Concurrent insert operations on multiple tables with full-text indexes caused a large number of full-text

index synchronization requests, resulting in an out of memory condition. (Bug #32831765, Bug #103523)

• The fix for a previous issue, following subsequent work which made it redundant and which led to invalid

results from expressions used in window functions, has been reverted. (Bug #32820802)

References: Reverted patches: Bug #26389508.

• In prepared statements, NULLIF() result type determination could be incorrect. (Bug #32816305, Bug

#103458)

• Creating and dropping of views within stored routines were not always handled correctly. (Bug

#32807430)

• The fix for a previous issue included a minor refactoring of how the precision and scale of a decimal

expression were determined. It later emerged that, for the TRUNCATE() function, we might end up with a

precision of zero, which is invalid.

We fix this problem by treating a precision of zero as one. (Bug #32802251)

References: See also: Bug #31348202.

• For legacy reasons, we can have composite access paths including Filter and Sort inside

table_path. For ease of analysis and better formatting, we move the EXPLAIN output for these

previous to the Materialize access path.

We show here examples of an EXPLAIN statement run both prior to and following this change:

# Table created as follows:

mysql> DROP TABLE IF EXISTS t1;

Query OK, 0 rows affected (0.02 sec)

mysql> CREATE TABLE t1 ( f1 INTEGER );

Query OK, 0 rows affected (0.03 sec)

# Previous to change:

mysql> EXPLAIN FORMAT=TREE

139

MySQL 8.0 Release Notes

-> SELECT * FROM ( SELECT * FROM t1 LIMIT 2 OFFSET 1 ) AS alias1

-> WHERE f1 <= ANY ( SELECT f1 FROM t1 ) ORDER BY f1\G

*************************** 1. row ***************************

EXPLAIN: -> Sort: alias1.f1

-> Filter: <nop>((alias1.f1 <= (select #3))) (cost=2.62 rows=2) [other sub-iterators not shown]

-> Table scan on alias1 (cost=2.62 rows=2)

-> Materialize (cost=0.35..0.35 rows=0)

-> Limit/Offset: 2/1 row(s) (cost=0.35 rows=0)

-> Table scan on t1 (cost=0.35 rows=1)

# Following change:

mysql> EXPLAIN FORMAT=TREE

-> SELECT * FROM ( SELECT * FROM t1 LIMIT 2 OFFSET 1 ) AS alias1

-> WHERE f1 <= ANY ( SELECT f1 FROM t1 ) ORDER BY f1\G

*************************** 1. row ***************************

EXPLAIN:

-> Sort: alias1.f1 (cost=0.35..0.35 rows=0)

-> Filter: <nop>((alias1.f1 <= (select #3))) (cost=2.62 rows=2)

-> Table scan on alias1 (cost=2.62 rows=2)

-> Materialize (cost=0.35..0.35 rows=0)

-> Limit/Offset: 2/1 row(s) (cost=0.35 rows=0)

-> Table scan on t1 (cost=0.35 rows=1)

-> Select #3 (subquery in condition; run only once)

-> Aggregate: max(t1.f1) (cost=0.45 rows=1)

-> Table scan on t1 (cost=0.35 rows=1)

After this change, the only legal access paths within table_path are TABLE_SCAN, REF,

REF_OR_NULL, EQ_REF, and ALTERNATIVE. (Bug #32788576, Bug #32915233)

• Constant folding did not always handle errors correctly when evaluating decimal expressions. (Bug

#32785804)

• A call order mismatch in Query_block::prepare_values() caused setup_order() to be called

after resolve_subquery(), which meant that, for a VALUES clause that was a subquery, the subquery

could be merged into the outer query block before calling setup_order(), leading to inconsistent data

structures and an error.

We fix this issue by performing setup_order() earlier, and, if the column is not found, resolution is

aborted. (Bug #32783943)

References: This issue is a regression of: Bug #31387510.

• In the Performance Schema table variables.info, the system variable skip_slave_start was

incorrectly listed as COMPILED when the global value was actually loaded from the persisted variables

file, so PERSISTED should have been used. (Bug #32640588)

• A SELECT query on the INFORMATION_SCHEMA.PROCESSLIST view with concurrent MySQL Server

load caused a failure. (Bug #32625376)

• When a query uses a temporary table for aggregation, the group by item is used as a unique constraint

on the temporary table: If the item value is already present, the row is updated; otherwise, a new row

is inserted into the temporary table. If the item has a result field or reference item, it evaluated twice,

once to check whether the result exists in the temporary table and, if not, again while constructing the

row to be inserted. When the group by item was nondeterministic, the result value used to check for

existence differed from that with which an insert was attempted, causing the insert to be rejected if the

value already existed in the table.

We fix this by using the hash of any nondeterministic items as the unique constraint, so that the hash is

evaluated once only. (Bug #32552332)

• Privilege-checking for table-specific roles was in some contexts not restrictive enough. (Bug #32400788)

140

MySQL 8.0 Release Notes

• Inconsistencies in how certain comparison predicates were evaluated (for example, when part of

a WHERE clause) could return different results if a function was used instead of a string literal. (Bug

#32345941, Bug #102151)

• Columns of type ENUM or SET are ordered based on numeric comparison, but the comparison function

for range expressions (that is, expressions used for ordering in case of a range frame specification) of a

window function is set based on the result type of the column, which for ENUM and SET is String. As a

result, processing of rows for a window frame (to see whether a row is before or after the frame) did not

work correctly; for example, a string comparison might determine that a row occurs before a frame, while

a numeric comparison would have placed the row after.

To fix this problem, we implement integer cache items for ENUM and SET, as well as integer comparison

functions for use when ENUM or SET types are involved in range expressions. (Bug #32328576)

• A DML statement, when accessing a subquery which had been optimized away and cleaned up, led to

an unplanned shutdown of the server. (Bug #32244822)

• When resolving columns, their names are compared in case-insensitive fashion using

utf8_general_ci, which does not always follow the same comparison rules as those for the collation

actually used for the table. Previously, when a table had in excess of 32 columns, name lookup was

performed using a hash table. Hashing is collation-aware, and so follows the collation's comparison

rules; this caused name lookup and duplication detection to be done in an inconsistent fashion. We solve

this problem by removing the hash, and performing column name resolution in the same way in all cases

regardless of the number of columns. (Bug #32169656)

• For a nullable column, when adjacent ranges were rounded off to the same value by range optimizer,

wrong results were returned. (Bug #31870920)

References: See also: Bug #98826, Bug #30988735.

• Quote handling was improved for the SHOW GRANTS statement. (Bug #31716706)

• An attempt could be made to write a JSON_TABLE() expression to the optimizer trace before the

temporary table backing the table function had been created, causing an assertion to be raised. Now

when the column type is not yet available, <column type not resolved yet> is written. (Bug

#31578783)

• Validity checks for mandatory_roles system variable settings are now synchronized with validity

checks performed for GRANT role statements. (Bug #31218040)

• The keyring_hashicorp_update_config() function was not safe for concurrent execution. (Bug

#31205028)

• The query rewrite plugin failed when refreshing the rewrite rules and the table holding the rewrite rules

contained rows that had been marked as deleted, but not physically removed.

We fix this by causing the query rewrite plugin to skip the deleted rows instead of failing when it sees

them. (Bug #22654105)

• Refactoring done as part of implementing window functions in MySQL made it possible to refer to aliases

of aggregates in ORDER BY clauses but also allowed direct references to such aggregates, even though

this should not be allowed. Now the server checks explicitly for such illegal references. (Bug #13633829,

Bug #30106081)

• In certain cases, the view reference cloned when pushing a condition down to a derived table was

not always resolved in the desired context. In addition, a check for a null condition was not performed

correctly. (Bug #104574, Bug #33209907, Bug #33197276)

141

MySQL 8.0 Release Notes

• Some queries using HAVING COUNT(DISTINCT ...) did not return any rows when one was

expected. (Bug #104411, Bug #33152269)

References: This issue is a regression of: Bug #31790217.

• Multi-valued indexes were not used in the following cases:

• In views

• In prepared statements

• In a WHERE containing MEMBER OF() combined using OR with another predicate

In addition, MySQL wrongly reported impossible condition for a WHERE clause in the form f()

AND f(), where f() was any of MEMBER OF(), JSON_CONTAINS(), or JSON_OVERLAPS().

Our thanks to Yubao Liu for the contribution. (Bug #104325, Bug #104700, Bug #104721, Bug

#33123079, Bug #33268466, Bug #33275457)

References: See also: Bug #102359, Bug #32427727. This issue is a regression of: Bug #30838807.

• When NULL was passed to a user-created function that called REGEXP_INSTR(), the first invocation of

the function returned NULL as expected, but each subsequent invocation of the function also returned

NULL without regard to the value passed to it. (Bug #104239, Bug #33089668)

• Some of the functions defined in mbr_utils.cc threw heap-allocated exceptions in some situations.

Memory allocated for the exception object in these cases was never freed, which meant that a small

amount of memory leaked each time an exception was thrown.

This is fixed by allocating the exception on the stack in such cases, instead. (Bug #104214, Bug

#33086286)

• Column names were not displayed correctly in the results of ROLLUP queries when the

subquery_to_derived optimization was enabled. (Bug #104139, Bug #33057397, Bug #33104036)

• A stored procedure containing an IF statement using EXISTS, which acted on one or more tables that

were deleted and recreated between executions, did not execute correctly for subsequent invocations

following the first one. (Bug #103607, Bug #32855634)

• When executing a range query with multiple identical ranges joined by OR (for example, a query with

WHERE (a=1 AND b=2 AND c=3) OR (a=1 AND b=2 AND c=3)), the optimizer lost part of the

range, and so chose a query plan that was not optimal.

Our thanks to Facebook for the contribution. (Bug #102634, Bug #32523520)

• While evaluating a loose index scan as a possible option for performing grouping and finding the

minimum value, the cost calculation did not reflect the fact that the query looked at one group only, due

to the equality predicates on the grouping attributes. This resulted in examination of additional rows

since grouping is performed after reading the rows from the index.

We fix this by determining whether a query produces only one group by checking for the presence of

equality predicates on grouping attributes and using these for calculating the cost. This causes the

optimizer to pick loose index scan for such cases when doing so is found to be beneficial. (Bug #101838,

Bug #32266286)

References: See also: Bug #18109609.

142

MySQL 8.0 Release Notes

• When resolving integer division, the precision of the result is taken from the dividend. When the divisor

is a decimal number, it may be less than 1, which may cause the result to use more digits than the

dividend. This yielded incorrect values in some cases in which the result of integer division was a

decimal or float. (Bug #100259, Bug #31641064)

• Added an in-memory estimate to the optimizer trace to indicate how much of a given table is buffered in

the buffer pool.

Our thanks to Øystein Grøvlen for the contribution. (Bug #99993, Bug #31544522)

• The EXPLAIN output for a DML statement contains the table identifier, which normally includes the

database name, in the output of SHOW WARNINGS. For some statements such as CREATE VIEW, the

database name should be omitted, which is enforced by setting the alias_name_used flag to true in

the cached table object, but when the cached table was reused following CREATE VIEW, the flag was

not reset, which caused the database name to be omitted from the warnings following EXPLAIN for

statements run after a CREATE VIEW which access the same cached table as the view.

We fix this by ensuring that the alias_name_used flag is always set to an appropriate value during

table initialization.

Our thanks to Kaiwang Chen for the contribution. (Bug #98635, Bug #30909064)

Changes in MySQL 8.0.26 (2021-07-20, General Availability)

• Audit Log Notes

• Authentication Notes

• Compilation Notes

• Component Notes

• Deprecation and Removal Notes

• Error Handling

• Event Scheduler Notes

• Firewall Notes

• Packaging Notes

• Pluggable Authentication

• Server Administration

• Spatial Data Support

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• Previously, each event logged by MySQL Enterprise Audit included the SQL statement literal text. To

provide an alternative (because it is possible that statements contain sensitive information), the audit

143

MySQL 8.0 Release Notes

log filtering language now supports logging a statement's digest rather than its literal text. For example,

instead of logging this statement:

SELECT * FROM orders WHERE some_sensitive_column=1234567

The audit log plugin can log this digest:

SELECT * FROM `orders` WHERE `some_sensitive_column` = ?

This is similar to what is already logged for prepared statements, for which parameter markers appear

rather than actual data values.

To perform digest logging, use audit filter definitions that replace the statement literal text by its

corresponding digest, as discussed in Replacement of Event Field Values.

Because text replacement occurs at an early auditing stage (during filtering), the choice of whether to log

statement literal text or digest values applies regardless of log format written later (that is, whether the

audit log plugin produces XML or JSON output). (Bug #31482609, WL #14267, WL #14724)

• For MySQL Enterprise Audit, the new audit_log_format_unix_timestamp system variable

enables inclusion of a time field in each audit record. The field value is an integer that represents the

UNIX timestamp value indicating the date and time when the audit event was generated. The time field

is supported only for JSON-format log files. (WL #14600)

• For MySQL Enterprise Audit, the new audit_log_max_size system variable enables audit log

file pruning based on combined log file size. To have an effect, audit_log_max_size requires

that audit_log_rotate_on_size be greater than 0. If that is true, the pruning algorithm uses

audit_log_max_size in conjunction with audit_log_prune_seconds, with nonzero values of

audit_log_max_size taking precedence over nonzero values of audit_log_prune_seconds. For

details, see Space Management of Audit Log Files. (WL #14525)

Authentication Notes

• Previously, as part of the “hello” packet sent by the server to clients, the server sent the name of the

server-side authentication plugin rather than the client-side plugin. The server now sends the client-side

name, which is more appropriate for the client's needs and may help to avoid extra protocol round trips.

(WL #14308)

Compilation Notes

• macOS: It is now possible to build MySQL for macOS 11 on ARM (that is, for Apple M1 systems). (Bug

#32386050, Bug #102259)

• Building on openSUSE 15 and SLES 15 now requires GCC 9, found in packages gcc-9 and gcc9-c++.

Building on SLES 12 now requires GCC 10, found in packages gcc-10 and gcc10-c++.

It is also recommended to use the named GCC version when building third-party applications that are

based on the libmysqlclient C API library. (Bug #32886268, Bug #32886439)

• Building on Ubuntu 18.04 (bionic) now requires GCC 8, found in packages gcc-8 and g++-8. It

is also recommended to use GCC 8 when building third-party applications that are based on the

libmysqlclient C API library. (Bug #32877062)

• It is now possible to build MySQL on Solaris using GCC 10, which becomes the default and

recommended compiler. It is also recommended to use GCC 10 when building third-party applications

that are based on the libmysqlclient C API library. (Bug #32552988)

144

MySQL 8.0 Release Notes

Component Notes

• A new component service enables server components to set system variable values. For information

about this service, see the MySQL Server Doxygen documentation, available at https://dev.mysql.com/

doc/index-other.html (search for s_mysql_mysql_system_variable_update_string and

mysql_system_variable_update_string_imp). (WL #12002)

Deprecation and Removal Notes

• The TLSv1 and TLSv1.1 connection protocols now are deprecated and support for them is subject to

removal in a future MySQL version. (For background, refer to the IETF memo Deprecating TLSv1.0 and

TLSv1.1.) It is recommended that connections be made using the more-secure TLSv1.2 and TLSv1.3

protocols. TLSv1.3 requires that both the MySQL server and the client application be compiled with

OpenSSL 1.1.1 or higher.

On the server side, this deprecation has the following effects:

• If the tls_version or admin_tls_version system variable is assigned a value containing a

deprecated TLS protocol, the server produces a warning for each deprecated protocol:

• If the assignment occurs during server startup, the warning appears in the error log.

• If the assignment occurs at runtime, the warning is added to the result of executing the ALTER

INSTANCE RELOAD TLS statement.

• If a client successfully connects using a deprecated TLS protocol, the server writes a warning to the

error log.

On the client side, the deprecation has no visible effect. Clients do not issue a warning if configured to

permit a deprecated TLS protocol. This includes:

• Client programs that support a --tls-version option for specifying TLS protocols for connections to

the MySQL server.

• Statements that enable replicas to specify TLS protocols for connections to the source server.

(CHANGE REPLICATION SOURCE TO has a SOURCE_TLS_VERSION option and CHANGE MASTER

TO has a MASTER_TLS_VERSION option.)

• The group_replication_recovery_tls_version system variable that enables joining members

to specify TLS protocols for distributed recovery connections.

(Bug #32565996, WL #14519)

• The system variable transaction_write_set_extraction is now deprecated, and a warning

message is issued if you attempt to set it or read its value; expect it be removed in a future MySQL

release. This system variable was used on a replication source server that has multithreaded replicas,

to specify the algorithm used to hash the writes extracted for a transaction’s write set. The XXHASH64

algorithm, which is the default in MySQL 8.0 and is required for Group Replication, is selected when the

system variable is not used. (WL #13950)

• The temptable_use_mmap variable is now deprecated and subject to removal in a future MySQL

version. (WL #14124)

• TLS support in MySQL has been moving toward a channel model using named sets of TLS parameters

that apply to different securable ports or protocols. For example, to query the state of a particular TLS

channel, use the Performance Schema tls_channel_status table:

145

MySQL 8.0 Release Notes

mysql> SELECT VALUE FROM performance_schema.tls_channel_status

WHERE CHANNEL = 'mysql_main' AND PROPERTY = 'Enabled';

+-------+

| VALUE |

+-------+

| Yes |

+-------+

This makes monolithic parameters that apply to TLS support as a whole less applicable, so the following

options and system variables are now deprecated and subject to removal in a future MySQL version:

• The --ssl and --admin-ssl server options.

• The have_ssl and have_openssl system variables.

The --ssl and --admin-ssl options are enabled by default, so it is normally unnecessary to specify

them. As an alternative to specifying those options in negated form, if it is desired to disable encrypted

connections for the main or administrative interface, set the corresponding TLS version system variable

to the empty value to indicate that no TLS versions are supported. For example, these lines in the server

my.cnf file disable encrypted connections for both interfaces:

[mysqld]

tls_version=''

admin_tls_version=''

(WL #14481)

Error Handling

• Information written to the server error log for client timeouts now includes (if available) the timeout value,

and client user and host. (Bug #31581289, Bug #100112)

Event Scheduler Notes

• If the Event Scheduler is enabled, enabling the super_read_only system variable prevents it from

updating event “last executed” timestamps in the events data dictionary table. This causes the Event

Scheduler to stop the next time it tries to execute a scheduled event, after writing a message to the

server error log.

Previously, if enabling super_read_only caused the Event Scheduler to stop, then after subsequently

disabling super_read_only, it was necessary to manually restart the Event Scheduler by enabling it

again. As a convenience, the server now automatically restarts the Event Scheduler as needed when

either read_only or super_read_only is disabled. (Bug #31633859)

Firewall Notes

• In MySQL 8.0.23, MySQL Enterprise Firewall implemented group profiles that each can apply to multiple

accounts, in addition to the previously implemented account profiles that each apply to a single account.

See Using MySQL Enterprise Firewall.

A group profile with a single member account is logically equivalent to an account profile for that

account, so it is possible to administer the firewall using group profiles exclusively, rather than a mix

of account and group profiles. For new firewall installations, that is accomplished by uniformly creating

new profiles as group profiles and avoiding account profiles. For upgrades from firewall installations that

already contain account profiles, MySQL Enterprise Firewall now includes a stored procedure named

sp_migrate_firewall_user_to_group() for converting account profiles to group profiles.

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MySQL 8.0 Release Notes

Due to the greater flexibility offered by group profiles, all aspects of the firewall related to account profiles

are now deprecated and subject to removal in a future MySQL version:

• INFORMATION_SCHEMA tables: MYSQL_FIREWALL_USERS, MYSQL_FIREWALL_WHITELIST

• mysql system schema tables: firewall_users, firewall_whitelist

• mysql system schema stored procedures: sp_reload_firewall_rules(),

sp_set_firewall_mode()

• Loadable functions: read_firewall_users(), read_firewall_whitelist(),

set_firewall_mode()

Additionally, if the server detects account profiles at startup, it writes a warning for every successfully

loaded account profile.

For information about converting account profiles to group profiles (which you should do at your earliest

convenience), see Migrating Account Profiles to Group Profiles. (WL #14174)

Packaging Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.77.0. (Bug #33077562)

• For Ubuntu packages, the AppArmor profile for mysqld was too restrictive regarding PID and socket

file names and failed for servers not using the exact names in the profile. Now the profile applies to the

directories in which the files live, enabling it to apply for different file names, and multiple servers. (Bug

#32857611)

• The dh-systemd package has been removed from Ubuntu 21.04, so the dependency on it has been

removed from MySQL packages built for that distribution. (Bug #32688072)

• For Debian packages, an EnvironmentFile directive was added to enable the systemd service to

read environmental variables from the /etc/default/mysql file if it is present. (Bug #32082863, Bug

#101363)

• Debian packages now use /run rather than /var/run for path names. (Bug #31955638)

• The bundled lz4 library was upgraded to version 1.9.3. (Bug #29747853)

• For Debian packages, the update-alternatives priority of the MySQL configuration file was

increased to ensure it replaces an existing file from a previously installed distribution. (Bug #29606955)

Pluggable Authentication

• Linux: MySQL Enterprise Edition now supports an authentication method that enables users to

authenticate to MySQL Server using Kerberos, provided that appropriate Kerberos tickets are available

or can be obtained. It is available only on MySQL server and client hosts running Linux, but can access

Kerberos services running on non-Linux hosts. For details, see Kerberos Pluggable Authentication.

This authentication method uses a pair of plugins, authentication_kerberos on the server side

and authentication_kerberos_client on the client side. The server-side Kerberos authentication

plugin is included only in MySQL Enterprise Edition. It is not included in MySQL community distributions.

The client-side plugin is included in all distributions, including community distributions. This enables

clients from any distribution to connect to a server that has the server-side plugin loaded. (WL #14336)

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MySQL 8.0 Release Notes

Server Administration

• Setting the session value of the innodb_strict_mode system variable is now a restricted operation

and the session user must have privileges sufficient to set restricted session variables.

For information about the privileges required to set restricted session variables, see System Variable

Privileges. (Bug #32944980, WL #14610)

Spatial Data Support

• The ST_Buffer() function now permits the geometry argument to have a geographic spatial reference

system (SRS), if the geometry is a point value. Previously, ST_Buffer() supported only geometry

arguments in a Cartesian SRS. The ST_Difference() and ST_Union() functions now permit the

geometry arguments to have a geographic SRS. Previously, ST_Difference() and ST_Union()

supported only geometry arguments in a Cartesian SRS. See Spatial Operator Functions. (WL #14126,

WL #14188, WL #14266)

X Plugin Notes

• When the X DevAPI Session.run_sql() method was used to execute a query that returned multiple

results, due to a caching issue, the result.columns property was not updated to reflect the columns

present in the active result, although the result.column_names property was. (Bug #32887586)

• During an upgrade process, X Plugin logged a message stating that it was ready for connections once

the TCP port and UNIX socket had been allocated. However, connections could not actually be accepted

until after the upgrade process was complete. The message is now issued only after the upgrade has

finished. (Bug #32814997)

Functionality Added or Changed

• Incompatible Change: From MySQL 8.0.26, new aliases or replacement names are provided for most

remaining identifiers that contain the terms “master”, which is changed to “source”; “slave”, which is

changed to “replica”; and “mts” (for “multithreaded slave”), which is changed to “mta” (for “multithreaded

applier”). Help text is also changed where applicable to use the new names.

The following name replacements are visible in the Performance Schema tables, the process list, and

the replica status information. These changes are incompatible with earlier releases. Monitoring tools

that work with these instrumentation names might be impacted:

• Instrumented locks (mutexes), visible in the mutex_instances and events_waits_* Performance

Schema tables with the prefix wait/synch/mutex/

• Read/write locks, visible in the rwlock_instances and events_waits_* Performance Schema

tables with the prefix wait/synch/rwlock/

• Instrumented condition variables, visible in the cond_instances and events_waits_*

Performance Schema tables with the prefix wait/synch/cond/

• Instrumented memory allocations, visible in the memory_summary_* Performance Schema tables

with the prefix memory/sql/

• Thread names, visible in the threads Performance Schema table with the prefix thread/sql/

• Thread stages, visible in the events_stages_* Performance Schema tables with the prefix stage/

sql/, and without the prefix in the threads and processlist Performance Schema tables, the

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MySQL 8.0 Release Notes

output from the SHOW PROCESSLIST statement, the Information Schema processlist table, and

the slow query log

• Thread commands, visible in the events_statements_history* and

events_statements_summary_*_by_event_name Performance Schema tables with the prefix

statement/com/, and without the prefix in the threads and processlist Performance Schema

tables, the output from the SHOW PROCESSLIST statement, the Information Schema processlist

table, and the output from the SHOW REPLICA STATUS statement

If the incompatible changes do have an impact for you, you can set the new system variable

terminology_use_previous to BEFORE_8_0_26 to make MySQL Server use the old versions of

the names for the objects specified in the previous list. This enables monitoring tools that rely on the

old names to continue working until they can be updated to use the new names. The system variable

can be set with session scope to support individual functions, or global scope to be a default for all new

sessions. When global scope is used, the slow query log contains the old versions of the names.

For semisynchronous replication, you can choose whether to use the new or the old versions of the

system variables and status variables. New versions of the plugins that implement semisynchronous

replication, one for the source server and one for the replica, are supplied that replace the terms master

and slave with source and replica, and you can install these versions instead of the old ones:

• The rpl_semi_sync_master plugin (semisync_master.so library) for the source has a new

version rpl_semi_sync_source (semisync_source.so library)

• The rpl_semi_sync_slave plugin (semisync_slave.so library) for the replica has a new version

rpl_semi_sync_replica (semisync_replica.so library)

You cannot have both the new and the old version of the relevant plugin installed on an instance. If you

use the new version of the plugins, the new system variables and status variables are available but the

old ones are not. If you use the old version of the plugins, the old system variables and status variables

are available but the new ones are not.

The following internal-use items are converted to use the new terms but are not externalized to users or

monitoring tools, and MySQL Server handles any necessary resolution internally:

• C++ filenames in source code

• Header guards in C++ files

• Debug symbols

• User variables passed in the replication protocol handshake by the replica when it connects to a

replication source server (the replica sets both the old and the new name)

The following categories of identifiers have a new alias, and a deprecation warning is issued when the

old name is used, although the old name continues to work. Both names are available in Performance

Schema tables and status displays, and no deprecation warning is issued when reading these. The new

aliases are not affected by the new system variable terminology_use_previous, and can still be

used when it is set:

• System variables that contain the terms “master”, “slave”, or “mts”, with the exception of some that

have already been deprecated or are scheduled for deprecation, and those defined by NDB. If these

system variables are persisted using a SET PERSIST statement, both the old and the new name are

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MySQL 8.0 Release Notes

persisted, regardless of which was specified in the statement. With a RESET PERSIST statement,

both are reset.

• Status variables that contain the terms “master”, “slave”, or “mts”, with the exception of those defined

by NDB.

• Command-line options for mysqld that contain the terms “master”, “slave”, or “mts”, with the exception

of some that have already been deprecated or are scheduled for deprecation, and those defined by

NDB.

• Command-line options for mysqladmin that contain the terms “master”, “slave”, or “mts”.

• Command-line options for mysqlbinlog that contain the terms “master”, “slave”, or “mts”.

• Command-line options for mysqldump that contain the terms “master”, “slave”, or “mts”.

• An SQL function that contains the term “master”.

The complete list of identifiers with new aliases (or in the case of semisynchronous replication,

replacements) is as follows:

• System variables:

• master_verify_checksum now has the alias source_verify_checksum

• sync_master_info now has the alias sync_source_info

• init_slave now has the alias init_replica

• rpl_stop_slave_timeout now has the alias rpl_stop_replica_timeout

• log_slow_slave_statements now has the alias log_slow_replica_statements

• slave_max_allowed_packet now has the alias replica_max_allowed_packet

• slave_compressed_protocol now has the alias replica_compressed_protocol

• slave_exec_mode now has the alias replica_exec_mode

• slave_type_conversions now has the alias replica_type_conversions

• slave_sql_verify_checksum now has the alias replica_sql_verify_checksum

• slave_parallel_type now has the alias replica_parallel_type

• slave_preserve_commit_order now has the alias replica_preserve_commit_order

• log_slave_updates now has the alias log_replica_updates

• slave_allow_batching now has the alias replica_allow_batching

• slave_load_tmpdir now has the alias replica_load_tmpdir

• slave_net_timeout now has the alias replica_net_timeout

• sql_slave_skip_counter now has the alias sql_replica_skip_counter

• slave_skip_errors now has the alias replica_skip_errors

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MySQL 8.0 Release Notes

• slave_checkpoint_period now has the alias replica_checkpoint_period

• slave_checkpoint_group now has the alias replica_checkpoint_group

• slave_transaction_retries now has the alias replica_transaction_retries

• slave_parallel_workers now has the alias replica_parallel_workers

• slave_pending_jobs_size_max now has the alias replica_pending_jobs_size_max

• pseudo_slave_mode now has the alias pseudo_replica_mode

• skip_slave_start now has the alias skip_replica_start

• If the new rpl_semi_sync_source and rpl_semi_sync_replica plugins are used for

semisynchronous replication:

• rpl_semi_sync_slave_enabled is replaced by rpl_semi_sync_replica_enabled

• rpl_semi_sync_slave_trace_level is replaced by

rpl_semi_sync_replica_trace_level

• rpl_semi_sync_master_wait_for_slave_count is replaced by

rpl_semi_sync_source_wait_for_replica_count

• rpl_semi_sync_master_enabled is replaced by rpl_semi_sync_source_enabled

• rpl_semi_sync_master_timeout is replaced by rpl_semi_sync_source_timeout

• rpl_semi_sync_master_trace_level is replaced by

rpl_semi_sync_source_trace_level

• rpl_semi_sync_master_wait_point is replaced by rpl_semi_sync_source_wait_point

• The following system variables are not changed:

• ndb_slave_conflict_role (NDB system variables are not changed)

• binlog_rotate_encryption_master_key_at_startup (“master key” is an accepted term)

• slave_rows_search_algorithms (This system variable is already deprecated)

• master_info_repository (This system variable is already deprecated)

• Status variables:

• Slave_open_temp_tables now has the alias Replica_open_temp_tables

• Slave_rows_last_search_algorithm_used now has the alias

Replica_rows_last_search_algorithm_used

• If the new rpl_semi_sync_source and rpl_semi_sync_replica plugins are used for semisynchronous

replication:

• Rpl_semi_sync_slave_status is replaced by Rpl_semi_sync_replica_status

• Rpl_semi_sync_master_status is replaced by Rpl_semi_sync_source_status

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MySQL 8.0 Release Notes

• Rpl_semi_sync_master_clients is replaced by Rpl_semi_sync_source_clients

• Rpl_semi_sync_master_yes_tx is replaced by Rpl_semi_sync_source_yes_tx

• Rpl_semi_sync_master_no_tx is replaced by Rpl_semi_sync_source_no_tx

• Rpl_semi_sync_master_wait_sessions is replaced by

Rpl_semi_sync_source_wait_sessions

• Rpl_semi_sync_master_no_times is replaced by Rpl_semi_sync_source_no_times

• Rpl_semi_sync_master_timefunc_failures is replaced by

Rpl_semi_sync_source_timefunc_failures

• Rpl_semi_sync_master_wait_pos_backtraverse is replaced by

Rpl_semi_sync_source_wait_pos_backtraverse

• Rpl_semi_sync_master_tx_wait_time is replaced by

Rpl_semi_sync_source_tx_wait_time

• Rpl_semi_sync_master_tx_waits is replaced by Rpl_semi_sync_source_tx_waits

• Rpl_semi_sync_master_tx_avg_wait_time is replaced by

Rpl_semi_sync_source_tx_avg_wait_time

• Rpl_semi_sync_master_net_wait_time is replaced by

Rpl_semi_sync_source_net_wait_time

• Rpl_semi_sync_master_net_waits is replaced by Rpl_semi_sync_source_net_waits

• Rpl_semi_sync_master_net_avg_wait_time is replaced by

Rpl_semi_sync_source_net_avg_wait_time

• NDB-related status variables are not changed.

• For mysqld, the command-line versions of all the aliased and replaced system variables in the lists

above have equivalent command-line aliases or replacements, plus the following command-line option

that is not a system variable:

• show-slave-auth-info has the alias show-replica-auth-info

• The following command-line options are not changed:

• abort-slave-event-count (This command-line option is scheduled for deprecation)

• disconnect-slave-event-count (This command-line option is scheduled for deprecation)

• master-info-file (This command-line option is already deprecated)

• master-retry-count (This command-line option is already deprecated)

• For mysqladmin, the option start-slave now has the alias start-replica, and the option

stop-slave now has the alias stop-replica.

• For mysqlbinlog, the option read-from-remote-master now has the alias read-from-

remote-source.

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MySQL 8.0 Release Notes

• For mysqldump, the following command-line options have new aliases:

• apply-slave-statements now has the alias apply-replica-statements

• delete-master-logs now has the alias delete-source-logs

• dump-slave now has the alias dump-replica

• include-master-host-port now has the alias include-source-host-port

• master-data now has the alias source-data

• The built-in SQL function MASTER_POS_WAIT has a new alias SOURCE_POS_WAIT.

(WL #14194, WL #14628)

• InnoDB: The new innodb_segment_reserve_factor system variable permits configuring the

percentage of tablespace file segment pages that are reserved as empty pages. For more information,

see Configuring the Percentage of Reserved File Segment Pages.

Thanks to Facebook for the contribution. (Bug #32312743, Bug #102044, WL #14521)

• Group Replication: For Group Replication, a group in single-primary mode can now be configured to

stay in super read-only mode, so that it only accepts replicated transactions and does not accept any

direct writes from clients. This setup means that when a group’s purpose is to provide a secondary

backup to another group for disaster tolerance, you can ensure that the secondary group remains

synchronized with the first. You can configure the group to remain in super read-only mode when a new

primary is elected, by disabling the action that normally takes place to remove that mode on the primary.

Administrators can configure a group in this way using the new Group

Replication functions group_replication_enable_member_action() and

group_replication_disable_member_action(), which can enable and disable actions for

members of a group to take in specified situations. The functions can also be used on servers that are

not part of a group, as long as the Group Replication plugin is installed. Member actions are configured

on the primary and propagated to other group members and joining members using group messages.

Another function group_replication_reset_member_actions() is available to reset the member

actions configuration to the default setting for all member actions. (WL #13855)

• Group Replication: You can now select an alternative UUID to form part of the GTIDs that are

used when internally generated transactions for view changes (View_change_log_event)

are written to the binary log. The system variable group_replication_view_change_uuid

added in this release specifies a UUID that is used instead of the group name (the value of

group_replication_group_name). The alternative UUID makes it easier to distinguish view change

events from transactions received by the group from clients. This can be useful if your setup allows for

failover between groups, and you need to identify and discard transactions that were specific to the

backup group. Note that all members of the group must have the same alternative UUID specified, so

groups set up in this way cannot include members from releases prior to MySQL 8.0.26. (WL #14539)

• The URL for downloading Boost was updated. Thanks to Marcelo Altmann for the contribution. (Bug

#32856104, Bug #103611)

• The clone plugin now permits cloning from a donor MySQL server instance to a hotfix MySQL server

instance of the same version and release. Previously, the hotfix server instance was not recognized as

the same MySQL version and release. (Bug #32523635)

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MySQL 8.0 Release Notes

• These statements now report utf8mb3 rather than utf8 when writing character set names: EXPLAIN,

SHOW CREATE PROCEDURE, SHOW CREATE EVENT.

Stored program definitions retrieved from the data dictionary now report utf8mb3 rather than utf8

in character set references. This affects any output produced from those definitions, such as SHOW

CREATE statements.

This error message now reports utf8mb3 rather than utf8 when writing character set names:

ER_INVALID_CHARACTER_STRING. (Bug #32233614, Bug #32392077, Bug #32392209, Bug

#32428538, Bug #32428598)

• On platforms that support fdatasync() system calls, the new innodb_use_fdatasync variable

permits using fdatasync() instead of fsync() for operating system flushes. An fdatasync()

system call does not flush changes to file metadata unless required for subsequent data retrieval,

providing a potential performance benefit. The innodb_use_fdatasync variable can be set

dynamically using a SET statement. (WL #14452)

Bugs Fixed

• Incompatible Change: Within trigger bodies, INSERT or UPDATE statements containing a SET clause

that used OLD or NEW values as assignment targets could raise an assertion or lead to a server exit.

Such assignments are no longer permitted. (Bug #32803211)

• Performance: Internal functions used to copy values between columns have been improved such that

computations not necessary when the values are of similar types are no longer performed. Queries using

temporary tables should be noticeably faster with this enhancement. Our internal testing has shown such

queries being executed up to 11% faster than previously; as always, your results may differ from these

depending on environment, configuration, and other factors. (Bug #32742537)

• InnoDB: To reduce the number of unnecessary warning messages in the error log, instances

of the fil_space_acquire() function in the InnoDB sources were replaced by the

fil_space_acquire_silent() function where possible. (Bug #32944543)

• InnoDB: The TRX_FORCE_ROLLBACK_ASYNC flag in the InnoDB sources, which indicates whether a

transaction was rolled back asynchronously or by the owning thread, was found to be redundant and has

been removed. (Bug #32912595)

• InnoDB: Use of the ut_delete symbol instead of the UT_DELETE macro in the InnoDB

sources caused a failure in builds that disable Performance Schema memory tracing (-

DDISABLE_PSI_MEMORY=ON). (Bug #32910699)

• InnoDB: Dictionary system mutex_enter and mutex_exit calls in the InnoDB sources were

renamed to dict_sys_mutex_enter() and dict_sys_mutex_exit(), respectively. (Bug

#32907980)

• InnoDB: Legacy UNIV_INLINE and UNIV_MATERIALIZE artifacts were removed from InnoDB

sources. UNIV_HOTBACKUP was added to method declarations in some header files. (Bug #32894165)

• InnoDB: The lock_sys sharded rw_lock index used random index values generated by the

ut_rnd_interval() function, which was not optimal for low-concurrency workloads. (Bug #32880577)

• InnoDB: A string value setting for the innodb_redo_log_encrypt variable was not handled properly.

(Bug #32851525)

• InnoDB: Read-write transaction set (trx_sys->rw_trx_set) shards, each with a dedicated mutex,

were introduced to alleviate transaction system mutex (trx_sys->mutex) contention caused by

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MySQL 8.0 Release Notes

transaction set insertions and removals. Related enhancements include moving transaction set modifiers

to less critical locations, eliminating heap allocation inside of the TrxUndoRsegs constructor, converting

transaction state (trx->state) and transaction start time (trx->start_time) fields to std::atomic

fields, and new assertion code to validate threads that operate on transactions. (Bug #32832196)

• InnoDB: Record buffer logic for the InnoDB memcached GET command was revised. (Bug #32828352)

• InnoDB: The ut_list base member in the InnoDB sources now locates list nodes using the element

portion of the list type rather than storing a member pointer in the base node of a list at runtime,

which waisted resources. The patch also includes other ut_list related code improvements. (Bug

#32820458)

• InnoDB: After upgrading from MySQL 5.6 to MySQL 5.7 and starting the server with undo log truncation

enabled (innodb_undo_log_truncate=ON), a deadlock occurred when an undo tablespace truncate

operation was initiated. The deadlock caused a long semaphore wait and an eventual failure. A direct

upgrade from MySQL 5.6 to MySQL 5.7.35 or later avoids this potential issue. (Bug #32800020)

• InnoDB: Type-safe enhancements for PSI_memory_key identifiers were introduced. PSI_memory_key

identifiers are used by Performance Schema for instrumentation of memory operations. With this

enhancement, ut::aligned_name library functions are able to report type errors at compile time.

(Bug #32797838)

• InnoDB: The buf_get_LRU_mutex() function was optimized to avoid acquiring the LRU mutex

unnecessarily when flushing from the flush list. (Bug #32797451, Bug #103391)

• InnoDB: In debug builds, an access to Fil_shard::m_deleted_spaces (deleted tablespaces

vector) was not protected by the Fil_shard mutex, causing a failure. (Bug #32792816)

• InnoDB: Enabling innodb_dedicated_server on a machine with 2GB of RAM resulted in a single

redo log file being created, causing a startup failure. The innodb_dedicated_server automated

configuration logic was revised to ensure that a minimum of two log files are created.

Thanks to Adam Cable for the contribution. (Bug #32788772, Bug #103372)

• InnoDB: A failure occurred when truncating a partitioned table after an operation that added too many

columns to the table, exceeding the column limit. The number of columns added is now evaluated before

an ADD COLUMN operation is permitted. (Bug #32788564, Bug #103363)

• InnoDB: On platforms that support punch hole where the disk is near full, creating a tablespace with a

large AUTOEXTEND_SIZE setting could lead to a no space on device failure and a subsequent InnoDB

recovery failures. (Bug #32771235)

• InnoDB: The list of table locks requested by a transaction (trx->lock.table_locks), which is a

subset of the transaction lock list (trx->lock.trx_locks), was removed. Table locks requested by a

transaction are now are now listed at the beginning of the transaction lock list instead. (Bug #32762881)

• InnoDB: A failure occurred during recovery with the disk being near full, leaving the data in an

inconsistent state. The failure occurred in the fil_tablespace_redo_extend() function, which is

used to redo a tablespace extension operation. (Bug #32749974, Bug #32748733)

• InnoDB: After relocating a file-per-table tablespace offline and making the new location known to

InnoDB using the innodb_directories option, an ALTER TABLE operation that used the COPY

algorithm failed with a storage engine error. The failure was due to a renaming check, which searched

the data directory instead of the new directory location. (Bug #32721533)

• InnoDB: ut_allocator() compliance issues with the C++ standard template library (STL) were

addressed. (Bug #32715698)

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MySQL 8.0 Release Notes

• InnoDB: Instances of ut_allocator::allocate() instantiated by std::vector in the InnoDB

sources failed to trace memory allocations and deallocations performed implicitly by std::vector. The

same issue was found for other C++ standard template library (STL) and STL-like data-structures. (Bug

#32715688)

• InnoDB: The ut_allocator::construct() interface in the InnoDB sources, which is a custom

interface implemented in a pre-C++11 style, caused unnecessary overhead. The interface was not

necessary and has been removed. (Bug #32715381)

• InnoDB: The ut_list length member variable in the InnoDB sources was replaced by an atomic field

to permit lock free access without undefined behavior. The default ut_list constructor was replaced by

a new constructor that performs all list initialization. (Bug #32715371)

• InnoDB: The ut_allocator() out of memory reporting mechanism in the InnoDB sources was not

reliable and has been removed. (Bug #32715359)

• InnoDB: Implicit handling of Performance Schema metadata was implemented for

ut_allocator::allocate_large() and ut_allocator::deallocate_large() functions

in the InnoDB sources. This modification aligns Performance Schema metadata handling with that of

similar allocation functions. (Bug #32714144)

• InnoDB: Stalls were caused by concurrent SELECT COUNT(*) queries where the number of parallel

read threads exceeded the number of machine cores. A patch for this issue was provided for Windows

builds in MySQL 8.0.24. The MySQL 8.0.26 patch addresses the same issue on other affected platforms.

(Bug #32678019)

References: See also: Bug #32224707.

• InnoDB: To avoid costly calls to the rec_get_offsets() function, which determines the offsets for

each field in a record, caching of offsets is extended to indexes that meet certain requirements such as

having a fixed length, no virtual columns, instant columns, and so on. (Bug #32673649)

• InnoDB: When starting the server with a data directory that was restored by MySQL Enterprise Backup,

the doublewrite buffer (controlled by the innodb_doublewrite variable) remained disabled until the

next server restart. (Bug #32642866)

• InnoDB: “Too many open files” errors were encountered when creating a large number of tables. (Bug

#32634620)

References: This issue is a regression of: Bug #32541241.

• InnoDB: InnoDB recovery was unable to proceed due to a page tracking system recovery failure, which

should have been non-blocking. (Bug #32630875)

• InnoDB: An integer underflow issue was addressed in the InnoDB mecached plugin sources. (Bug

#32620378, Bug #32620398)

• InnoDB: When a transaction started waiting for lock, the InnoDB lock system provided information

to the server about the transaction currently holding the lock but failed to inform the server after

releasing the lock and grating it to another waiting transaction. As a result, the replication applier thread

coordinator was unable to detect potential deadlocks in the intended transaction commit order that

could occur if the third transaction in this scenario committed after the initial waiting transaction. (Bug

#32618301)

• InnoDB: When inserting a record into a unique secondary index, the index record locks taken to

prevent concurrent transactions from inserting a conflicting record into the affected range included an

unnecessary gap lock on the first record after the range. (Bug #32617942)

156

MySQL 8.0 Release Notes

• InnoDB: InnoDB code that creates dynamically allocated over-aligned types was replaced by

ut::aligned_name library functions. (Bug #32601599)

• InnoDB: Memory allocation functions belonging to the API that handles dynamic storage of over-

aligned types (ut::aligned_name library functions) were extended to support memory tracing using

Performance Schema. The HAVE_PSI_MEMORY_INTERFACE source configuration option enables the

memory tracing module.

An aligned_zalloc() library function, which provides support for zero-initialized memory allocations,

was added to the API. (Bug #32600981)

References: See also: Bug #32601599, Bug #32246061, Bug #32246200.

• InnoDB: Sampling of InnoDB data for the purpose of generating histogram statistics is now supported

with all transaction isolation levels supported by InnoDB. Previously, sampling was performed using only

the READ UNCOMMITTED isolation level. (Bug #32555575)

• InnoDB: An index with a key prefix length greater than 767 bytes was permitted on a table defined with

the REDUNDANT row format, exceeding the index key prefix length limit for that row format. The ALTER

TABLE operation that added the index validated the index key prefix length for the row format defined

by the innodb_default_row_format variable instead of the actual row format of the table. The

fix ensures that index key prefix length is validated for the correct row format. (Bug #32507117, Bug

#102597)

• InnoDB: Adaptive hash index latches did not provide meaningful latch location information. (Bug

#32477773)

• InnoDB: A dependency related to redo and undo log encryption at server initialization time was

removed. (Bug #32476724)

• InnoDB: An online buffer pool resizing operation freed the previous buffer pool page hash, conflicting

with a concurrent buffer pool lookup that required the previous page hash. (Bug #32460315)

• InnoDB: When using the TempTable storage engine

(internal_tmp_mem_storage_engine=TempTable), more than 255 aggregate functions in a

SELECT list caused errors due to overflow of an internal variable that stores indexed column field

positions. (Bug #32458104, Bug #102468)

• InnoDB: A workload stalled while executing a undo tablespace truncation operation on an instance

with a large buffer pool. The function that truncates marked undo tablespaces now takes a shared latch

instead of an exclusive latch, and the shared latch is taken for a shorter period of time. (Bug #32353863,

Bug #102143)

• InnoDB: A programming interface was added for handling dynamic storage of over-aligned types. (Bug

#32246200, Bug #32246061)

• InnoDB: Under certain circumstances, a failure during InnoDB recovery could have caused a

loss of committed changes. Checkpoints permitted during recovery did not handle page flushing,

flush list maintenance, or persisting changes to the data dictionary table buffer as necessary for

a proper checkpoint operations. Checkpoints and advancing the checkpoint LSN are therefore

no longer permitted until redo log recovery is complete and data dictionary dynamic metadata

(srv_dict_metadata) is transferred to data dictionary table (dict_table_t) objects. Should the

redo log run out of space during recovery or after recovery (but before data dictionary dynamic metadata

is transferred to data dictionary table objects) as a result of this change, an innodb_force_recovery

restart may be required, starting with at least the SRV_FORCE_NO_IBUF_MERGE setting or, in case

that fails, the SRV_FORCE_NO_LOG_REDO setting. If an innodb_force_recovery restart fails in this

scenario, recovery from backup may be necessary. (Bug #32200595)

157

MySQL 8.0 Release Notes

• InnoDB: Rollback segments are now initialized in parallel during startup. Previously, rollback segments

were initialized serially.

Thanks to Zheng Lai and the Tencent Cloud-Native Database team for submitting the contribution this

bug fix is based on. (Bug #32170127, Bug #101658)

• InnoDB: A failure occurred during testing of innodb_log_writer_threads variable configuration.

The failure was caused by a race condition. (Bug #32129814)

References: This issue is a regression of: Bug #30088404.

• InnoDB: A race condition occurred between a purge thread that was truncating an undo tablespace

and a server thread that queried the INFORMATION_SCHEMA.FILES table. As a result, the

truncated undo tablespace did not appear in the INFORMATION_SCHEMA.FILES table when

queried, which in turn caused a MySQL Enterprise Backup failure due to a dependency on the

INFORMATION_SCHEMA.FILES table for undo tablespace file locations. (Bug #32104924, Bug

#32654667)

• InnoDB: When DML operations are concentrated on a single table, purge work was performed by a

single purge thread, which could result in slowed purge operations, increased purge lag, and increased

tablespace file size if DML operations involve large object values. To address this issue, purge work

is now automatically redistributed among available purge threads when the purge lag exceeds the

innodb_max_purge_lag setting. (Bug #32089028)

• InnoDB: The function that populates the INFORMATION_SCHEMA.INNODB_TABLESPACES table

accessed the space for a file and performed an unprotected stat() operation and retrieval of file size

information. (Bug #32025344)

• InnoDB: Code related to the trx_t::is_recovered flag in the InnoDB sources was revised

to address various complexity and correctness issues. One of the issues addressed caused an

XA transaction to be described incorrectly as “recovered”, which occurred when a client session

disconnected from an XA transaction after XA PREPARE. (Bug #31870582)

• InnoDB: TempTable debug assertion code for an Indexed_cells member function

(cell_from_mysql_buf_index_read()) did not account for non-nullable columns with zero length.

(Bug #31091089)

• InnoDB: Using the InnoDB memcached plugin, attempting to retrieve multiple values in a single get

command returned an incorrect value. (Bug #29675958, Bug #95032)

• InnoDB: The trx_sys_t::serialisation_mutex was introduced to reduce contention on the on

the trx_sys_t::mutex. The new mutex protects the trx_sys_t::serialisation_list when a

transaction number is assigned, which was previously protected by the trx_sys_t::mutex.

Thanks to Zhai Weixiang for the contribution. (Bug #27933068, Bug #90643)

• Partitioning: When a table was partitioned by TIMESTAMP and a timestamp literal with a time zone

offset was used in the WHERE clause of a SELECT statement, it was possible for a partition to be omitted

from the result set.

When a time zone offset is specified in a timestamp literal, it is expected to be converted to a timestamp

without a time zone offset, and then compared against a timestamp column, but this was not done

properly in all cases, with the result that a partition could be pruned while selecting the partitions to be

scanned for the query.

We fix this by making sure that a timestamp with a time zone offset is always converted as described

before comparing with values from the column. (Bug #101530, Bug #32134145)

158

MySQL 8.0 Release Notes

• Replication; Group Replication: When the system variable

replication_optimize_for_static_plugin_config was set, the plugins for Group Replication

and semi-synchronous replication could not be uninstalled cleanly on server shutdown. (Bug #32798287)

• Replication: When the SOURCE_CONNECTION_AUTO_FAILOVER=1 option was set on the CHANGE

REPLICATION SOURCE TO statement for a replication channel, a STOP REPLICA IO_THREAD

statement did not stop the monitor thread that monitors for connection failures on the channel, and could

incorrectly stop the applier thread. (Bug #32892977)

• Replication: A deadlock could occur when START GROUP_REPLICATION and STOP

GROUP_REPLICATION statements were issued at the same time that a view change was taking place for

the group. (Bug #32738137, Bug #32836868)

• Replication: An incorrect default value in code meant that the allowlist of IP addresses permitted for a

replication group was implicitly reconfigured although no value had been supplied. (Bug #32714911)

• Replication: A deadlock could occur if a STOP GROUP_REPLICATION statement was issued when a

replication channel on a group member was attempting to commit a transaction. The server now rolls

back the transaction immediately if it cannot acquire the relevant lock, rather than waiting for the lock

and the commit to complete and causing the deadlock. (Bug #32633176)

• Replication: On a multithreaded replica, the reference to the active event was sometimes managed

incorrectly when retrying a transaction. (Bug #32590974)

• Replication: After a DML operation was performed on the last partition of a table with more than 128

partitions, MySQL Server and MySQL clients (such as mysqlbinlog) parsed the event information from

the binary log incorrectly, resulting in an inaccurate partition ID being stated. The information is now read

using an event reader function that is endianness independent. (Bug #32358736, Bug #102191)

• Replication: In a new MySQL Server installation, the mysql.gtid_executed system table was

missing the property STATS_PERSISTENT=0 to disable persistent statistics, which is present for the

other replication-related tables. (Bug #32250735)

• Replication: When the same row in a table was updated multiple times by the same event, the

replication applier’s hash scan algorithm omitted to check for JSON partial updates, which are logged

when binlog_row_value_options=PARTIAL_JSON is set. This could result in replication stopping

with a “key not found” error. (Bug #32221703)

• Replication: Replica servers now check and validate the transaction ID part of a GTID before applying

and committing the transaction associated with it. (Bug #32103192)

• Replication: Replication could stop on a multithreaded replica if a unique secondary key was omitted

from the writeset hashes used to compute transaction dependencies, leading to errors when executing

the transactions on the multithreaded replica. Write set hashes now always include unique secondary

keys even if they are not included in the read set and write set. (Bug #31636339)

• Replication: MySQL semisynchronous replication did not clean up connection artifacts correctly after

sending a reply to the source, causing a mismatch that meant the connection had to be re-established.

The issue has now been fixed. (Bug #31363518, Bug #32441220, Bug #32759421)

• Replication: On a multithreaded replica (with slave_parallel_workers > 0 ), the algorithm used

by GTID auto-positioning to check for missing transactions briefly sets a low value (4) for the event

position in the course of its calculations. If the operation is stopped at that moment, the recovery process

159

MySQL 8.0 Release Notes

that resolves gaps in the sequence of transactions can fail. The process to resolve gaps is not actually

necessary when GTID auto-positioning is used, so the process has now been disabled in that situation.

As a result, on a multithreaded replica, when GTID_MODE = ON is set for the instance and

SOURCE_AUTO_POSITION is set for the channel using the CHANGE REPLICATION SOURCE TO

statement, the following behaviors now apply:

• A START REPLICA UNTIL SQL_AFTER_MTS_GAPS statement just stops the applier thread

when it finds the first event to execute, and does not attempt to check for gaps in the sequence of

transactions.

• A CHANGE REPLICATION SOURCE TO statement does not automatically fail if there are gaps in the

sequence of transactions.

These changed behaviors only apply on a multithreaded replica that uses GTIDs and GTID auto-

positioning, and not on a replica that uses binary log position-based replication. (Bug #30571587, Bug

#97694)

• Group Replication: When running Group Replication in single-primary mode, unnecessary copies of the

transaction data were created during data serialization. This is now done in a single step to reduce the

memory footprint. (Bug #32781945)

• Group Replication: Replicated transactions in GTID-based replication include an

original_commit_timestamp to show when the transaction was committed on the original source

server, and an immediate_commit_timestamp to show when it was committed on the replica.

Previously, the original_commit_timestamp was not set for Group Replication view change

events, which are agreed by the group but then generated and applied by each group member, so the

timestamp appeared as zero in viewable output. For improved observability, group members now set

local timestamp values for transactions associated with view change events. (Bug #32668567)

• Group Replication: Previously, a warning message was written to the error log if the original commit

timestamp on a replicated transaction was more recent than the immediate commit timestamp on the

replica applying it. The message could occur inappropriately if the fluctuation in the replication lag had

a similar value to the clock difference between the machines involved, which could be made more likely

by better quality connections between them. During Group Replication failover, it was possible for a

message to be returned for every transaction, flooding the log. To avoid this situation, the warning

message has been withdrawn. (Bug #32554807)

• Group Replication: When group_replication_consistency was set to AFTER, and a view

change event was delayed until after a locally prepared transaction was completed, a different GTID

could be applied to it, causing errors in replication. The data is now processed in the same sequence it is

received to avoid the situation. (Bug #31872708)

• Microsoft Windows: Writing to Windows event logs could be unsuccessful. (Bug #32890918)

• JSON: Reading JSON values from tables that used the CSV storage engine raised an error such as

Cannot create a JSON value from a string with CHARACTER SET 'binary'. This

happened because the CSV engine uses my_charset_bin as the character set for the record buffer

but creation of JSON values includes an explicit check for my_charset_bin, and raises an error if this

character set is given.

We handle this issue by passing the actual character set of the column instead of the character set of the

buffer holding the data, which is always binary. (Bug #102843, Bug #32597017)

• A query for which the derived condition pushdown optimization could be applied was not so optimized

when the query was part of INSERT ... SELECT. (Bug #32959186)

160

MySQL 8.0 Release Notes

• Import operations for access privilege information became very slow for large numbers of accounts and

schemas. (Bug #32934351)

• Queries which needed to sort the results of a full-text index scan were in some circumstances not

handled correctly. (Bug #32924198)

• Thanks to Xiaoyu Wang for a code correction to PFS_notification_registry::is_empty(). (Bug

#32919118, Bug #103788)

• Queries containing GROUP BY, ORDER BY, and LIMIT in a subquery and accessed using a cursor could

cause a server exit. (Bug #32918240)

• When invoked with the --help and --verbose options, mysqld created an auto.cnf file in the

current directory. (Bug #32906164)

• Queries that involved pushing a condition with view references down to a materialized derived table

could cause a server exit. (Bug #32905044, Bug #32324234)

• Messages for ER_CANT_INITIALIZE_UDF errors could be truncated. (Bug #32891703)

• A regression was found in the simplification of streaming aggregation (GROUP BY of data already sorted)

that was performed in MySQL 8.0.23.

We fix this issue as follows: When there is an implicit grouping on a single table which is the subject of a

fulltext search, we now force insertion of a temporary table to materialize MATCH() temporaries before

they are sent to the AggregateIterator, since it tries to save and restore the rows it receives, but

cannot properly include the fulltext search information, as it is hidden. (Bug #32889491)

References: This issue is a regression of: Bug #31790217.

• For conversion of -DBL_MAX to string and back to double, the new double value differed from the

original and was rejected as out of bounds. (Bug #32888982, Bug #103709)

• Now, whenever the JSON_LENGTH() function includes the optional path argument, the server rewrites

it as JSON_LENGTH(JSON_EXTRACT(doc, path)). This means that JSON_LENGTH() now supports

wildcards (such as $, ., and *) and array ranges in the path, as shown here:

mysql> SELECT JSON_LENGTH('[1,2,3,4,5,6,7]', '$[2 to 4]') AS x;

+------+

| x |

+------+

| 3 |

+------+

(Bug #32877703)

• For flags typically used for RPM and Debian packages, the new WITH_PACKAGE_FLAGS CMake option

controls whether to add those flags to standalone builds on those platforms. The default is ON for

nondebug builds. This is used to “harden” the builds; for example, by adding -D_FORTIFY_SOURCE=2.

(Bug #32876974)

• The NULLIF() function did not perform all necessary checks for errors. (Bug #32865008)

• For views that depended on other views, output from the SHOW CREATE VIEW statement used during

production of dump files could cause an error at restore time. (Bug #32854203, Bug #103583)

• The query-attributes code did not properly handle large 64-bit numbers. (Bug #32847269)

• Information retrieved from the Performance Schema metadata_locks table could be incorrect for

foreign keys and CHECK constraints. (Bug #32832004, Bug #103532)

161

MySQL 8.0 Release Notes

• When generating unique names for view columns, the server now considers only those objects whose

names are visible. (Bug #32821372)

• When a condition is pushed down to a materialized derived table, a clone of the derived table expression

replaces the column (from the outer query block) in the condition. When the cloned item included a

FULLTEXT function, it was added to the outer query block instead of the derived table query block, which

led to problems. To fix this, we now use the derived query block to clone such items. (Bug #32820437)

• A common table expression which was used more than once in a statement, at least once within a

subquery that was subsequently removed during resolution due to being always true, or always false.

(Bug #32813547, Bug #32813554)

• If a statement is prepared against a table that is persistent at preparation time but temporary at the time

of first execution, an assertion could be raised. (Bug #32799797)

• An internal function used by spatial functions could reference memory after freeing it. (Bug #32793104)

• The impossible filter optimization removed MRR access paths that were required by the

corresponding BKA access paths. (Bug #32787415)

• The new WITH_AUTHENTICATION_CLIENT_PLUGINS CMake option is enabled automatically if any

corresponding server authentication plugins are built. Its value thus depends on other CMake options

and it should not be set explicitly. (Bug #32778378)

• The MRR iterator normally filters out NULL keys by checking impossible_null_ref(), but when

a join condition either contained an IS NULL predicate, or used the NULL-safe equals operator

≪=>, the optimizer had to check whether the join condition used the predicate terms as part of its

join condition, and not set the internal flag HA_MRR_NO_NULL_ENDPOINTS in such cases. Now we

check, using a bitmask, whether the each column in the key rejects NULL, in which case we can set

HA_MRR_NO_NULL_ENDPOINTS without further checks. (Bug #32774281)

• For system variables with an enumeration type, SET PERSIST_ONLY var_name = DEFAULT

persisted the numeric value and not the symbolic name. (Bug #32761053)

• The X DevAPI operations Collection.replaceOne and Collection.addOrReplaceOne now verify that the

value of the _id field in a document matches the id parameter specified for the operation. If it does not,

an error is returned. (Bug #32753547)

• For applications that use the C API to execute prepared statements, query attributes could not be used

for prepared statements with no parameters. (Bug #32753030, Bug #32790714, Bug #32955044)

• The arguments to IN() were not always converted to the correct character set. (Bug #32746552)

• The LOCATE() function unconditionally returned NULL when an argument could not be evaluated. Now,

when used in an expression that is determined to be non-nullable, the function returns zero instead. (Bug

#32746536)

• The internal function my_well_formed_len_utf32() asserted when presented with a string of invalid

length. Now in such cases, the function reports an invalid string instead. (Bug #32745294)

• The functions TRIM(), RTRIM(), and LTRIM() did not always perform proper error checking. (Bug

#32744772)

• A previous fix in an internal resolver function ensured that it raises an error when a generated column

cannot be resolved. This worked without any problem when the generated column is part of a CREATE

TABLE statement, but in the case where the table with the generated column was generated on a

MySQL 5.7 database and then upgraded to MySQL 8.0, an error was reported and the upgrade

terminated.

162

MySQL 8.0 Release Notes

We fix this by using the correct pointer when reporting the table causing the error in the function

fix_generated_columns_for_upgrade(). (Bug #32738972)

• When looking inside rollup wrappers in the SELECT list, and trying to find the same item in the GROUP

BY list, the server did not take into account that a cache might have been added around the expression.

Now any such caches are unwrapped before looking for the item. (Bug #32729377, Bug #32918400)

• A prepared statement that used MIN() or MAX() could return an incorrect result if it also included

dynamic parameters. (Bug #32713860, Bug #103170)

• Replication could fail if a DML statement was executed immediately after an XA transaction was rejected

or forced to rollback due to a deadlock. (Bug #32707060)

• Queries containing multiple instances of GROUPING() were not always handled correctly. (Bug

#32695103)

• When executing EXPLAIN ANALYZE, materialization iterators count every single init() call, even

those that only retain existing data, causes materializations to appear to cost too little compared to the

number of underlying calls. We fix this by allowing the materialization iterator to override the call and row

counts with its own data. (Bug #32688540)

• A race condition in the metadata locking code could result in a server exit. (Bug #32686116)

• An index-only scan on a covering full-text index could return incorrect results for queries with multiple

calls to MATCH() function depending on the order in which the MATCH() calls were evaluated. (Bug

#32685616)

• Including query attributes for a prepared statement could cause a statement execution failure. (Bug

#32676878)

• Executing DDL statements on a system table could cause a server exit. (Bug #32665990)

• With the --online-migration option, mysql_migrate_keyring could exit during connection

establishment to the migration server. (Bug #32651203)

• mysql_migrate_keyring failed to enforce the condition that the source and destination keystores

must differ. (Bug #32637784)

• System cache size checking could be inaccurate on Ubuntu. (Bug #32619199, Bug #102926)

• The server did not process correctly some queries that used MATCH ... AGAINST on a column with a

fulltext index in a HAVING clause. (Bug #32617181)

References: This issue is a regression of: Bug #30969045.

• Replicated transactions in GTID-based replication include an original_commit_timestamp

to show when the transaction was committed on the original source server, and an

immediate_commit_timestamp to show when it was committed on the replica. Previously,

Group Replication servers set the original_commit_timestamp when they committed

locally generated transactions, but they did not set the immediate_commit_timestamp. For

improved observability, group members now set this timestamp. If the transaction originated in

the group, the original_commit_timestamp and immediate_commit_timestamp are both

generated by Group Replication, and are equal. If the transaction originated outside the group, the

original_commit_timestamp is preserved, and an immediate_commit_timestamp is set. (Bug

#32613896)

• The internal function Item_func_match::eq() raised an assert failure in debug builds when

it was called with an argument that was an Item_func_match_predicate. The assertion was

163

MySQL 8.0 Release Notes

added with the expectation that an Item_func_match object would not be compared with an

Item_func_match_predicate object, but it was later found that this can happen during the

ONLY_FULL_GROUP_BY check when the predicate is in a HAVING clause.

We fix this by removing the assertion so that the function returns false, instead. (Bug #32611913)

• SELECT using DISTINCT with a GROUP BY ... WITH ROLLUP on a primary key column returned a

different result than when the column was not a primary key. (Bug #32565875)

• When an item in the SELECT list came from a table that was found to be constant, it was possible to add

caches around it before adding ROLLUP wrappers, causing it to be unfindable in the group list (which had

no such wrappers). This is addressed by unwrapping the caches. (Bug #32559356)

• The C client library could produce a Malformed communication packet error if a prepared

statement parameter was longer than 8KB and the next parameter represented a NULL value. (Bug

#32558782)

• When comparing arguments of different types, and the arguments are deemed constants, the server

may insert its own hidden item cache to save on repeated conversion (and possible warnings). This is

not visible in the output of any statements such as EXPLAIN.

An issue arose due to the fact that resolution of ROLLUP runs after the comparisons are set up, and may

replace the arguments, which could lead to incorrect results from comparisons. Now when this happens,

we signal that the comparison needs to reconsider its caches, and not possibly re-use stale values. (Bug

#32548377)

• Incorrect reference counting for a destructor in the implementation of a loadable function could raise

an assertion for debug builds or report that the function does not exist for nondebug builds. (Bug

#32528898, Bug #102649)

• MySQL source distributions now bundle the Google Test source code, which no longer need

be downloaded to run Google Test-based unit tests. Consequently, the WITH_GMOCK and

ENABLE_DOWNLOADS CMake options have been removed and are ignored if specified.

This change also corrects a couple of build issues whereby source distributions incorrectly included an

empty source_downloads directory, and CMake did not fail when WITH_UNIT_TESTS was enabled

but the Google Test source was not found. (For the latter issue, it can no longer occur because the

source is always present.) (Bug #32512077, Bug #27326599, Bug #29935278)

• When outer batched key access and block-nested loop (or hash join) occurred together in a query, both

were reverted to nested loops in the plan interpretation to access paths. Problems arose in some cases

in which non-equality join conditions had been pushed to a special kind of BKA index condition, and by

converting to a regular index lookup (which does not check the BKA condition), it was possible to drop

conditions that should have been checked.

We fix this by removing the BKA index condition; since its use is very rare, potential gains in most

practical queries are very low, and removing it decreases complexity significantly. (Bug #32424884)

• SHOW CREATE USER could cause an unexpected server exit if the structure of the mysql.user system

table was manually altered. (Bug #32417780, Bug #31654586)

• For large values of the group_concat_max_len system variable, prepared statements that used the

GROUP_CONCAT() function could be unnecessarily re-prepared across executions. (Bug #32413530,

Bug #102344)

• Changes were not properly rolled back on re-execution of prepared statements or stored procedures for

which walk and replace was performed as part of optimization. (Bug #32384324, Bug #32573871)

164

MySQL 8.0 Release Notes

• Client programs using the asynchronous C API functions could leak memory if a connection timeout

occurred. Thanks to Facebook for a contribution used in fixing this issue. (Bug #32372038, Bug

#102189, Bug #32800091, Bug #103409, Bug #33171164, Bug #104461)

• The dynamic statistics cache exposed by the INFORMATION_SCHEMA could be updated in the middle of

a transaction before it was known whether the transaction would commit, potentially caching information

corresponding to no committed state. (Bug #32338335)

• Repreparation of a prepared statement at the beginning of an implicit transaction could cause an

ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error. (Bug #32326510, Bug #102031)

• USING HASH was removed from the definitions of Performance Schema thread pool tables because the

Performance Schema does not support hash indexes. (Bug #32194617)

• Inserting a datetime literal with an explicit time zone offset into a TIMESTAMP column could produce the

wrong time if time_zone=SYSTEM and the system time zone has DST transitions. (Bug #32173664,

Bug #101670)

• While setting up ORDER BY for a window function, a window definition including a subquery was

removed along with the subquery in the ORDER BY. (Bug #32103260)

• The use of a SET PERSIST or SET PERSIST_ONLY statement is now disallowed for the

group_replication_force_members system variable. This system variable must be cleared after

use before you can issue a START GROUP_REPLICATION statement, so it should not be persisted to

the MySQL server instance’s option file. (Bug #31983203)

• Upgrades from MySQL 5.7 to 8.0 failed if the MySQL installation had FEDERATED tables. (Bug

#31973053)

• Persisting component-related system variables could result in unnecessary “unknown variable” error

messages. (Bug #31968366)

• An out-of-memory error occurred when loading large amounts of data into tables with full-text search

indexes. Not all of the memory allocated to the full-text search cache was accounted for when inserting

data into the full-text search auxiliary tables. (Bug #31576731)

• The precision for a UNION between integer and decimal values could be calculated incorrectly, leading to

truncation of the integer in the result. (Bug #31348202, Bug #99567)

• InnoDB wrote unnecessary warnings to the error log indicating that table statistics could not be

calculated. (Bug #30865032)

• A secondary index over a virtual column became corrupted when the index was built online.

For UPDATE statements, we fix this as follows: If the virtual column value of the index record is set to

NULL, then we generate this value from the cluster index record. (Bug #30556595)

• DROP DATABASE for a database with a large number of tables (one million) could result in an out-of-

memory condition. (Bug #29634540)

• The system_time_zone system variable is initialized at server startup from the server host settings

and the mysqld environment, but if the server host time zone changed (for example, due to daylight

saving time), system_time_zone did not reflect the change. Now it does. (Bug #29330089, Bug

#94257)

• For upgrades on Ubuntu, if an existing my.cnf file is found, it is renamed to my.cnf.bak and a warning

is issued. (Bug #24486556, Bug #82639)

• Boolean system variables could be assigned a negative value. (Bug #11758439, Bug #50643)

165

MySQL 8.0 Release Notes

• Prepared statements did not always make use of index extensions (see Use of Index Extensions). (Bug

#103711, Bug #32897525)

References: See also: Bug #103710, Bug #32897503.

• When enabled, the prefer_ordering_index optimizer switch had a negative effect on the

performance of prepared statements. (Bug #103710, Bug #32897503)

References: See also: Bug #103711, Bug #32897525.

• Successive INSERT() function calls could sometimes yield invalid NULL results. (Bug #103513, Bug

#32824978)

• Some NOT IN subqueries did not return correct results due to a regression in NULL handling. (Bug

#103331, Bug #32773801)

References: This issue is a regression of: Bug #30473261.

• Whenever a SELECT ... FOR UPDATE NOWAIT statement was unable to obtain a record lock, a

message Got error 203 when reading table ... was written to the error log, even though

though this is a relatively common occurrence, the logging of which led to excessive use of disk space.

Our thanks to Brian Yue for this contribution. (Bug #103159, Bug #32705614)

• 0 - (MAX(BIGINT) + 1) returned -(MAX(BIGINT) + 1). Now an out of range error is returned

instead. (Bug #103093, Bug #32693863)

Changes in MySQL 8.0.25 (2021-05-11, General Availability)

• Packaging Notes

• Bugs Fixed

Packaging Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.76.0.

Bugs Fixed

• On Fedora 34, builds from source failed due to an undefined reference to symbol

crc32_z@@ZLIB_1.2.9. (Bug #32702860)

• Docker containers for MySQL Enterprise Edition no longer need to run with root privileges. (Bug

#32472242)

• For a prepared, implicitly grouped SELECT statement in which the WHERE clause was determined always

to be false, the result of some aggregate functions could sometimes be picked up from the previous

execution of the statement. (Bug #103192, Bug #32717969)

Changes in MySQL 8.0.24 (2021-04-20, General Availability)

• Audit Log Notes

• Compilation Notes

• Connection Management Notes

166

MySQL 8.0 Release Notes

• Error Handling

• Keyring Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Pluggable Authentication

• Security Notes

• Spatial Data Support

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• MySQL Enterprise Audit now supports audit log file pruning, for JSON-format log files. See Space

Management of Audit Log Files. (WL #14268)

Compilation Notes

• GCC 10 is now a supported compiler for building MySQL on EL7 or EL8. This compiler is available in

the devtoolset-10 (EL7) or gcc-toolset-10 (EL8) package. It is also recommended to use GCC

10 when building third-party applications that are based on the libmysqlclient C API library. (Bug

#32381003)

Connection Management Notes

• Previously, if a client did not use the connection to the server within the period specified by the

wait_timeout system variable and the server closed the connection, the client received no notification

of the reason. Typically, the client would see Lost connection to MySQL server during query

(CR_SERVER_LOST) or MySQL server has gone away (CR_SERVER_GONE_ERROR).

In such cases, the server now writes the reason to the connection before closing it, and client receives

a more informative error message, The client was disconnected by the server because

of inactivity. See wait_timeout and interactive_timeout for configuring this

behavior. (ER_CLIENT_INTERACTION_TIMEOUT).

The previous behavior still applies for client connections to older servers and connections to the server

by older clients. (WL #12999)

Error Handling

• Client connection failure messages now include the port number. For example: Can't connect to

MySQL server on '127.0.0.1:63333'.. Thanks to Daniël van Eeden for the contribution. (Bug

#30787660, Bug #98311)

Keyring Notes

• MySQL Keyring previously implemented keystore capabilities using server plugins, but now is

transitioning to use the MySQL component infrastructure, beginning with these keyring components:

167

MySQL 8.0 Release Notes

• component_keyring_file stores keyring data in a file local to the server host. This component is

available in MySQL Community Edition and MySQL Enterprise Edition distributions. See Using the

component_keyring_file File-Based Keyring Component.

• component_keyring_encrypted_file stores keyring data in an encrypted, password-protected

file local to the server host. This component is available in MySQL Enterprise Edition distributions. See

Using the component_keyring_encrypted_file Encrypted File-Based Keyring Component.

The new keyring components have similarities to the existing keyring_file and

keyring_encrypted_file plugins, but are configured differently, use distinct on-disk storage

formats, and have fewer restrictions on key type and key size.

Keyring components are not loaded using the --early-plugin-load server option during startup or

configured during startup or at runtime using system variables:

• During startup, the server determines which keyring component to load using a manifest file, and

the loaded component consults its own configuration file when it initializes. See Keyring Component

Installation.

• At runtime, the new ALTER INSTANCE RELOAD KEYRING statement enables reconfiguring an

installed keyring component after changes to its configuration file. See ALTER INSTANCE Statement.

If a keyring component is installed, the new Performance Schema keyring_component_status table

provides status information about it. See The keyring_component_status Table.

Key migration capabilities have been expanded. Previously, key migration occurred only from one

keyring plugin to another. The new --keyring-migration-to-component server option enables

key migration from a keyring plugin to a keyring component; this facilitates transitioning a MySQL

installation from keyring plugins to keyring components. The new mysql_migrate_keyring utility

enables key migration from one keyring component to another. See Migrating Keys Between Keyring

Keystores. There is no provision for migrating keys from a keyring component to a keyring plugin.

Existing keyring plugins remain available with no change to user-visible characteristics, but their

implementation was revised to use the component infrastructure. This is facilitated using the built-

in plugin named daemon_keyring_proxy_plugin that acts as a bridge between the plugin and

component service APIs. See The Keyring Proxy Bridge Plugin. (WL #13446)

Optimizer Notes

• The MySQL query optimizer can now apply the derived table optimization to correlated scalar

subqueries, whenever the subquery_to_derived flag of the optimizer_switch variable is

enabled. This is done by applying an extra grouping and then an outer join on the lifted predicate. For

example, a query such as SELECT * FROM t1 WHERE (SELECT a FROM t2 WHERE t2.a=t1.a)

> 0 can be rewritten as SELECT t1.* FROM t1 LEFT OUTER JOIN (SELECT a, COUNT(*) AS

ct FROM t2 GROUP BY a) AS derived ON t1.a = derived.a WHERE derived.a > 0.

If the subquery already has an explicit grouping, MySQL adds the extra grouping to the end of the

existing grouping list.

MySQL performs a cardinality check to ensure that the subquery does not return more than one row, and

raises ER_SUBQUERY_NO_1_ROW if it does. The check is performed as part of evaluating any WHERE or

JOIN clause in the rewritten query, before evaluating the lifted predicate.

For more information, see Correlated Subqueries, as well as Derived Tables. (WL #13520)

168

MySQL 8.0 Release Notes

Packaging Notes

• The bundled libedit library was upgraded to version 20190324-3.1. (Bug #32433089)

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.74.0.

Performance Schema Notes

• Incompatible Change: Instrumentation in the Performance Schema setup_instruments table was

revised as follows:

• There are new memory instruments to account for memory allocated to data dictionary infrastructure

and objects:

memory/sql/dd::infrastructure

memory/sql/dd::objects

• Some instruments were renamed for improved uniformity of instrument naming. Affected instrument

names are grouped using a key prefix in the same style as C++ namespaces. For example, error-

related instruments use a error:: prefix and partition-related instruments use a Partition::

prefix. The following table displays the affected instruments.

Old Instrument Name New Instrument Name

debug_sync_control::debug_sync_action THD::debug_sync_action

errmsgs errmsgs::server

handler::errmsgs errmsgs::handler

handlerton handlerton::objects

log_error_loaded_services log_error::loaded_services

log_error_stack log_error::stack

LOG_name LOG::file_name

MDL_context_backup_manager MDL_context::backup_manager

Partition_admin Partition::admin

Partition_share Partition::share

partition_sort_buffer Partition::sort_buffer

partition_syntax_buffer Partition::syntax_buffer

Prepared_statement_map Prepared_statement::infrastructure

prune_partitions::exec Partition::prune_exec

Recovered_xa_transactions XA::recovered_transactions

thd::main_mem_root THD::main_mem_root

XID XA::transaction_contexts

In addition, the servers instrument is a duplicate of servers_cache and has been removed.

Applications that use the old or removed instrument names should be adjusted to account for this

change.

• Several instruments were given a value in the DOCUMENTATION column (it is no longer NULL),

improving runtime instrumentation documentation availability.

169

MySQL 8.0 Release Notes

(WL #14079)

Pluggable Authentication

• The new caching_sha2_password_digest_rounds system variable enables configuring the

number of hash rounds used by the caching_sha2_password authentication plugin for password

storage. (WL #14281)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.1.1k. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/vulnerabilities.html. (Bug

#32680637)

Spatial Data Support

• The new ST_LineInterpolatePoint() and ST_LineInterpolatePoints() functions return

a single point or multiple points interpolated between the start point and endpoint of a LineString

geometry. The new ST_PointAtDistance() function returns a single point a given distance along a

LineString geometry. See Spatial Operator Functions.

The new ST_Collect() aggregate function takes multiple geometry arguments and produces from

them a single geometry collection value. See Spatial Aggregate Functions

The CAST() and CONVERT() functions have been extended to support casting geometry values from

one spatial type to another. See Cast Functions and Operators. (WL #13454, WL #14160, WL #14161,

WL #14178, WL #14127)

Functionality Added or Changed

• InnoDB: The AUTOEXTEND_SIZE maximum setting was increased from 64M to 4GB. The

AUTOEXTEND_SIZE option, introduced in MySQL 8.0.23, defines the amount by which InnoDB extends

the size of a tablespace when it becomes full. The option is supported with the CREATE TABLE, ALTER

TABLE, CREATE TABLESPACE, and ALTER TABLESPACE statements. For more information, see

Tablespace AUTOEXTEND_SIZE Configuration. (Bug #32438606)

• Group Replication: It is now possible to use START REPLICA SQL_THREAD and STOP REPLICA

SQL_THREAD statements for the group_replication_applier channel when Group Replication is

stopped. This enables an operator to apply any remaining unapplied transactions on a server that left the

group, without having to rejoin the server to the group. (Bug #32027612, Bug #32414767)

• Group Replication: Group Replication’s allowlist of hosts from which an incoming Group

Communication System connection can be accepted, can now be updated while Group

Replication is still running. You can therefore add new members to a group controlled by an

allowlist without needing to stop and restart Group Replication. The allowlist is specified by the

group_replication_ip_allowlist system variable on each group member. (WL #14563)

• Microsoft Windows: The /RTC1 compiler flag was removed from the debug compiler flags to reduce

the time needed to run all tests invoked by the mysql-test-run.pl script when using MSVC on

Windows. Initially, this compiler flag was introduced with the CMake program (by default for debug

builds) and it generated code to test for stack corruption around function calls and the use of uninitialized

variables at runtime. No loss of bug discovery is expected with the removal of the /RTC1 compiler flag.

Memory errors, such as stack corruption, are more likely to be found by Address Sanitizer (ASAN)

testing and the use of uninitialized variables are detected by compiler warnings. (Bug #32525732)

170

MySQL 8.0 Release Notes

• Microsoft Windows: The named_pipe_full_access_group system variable now defaults to an

empty string (''), making named pipe connections secure. Previously, '*everyone*' was the default

value. A valid Windows local group name may be substituted. (WL #12671)

• The new clone_donor_timeout_after_network_failure Clone plugin variable defines the

amount of time the donor allows for the recipient to reconnect and restart a cloning operation following a

network failure. The timeout was previously fixed at 5 minutes. The timeout can now be extended up to

30 minutes to provide more time for network issues to be resolved.

Thanks to Daniël van Eeden for the contribution. (Bug #32335434, Bug #102103)

• Client applications and test suite plugins now report utf8mb3 rather than utf8 when writing character

set names. (Bug #32164079, Bug #32164125)

• The --skip-slave-start command line parameter is used to prevent the replication I/O thread

and replication SQL thread from starting when a replica server restarts. However, using the parameter

on the command line or in a my.cnf option file might require login access to the server host. The

skip_slave_start system variable is now provided to give access to this feature using MySQL

Server’s privilege structure, so that database administrators do not need any privileged access

to the operating system. The new global system variable is read-only and can be set using a SET

PERSIST_ONLY statement. As a system variable, its value can also be queried from a MySQL client and

used by MySQL APIs. The --skip-slave-start command line parameter can still be used as an

alternative, and it sets the new global system variable. (WL #14450)

Bugs Fixed

• Important Note: When a utf8mb3 collation was specified in a CREATE TABLE statement, SHOW

CREATE TABLE, DEFAULT CHARSET, the values of system variables containing character set names,

and the binary log all subsequently displayed the character set as utf8 which is becoming a synonym

for utf8mb4. Now in such cases, utf8mb3 is shown instead, and CREATE TABLE raises the warning

'collation_name' is a collation of the deprecated character set UTF8MB3.

Please consider using UTF8MB4 with an appropriate collation instead. (Bug

#27225287, Bug #32085357, Bug #32122844)

References: See also: Bug #30624990.

• InnoDB: Stale pages encountered by the buf_page_create() function were freed and then read from

disk again without being reinitialized. (Bug #32622548)

• InnoDB: C++ enum type values in buffer pool page and buffer pool block data structures in the

InnoDB source code were changed from int to uint8_t in MySQL 8.0.23, causing the data to

be printed as ascii characters instead of integers in different outputs including messages and

INFORMATION_SCHEMA tables.

The function that populates the INNODB_BUFFER_PAGE_LRU table did not print the IO_PIN state for the

IO_FIX field. (Bug #32575469)

• InnoDB: The btr_pcur_t::copy_stored_position function, which copies the position of one

index tree persistent cursor to another, performed unnecessary free and malloc calls. (Bug #32574835)

• InnoDB: A function that checks for locks on a table tried to acquire an exclusive lock system

(lock_sys) latch, causing long semaphore waits. (Bug #32545030)

• InnoDB: Counting temporary tablespaces as open files caused the innodb_open_files limit to be

exceeded, preventing other files from being opened. Temporary tablespaces are now ignored when

counting open files. (Bug #32541241)

171

MySQL 8.0 Release Notes

• InnoDB: The buf_flush_ready_for_flush() function identified a stale page as ready to flush

without first checking if the page was dirty or I/O fixed, causing an assertion failure. (Bug #32530147)

• InnoDB: Rollback of a transaction that modified generated columns raised an assertion failure. The

failure occurred when attempting to free space occupied by externally stored columns. The update

vector containing the externally stored columns did not account for the generated columns. (Bug

#32529561)

• InnoDB: When starting the server with innodb_validate_tablespace_paths disabled, user-

created undo tablespaces, which are temporarily set to inactive during the initial stages of the startup

process, were not reactivated. (Bug #32493885)

• InnoDB: Disabling innodb_extend_and_initialize, which causes InnoDB to use fallocate()

when allocating space to tablespace files, caused a performance regression for insert-oriented

workloads. (Bug #32437020)

• InnoDB: An unnecessary full flush list scan was removed, improving the speed with which session

temporary tablespaces are created. Previously, depending on the size of the buffer pool and the

number of dirty pages, creation of session temporary tablespaces could take a long time, affecting write

transaction performance. (Bug #32423860)

• InnoDB: A function that checks if a given page type is valid raised an assertion when testing valid but

undefined page type for an undo tablespace. (Bug #32366301)

• InnoDB: Sharded read-write lock function instrumentation was improved. (Bug #32333168)

• InnoDB: On Windows, when creating a table with the COMPRESSION option, InnoDB failed to check the

error status of a system call before checking the punch hole support flag set by the same system call,

which resulted in reading an uninitialized flag. (Bug #32322645)

• InnoDB: Geometry columns created in MySQL 5.6 caused failure when restarting the server after

upgrading from MySQL 5.7 to MySQL 8.0 due to a geometry type change introduced in MySQL 5.7.

(Bug #32299738)

• InnoDB: During recovery, log records for multiple record group mini transactions were parsed twice.

The log record from the first parsing operation is now saved to avoid the second pass, which improves

recovery performance.

Thanks to Zhai Weixiang for the contribution. (Bug #32293797, Bug #102010)

• InnoDB: In debug builds, an end range condition check for a secondary index raised an assertion

failure, and Valgrind testing uncovered an end range condition check for secondary index on a virtual

column that read an uninitialized value. (Bug #32291506)

• InnoDB: With the innodb_log_writer_threads variable disabled, extensive log writing by one

thread could block log flushing opportunities for other threads. (Bug #32255538)

• InnoDB: In SHOW ENGINE INNODB STATUS deadlock information, in cases where a single rw-lock

reader thread holds a shared latch, the reader thread id was not printed. (Bug #32252477)

• InnoDB: Running concurrent SHOW CREATE TABLE and ALTER TABLE operations on the same table

raised an assertion failure. The SHOW CREATE TABLE thread referenced a tablespace object that had

been made stale by the ALTER TABLE operation. (Bug #32235621)

• InnoDB: The introduction of sharded rw_lock_stats counters in MySQL 5.7 caused a regression

in CPU cache efficiency. To address this issue in MySQL 5.7, the sharding method was changed. For

optimal performance, the rw_lock_stats counter is removed in MySQL 8.0. (Bug #32225367)

172

MySQL 8.0 Release Notes

• InnoDB: On Windows, stalls were caused by concurrent SELECT COUNT(*) queries where the number

of parallel read threads exceeded the number of machine cores. (Bug #32224707, Bug #101789)

• InnoDB: An IS_STALE column, which indicates whether a buffer pool page is stale, was added to the

INFORMATION_SCHEMA.INNODB_BUFFER_PAGE table. (Bug #32194434)

• InnoDB: In debug builds, the log_free_check() function in the redo log code, which ensures

that there is available space in the logs when holding latches on dirty pages, now uses a list of mini-

transactions opened by the current thread to search for potential constraint violations. (Bug #32189367)

• InnoDB: During a slow shutdown on a system with a 64k InnoDB page size and

innodb_max_undo_log_size setting that was less than the initial undo tablespace size, the two undo

tablespaces were truncated in an endless loop. Undo tablespace truncation is now restricted to undo

tablespaces that are larger than the initial undo tablespace size and the innodb_max_undo_log_size

setting.

The function that retrieves the next redo rollback segment for an undo tablespace was modified to

ensure that undo logs are evenly split between two active undo tablespaces when an inactive tablespace

is found. (Bug #32173457)

• InnoDB: Starting the server in upgrade mode following an unexpected stoppage while the undo_001

undo tablespace was being truncated caused failure. When upgrade processing was completed

and shutdown initiated, the function that determines if undo truncation is required could not find the

undo_001 undo tablespace. To address this issue, undo tablespace truncation is no longer performed

when starting the server in upgrade mode. (Bug #32127912)

• InnoDB: A delete operation on a parent table that initiated a cascading update on a child table with an

indexed virtual column and indexed foreign key constraint column caused a virtual column corruption.

(Bug #32124113)

• InnoDB: The open and close sequence for table share instances (m_share objects) and dictionary table

instances was modified to prevent accessing old m_share objects that could point to stale dictionary

indexes.

Thanks to Yuxiang Jiang for the contribution. (Bug #31899685)

• InnoDB: An debug assertion failure occurred when issuing a TRUNCATE TABLE operation after a

successful server restart following a server initialization failure. (Bug #31763837)

• InnoDB: A fast shutdown (innodb_fast_shutdown=0) raised an assertion failure. The assertion code

checks for transactions in the transaction list (mysql_trx_list) before halting purge operations. The

check occurred before shutting down the GTID persister background thread, which was still inserting

transactions into the transaction list. (Bug #31693627)

• InnoDB: Undo tablespace truncation error handling was improved, and a Windows-specific InnoDB file

deletion procedure was made more POSIX-compatible. (Bug #31684783)

• InnoDB: An online ALTER TABLE operation failed with an Incorrect key file for table error

due to an unnecessary encryption status check that was performed when reading online DDL row logs.

(Bug #31529221, Bug #99938)

• InnoDB: Initializing the server with an with a 4K InnoDB page size caused “key too long” errors to be

written to the error log. (Bug #31496943, Bug #99892)

• InnoDB: A table created with a reserved name caused a failure. (Bug #31382599)

• InnoDB: Creating an index on virtual columns raised an invalid debug assertion failure. (Bug

#31279528, Bug #99421, Bug #27168185)

173

MySQL 8.0 Release Notes

• InnoDB: In debug mode, the buf_pool_validate_instance() function accessed the

buf_page_t::io_fix field without properly synchronizing with a thread that was modifying the same

field in the buf_page_io_complete() function, causing an assertion failure. In addition to correcting

that issue, the buf_page_get_io_fix_unlocked() function was replaced by several specific

functions that test the buf_page_t::io_fix field for particular values. A series of other small, related

code changes were also implemented. (Bug #31027553)

• InnoDB: The TempTable memory allocator did not track RAM consumption when allocating blocks

of memory shared by different queries for a given session, which could result in nonadherence to the

temptable_max_ram limit. (Bug #29890126)

• Partitioning: In some cases, invalid PARTITION clauses were not handled correctly in ALTER TABLE

statements. (Bug #32235085)

• Replication: With row-based replication in use (binlog_format=ROW), stored generated columns

that existed only on the replica were not being updated when the other fields in the row were inserted or

updated. These columns are now evaluated when the row image is unpacked, and their value is updated

in the row image before it is applied. (Bug #32292413, Bug #101978)

• Replication: Binary log transaction compression could not continue if a row event included a BLOB

column containing uncompressable data, and the compressed size of the row event was higher than its

uncompressed size. The function now handles the additional post-compression bytes correctly. (Bug

#32174715, Bug #101611)

• Replication: If all previous binary log files were purged at startup because their retention period had

expired, the new binary log file contained an empty Previous_gtids event, which could cause errors

in replication. The order of initialization has now been changed so that previous binary log files are only

purged after the previous GTID set has been written to the new binary log file that is created at startup.

(Bug #32134875, Bug #101533)

• Replication: When MySQL Server counted the number of GTIDs in a set, it was possible for the return

value to wrap, returning an incorrect result. This could lead to an incorrect decision to use state transfer

from the binary log for Group Replication distributed recovery, when a remote cloning operation would

have been more efficient. The logic has now been corrected. (Bug #32086209)

• Replication: An assertion was raised in debug builds relating to lost GTIDs if binary log files were

removed at startup because their retention period had expired. (Bug #32008512, Bug #101137)

• Replication: The sql_slave_skip_counter system variable, which is used to make a replica skip

a specified number of transactions, ignored transaction payloads that had been compressed using

binary log transaction compression (activated using the binlog_transaction_compression system

variable). Only events in uncompressed transaction payloads were counted towards the total skipped.

(Bug #31973055)

• Replication: A deadlock could occur if the binary log file was rotated while system variables were being

updated and read by different clients. (Bug #31774422)

• Replication: The output of a SHOW PROCESSLIST statement for a replica’s SQL thread sometimes

showed the last query as currently being applied when the replica was actually caught up. (Bug

#30521198, Bug #97560)

• Group Replication: A race condition could occur if a STOP GROUP_REPLICATION statement was used

to stop a group member, while the Performance Schema statistics for Group Replication were being

queried by another client. Group Replication now prevents STOP GROUP_REPLICATION statements and

Performance Schema queries from running concurrently. (Bug #32100147)

• Microsoft Windows: Running MySQL Server (64-bit) on a Windows system with more than 32

logical processors and setting the VCPU attribute of a resource group to greater than 30 produced

174

MySQL 8.0 Release Notes

an incorrect CPU mask value, which is used to set the thread affinity. Under these conditions,

the MSVC compiler reported warnings that the 32-bit shift was converted implicitly to 64-bit in the

thread_attrs_api_win.cc file. The conversion resulted in the wrong CPU mask calculation on

systems that have more than 32 logical processors. This fix ensures that a 64-bit shift is used when

calculating the CPU mask by replacing argument 1 of the shift with 1LL. (Bug #32079726)

• JSON: The IF() function sometimes hit an assertion in debug builds when an error was raised from its

first argument; this also could occur under similar circumstances with the additional condition that the

function's return type was JSON. (Bug #32231393, Bug #32231620)

• JSON: A number of JSON functions did not propagate errors correctly, which could lead to assert

failures in debug builds. (Bug #32047630)

• JSON: JSON_TABLE() inside triggers was sometimes handled incorrectly when re-used in different

sessions. Fixed by ensuring that JSON_TABLE() and its temporary table are processed in the context of

the current session. (Bug #31644193)

• JSON: A multi-valued index defined on an expression that cast a column into a typed array was not

used for speeding up queries. This was because the server, when substituting an expression with

an equivalent indexed generated column, did not attempt to replace a reference to a column with a

reference to an equivalent generated column; for multi-valued indexes, it makes sense to replace the

column reference with a reference to a generated column backing a multi-valued index on an expression

that cast that column into a typed array.

This fix lifts the restriction that the server attempts to substitute only function expressions and conditional

expressions with indexed generated columns, by allowing substitution of column references when they

appear in a context where they can make use of a multi-valued index, that is, when they are used as

arguments to MEMBER OF(), JSON_CONTAINS(), or JSON_OVERLAPS(). The restriction remains in

force for cases in which the column reference is used in a non-array context. (Bug #30838807)

• JSON: The JSON_SEARCH() function interpreted all search string and path values as utf8mb4 strings,

regardless of their actual encoding, which could lead to wrong results. (Bug #102443, Bug #32443143)

• JSON: In some cases, when used in a left join, some MySQL JSON functions caused the optimizer to

transform it into an inner join, even though the inner join was not equivalent to the original left join. This

was due to the fact that they return a value which is not NULL, even though one of their arguments is

NULL, and the optimizer expected them to return NULL on NULL input.

Functions affected by this issue included JSON_ARRAY(), JSON_OBJECT(), JSON_ARRAY_APPEND(),

JSON_ARRAY_INSERT(), JSON_INSERT(), JSON_REPLACE(), and JSON_SET(). See JSON

Functions, for more information about these functions. (Bug #101861, Bug #32248705)

• Community packages for generic Linux were not built with the necessary LDAP/SASL/Kerberos

dependencies, and did not bundle the associated required libraries. (Bug #32619858)

• The functions BIT_AND(), BIT_OR(), BIT_XOR(), and JSON_ARRAYAGG() did not always provide

proper error handling. (Bug #32594813)

• The server did not always provide proper error messages when IN was incorrectly used with UNION.

(Bug #32593846)

• It was possible for casting from DECIMAL to a signed integer type to hit an assertion when the result had

more digits than the metadata in Item_typecast_signed indicated it would have. This happened

because the decimal value is rounded when converted to an integer, and Item_typecast_signed did

not take into account that the rounding might increase the number of digits in what was the integer part

of the decimal value, such as when rounding 9.9 up to 10.

175

MySQL 8.0 Release Notes

This is fixed by removing the logic that tried to compute a minimal maximum length for the result of

the cast, and instead using the default set by the parent class Item_int_func. That default is the

maximum width of a 64-bit integer, which should be safe regardless of the input value. (Bug #32591589)

References: This issue is a regression of: Bug #32371039.

• The name my_row_id was not permitted for invisible columns. This restriction has been lifted. (Bug

#32586231)

• On a system with many concurrent connections, execution of grant statements could take excessively

long waiting for metadata locks, causing the server to become unresponsive. (Bug #32483597)

• Windows binaries and libraries were not being properly signed. (Bug #32458533)

• Privilege checks for INFORMATION_SCHEMA tables could fail to take the lower_case_table_names

value into account. (Bug #32448364)

• LIKE ... ESCAPE, where ESCAPE did not reference a constant value, was not handled correctly within

a prepared statement. (Bug #32446728)

• MySQL has traditionally interpreted an empty value in the ESCAPE clause (that is, ESCAPE '') for

LIKE as “no escape character”. Problems could arise when either of the first two arguments to LIKE

was a string using a multibyte character set, because the empty value in such cases was interpreted

as meaning that the backslash (\) should be used as the escape character, breaking the expected

behavior.

This fix causes LIKE to interpret ESCAPE '' as meaning that there is no escape character regardless of

character set, restoring the previous, expected behavior.

In addition, we now raise an error if the specified escape character cannot be converted to the target

character set. This supersedes the original behavior in such cases, which was to fall back silently to

using the backslash as the escape character. (Bug #32446508)

• Windows packages were subject to an OpenSSL vulnerability. (Bug #32431519)

• Loadable function arguments containing window functions or subqueries could produce unexpected

results. (Bug #32424455)

• Improper handling of temporary tables used for cursors within stored procedures could result in

unexpected server behavior. (Bug #32416811)

• Use of the symbol TRUE in the source resulted in a build failure on some platforms. This was replaced by

true. (Bug #32406197, Bug #102308)

• The privilege check used to determine whether users can see view definitions in the

INFORMATION_SCHEMA.VIEWS table worked incorrectly. (Bug #32405811)

• For recursive common table expressions, an assertion could be raised if it became necessary to convert

an in-memory temporary table to on-disk. (Bug #32404597)

• A prepared statement employing a user-created function was not handled correctly when the function

took no arguments. (Bug #32404542)

• A clone plugin installation failure could cause subsequent installation attempts to fail. (Bug #32402158,

Bug #102240)

• Some internal functions used with temporal column types did not provide proper handling for YEAR

values. (Bug #32395335)

176

MySQL 8.0 Release Notes

• The internal constants MAX_FLOAT_STR_LENGTH = 12 and MAX_DOUBLE_STR_LENGTH = 22 represent

the maximum lengths of strings representing FLOAT and DOUBLE values, respectively. The heuristic

employed by the conversion routine my_gcvt for determining whether to use scientific notation

sometimes generated strings that were longer than these.

These long strings caused problems for some string conversion routines, since their actual lengths could

exceed the expected maximums. We fix this by explicitly telling my_gcvt the desired length whenever

we fetch a FLOAT or DOUBLE in a string context. (Bug #32385934)

• Within triggers, use of RAND() with no arguments could lead to unexpected server behavior. (Bug

#32372805)

• When an Item_cache object was used in a prepared statement or stored procedure, it might point to a

Field object that was used in a previous execution. We solve this issue by replacing the cached field

member with an Item_field, which is persistent for the lifetime of the procedure. (Bug #32367019)

• A missing tablespace error was reported on the recipient MySQL server instance after a remote cloning

operation. The tablespace was not cloned due to the innodb_validate_tablespace_paths

variable being disabled on the donor instance, which resulted in the associated tablespace object not

being loaded. A check is now performed before a cloning operation to ensure that all tablespace objects

are loaded. (Bug #32354908, Bug #102137)

• Some query blocks containing large numbers of EXISTS subqueries were not always handled correctly.

(Bug #32343143)

• mysqlpump could exit unexpectedly if a SHOW CREATE TABLE statement failed. (Bug #32340208)

• A long running remote cloning operation failed due to a low wait_timeout setting on the donor MySQL

Server instance. Donor threads use the MySQL Server wait_timeout setting when listening for Clone

protocol commands. To avoid timeout failures on donor instances with a low wait_timeout setting, the

Clone idle timeout is now set to the default wait_timeout setting, which is 28800 seconds (8 hours).

Clone network read and write timeout values were also increased. (Bug #32340112, Bug #102097)

• Replication threads running in the server were visible in the Performance Schema threads table, but

failed to appear in the variables_by_thread or status_by_thread tables. Now they appear in all

three tables. Thanks to Facebook for the contribution. (Bug #32335496, Bug #102115)

• A query string was displayed before it had been rewritten. (Bug #32335263, Bug #32628376)

• For builds compiled using the libedit library, if the mysql client was invoked with the --default-

character-set=utf8 option, libedit rejected input of multibyte characters. (Bug #32329078, Bug

#32583436, Bug #102806)

• On Windows, large result sets could cause the mysql client to exit unexpectedly. (Bug #32316323, Bug

#102051)

• Preparing a query expression for repeated execution could raise an assertion if an error occurred during

preparation. (Bug #32291841)

• Functional index creation did not handle the column name as not case-sensitive. (Bug #32287186, Bug

#101994)

• Temporary tables bound to triggers during statement execution could cause an unexpected server exit.

(Bug #32267749, Bug #32288089, Bug #32299045)

• Improved NULL and error handling in calculations involving decimal values. (Bug #32258228, Bug

#32497850)

177

MySQL 8.0 Release Notes

• An assertion was raised if there was an open handler to a table in a schema when the schema was

altered to be read only. (Bug #32248313)

• Selecting from the Performance Schema replication_group_members table in some cases raised

Error 1267 Illegal mix of collations .... This was due to a change in MySQL 8.0.22 in the

handling of comparisons between a column value and a system variable. (Bug #32244631)

References: See also: Bug #32501472, Bug #32579184.

• MySQL produced invalid metadata for a number of temporal functions returning integer values. These

functions included TO_DAYS(), PERIOD_DIFF(), PERIOD_ADD(), TO_SECONDS(), DAYOFMONTH(),

DAYOFYEAR(), HOUR(), and MINUTE(), among others. (Bug #32239578)

• Table subqueries of a natural join which retrieved only invisible columns were not handled correctly.

(Bug #32235285)

• For debug builds, using ALTER TABLE to set a column to have a DEFAULT value of TRUE raised an

assertion. (Bug #32235058)

• When an error was raised while evaluating a condition that was pushed down to the storage engine

using index condition pushdown, the storage engine sometimes ignored the error and returned an error

code indicating success, which could lead to assertion failures later.

Now in such cases, we make sure that the executor detects that an error has been raised, and stop

execution at that point. (Bug #32234773)

• For debug builds with binary logging disabled, ALTER TABLE ... MODIFY COLUMN with an invalid

DEFAULT value raised an assertion. (Bug #32234194)

• Preparation of an aggregate function sometimes hit an assertion in debug builds when the function took

a constant scalar subquery as argument and the scalar subquery raised an error. (Bug #32231698)

• For debug builds, improper character set handling for NULLIF() evaluated in aggregate context raised

an assertion. (Bug #32231557)

• A CREATE TABLE statement with an unsupported KEY_BLOCK_SIZE value raised an assertion. (Bug

#32227101)

• Upgrading a MySQL instance with a very large number of tables consumed an excessive amount of

memory. Memory allocated to analyze data dictionary entities for possible upgrade was not released

until all entities were processed. (Bug #32226180, Bug #101818)

• ANALYZE TABLE executed on a table concurrently with a long-running query on the same table caused

subsequent queries on the table to wait for the long-running query to finish. This wait induced by

ANALYZE TABLE is now eliminated, thus allowing the subsequent queries to execute with no wait. (Bug

#32224917)

• Statements using a LIKE expression with an ESCAPE clause were not always handled correctly. (Bug

#32213959)

• On ARM platforms, an assertion could be raised in utilities used during the build process. (Bug

#32209415)

• InnoDB did not always handle some legal names for table partitions correctly. (Bug #32208630)

• With the explicit_defaults_for_timestamp variable disabled, Clone plugin installation failed with

PFS table creation error. The variable setting caused TIMESTAMP columns in the Clone Performance

Schema tables to be created incorrectly as NOT NULL columns. (Bug #32199611)

178

MySQL 8.0 Release Notes

• SHOW CREATE VIEW produced invalid syntax for views created with a ROLLUP clause. This issue also

affected mysqldump, which uses SHOW CREATE VIEW. (Bug #32197353, Bug #101740)

• A failed CREATE TABLE or ALTER TABLE with SECONDARY_ENGINE_ATTRIBUTE could leak memory.

(Bug #32187507)

• Connection establishment failure could cause the server to count the number of open connections

incorrectly. (Bug #32156518)

• Refactoring work done in MySQL 8.0.19 did not handle left joins correctly on columns using functions

such as IFNULL(). (Bug #32141711)

References: This issue is a regression of: Bug #30320525.

• The optimizer could choose to use a Skip Scan even for backward index scans for which it is

inapplicable, resulting in unpredictable server behavior. (Bug #32127290)

• SHOW CREATE USER caused any pending transaction to commit. (Bug #32123671)

• Loadable function arguments containing window functions were evaluated at prepare time despite

the fact that window functions are set up quite late in the prepare process. Now evaluation of these

is delayed until execution time, similarly to how this is performed with respect to loadable function

arguments containing subqueries. (Bug #32122078, Bug #32393265)

• Creating a table containing a column with a nonconstant default expression caused subsequent ALTER

TABLE statements to fail. (Bug #32121425, Bug #101486)

• Updating a BLOB-like column with a value from a larger BLOB-like column could cause the updated

column to have the wrong size, even zero. (Bug #32112403)

• Improper locking on an internal queue could cause mysqlpump to exit unexpectedly. (Bug #32067013)

• On MacOS, the preference pane now includes an option to load the configured my.cnf file during

initialization. (Bug #32057159)

• The server did not always prepare correctly a statement using GROUP_CONCAT() on a SELECT with an

ORDER BY clause. (Bug #32053547, Bug #31947466)

• The sys schema create_synonym_db() procedure fail to create INFORMATION_SCHEMA synonyms.

(Bug #32050275, Bug #101258)

• Errors occurring in window functions were not always correctly propagated, which could lead to assertion

failures in debug builds. (Bug #32028154)

• Calling XA COMMIT on a transaction started by another thread could result in Address Sanitizer

warnings. (Bug #32025408)

• When the mysql client was used in batch mode, its parser could be confused by USE followed by DROP

DATABASE when the USE database name was quoted. (Bug #32015466, Bug #101124)

• A change in MySQL 8.0.17 caused comp_err to become much slower. Normal performance has been

restored. (Bug #32014733)

References: This issue is a regression of: Bug #29781631, Bug #95377.

• Using CAST() on a DATE or DATETIME value in an INSERT statement raised a warning for

"0000-00-00" and "2000-02-31", but not for "2000-01-00" or "2000-00-01". Now a warning is

shown in each of these cases also. (Bug #32013612)

179

MySQL 8.0 Release Notes

• The maximum length of the MASTER_COMPRESSION_ALGORITHMS value for the CHANGE MASTER TO

statement was checked incorrectly. (Bug #32008597)

• When casting a dynamic parameter to YEAR (such as in PREPARE s FROM "SELECT CAST(? AS

YEAR)"), type propagation was not preformed, causing execution of the prepared statement in which the

parameter was used to fail. (Bug #32002844)

• Definitions of some system tables for a MySQL 5.7 instance upgraded to MySQL 8.0 differed from the

definitions of the system tables in a new MySQL 8.0 installation. (Bug #31989290)

• Some SHOW statements using subqueries could result in unexpected server behavior. (Bug #31853180)

• A query using GROUP BY column HAVING column_expression IS [NOT] NULL returned correct

results, but when WITH ROLLUP was added did not. (Bug #31848191)

• The SHOW ENGINE PERFORMANCE SCHEMA STATUS statement reported incorrect memory usage for

the Performance Schema. (Bug #31795132, Bug #100624)

• When trying to generate an entity data model using Visual Studio 2019, some tables could not be

imported with the entity framework wizard. This was due to a change in MySQL 8.0.21 made to

orthogonal data type aggregation, which handles columns from UNION and from functions or operators

such as CASE and IF(). This makes it possible to return a value of type ENUM or SET, which did not

need to be handled previously in such cases. (Bug #31750645)

References: See also: Bug #29698617.

• While optimizing the ORDER BY clause of a subquery there was a possibility of cleaning up a subquery

tree referenced in the outer SELECT, which could lead to a premature exit. (Bug #31721430)

• A malformed name in the mysql.func system table could cause unexpected server behavior. (Bug

#31674599)

• LOAD DATA performance degraded if many long rows were loaded. (Bug #31637142)

• Sessions could disable their own auditing. (Bug #31630954)

• Compiler options for using profile guided optimization with GCC were improved to include -fprofile-

partial-training and -fprofile-update=prefer-atomic when appropriate. Thanks to Dmitriy

Philimonov for the suggestion. (Bug #31450064, Bug #99781)

• Starting the server with the performance_schema_max_thread_classes and

performance_schema_max_thread_instances system variables set to zero caused MySQL

Enterprise Firewall to be unable to create new rules. (Bug #31335080, Bug #24947654, Bug #83519)

• A null pointer was incremented during recovery from the redo log, causing a runtime error in an

Undefined Behavior Sanitizer (UBSAN) build. (Bug #31173032, Bug #32428131, Bug #32483976)

• With the log_slow_extra system variable enabled to add the Errno field to slow query log output, the

error number was 0 even for failed statements. (Bug #30769965, Bug #98220)

• On debug builds, certain conversion operations using the utf32 character set could cause unexpected

server behavior. (Bug #30746908)

• SELECT ... FOR UPDATE from a nonexistent Performance Schema table produced

ER_TABLEACCESS_DENIED_ERROR rather than ER_NO_SUCH_TABLE. (Bug #30701047, Bug #98068)

• Mishandling of stored program local variables could lead to unexpected server behavior. (Bug

#30366310)

180

MySQL 8.0 Release Notes

• The Performance Schema metadata_locks table could show incorrect DURATION values, such as

when a metadata lock taken for a TRANSACTION duration was later modified to EXPLICIT duration by a

RENAME TABLE operation. (Bug #30065213, Bug #96237)

• The audit_log plugin could fail to store its encryption password if it generated one at startup. (Bug

#29559793)

• Uninstalling a plugin could affect subsequent execution of prepared statements. (Bug #29363867)

• Conversion of string-valued user-defined variables or function results to double (for example, using

CAST()) did not emit a warning when truncation occurred. (Bug #27969934, Bug #21943299)

• When a view definition used LIKE with an ESCAPE clause, the contents of the ESCAPE clause were

ignored, leading to wrong results. (Bug #26086751)

• It was possible to insert illegal ASCII values (outside 7-bit range) into character columns that used the

ascii character set. This is now prohibited. (Bug #24847620)

• To enable use of spaces and other special characters within configuration values,

mysql_config_editor now surrounds values it writes to the configuration file with double quote

characters, and also escapes double quote characters used within values. (Bug #19953349, Bug

#74691)

• When the aggregate iterator finds no rows, it calls on each item in its SELECT list to inform them of this

(for example, so that COUNT(*) can set itself to zero, or SUM(foo) can set itself to NULL). After internal

work done in MySQL 8.0.22, it could also inadvertently call hidden items. In some queries with doubly

nested subqueries, one such hidden item could become its own parent subquery (and scalar subqueries

in MySQL have special legacy handling of this call, for queries which are not ONLY_FULL_GROUP_BY),

causing the entire subquery to return NULL when it should not have done so.

This is fixed by making the call only on visible items, as in MySQL 8.0.21 and earlier. (Bug #102101, Bug

#32335256)

• When interpreting the old-style plan to access paths, cache invalidators for LATERAL were delayed until

all outer joins were completed, since outer joins could produce null-complemented rows that should

also invalidate caches. Problems arose when an outer join contained a LATERAL, and that LATERAL

referred only to tables from within the same outer join; in such cases the invalidator should be applied

immediately and not delayed, lest we miss emitted rows, and the cache be incorrectly kept. In particular,

this could happen when certain Information Schema tables were on the right side of an outer join, as

these are now views defined using LATERAL.

We fix this by delaying emission of the invalidator until we are inside the same (outer) join nest as the

materialization to be invalidated, but no further. This also deals correctly with the case where rows from

a table should invalidate two or more separate materializations, where some are within the join and

some are higher up. (Bug #101460, Bug #32113029, Bug #32311147)

References: This issue is a regression of: Bug #98238, Bug #30766181.

• An optimizer trace printed floating-point numbers with a maximum six characters, which meant that the

precision could be very low for many values, given that sign, decimal point, and exponent could use

many of these characters. This was especially problematic for large numbers, whose precision could

181

MySQL 8.0 Release Notes

thus be as small as 1, and which could be rounded to values whose absolute value exceeded DBL_MAX

and so could be rejected by JSON parsers.

Now such numbers are always printed in an optimizer trace with a precision of 6. (Bug #101457, Bug

#32113020)

References: See also: Bug #94672, Bug #29493604.

• Filesort was used for a query having an ORDER BY ... DESC clause, even when an index on the

descending column was available and used. This happened because an ORDER BY sub-clause was

not removed due to matching a field in an equality predicate, even though it should have, so that the

optimizer did not match the query with the descending index, leading to suboptimal performance. (Bug

#101220, Bug #32038406)

• The debug server hit an assert when optimizer_search_depth was less than the number of

JOIN_TAB structures used for a join. (Bug #100288, Bug #31655483)

• Following the ALTER TABLE operations EXCHANGE PARTITION, IMPORT TABLESPACE, and IMPORT

PARTITION TABLESPACE, serialized digital information reflecting the previous role of the tablespace

was left behind. Now in such cases, the old SDI is explicitly removed from both tablespaces involved in

the exchange or import of a tablespace. (Bug #98501, Bug #30878065)

• Type resolution performed by the integer division operator (DIV) yielded a precision of one less than

expected in the result.

Our thanks to Kaiwang Chen for the contribution. (Bug #96459, Bug #30156563)

Changes in MySQL 8.0.23 (2021-01-18, General Availability)

This release adds support for macOS 11 (Big Sur).

• Account Management Notes

• C API Notes

• Compilation Notes

• Connection Management Notes

• Deprecation and Removal Notes

• Firewall Notes

• Optimizer Notes

• Performance Schema Notes

• Pluggable Authentication

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

182

MySQL 8.0 Release Notes

Account Management Notes

• Granting the RELOAD privilege enables a user to perform a wide variety of operations. In some cases,

it may be desirable for a user to be able to perform only some of these operations. To enable DBAs to

avoid granting RELOAD and tailor user privileges more closely to the operations permitted, these new

privileges of more limited scope are available:

• FLUSH_OPTIMIZER_COSTS: Enables use of the FLUSH OPTIMIZER_COSTS statement.

• FLUSH_STATUS: Enables use of the FLUSH STATUS statement.

• FLUSH_TABLES: Enables use of the FLUSH TABLES statement.

• FLUSH_USER_RESOURCES: Enables use of the FLUSH USER_RESOURCES statement.

The new privileges apply only at the global level. For more information, see Privileges Provided by

MySQL, and FLUSH Statement.

The mysql_refresh() C API function performs operations similar to those of various FLUSH

statements, but is unaffected by this change. It still requires the RELOAD privilege regardless of the

operation for which it is invoked. (WL #14303)

C API Notes

• For some applications, it may be useful to define metadata on a per-query basis. Examples include the

URL of the page that produced a query, or extra processing information to be passed with a query for

use by a plugin such as an audit plugin or query rewrite plugin. MySQL now supports this capability

without the use of workarounds such as specially formatted comments included in query strings:

• On the client side, the mysql_bind_param() C API function enables defining query attributes.

These attributes apply to the next SQL statement sent to the server for execution. Additionally, the

mysql and mysqltest clients have a query_attributes command that enables defining query

attributes.

• On the server side, a component service provides access to query attributes. A component named

query_attributes uses this service to implement a mysql_query_attribute_string()

loadable function that enables obtaining attribute values within SQL statements. The

query_attributes component is optional but must be installed for the function to be available.

For more information, see Query Attributes.

Thanks to Facebook for suggesting the idea (and for contributing code, although it was not used). (Bug

#27855905, Bug #28686334, WL #12542)

Compilation Notes

• Thanks to Tzachi Zidenberg, who contributed a patch for compiling MySQL on aarch64 (ARM64). (Bug

#31815236, Bug #100664)

Connection Management Notes

• Selection of the account that matches incoming TCP client connections could be affected by account

creation order. To make the matching algorithm more deterministic, matching the host name part of

accounts now checks accounts specified using host IP addresses, in a specific order, before attempting

to match accounts specified using host names. Host name matching remains unchanged. See Access

Control, Stage 1: Connection Verification. (WL #14074)

183

MySQL 8.0 Release Notes

Deprecation and Removal Notes

• From MySQL 8.0.23, the statement CHANGE MASTER TO is deprecated. The alias CHANGE

REPLICATION SOURCE TO should be used instead. The parameters for the statement also have

aliases that replace the term MASTER with the term SOURCE. For example, MASTER_HOST and

MASTER_PORT can now be entered as SOURCE_HOST and SOURCE_PORT. The START REPLICA

| SLAVE statement’s parameters MASTER_LOG_POS and MASTER_LOG_FILE now have aliases

SOURCE_LOG_POS and SOURCE_LOG_FILE. The statements work in the same way as before, only the

terminology used for each statement has changed. A deprecation warning is issued if the old versions

are used.

A new status variable, Com_change_replication_source, has been added as an alias for the

Com_change_master status variable. Both the old and new version of the statement update both the

old and new version of the status variable.

The server rewrites all CHANGE MASTER TO statements as CHANGE REPLICATION SOURCE TO

statements in the query log. The same is done for the statements START SLAVE, STOP SLAVE, SHOW

SLAVE STATUS, SHOW SLAVE HOSTS and RESET SLAVE. The event name for the CHANGE MASTER

TO statement is set to statement/sql/change_replication_source in the statement history

table. (Bug #32145023, WL #14189)

• The gen_blacklist() user-defined function is deprecated. Use gen_blocklist() instead, which

performs the same term-replacement operation. (WL #14176)

• The use of the system variables master_info_repository and relay_log_info_repository

is now deprecated, and a warning message is issued if you attempt to set them or read their values.

The system variables will be removed in a future MySQL version. These system variables were used

to specify whether the replica’s connection metadata repository and applier metadata repository were

written to an InnoDB table in the mysql system database, or to a file in the data directory. The FILE

setting was already deprecated in a previous release, and tables are the default for the replication

metadata repositories in MySQL 8.0. (WL #13958)

• Flushing the host cache can be done using any of these methods:

• Execute a TRUNCATE TABLE statement that truncates the Performance Schema host_cache table.

This requires the DROP privilege for the table.

• Execute a FLUSH HOSTS statement. This requires the RELOAD privilege.

• Execute a mysqladmin flush-hosts command. This requires the RELOAD privilege.

Although those methods are equivalent in effect, granting the RELOAD privilege enables a number of

other operations in addition to host cache flushing, which is undesirable from a security standpoint.

Granting the DROP privilege for the host_cache table is preferable because it has a more limited scope.

Therefore, the FLUSH HOSTS statement is deprecated and will be removed in a future MySQL version.

Instead, truncate the host_cache table.

mysqladmin flush-hosts previously executed a FLUSH HOSTS statement. Now it attempts to

truncate the host_cache table, falling back to FLUSH HOSTS only if the truncate operation fails. (WL

#14329)

Firewall Notes

• Administrators perform MySQL Enterprise Firewall management by registering profiles that specify sets

of rules for permitted statements (allowlists). Previously, profiles could be associated only with individual

accounts, so that, to apply a given allowlist to multiple account profiles, it was necessary to duplicate the

184

MySQL 8.0 Release Notes

rule set for each profile. For easier administration and greater flexibility, the firewall now provides group

profile capabilities:

• Named group profiles can be created. A group profile can include multiple accounts as members, and

an account can be a member of multiple group profiles.

• Each group profile has its own allowlist. The profile allowlist applies to all member accounts,

eliminating the need to duplicate it across multiple account profiles.

For more information, see MySQL Enterprise Firewall. (WL #11740)

Optimizer Notes

• Switched the hash table used for hash joins from an unordered multimap to an unordered flat map

implemented with a multimap adapter. This change yields the following improvements:

• A faster hash table

• Less memory usage due to less hash table overhead, less space used for alignment and key/value

lengths, and better memory usage with many equal keys; this should also reduce the frequency at

which it is necessary to spill to disk

• Better memory control by approaching the allowed join buffer size more closely rather than being

effectively limited to approximately 2/3 of join_buffer_size, and by making it possible to free old

memory when the hash table grows

(Bug #99933, Bug #31516149, WL #13459)

Performance Schema Notes

• Performance Schema macros that previously expanded to dynamic calls now expand to static calls when

possible to reduce processing overhead. (Bug #32028160)

• Performance overhead of timer code was reduced. This should be of most benefit to workloads with high

concurrency using the Performance Schema. Thanks to Georgy Kirichenko for the contribution. (Bug

#31960377, Bug #101018)

Pluggable Authentication

• The MySQL Enterprise Edition SASL LDAP authentication plugin now supports SCRAM-SHA-256 as an

authentication method for MySQL clients and servers. SCRAM-SHA-256 is similar to SCRAM-SHA-1 but

is more secure. Use of SCRAM-SHA-256 requires an OpenLDAP server built using Cyrus SASL 2.1.27

or higher. See LDAP Authentication Methods. (WL #14180)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.1.1i. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/vulnerabilities.html. (Bug

#32260610)

Spatial Data Support

• The new ST_HausdorffDistance() and ST_FrechetDistance() functions return the discrete

Fréchet and Hausdorff distances between two geometries, reflecting how similar the geometries are.

See Spatial Relation Functions That Use Object Shapes. (WL #14128, WL #14129)

185

MySQL 8.0 Release Notes

SQL Syntax Notes

• MySQL now supports invisible columns, which normally are hidden to queries, but can be accessed if

explicitly referenced. See Invisible Columns. (WL #10905)

X Plugin Notes

• For X Protocol connections using the MYSQL41 authentication method, if the nonce sent by the server

was shorter than 20 bytes, the connection logic did not handle it correctly. (Bug #32036194)

• If a query that was building up a resultset was killed, X Plugin interpreted this as meaning the server

session had been killed, and dropped the connection. The status of a query is now checked separately

from the status of the server session. (Bug #31954296)

• A deadlock could occur if an X Protocol session attempted to display X Plugin status variables or

settings at the same time as another X Protocol session was being released and reset. The situation is

now handled appropriately. (Bug #31931873)

• If an X Protocol client with a connection to a server remains idle (not sending to the server) for

longer than the relevant X Plugin timeout setting (read, write, or wait timeout), X Plugin closes the

connection. In the case of a read timeout, the plugin returns a warning notice with the error code

ER_IO_READ_ERROR to the client application.

From MySQL 8.0.23, X Plugin now also sends a warning notice if a connection is actively closed due to

a server shutdown, or by the connection being killed from another client session. In the case of a server

shutdown, the warning notice is sent to all authenticated X Protocol clients with open connections, with

the ER_SERVER_SHUTDOWN error code. In the case of a killed connection, the warning notice is sent

to the relevant client with the ER_SESSION_WAS_KILLED error code, unless the connection was killed

during SQL execution, in which case a fatal error is returned with the ER_QUERY_INTERRUPTED error

code.

Client applications can use the warning notices to display to users, or to analyze the reason for

disconnection and decide whether to attempt reconnection to the same server, or to a different server.

(WL #14166)

• For classic MySQL protocol, if an SQL query is using metadata locking or the sleep function, the

connection to the server is checked periodically to verify that it is still alive. If not, the query can be

stopped so that it does not continue to consume resources. Previously, X Protocol did not carry out

these checks, and assumed that the connection was still alive. The check has now been added for X

Protocol. (WL #14167)

Functionality Added or Changed

• InnoDB: Performance was improved for the following operations:

• Dropping a large tablespace on a MySQL instance with a large buffer pool (>32GBs).

• Dropping a tablespace with a significant number of pages referenced from the adaptive hash index.

• Truncating temporary tablespaces.

The pages of dropped or truncated tablespaces and associated AHI entries are now removed from

the buffer pool passively as pages are encountered during normal operations. Previously, dropping or

truncating tablespaces initiated a full list scan to remove pages from the buffer pool immediately, which

negatively impacted performance. (Bug #31008942, Bug #98869, WL #14100)

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MySQL 8.0 Release Notes

• InnoDB: The new AUTOEXTEND_SIZE option defines the amount by which InnoDB extends the size

of a tablespace when it becomes full, making it possible to extend tablespace size in larger increments.

Allocating space in larger increments helps to avoid fragmentation and facilitates ingestion of large

amounts of data. The AUTOEXTEND_SIZE option is supported with the CREATE TABLE, ALTER TABLE,

CREATE TABLESPACE, and ALTER TABLESPACE statements. For more information, see Tablespace

AUTOEXTEND_SIZE Configuration.

An AUTOEXTEND_SIZE size column was added to the

INFORMATION_SCHEMA.INNODB_TABLESPACES table. (WL #13895)

• InnoDB: InnoDB now supports encryption of doublewrite file pages belonging to encrypted tablespaces.

The pages are encrypted using the encryption key of the associated tablespace. For more information,

see InnoDB Data-at-Rest Encryption. (WL #13775)

• InnoDB: InnoDB atomics code was revised to use C++ std::atomic. (WL #14235)

• Group Replication: The MySQL Server asynchronous connection failover mechanism

now supports Group Replication topologies, by automatically monitoring changes to

group membership and distinguishing between primary and secondary servers. When

you add a group member to the source list and define it as part of a managed group, the

asynchronous connection failover mechanism updates the source list to keep it in line

with membership changes, adding and removing group members automatically as they

join or leave. The new asynchronous_connection_failover_add_managed() and

asynchronous_connection_failover_delete_managed() functions are used to add and

remove managed sources.

The connection is failed over to another group member in the following situations:

• The currently connected source goes offline or leaves the group.

• The currently connected source is no longer in the majority.

• The currently connected source does not have the highest weighted priority in the group.

For a managed group, a source’s weight is assigned depending on whether it is a primary or a

secondary server. So assuming that you set up the managed group to give a higher weight to a primary

and a lower weight to a secondary, when the primary changes, the higher weight is assigned to the new

primary, so the replica changes over the connection to it. This also applies to single (non- managed)

servers, so the connection for a single server is also now failed over if another source server is available

that has a higher weighted priority. (WL #14019)

• When invoked with the --all-databases option, mysqldump now dumps the mysql database first,

so that when the dump file is reloaded, any accounts named in the DEFINER clause of other objects will

already have been created. (Bug #32141046)

• Some overhead for disabled Performance Schema and LOCK_ORDER tool instrumentation was identified

and eliminated. (Bug #32105698)

• For BLOB and TEXT columns that have a default value expression, the

INFORMATION_SCHEMA.COLUMNS table and SHOW COLUMNS statement now display the expression.

(Bug #31856459)

• For a multithreaded replica (where slave_parallel_workers is greater than 0), setting

slave_preserve_commit_order=1 ensures that transactions are executed and committed on

the replica in the same order as they appear in the replica's relay log. Each executing worker thread

waits until all previous transactions are committed before committing. If a worker thread fails to execute

a transaction because a possible deadlock was detected, or because the transaction's execution

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MySQL 8.0 Release Notes

time exceeded a relevant wait timeout, it automatically retries the number of times specified by

slave_transaction_retries before stopping with an error. Transactions with a non-temporary error

are not retried.

The replication applier on a multithreaded replica has always handled data access deadlocks that

were identified by the storage engines involved. However, some other types of lock were not detected

by the replication applier, such as locks involving access control lists (ACLs) or metadata locking (for

example, FLUSH TABLES WITH READ LOCK statements). This could lead to three-actor deadlocks

with the commit order locking, which could not be resolved by the replication applier, and caused

replication to hang indefinitely. From MySQL 8.0.23, deadlock handling on multithreaded replicas that

preserve the commit order has been enhanced to mitigate these types of deadlocks. The deadlocks

are not specifically resolved by the replication applier, but the applier is aware of them and initiates

automatic retries for the transaction, rather than hanging. If the retries are exhausted, replication stops in

a controlled manner so that the deadlock can be resolved manually. (Bug #107574, Bug #34291887, WL

#13574)

• CRC calculations for binlog checksums are faster on ARM platforms. Thanks to Krunal Bauskar for the

contribution. (Bug #99118, Bug #31101633, Bug #32163391)

• Replication channels can now be set to assign a GTID to replicated transactions that do not already

have one, using the ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS option of the CHANGE

REPLICATION SOURCE TO statement. This feature enables replication from a source that does not

use GTID-based replication, to a replica that does. For a multi-source replica, you can have a mix of

channels that use ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS, and channels that do not. The

GTID can include the replica’s own server UUID or a server UUID that you assign to identify transactions

from different sources.

Note that a replica set up with ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS on any

channel cannot be promoted to replace the replication source server in the event that a failover

is required, and a backup taken from the replica cannot be used to restore the replication

source server. The same restriction applies to replacing or restoring other replicas that use

ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS on any channel. The GTID set (gtid_executed) from

a replica set up with ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS is nonstandard and should not

be transferred to another server, or compared with another server's gtid_executed set. (WL #12819)

• The new temptable_max_mmap variable defines the maximum amount of memory the TempTable

storage engine is permitted to allocate from memory-mapped temporary files before it starts storing

data to InnoDB internal temporary tables on disk. A setting of 0 disables allocation of memory from

memory-mapped temporary files. For more information, see Internal Temporary Table Use in MySQL.

(WL #14125)

Bugs Fixed

• InnoDB: A CREATE TABLE operation that specified the COMPRESSION option was permitted with a

warning on a system that does not support hole punching. The operation now fails with an error instead.

(Bug #32174200)

• InnoDB: A MySQL DB system restart following an upgrade that was initiated while a data load operation

was in progress raised an assertion failure. (Bug #32173596)

• InnoDB: An error message regarding the number of truncate operations on the same undo tablespace

between checkpoints incorrectly indicated a limit of 64. The limit was raised from 64 to 50,000 in MySQL

8.0.22. (Bug #32151601, Bug #101601)

• InnoDB: rw_lock_t and buf_block_t source code structures were reduced in size. (Bug

#32084500)

188

MySQL 8.0 Release Notes

• InnoDB: An InnoDB transaction became inconsistent after creating a table using a storage engine other

than InnoDB from a query expression that operated on InnoDB tables. (Bug #32079103)

• InnoDB: In some circumstances, such as when an existing gap lock inherits a lock from a deleted

record, the number of locks that appear in the INFORMATION_SCHEMA.INNODB_TRX table could

diverge from the actual number of record locks.

Thanks to Fungo Wang from Alibaba for the patch. (Bug #32068538, Bug #101305)

• InnoDB: An off-by-one error in Fil_system sharding code was corrected, and the maximum number of

shards (MAX_SHARDS) was changed to 69. (Bug #32052821, Bug #101260)

• InnoDB: The TempTable storage engine memory allocator allocated extra blocks of memory

unnecessarily. (Bug #32018553)

• InnoDB: A SELECT COUNT(*) operation on a table containing uncommitted data performed poorly due

to unnecessary I/O.

Thanks to Brian Yue for the contribution. (Bug #31997733, Bug #100966)

• InnoDB: A race condition when shutting down the log writer raised an assertion failure. (Bug

#31997362)

• InnoDB: Page cleaner threads were not utilized optimally in sync-flush mode, which could cause page

flush operations to slow down or stall in some cases. Sync-flush mode occurs when InnoDB is close

to running out of free space in the redo log, causing the page cleaner coordinator to initiate aggressive

page flushing. (Bug #31994031)

• InnoDB: A high frequency of updates while undo log truncation was enabled caused purge to lag. The

lag was due to the innodb_purge_rseg_truncate_frequency setting being changed temporarily

from 128 to 1 when an undo tablespace was selected for truncation. The code that modified the setting

has been removed. (Bug #31991688)

• InnoDB: Automated truncation of undo tablespaces caused a performance regression. To address this

issue, undo tablespace files are now initialized at 16MB and extended by a minimum of 16MB. To handle

aggressive growth, the file extension size is doubled if the previous file extension happened less than

0.1 seconds earlier. Doubling of the extension size can occur multiple times to a maximum of 256MB.

If the previous file extension occurred more than 0.1 seconds earlier, the extension size is reduced by

half, which can also occur multiple times, to a minimum of 16MB. Previously, the initial size of an undo

tablespace depended on the InnoDB page size, and undo tablespaces were extended four extents at a

time.

If the AUTOEXTEND_SIZE option is defined for an undo tablespace, the undo tablespace is extended by

the greater of the AUTOEXTEND_SIZE setting and the extension size determined by the logic described

above.

When an undo tablespace is truncated, it is normally recreated at 16MB in size, but if the current file

extension size is larger than 16MB, and the previous file extension happened within the last second, the

new undo tablespace is created at a quarter of the size defined by the innodb_max_undo_log_size

variable.

Stale undo tablespace pages are no longer removed at the next checkpoint. Instead, the pages are

removed in the background by the InnoDB master thread. (Bug #31965404, Bug #32020900, Bug

#101194)

189

MySQL 8.0 Release Notes

• InnoDB: A posix_fallocate() failure while preallocating space for a temporary tablespace raised an

error and caused an initialization failure. A warning is now issued instead, and InnoDB falls back to the

non-posix_fallocate() method for preallocating space. (Bug #31965379)

• InnoDB: An invalid pointer caused a shutdown failure on a MySQL Server compiled with the

DISABLE_PSI_MEMORY source configuration option enabled. (Bug #31963333)

• InnoDB: A long SX lock held by an internal function that calculates new statistics for a given index

caused a failure. (Bug #31889883)

• InnoDB: The INFORMATION_SCHEMA.INNODB_TABLESPACES table reported a FILE_SIZE of 0

for some tables and schemas. When the associated tablespace was not in the memory cache, the

tablespace name was used to determine the tablespace file name, which was not always a reliable

method. The tablespace ID is now used instead. Using the tablespace name remains as a fallback

method. (Bug #31841617)

• InnoDB: After dropping a FULLTEXT index and renaming the table to move it to a new schema, the

FULLTEXT auxiliary tables were not renamed accordingly and remained in the old schema directory.

(Bug #31773368, Bug #100570)

• InnoDB: After upgrading to MySQL 8.0, a failure occurred when attempting to perform a DML operation

on a table that was previously defined with a full-text search index. (Bug #31749490)

• InnoDB: Importing a tablespace with a page-compressed table did not report a schema mismatch error

for source and destination tables defined with a different COMPRESSION setting. The COMPRESSION

setting of the exported table is now saved to the .cfg metadata file during the FLUSH TABLES ...

FOR EXPORT operation, and that information is checked on import to ensure that both tables are defined

with the same COMPRESSION setting. (Bug #31744694)

• InnoDB: Dummy keys used to check if the MySQL Keyring plugin is functioning were left behind in an

inactive state, and the number of inactive dummy keys increased over time. The actual master key is

now used instead, if present. If no master key is available, a dummy master key is generated. (Bug

#31737924)

• InnoDB: Querying the INFORMATION_SCHEMA.FILES table after moving the InnoDB system

tablespace outside of the data directory raised a warning indicating that the innodb_system filename is

unknown. (Bug #31603047)

• InnoDB: In a replication scenario involving a replica with binary logging or log_slave_updates

disabled, the server failed to start due to an excessive number of gaps in the mysql.gtid_executed

table. The gaps occurred for workloads that included both InnoDB and non-InnoDB transactions.

GTIDs for InnoDB transactions are flushed to the mysql.gtid_executed table by the GTID persister

thread, which runs periodically, while GTIDs for non-InnoDB transactions are written to the to the

mysql.gtid_executed table directly by replica server threads. The GTID persister thread fell behind

as it cycled through merging entries and compressing the mysql.gtid_executed table. As a result,

the size of the GTID flush list for InnoDB transactions grew over time along with the number of gaps in

the mysql.gtid_executed table, eventually causing a server failure and subsequent startup failures.

To address this issue, the GTID persister thread now writes GTIDs for both InnoDB and non-InnoDB

transactions, and foreground commits are forced to wait if the GTID persister thread falls behind. Also,

the gtid_executed_compression_period default setting was changed from 1000 to 0 to disabled

explicit compression of the mysql.gtid_executed table by default.

Thanks to Venkatesh Prasad for the contribution. (Bug #31599938, Bug #100118)

• InnoDB: Persisting GTID values for XA transactions affected XA transaction performance. Two GTID

values are generated for XA transactions, one for the prepare stage and another for the commit stage.

The first GTID value is written to the undo log and later overwritten by the second GTID value. Writing

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MySQL 8.0 Release Notes

of the second GTID value could only occur after flushing the first GTID value to the gtid_executed

table. Space is now reserved in the undo log for both XA transaction GTID values. (Bug #31467953, Bug

#99638)

• InnoDB: InnoDB source files were updated to address warnings produced when building Doxygen

source code documentation. (Bug #31354760)

• InnoDB: The full-text search synchronization thread attempted to read a previously-freed word from the

index cache. (Bug #31310404)

• InnoDB: A 20µs sleep in the buf_wait_for_read() function introduced with parallel read

functionality in MySQL 8.0.17 took 1ms on Windows, causing an unexpected timeout when running

certain tests. Also, AIO threads were found to have uneven amounts of waiting operating system IO

requests. (Bug #31095274)

References: This issue is a regression of: Bug #31123564.

• InnoDB: Cleanup in certain replicated XA transactions failed to reattach transaction object (trx_t),

which raised an assertion failure. (Bug #31006095)

• InnoDB: The tablespace encryption type setting was not properly updated due to a failure during

the resumption of an ALTER TABLESPACE ENCRYPTION operation following a server failure. (Bug

#30883833, Bug #98537)

• InnoDB: An interrupted tablespace encryption operation did not update the encrypt_type table option

information in the data dictionary when the operation resumed processing after the server was restarted.

(Bug #30883833, Bug #98537, Bug #30888919, Bug #98564)

• InnoDB: Internal counter variables associated with thread sleep delay and threads entering an leaving

InnoDB were revised to use C++ std::atomic. Built-in atomic operations were removed. Thanks to

Yibo Cai from ARM for the contribution. (Bug #30567060, Bug #97704)

• InnoDB: A relaxed memory order was implemented for dictionary memory variable fetch-add

(dict_temp_file_num.fetch_add) and store (dict_temp_file_num.store) operations.

Thanks to Yibo Cai for the contribution. (Bug #30567054, Bug #97703)

• InnoDB: A background thread that resumed a tablespace encryption operation after the server started

failed to take an metadata lock on the tablespace, which permitted concurrent DDL operations and led to

a race condition with the startup thread. The startup thread now waits until the tablespace metadata lock

is taken. (Bug #28531637)

• InnoDB: Calls to numa_all_nodes_ptr were replaced by the numa_get_mems_allowed() function.

Thanks to Daniel Black for the contribution. (Bug #24693086, Bug #83044)

• Partitioning: ALTER TABLE t1 EXCHANGE PARTITION ... WITH TABLE t2 led to an assert

when t1 was not a partitioned table. (Bug #100971, Bug #31941543)

References: This issue is a regression of: Bug #29706669.

• Replication: The network_namespace parameter for the

asynchronous_connection_failover_add_source() and

asynchronous_connection_failover_delete_source() function is no longer used. These

functions add and remove replication source servers from the source list for a replication channel for

the asynchronous connection failover mechanism. The network namespace for a replication channel

is managed using the CHANGE REPLICATION SOURCE statement, and has special requirements for

Group Replication source servers, so it should no longer be specified in the functions. (Bug #32078189)

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MySQL 8.0 Release Notes

• Replication: When mysqlbinlog’s --print-table-metadata option was used, mysqlbinlog

used a different method for assessing numeric fields to the method used by the server when writing to

the binary log, resulting in incorrect metadata output relating to these fields. mysqlbinlog now uses the

same method as the server. (Bug #31956206)

• Replication: When using network namespaces in a replication channel and the initial connection from

the replica to the master was interrupted, subsequent connection attempts failed to use the correct

namespace information. (Bug #31954087)

• Replication: If a group member was expelled and made an auto-rejoin attempt at a point when some

tables on the instance were locked (for example while a backup was running), the attempt failed and no

further attempts were made. This scenario is now handled correctly. (Bug #31460690)

• Replication: As the number of replicas replicating from a semisynchronous source server increased,

locking contention could result in a performance degradation. The locking mechanisms used by the

plugins have been changed to use shared locks where possible, avoid unnecessary lock acquisitions,

and limit callbacks. The new behaviors can be implemented by enabling the following system variables:

• replication_sender_observe_commit_only=1 limits callbacks.

• replication_optimize_for_static_plugin_config=1 adds shared locks and avoids

unnecessary lock acquisitions. This system variable must be disabled if you want to uninstall the

plugin.

Both system variables can be enabled before or after installing the semisynchronous replication plugin,

and can be enabled while replication is running. Semisynchronous replication source servers can also

get performance benefits from enabling these system variables, because they use the same locking

mechanisms as the replicas. (Bug #30519928)

• Replication: On a multi-threaded replica where the commit order is preserved, worker threads must wait

for all transactions that occur earlier in the relay log to commit before committing their own transactions.

If a deadlock occurs because a thread waiting to commit a transaction later in the commit order has

locked rows needed by a transaction earlier in the commit order, a deadlock detection algorithm signals

the waiting thread to roll back its transaction. Previously, if transaction retries were not available, the

worker thread that rolled back its transaction would exit immediately without signalling other worker

threads in the commit order, which could stall replication. A worker thread in this situation now waits for

its turn to call the rollback function, which means it signals the other threads correctly. (Bug #26883680,

Bug #87796)

• Replication: GTIDs are only available on a server instance up to the number of non-negative values for

a signed 64-bit integer (2 to the power of 63 minus 1). If you set the value of gtid_purged to a number

that approaches this limit, subsequent commits can cause the server to run out of GTIDs and take the

action specified by binlog_error_action. From MySQL 8.0.23, a warning message is issued when

the server instance is approaching the limit. (Bug #26035544)

• Group Replication: When the system variable transaction_write_set_extraction=XXHASH64

is set, which is the default in MySQL 8.0 and a requirement for Group Replication, the collection of writes

for a transaction previously had no upper size limit. Now, for standard source to replica replication,

the numeric limit on write sets specified by binlog_transaction_dependency_history_size

is applied, after which the write set information is discarded but the transaction continues to execute.

Because the write set information is then unavailable for the dependency calculation, the transaction

is marked as non-concurrent, and is processed sequentially on the replica. For Group Replication, the

process of extracting the writes from a transaction is required for conflict detection and certification on all

group members, so the write set information cannot be discarded if the transaction is to complete. The

byte limit set by group_replication_transaction_size_limit is applied instead of the numeric

limit, and if the limit is exceeded, the transaction fails to execute. (Bug #32019842)

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MySQL 8.0 Release Notes

• Group Replication: If the Group Replication applier channel (group_replication_applier)

was holding a lock on a table, for example because of a backup in progress, and the member was

expelled from the group and tried to rejoin automatically, the auto-rejoin attempt was unsuccessful

and did not retry. Now, Group Replication checks during startup and rejoin attempts whether the

group_replication_applier channel is already running. If that is the case at startup, an error

message is returned. If that is the case during an auto-rejoin attempt, that attempt fails, but further

attempts are made as specified by the group_replication_autorejoin_tries system variable.

(Bug #31648211)

• Microsoft Windows: On Windows, running the MySQL server as a service caused shared-memory

connections to fail. (Bug #32009251)

• JSON: JSON_ARRAYAGG() did not always perform proper error handling. (Bug #31856260, Bug

#32012559, Bug #32181438)

• JSON: When updating a JSON value using JSON_SET(), JSON_REPLACE(), or JSON_REMOVE(),

the target column can sometimes be updated in-place. This happened only when the target table of the

update operation was a base table, but when the target table was an updatable view, the update was

always performed by writing the full JSON value.

Now in such cases, an in-place update (that is, a partial update) is also performed when the target table

is an updatable view. (Bug #25840784)

• JSON: Work done in MySQL 8.0.22 to cause prepared statements to be prepared only once introduced

a regression in the handling of dynamic parameters to JSON functions. All JSON arguments were

classified as data type MYSQL_TYPE_JSON, which overlooked the fact that JSON functions take two

kinds of JSON parameters—JSON values and JSON documents—and this distinction cannot be made

with the data type only. For Bug #31667405, this problem was solved for comparison operators and

the IN() operator by making it possible to tag a JSON argument as being a scalar value, while letting

arguments to other JSON functions be treated as JSON documents.

The present fix restores for a number of JSON functions their treatment of certain arguments as JSON

values, as listed here:

The first argument to MEMBER OF()

The third, fifth, seventh, and subsequent odd-numbered arguments to the functions JSON_INSERT(),

JSON_REPLACE(), JSON_SET(), JSON_ARRAY_APPEND(), and JSON_ARRAY_INSERT(). (Bug

#101284, Bug #32063203)

References: See also: Bug #31667405.

• JSON: When mysqld was run with --debug, attempting to execute a query that made use of a multi-

valued index raised an error. (Bug #99833, Bug #31474182)

• Use of the thread_pool plugin could result in Address Sanitizer warnings. (Bug #32213294)

• While pushing a condition down to a materialized derived table, and a condition is partially pushed down,

the optimizer may, in some cases in which a query transformation has added new conditions to the

WHERE condition, call the internal fix_fields() function for the condition that remains in the outer

query block. A successful return from this function call was misinterpreted as an error, leading to the

silent failure of the original statement. (Bug #32150145)

• Multiple calls to a stored procedure containing an ALTER TABLE statement that included an ORDER BY

clause could cause a server exit. (Bug #32147402)

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MySQL 8.0 Release Notes

• Prepared statements involving stored programs could cause heap-use-after-free memory problems.

(Bug #32131022, Bug #32045681, Bug #32051928)

• Queries on INFORMATION_SCHEMA tables that involved materialized derived tables could fail. (Bug

#32127562, Bug #101504)

• A potential buffer overflow was fixed. Thanks to Sifang Zhao for pointing out the issue, and for

suggesting a fix (although it was not used). (Bug #32113015, Bug #101448)

• Conversion of FLOAT values to values of type INT could generate Undefined Behavior Sanitizer

warnings. (Bug #32099994, Bug #32100033)

• In multiple-row queries, the LOAD_FILE() function evaluated to the same value for every row. (Bug

#32096341, Bug #101401)

• Generic Linux tar file distributions had too-restrictive file permissions after unpacking, requiring a

manual chmod to correct. (Bug #32080900)

• For debug builds, prepared SET statements containing subqueries in stored procedures could raise an

assertion. (Bug #32078387)

References: See also: Bug #32100210.

• For prepared statements, illegal mix of collations errors could occur for legal collation mixes.

(Bug #32077842, Bug #101346, Bug #32145078, Bug #101575)

• The functions REGEXP_LIKE(), REGEXP_INSTR(), and REGEXP_REPLACE() raise errors for

malformed regular expression patterns, but could also return NULL for such cases, causing subsequent

debug asserts. Now we ensure that these functions do not return NULL except in certain specified cases.

The function REGEXP_SUBSTR() can always return NULL, so no such check is needed, and for this

function we make sure that one is not performed. (Bug #32053093)

• Testing an aggregate function for IS NULL or IS NOT NULL in a HAVING condition using WITH

ROLLUP led to wrong results. (Bug #32049313)

• When a new aggregate function was added to the current query block because an inner query block had

an aggregate function requiring evaluation in the current one, the server did not add rollup wrappers to it

as needed. (Bug #32034914)

• For debug builds, certain CREATE TABLE statements with CHECK constraints could raise an assertion.

(Bug #32018406, Bug #101180)

• Incorrect BLOB field values were passed from InnoDB during a secondary engine load operation. (Bug

#32014483)

• The LOCK_ORDER tool did not correctly represent InnoDB share exclusive locks. (Bug #31994052)

• The server did not handle properly an error raised when trying to use an aggregation function with an

invalid column type as part of a hash join. (Bug #31989333)

• The length of the WORD column of the INFORMATION_SCHEMA.KEYWORDS table could change

depending on table contents. (Bug #31982157)

• The Performance Schema host_cache table was empty and did not expose the contents of the host

cache if the Performance Schema was disabled. The table now shows cache contents regardless of

whether the Performance Schema is enabled. (Bug #31978763)

• A HANDLER READ statement sometimes hit an assert when a previous statement did not restore the

original value of THD::mark_used_columns after use. (Bug #31977414)

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MySQL 8.0 Release Notes

• Importing a compressed table could cause an unexpected server exit if the table contained values that

were very large when uncompressed. (Bug #31943021)

• Removed a memory leak that could occur when a subquery using a hash join and LIMIT was executed

repeatedly. (Bug #31940549)

• A compilation failure on Ubuntu was corrected. (Bug #31930934, Bug #100938)

• Memory used for storing partial-revokes information could grow excessively for sessions that executed a

large number of statements. (Bug #31919448)

• The server did not handle all cases of the WHERE_CONDITION optimization correctly. (Bug #31905199)

• FLUSH TABLES WITH READ LOCK could block other sessions from executing SHOW TABLE STATUS.

(Bug #31894662)

• In some cases, MIN() and MAX() incorrectly returned NULL when used as window functions with

temporal or JSON values as arguments. (Bug #31882291)

• GRANT ... GRANT OPTION ... TO and GRANT ... TO .. WITH GRANT OPTION sometimes

were not correctly written to the server logs. (Bug #31869146, Bug #100793)

• For debug builds, CREATE TABLE using a partition list of more than 256 entries raised an assertion.

(Bug #31867653)

• It was possible for queries in the file named by the init_file system variable to cause server startup

failure. (Bug #31835782)

• When performing a hash join, the optimizer could register a false match between a negative integer

value and a very large unsigned integer value. (Bug #31832001, Bug #31940639, Bug #100967)

• SHOW VARIABLES could report an incorrect value for the partial_revokes system variable. (Bug

#31819558, Bug #100677)

• In the Performance Schema user_defined_functions table, the value of the UDF_LIBRARY column

is supposed to be NULL for loadable functions registered via the service API. The value was incorrectly

set to the empty string. (Bug #31791754)

• The server automatic upgrade procedure failed to upgrade older help tables that used the latin1

character set. (Bug #31789964)

• Duplicate warnings could occur when executing an SQL statement that read the grant tables in

serializable or repeatable-read transaction isolation level. (Bug #31769242)

• In certain queries with DISTINCT aggregates (which in general are solved by sorting before

aggregation), the server used a temporary table instead of streaming due to the mistaken assumption

that the logic for handling the temporary table performed deduplication. Now the server checks for the

implied unique index instead, which is more robust and allows for the removal of unnecessary logic. (Bug

#31762806)

• Certain combinations of lower_case_table_names values and schema names in Event Scheduler

event definitions could cause the server to stall. (Bug #31733090)

• Calling one stored function from within another could produce a conflict in field resolution, resulting in a

server exit. (Bug #31731334)

• Loadable functions defined without a udf_init() method could cause an unexpected server exit. (Bug

#31701219)

195

MySQL 8.0 Release Notes

• Setting the secure_file_priv system variable to NULL should disable its action, but instead caused

the server to create a directory named NULL. (Bug #31700734, Bug #100384)

• mysqlpump could exit unexpectedly due to improper simultaneous accesses to shared structures. (Bug

#31696241)

• Uninstalling a component and deregistering loadable functions installed by the component was not

properly synchronized with whether the functions were currently in use. (Bug #31646698)

• Cleanup following execution of a prepared statement that performed a multi-table UPDATE or DELETE

was not always done correctly, which meant that, following the first execution of such a prepared

statement, the server reported a nonzero number of rows updated, even though no rows were actually

changed. (Bug #31640267)

References: See also: Bug #32100210.

• For the engines which support primary key extension, when the total key length exceeded

MAX_KEY_LENGTH or the number of key parts exceeded MAX_REF_PARTS, key parts of primary keys

which did not fit within these limits were not added to the secondary key, but key parts of primary keys

were unconditionally marked as part of secondary keys.

This led to a situation in which the secondary key was treated as a covering index, which meant

sometimes the wrong access method was chosen.

This is fixed by modifying the way in which key parts of primary keys are added to secondary keys so

that those which do not fit within which do not fit within the limits mentioned previously mentioned are

cleared. (Bug #31617858)

• When MySQL is configured with -DWITH_ICU=system, CMake now checks that the ICU library version

is sufficiently recent. (Bug #31600044)

• When invoked with the --binary-as-hex option, mysql displayed NULL values as empty binary

strings (0x).

Selecting an undefined variable returned the empty binary string (0x) rather than NULL. (Bug

#31549724, Bug #31638968, Bug #100251)

• Enabling DISABLE_PSI_xxx Performance Schema-related CMake options caused build failures. (Bug

#31549724)

• Some queries returned different results depending on the value of

internal_tmp_mem_storage_engine.

The root cause of this issue related to the fact that, when buffering rows for window functions, if the

size of the in-memory temporary table holding these buffered rows exceeds the limit specified, a new

temporary table is created on disk; the frame buffer partition offset is set at the beginning of a new

partition to the total number of rows that have been read so far, and is updated specifically for use when

the temporary table is moved to disk (this being used to calculate the hints required to process window

functions). The problem arose because the frame buffer partition offset was not updated for the specific

case when a new partition started while creating the temporary table on disk, which caused the wrong

rows to be read.

This issue is fixed by making sure to update the frame buffer partition offset correctly whenever a new

partition starts while a temporary table is moved to disk. (Bug #31546816)

• While buffering rows for window functions, if the size of the in-memory temporary table holding these

buffered rows exceeds the limit specified by temptable_max_ram, a new temporary table is created on

196

MySQL 8.0 Release Notes

disk. After the creation of the temporary table, hints used to process window functions need to be reset,

since the temporary table is now moved to disk, making the existing hints unusable. When the creation

of the temporary table on disk occurred when the first row in the frame buffer was being processed, the

hints had not been initialized and trying to reset these uninitialized hints resulted in an unplanned server

exit.

This issue is fixed by adding a check to verify whether frame buffer hints have been initialized, prior to

resetting them. (Bug #31544404)

• The Performance Schema could produce incorrect results for joins on a CHANNEL_NAME column when

the index for CHANNEL_NAME was disabled with USE INDEX (). (Bug #31544023, Bug #99989)

• When removing unused window definitions, a subquery that was part of an ORDER BY was not removed.

(Bug #31518806)

• In certain cases, the server did not handle multiply-nested subqueries correctly. (Bug #31472704)

• The recognized syntax for a VALUES statement includes an ORDER BY clause, but this clause was not

resolved, so the execution engine could encounter invalid data. (Bug #31387510)

• The server attempted to access a non-existent temporary directory at startup, causing a failure. Checks

were added to ensure that temporary directories exist, and that files are successfully created in the

tmpdir directory. (Bug #31377118)

• While removing redundant sorting, a window's ordering was removed due to the fact that rows were

expected to come in order because of the ordering of another window. When the other window was

subsequently removed because it was unused, this resulted in unordered rows, which was not expected

during evaluation.

Now in such cases, removal of redundant sorts is not performed until after any unused windows have

been removed. In addition, resolution of any rollups has been moved to the preparation phase. (Bug

#31361393)

• Semisynchronous replication errors were incorrectly written to the error log with a subsystem tag

of Server. They are now written with a tag of Repl, the same as for other replication errors. (Bug

#31327337)

• A user could grant itself as a role to itself. (Bug #31222230)

• The server did not always correctly handle cases in which multiple WHERE conditions, one of which was

always FALSE, referred to the same subquery. (Bug #31216115)

• With a lower_case_table_names=2 setting, InnoDB background threads sometimes acquired table

metadata locks using the wrong character case for the schema name part of a lock key, resulting in

unprotected metadata and race conditions. The correct character case is now applied. Changes were

also implemented to prevent metadata locks from being released before corresponding data dictionary

objects, and to improve assertion code that checks lock protection when acquiring data dictionary

objects. (Bug #31165802)

• If a CR_UNKNOWN_ERROR was to be sent to a client, an exception occurred. (Bug #31123643)

• Conversion of DOUBLE values to values of type BIT, ENUM, or SET could generate Undefined Behavior

Sanitizer warnings. (Bug #31019130)

• Certain accounts could cause server startup failure if the skip_name_resolve system variable was

enabled. (Bug #31018510)

• Client programs could unexpectedly exit if communication packets contained bad data. (Bug #30890850)

197

MySQL 8.0 Release Notes

• A buffer overflow in the client library was fixed. (Bug #30885987)

• When creating a multi-valued or other functional index, a performance drop was seen when executing

a query against the table on which the index was defined, even though the index itself was not actually

used. This occurred because the hidden virtual column that backs such indexes was evaluated

unnecessarily for each row in the query. (Bug #30838749)

References: This issue is a regression of: Bug #28069731.

• CMake checks for libcurl dependencies were improved. (Bug #30268245)

• mysql_config_editor incorrectly treated # in password values as a comment character. (Bug

#29861961, Bug #95597)

• In some cases, the optimizer attempted to compute the hash value for an empty string. Now a fixed

value is always used instead. (Bug #22588319)

• The INSERT() and RPAD() functions did not correctly set the character set of the result. (Bug

#22523946, Bug #79909, Bug #31887870, Bug #100841)

• Some corner cases for val1 BETWEEEN val2 AND val3 were fixed, such as that -1 BETWEEN

9223372036854775808 AND 1 returned true. (Bug #22515857, Bug #79878)

• For the Performance Schema memory_summary_global_by_event_name table, the low watermark

columns could have negative values, and the high watermark columns had ever-increasing values even

when the server memory usage did not increase. (Bug #22246001, Bug #79285)

• Several issues converting strings to numbers were fixed. (Bug #19186271, Bug #73248)

• Certain group by queries that performed correctly did not return the expected result when WITH ROLLUP

was added. This was due to the fact that decimal information was not always correctly piped through

rollup group items, causing functions returning decimal values such as TRUNCATE() to receive data of

the wrong type. (Bug #101684, Bug #32179240)

• When creating fields for materializing temporary tables (that is, when needing to sort a join), the

optimizer checks whether the item needs to be copied or is only a constant. This was not done correctly

in one specific case; when performing an outer join against a view or derived table containing a constant,

the item was not properly materialized into the table, which could yield spurious occurrences of NULL in

the result. (Bug #101622, Bug #32162862)

References: See also: Bug #31790217.

• When REGEXP_REPLACE() was used in an SQL statement, the internal function

Regexp_engine::Replace() did not reset the error code value after handling a record, which could

affect processing of the next record, which lead to issues.

Our thanks to Hope Lee for the contribution. (Bug #101256, Bug #32050219)

• For a query having the following form, the column list sometimes assumed an inconsistent state after

temporary tables were created, causing out-of-bounds indexing later:

SELECT * FROM (

SELECT PI()

FROM t1 AS table1, t1 AS table2

ORDER BY PI(), table1.a

) AS d1;

(Bug #101012, Bug #31955761, Bug #31978439)

References: This issue is a regression of: Bug #31790217.

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MySQL 8.0 Release Notes

• When aggregating data that was already sorted (known as performing streaming aggregation, due to

no temporary tables being used), it was not possible to determine when a group ended until processing

the first row in the next group, by which time the group expressions to be output were often already

overwritten.

This is fixed by replacing the complex logic previously used with the much simpler method of saving

a representative row for the group when encountering it the first time, so that its columns can easily

be retrieved for the output row when needed. (Bug #100791, Bug #27272052, Bug #31073167, Bug

#31790217, Bug #31868610)

• Subqueries making use of fulltext matching might not perform properly when subquery_to_derived

was enabled, and could lead to an assert in debug builds. (Bug #100749, Bug #31851600)

• When an ALTER TABLE ... CONVERT TO CHARACTER SET statement is executed, the character set

of every CHAR, VARCHAR, and TEXT column in the table is updated to the new CHARACTER SET value.

This change was also applied to the hidden CHAR column used by an ARRAY column for a multi-valued

index; since the character set of the hidden column must be one of my_charset_utf8mb4_0900_bin

or binary, this led to an assert in debug builds of the server.

This issue is resolved by no longer setting the character set of the hidden column to that of the table

when executing the ALTER TABLE statement referenced previously; this is similar to what is done for

BLOB columns in similar circumstances. (Bug #99403, Bug #31301101)

• In some cases, the server's internal string-conversion routines had problems handling floating-point

values which used length specifiers and triggered use of scientific notation. (Bug #92537, Bug #101570,

Bug #28691605, Bug #32144265)

References: See also: Bug #88256, Bug #27041543.

Changes in MySQL 8.0.22 (2020-10-19, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• Audit Log Notes

• C API Notes

• Compilation Notes

• Configuration Notes

• Deprecation and Removal Notes

• Keyring Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Pluggable Authentication

• SQL Syntax Notes

• X Plugin Notes

199

MySQL 8.0 Release Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• Lock handling for statements involving the grant tables was improved. (Bug #31291237, Bug

#31576185, WL #14084)

• Modifying the mysql.infoschema and mysql.sys reserved accounts now requires the

SYSTEM_USER privilege. (Bug #31255458)

• For the CREATE USER, DROP USER, and RENAME USER account-management statements, the server

now performs additional security checks designed to prevent operations that (perhaps inadvertently)

cause stored objects to become orphaned or that cause adoption of stored objects that are currently

orphaned. Such operations now fail with an error. If you have the SET_USER_ID privilege, it overrides

the checks and those operations produce a warning rather than an error; this enables administrators to

perform the operations when they are deliberately intended. See Orphan Stored Objects. (WL #14073)

Audit Log Notes

• For JSON-format log files, MySQL Enterprise Audit supports log-reading operations using the

audit_log_read() user-defined function. Previously, specifying the position at which to begin reading

was possible only by passing to audit_log_read() an argument containing a bookmark indicating

the exact timestamp and event ID of a particular event. For greater flexibility, the argument now can be a

start specifier that names any timestamp, to read starting from the first event that occurs on or after that

timestamp. See Reading Audit Log Files. (WL #13936)

C API Notes

• The MySQL client library now includes a mysql_real_connect_dns_srv() C API function that is

similar to mysql_real_connect() but uses a DNS SRV record to determine the candidate hosts for

establishing a connection to a MySQL server, rather than explicit host, port, and socket arguments.

Applications that use the C API can call the new function directly. In addition, the mysql client

program is modified to use DNS SRV capability; it now supports a --dns-srv-name option that

takes precedence over --host and causes the connection to be based on a DNS SRV record. See

mysql_real_connect_dns_srv().

Connection establishment in other contexts is unaffected, including connections made by replicas, the

FEDERATED storage engine, and client programs other than mysql. (WL #13905)

Compilation Notes

• On Windows, Visual Studio 2019 Update 4 is now the minimum version for MySQL compilation. (Bug

#31655401)

• The minimum version of the Boost library for server builds is now 1.73.0. (Bug #31309800)

Configuration Notes

• The new WITH_TCMALLOC CMake option indicates whether to link with -ltcmalloc. If enabled,

built-in malloc(), calloc(), realloc(), and free() routines are disabled. The default is OFF.

WITH_TCMALLOC and WITH_JEMALLOC are mutually exclusive. (Bug #31785166)

• The new COMPRESS_DEBUG_SECTIONS CMake option indicates whether to compress the debug

sections of binary executables (Linux only). Compressing executable debug sections saves space at

200

MySQL 8.0 Release Notes

the cost of extra CPU time during the build process. The default is OFF. If this option is not set explicitly

but the COMPRESS_DEBUG_SECTIONS environment variable is set, the option takes its value from that

variable. (Bug #31498296)

• The WITH_DEFAULT_FEATURE_SET CMake option was removed. (Bug #31122507)

• On platforms that implement network namespace support (such as Linux), MySQL now enables

configuring the network namespace for TCP/IP connections from client programs to the MySQL server or

X Plugin:

• On the server side, the bind_address, admin_address, and mysqlx_bind_address system

variables have extended syntax for specifying the network namespace to use for a given IP address or

host name on which to listen for incoming connections.

• For client connections, the mysql client and the mysqlxtest test suite client support a --network-

namespace option for specifying the network namespace.

• For replication connections from replica servers to source servers, the CHANGE MASTER TO

statement supports a NETWORK_NAMESPACE option for specifying the network namespace.

For replication monitoring purposes, the Performance Schema

replication_connection_configuration table, the replica server connection metadata

repository (see Replication Metadata Repositories), and the SHOW REPLICA | SLAVE STATUS

statement have a new column that displays the applicable network namespace for connections.

For more information, including the host system prerequisites that must be satisfied to use this feature,

see Network Namespace Support. (WL #12720)

Deprecation and Removal Notes

• From MySQL 8.0.22, the group_replication_ip_whitelist system variable is deprecated, and

the system variable group_replication_ip_allowlist has been added to replace it. The system

variable works in the same way as before, only the terminology has changed.

For both system variables, the default value is AUTOMATIC. If either one of the system variables has

been set to a user-defined value and the other has not, the changed value is used. If both of the system

variables have been set to a user-defined value, the value of group_replication_ip_allowlist is

used. (WL #14175)

• From MySQL 8.0.22, the statements START SLAVE, STOP SLAVE, SHOW SLAVE STATUS, SHOW

SLAVE HOSTS and RESET SLAVE are deprecated. The following aliases should be used instead:

• Instead of START SLAVE use START REPLICA

• Instead of STOP SLAVE use STOP REPLICA

• Instead of SHOW SLAVE STATUS use SHOW REPLICA STATUS

• Instead of SHOW SLAVE HOSTS use SHOW REPLICAS

• Instead of RESET SLAVE use RESET REPLICA

The statements work in the same way as before, only the terminology used for each statement and its

output has changed.

New status variables have been added as aliases for the related status variables. Both the old and new

versions of the statements update both the old and new versions of these status variables:

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MySQL 8.0 Release Notes

• Com_slave_start is equivalent to Com_replica_start

• Com_slave_stop is equivalent to Com_replica_stop

• Com_show_slave_status is equivalent to Com_show_replica_status

• Com_show_slave_hosts is equivalent to Com_show_replicas

(WL #14171)

• The InnoDB memcached plugin is deprecated and support for it will be removed in a future MySQL

version. (WL #14131)

• The INFORMATION_SCHEMA.TABLESPACES table is unused. It is now deprecated and will be removed

in a future MySQL version. Other INFORMATION_SCHEMA tables may provide related information, as

described in The INFORMATION_SCHEMA TABLESPACES Table. (WL #14064)

Keyring Notes

• MySQL Enterprise Edition now includes a keyring_oci plugin that uses Oracle Cloud Infrastructure

Vault as a back end for keyring storage. No key information is permanently stored in MySQL server local

storage. All keys are stored in Oracle Cloud Infrastructure Vault, making this plugin well suited for Oracle

Cloud Infrastructure MySQL customers for management of their MySQL Enterprise Edition keys. For

more information, see The MySQL Keyring. (WL #9770)

Optimizer Notes

• Important Change: A prepared statement is now prepared only once, when executing PREPARE,

rather than once each time it is executed. In addition, a statement inside a stored procedure is also now

prepared only once, when the stored procedure is first executed. This change enhances performance

of such statements, since it avoids the added cost of repeated preparation and rollback of preparation

structures, the latter being the source of several bugs.

As part of this work, the manner in which dynamic parameters used in prepared statements are resolved

is changed, with the resulting changes in prepared statement use cases listed here:

• A parameter used in a prepared statement has its data type determined when the statement is

prepared, and the type persists for each subsequent execution of the statement, unless the statement

is reprepared (see PREPARE Statement, for information about when this may occur).

• For a prepared statement of the form SELECT expr1, expr2, ... FROM table ORDER

BY ?, passing an integer value N for the parameter no longer causes ordering of the results by the

expression in the select list; the results are no longer ordered, as is expected with ORDER BY

constant.

• It was possible (although unsupported) to insert a floating point value into a LIMIT or OFFSET clause

by means of a parameter (and possibly a user variable). This is now explicitly disallowed; such values

must be integers.

• The window functions NTILE(NULL), NTH_VALUE(expr, NULL), LEAD(expr, nn), and

LAG(expr, nn), where nn is a negative number, are now disallowed, to comply with the SQL

standard.

• A user variable that is read by a prepared statement now has its type determined when the statement

is prepared; the type persists for each subsequent execution of the statement.

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MySQL 8.0 Release Notes

• A user variable that is read by a statement within a stored procedure now has its type determined the

first time the statement is executed; the type persists for all subsequent invocations of the containing

stored procedure.

• For parameters for which no contextual information is available to determine the parameter type, the

server assumes the parameter is a character string with the default character set, not a binary string.

Parameters for which this is incorrect may be placed within a CAST() expression.

See PREPARE Statement, for the rules governing how the effectiue data types of parameters and user

variables used within prepared statements are determined.

In addition, the rows (N) argument to the window functions LAG(), LEAD(), and NTILE() must now be

an integer in the range 0 to 2

, inclusive, in any of the following forms:

• an unsigned integer constant literal

• a positional parameter marker (?)

• a user-defined variable

• a local variable in a stored routine

In addition, this argument is no longer permitted to be NULL. See the descriptions of the functions

just referenced for more information. (Bug #48612, Bug #99601, Bug #100150, Bug #105166, Bug

#11756670, Bug #23599127, Bug #31119132, Bug #31365678, Bug #31393719, Bug #31592822, Bug

#31810577, Bug #33448735, WL #9384)

• The filesort algorithm now supports sorting a join on multiple tables, and not just a single table. (Bug

#31310238, Bug #31559978, Bug #31563876)

• When using a RIGHT JOIN, some internal objects, were not converted to those suitable for use with

a LEFT JOIN as intended. These included some lists of tables built at parse time, but which did not

have their order reversed. This required maintaining code to handle instances in which a LEFT JOIN

was originally a RIGHT JOIN as special cases, and was the source of several bugs. Now the server

performs any necessary reversals at parse time, so that after parsing, a RIGHT JOIN is in fact, in all

respects, a LEFT JOIN. (Bug #30887665, Bug #30964002, WL #6509)

References: See also: Bug #12567331, Bug #21350125.

• Added support for periodic synchronization when writing to files with SELECT INTO DUMPFILE

and SELECT INTO OUTFILE statements. This feature can be enabled by setting the

select_into_disk_sync system variable to ON; the size of the write buffer cn be set using the server

system variable select_into_buffer_size; the default buffer size is 131072 (2

) bytes. An optional

delay following synchronization to disk can also be set using the select_into_disk_sync_delay

system variable; the default behaviour is not to allow any delay (that is, a delay time of 0 milliseconds).

For more information, see the descriptions of the system variables referenced previously.

Our thanks to Facebook for this contribution to MySQL 8.0. (Bug #30284861, WL #13926)

• MySQL now implements derived condition pushdown for eligible queries. What this means is that, for

a query such as SELECT * FROM (SELECT i, j FROM t1) AS dt WHERE i > constant,

it is now possible in many cases to push the outer WHERE condition down to the derived table, in this

case resulting in SELECT * FROM (SELECT i, j FROM t1 WHERE i > constant) AS dt.

Previously, if the derived table was materialized and not merged, MySQL materialized the entire table—

in this case t1—then qualified the rows with the WHERE condition.

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MySQL 8.0 Release Notes

When the derived table cannot be merged into the outer query (for example, if the derived table uses

aggregation), pushing the outer WHERE condition down to the derived table can reduce the number of

rows that need to be processed, which should improve the query's performance.

An outer WHERE condition can be pushed down directly to a materialized derived table when the derived

table uses no aggregate or window functions. In addition, when the derived table has a GROUP BY and

uses no window functions, the outer WHERE condition can be pushed down to the derived table as a

HAVING condition. If the derived table uses a window function and the outer WHERE references columns

used in the window function's PARTITION clause, the WHERE condition can also be pushed down.

This optimization cannot be employed for a derived table that contains a UNION or LIMIT clause.

To enable derived condition pushdown, the optimizer_switch system variable's

derived_condition_pushdown flag (added in this release) must be set to on. This is the default

setting. If this optimization is disabled by the optimizer switch setting, you can enable it for a specific

query using the DERIVED_CONDITION_PUSHDOWN optimizer hint (also added in this release). Use the

NO_DERIVED_CONDITION_PUSHDOWN optimizer hint to disable the optimization for a given query.

For further information and examples, see Derived Condition Pushdown Optimization. (Bug #59870, Bug

#88381, Bug #11766303, Bug #27590273, WL #8084)

Packaging Notes

• For RPM and Debian packages, client-side plugins were moved to their own client-plugins package.

(Bug #31584093)

• The VERSION file in MySQL source distributions is now named MYSQL_VERSION due to a naming

conflict with Boost. (Bug #31466846)

• For platforms on which systemd is used to run MySQL, packages no longer include legacy System

V files: the mysqld_multi.server and mysql.server scripts, and the mysql.server.1,

mysqld_multi.1, and mysqld_safe.1 man pages. (Bug #31450888)

Performance Schema Notes

• The SHOW PROCESSLIST statement provides process information by collecting thread data from all

active threads. However, because the implementation iterates across active threads from within the

thread manager while holding a global mutex, it has negative performance consequences, particularly on

busy systems.

An alternative SHOW PROCESSLIST implementation is now available based on the new Performance

Schema processlist table. This implementation queries active thread data from the Performance

Schema rather than the thread manager and does not require a mutex:

• To enable the alternative implementation, enable the performance_schema_show_processlist

system variable.

• The alternative implementation of SHOW PROCESSLIST also applies to the mysqladmin

processlist command.

• The alternative implementation does not apply to the INFORMATION_SCHEMA PROCESSLIST table or

the COM_PROCESS_INFO command of the MySQL client/server protocol.

• To ensure that the default and alternative implementations yield the same information, certain

configuration requirements must be met; see The processlist Table.

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MySQL 8.0 Release Notes

(WL #9090)

• An SQL interface to the most recent events written to the MySQL server error log is now available by

means of queries on the new Performance Schema error_log table. This table has a fixed size, with

old events automatically discarded as necessary to make room for new ones. The table is populated

if error log configuration includes a log sink component that supports this capability (currently the

traditional-format log_sink_internal and JSON-format log_sink_json sinks). Several new status

variables provide information about error_log table operation. See The error_log Table. (WL #13681)

Pluggable Authentication

• These changes were made for the LDAP authentication plugins:

• For the SASL LDAP authentication plugin, the SCRAM-SHA-1 authentication method is not supported

on On SLES 12 and 15 and EL6 systems. The default method on those systems is now GSSAPI.

• If the LDAP host is not set, the LDAP connection pool will not be initialized, which enables successful

authentication plugin installation in cases when previously it would fail. (This might be the case when a

site installs a plugin first, then configures it later.)

• If an LDAP connection parameter is changed at runtime, the LDAP connection pool is reinitialized for

the first subsequent authentication attempt.

• If the LDAP server is restarted, existing connections in the connection pool become invalid. The LDAP

authentication plugin detects this case and reinitializes the connection pool and (for the SASL LDAP

plugin) the SASL challenge is resent.

(Bug #31664270, Bug #31219323)

SQL Syntax Notes

• The parser now supports parenthesized query expressions using this syntax:

( query_expression )

[order_by_clause]

[limit_clause]

[into_clause]

Other variations are possible; see Parenthesized Query Expressions (Bug #30592703)

• It is now possible to cast values of other types to YEAR, using either the CAST() function or the

CONVERT() function. These functions now support YEAR values of one or two digits in the range 0-99,

and four-digit values in the range 1901-2155. Integer 0 is converted to Year 0; a string consisting of

one or more zeroes (following possible truncation) is converted to the year 2000. Casting adds 2000 to

values in the range 1-69 inclusive, and 1900 to values in the range 70-99 inclusive.

Strings beginning with one, two, or four digits followed by at least one non-digit character (and possibly

other digit or non-digit characters) are truncated prior to conversion to YEAR; in such cases, the server

emits a truncation warning. Floating-point values are rounded prior to conversion; CAST(1944.5 AS

YEAR) returns 1945 due to rounding, and CAST("1944.5" AS YEAR) returns 1944 (with a warning)

due to truncation.

DATE, DATETIME, and TIMESTAMP are cast to the YEAR portion of the value. A TIME value is cast to

the current year. Not specifying the value to be cast as a TIME value may yield a different result from

what is expected; CAST("13:47" AS YEAR) returns 2013 due to truncation of the string value, and

CAST(TIME "13:47" AS YEAR) returns 2020 as of the year of this release.

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MySQL 8.0 Release Notes

Casting of GEOMETRY values to YEAR is not supported. A cast of an incompatible type or an out-of-range

or illegal value returns NULL.

YEAR can also be used as the return type for the JSON_VALUE() function. This function supports

four-digit years only, and otherwise follows the same rules as apply to CAST() and CONVERT() when

performing casts to YEAR.

For more information, see the description of the CONVERT() function. (WL #14015)

• When selecting a TIMESTAMP column value, it is now possible to convert it from the system time zone

to a UTC DATETIME when retrieving it, using the AT TIME ZONE operator which is implemented for the

CAST() function in this release.

The syntax is CAST(value AT TIME ZONE specifier AS DATETIME[(precision)]), where

the value is a TIMESTAMP, and the specifier is one of [INTERVAL] '+00:00' or 'UTC'.

(INTERVAL is optional with the first form of the specifier, and cannot be used with 'UTC'.) The

precision of the DATETIME value returned by the cast can optionally be specified up to 6 decimal

places.

Values that were inserted into the table using a timezone offset are also supported.

AT TIME ZONE cannot be used with CONVERT(), or in any other context other than as part of a

CAST() function call. The ARRAY keyword and creation of multi-valued indexes are also not supported

when using AT TIME ZONE.

A brief example is shown here:

mysql> SELECT @@system_time_zone;

+--------------------+

| @@system_time_zone |

+--------------------+

| EDT |

+--------------------+

1 row in set (0.00 sec)

mysql> CREATE TABLE ex (ts TIMESTAMP);

Query OK, 0 rows affected (0.81 sec)

mysql> INSERT INTO ex VALUES

> ROW(CURRENT_TIMESTAMP),

> ROW('2020-07-31 21:44:30-08:00');

Query OK, 2 rows affected (0.09 sec)

Records: 2 Duplicates: 0 Warnings: 0

mysql> TABLE ex;

+---------------------+

| ts |

+---------------------+

| 2020-07-28 21:39:31 |

| 2020-08-01 01:44:30 |

+---------------------+

2 rows in set (0.00 sec)

mysql> SELECT ts, CAST(ts AT TIME ZONE 'UTC' AS DATETIME) AS ut FROM ex;

+---------------------+---------------------+

| ts | ut |

+---------------------+---------------------+

| 2020-07-28 21:39:31 | 2020-07-29 01:39:31 |

| 2020-08-01 01:44:30 | 2020-08-01 05:44:30 |

+---------------------+---------------------+

206

MySQL 8.0 Release Notes

2 rows in set (0.00 sec)

For more information and examples, see the description of the CAST() function in the MySQL Manual.

(WL #12535)

X Plugin Notes

• In specific conditions, terminating an X Protocol connection could cause MySQL Server to stop

unexpectedly. (Bug #31671503)

Functionality Added or Changed

• LOCK TABLES privilege checking for views was improved. (Bug #31304432, WL #14092)

• You can use MySQL Server's new asynchronous connection failover mechanism to automatically

establish an asynchronous (source to replica) replication connection to a new source after

the existing connection from a replica to its source fails. The connection fails over if the

replication I/O thread stops due to the source stopping or due to a network failure. The

asynchronous connection failover mechanism can be used to keep a replica synchronized

with multiple MySQL servers or groups of servers that share data. To activate asynchronous

connection failover for a replication channel set SOURCE_CONNECTION_AUTO_FAILOVER=1

on the CHANGE MASTER TO statement for the channel, and set up a source list for

the channel using the asynchronous_connection_failover_add_source and

asynchronous_connection_failover_delete_source functions. (WL #12649)

• The new innodb_extend_and_initialize variable permits configuring how InnoDB allocates

space to file-per-table and general tablespaces on Linux. By default, when an operation requires

additional space in a tablespace, InnoDB allocates pages to the tablespace and physically writes NULLs

to those pages. This behavior affects performance if new pages are allocated frequently. As of MySQL

8.0.22, you can disable innodb_extend_and_initialize on Linux systems to avoid physically

writing NULLs to newly allocated tablespace pages. When innodb_extend_and_initialize is

disabled, space is allocated using posix_fallocate() calls, which reserve space without physically

writing NULLs.

A posix_fallocate() operation is not atomic, which makes it possible for a failure to occur between

allocating space to a tablespace file and updating the file metadata. Such a failure can leave newly

allocated pages in an uninitialized state, resulting in a failure when InnoDB attempts to access those

pages. To prevent this scenario, InnoDB writes a redo log record before allocating a new tablespace

page. If a page allocation operation is interrupted, the operation is replayed from the redo log record

during recovery. (WL #13782)

• To permit concurrent DML and DDL operations on MySQL grant tables, read operations that previously

acquired row locks on MySQL grant tables are now executed as non-locking reads. The operations that

are now performed as non-locking reads on MySQL grant tables include:

• SELECT statements and other read-only statements that read data from grant tables through join lists

and subqueries, including SELECT ... FOR SHARE statements, using any transaction isolation level.

• DML operations that read data from grant tables (through join lists or subqueries) but do not modify

them, using any transaction isolation level.

Statements that no longer acquire row locks when reading data from grant tables report a warning if

executed while using statement-based replication.

When using -binlog_format=mixed, DML operations that read data from grant tables are now written

to the binary log as row events to make the operations safe for mixed-mode replication.

207

MySQL 8.0 Release Notes

SELECT ... FOR SHARE statements that read data from grant tables now report a warning. With the

FOR SHARE clause, read locks are not supported on grant tables.

DML operations that read data from grant tables and are executed using the SERIALIZABLE isolation

level now report a warning. Read locks that would normally be acquired when using the SERIALIZABLE

isolation level are not supported on grant tables. (WL #14087)

• The ALTER DATABASE statement now supports a READ ONLY option that controls whether to permit

modification of a database and objects within it. This option is useful for database migration because a

database for which READ ONLY is enabled can be migrated to another MySQL instance without concern

that the database might be changed during the operation. See ALTER DATABASE Statement.

A new INFORMATION_SCHEMA table named SCHEMATA_EXTENSIONS displays database options.

Currently, it displays READ ONLY=1 for read-only databases. See The INFORMATION_SCHEMA

SCHEMATA_EXTENSIONS Table. (WL #13369)

Bugs Fixed

• InnoDB: Code related to transaction support for histogram sampling was removed, including related

assertion code that caused test failures. Transaction support is not required for histogram sampling.

(Bug #31787736)

• InnoDB: Encryption information was not set for redo log archive log writer thread write operations. (Bug

#31690196)

• InnoDB: The TTASEventMutex::exit function was optimized for ARM64. Thanks to Krunal Bauskar

for the contribution. (Bug #31589019, Bug #100132)

• InnoDB: InnoDB failed to compile with the DISABLE_PSI_RWLOCK CMake option enabled. (Bug

#31578289)

• InnoDB: The transaction isolation level, which is set to READ UNCOMMITTED for histogram sampling to

avoid unnecessary lookups of old record versions, was not reset after the sampling operation completed.

(Bug #31564407)

• InnoDB: A query that updated the clustered index of an internal temporary table returned an incorrect

result. The modified pages of the clustered index were not added to the flush list resulting in lost

changes when the modified pages were evicted from the buffer pool. (Bug #31560679)

References: This issue is a regression of: Bug #29207450.

• InnoDB: A build dependency on the Boost library defined for the TempTable storage engine was

removed. (Bug #31505048)

• InnoDB: A workaround was implemented to handle a Clang compiler issue in 32-bit builds that

causes the ATOMIC_LLONG_LOCK_FREE value to be defined as “sometimes lock-free” while

__atomic_always_lock_free returns true for the same type on the same platform. (Bug #31504609)

• InnoDB: A REDUNDANT row format table created in an earlier version of MySQL, where the row format

was not defined explicitly, permitted the addition of an index that exceeded the REDUNDANT row format

index column size limit. (Bug #31479542, Bug #99791)

• InnoDB: A DML operation on a column defined with a multi-valued index caused a failure. (Bug

#31479282)

• InnoDB: A failure occurred during master key rotation. An undo tablespace in-memory object was freed

prematurely. (Bug #31467626)

208

MySQL 8.0 Release Notes

• InnoDB: Unused physical read ahead code was removed from the parallel read interface. (Bug

#31429385)

• InnoDB: A master key rotation operation failed to skip an undo tablespace that was already truncated,

which lead to an assertion failure when shutting down the server. (Bug #31400195)

• InnoDB: After importing a tablespace for a page-compressed table, pages were no longer compressed,

and INFORMATION_SCHEMA.INNODB_TABLESPACES metadata incorrectly indicated that pages were

compressed. The table's compression information was unavailable during the import operation. (Bug

#31396947)

• InnoDB: A rollback and update operation after performing an instant DDL operation raised an assertion.

(Bug #31391126)

• InnoDB: The log system (log_sys) sharded read-write lock caused a performance regression in CPU-

bound workloads. (Bug #31389135)

• InnoDB: Compiling with the UNIV_ENCRYPT_DEBUG option enabled caused compilation errors. (Bug

#31369540)

• InnoDB: DDL operations on a partitioned table could cause a failure. TABLE_SHARE and table instance

objects were opened for all partitions unnecessarily. (Bug #31365127)

• InnoDB: After changing a VARCHAR column collation from utf8mb4 to utf8mb4_bin in an in-place

ALTER TABLE operation and adding an index on the same column, a case-sensitive query on the

VARCHAR column returned an incorrect result. The VARCHAR column collation was changed in the data

dictionary but not in the in-memory table object. Consequently, the index created on the VARCHAR

column used stale column information causing comparisons to use the previously defined collation. (Bug

#31361838)

• InnoDB: An ALTER TABLE ... IMPORT TABLESPACE operation on a large encrypted and

compressed table failed with a Page decompress failed after reading from disk error. The

decryption operation did not use the encryption block size used during encryption. Also, the encryption

process did not consider compressed length, while the decryption process decrypts data by compressed

length only. (Bug #31313533)

• InnoDB: A failure occurred during a concurrent update operation. The failure was due to an invalid

previous record value. (Bug #31205266, Bug #99286)

• InnoDB: Upgrade from MySQL 5.7 to MySQL 8.0 failed on an instance with a table created in a general

tablespace and defined with a FULLTEXT index. The correct data dictionary space ID for table could not

determined. (Bug #31154128, Bug #99211)

• InnoDB: The function used to process the SHOW ENGINE INNODB MUTEX statement was insufficiently

isolated from other threads adding new mutexes concurrently. (Bug #31105262)

• InnoDB: Failure to call a buffer pool page I/O completion routine resulted in orphan buffer pool I/O write

pages. (Bug #31073853)

• InnoDB: Numerous system temporary table pages at the tail of the buffer pool flush list caused a

performance degradation. The flush_list_mutex was held while the flush list scan traversed over

system temporary table pages. The flush list scan now excludes system temporary table pages. (Bug

#31060470, Bug #98974)

• InnoDB: The buffer control block structure (buf_block_t) was freed while reducing the

size of the buffer pool, causing an assertion failure. The fix for this bug also backports

important aspects of the fix for Bug #20735882 / Bug #76343, and replaces the internal

209

MySQL 8.0 Release Notes

buf_block_is_uncompressed() function with the buf_pointer_is_block_field_instance()

function. The buf_block_is_uncompressed() function returned false in too many cases, affecting

OLTP query throughput. (Bug #31036301, Bug #31389823)

• InnoDB: Parallel read threads failed to respond to an explicit transaction interruption. (Bug #31016076)

• InnoDB: In session started with START TRANSACTION WITH CONSISTENT SNAPSHOT, a range query

returned a truncated result. The end range flag was not reset at the beginning of the index read resulting

in an aborted read and missing rows. (Bug #30950714, Bug #98642)

References: This issue is a regression of: Bug #23481444.

• InnoDB: A full-text phrase search raised an assertion failure. Thanks to TXSQL (Tencent MySQL) for

the contribution. (Bug #30933728, Bug #31228694)

References: This issue is a regression of: Bug #22709692.

• InnoDB: A failure occurred while attempting to initialize the system tablespace on a raw disk partition.

Additionally, a INPLACE DDL operation on the raw-disk partition tablespace failed with an error instead

of switching to the COPY algorithm. (Bug #30867065, Bug #98091)

• InnoDB: LOB purge code (lob::purge()) did not properly handle latches taken during B-tree mini-

transaction (btr_mtr) commit and restore operations, which could lead to conflicts between B-tree and

LOB mini-transactions. (Bug #30620011)

• InnoDB: A long running statistics calculation operation on a large table blocked other operations

requiring access to the table's statistics, causing those operations to fail. A new statistics calculation

mutex was introduced, which permits concurrent access table statistics. Thanks to Kamil Holubicki for

the contribution. (Bug #30607708)

• InnoDB: Two connections attempted to use the same transaction handler object resulting in a stalled

query. (Bug #30594501)

• InnoDB: Shutting down the server with innodb_fast_shutdown setting greater than 0 raised an

assertion failure. The assertion was caused by the presence of recovered transactions that were not

yet rolled back. Assertion code was revised to ignore recovered transactions during a fast shutdown.

Messages are now written to the error log when recovered transactions that are not rolled back are

left behind by a fast shutdown. Slow shutdown now waits for recovered transactions to be rolled back.

Various other shutdown logic improvements were implemented. (Bug #30226841)

• InnoDB: Dedicated log writer threads, introduced in MySQL 8.0.11, caused a CPU-bound

performance regression on low-concurrency systems. To address this issue, the new

innodb_log_writer_threads variable permits disabling dedicated log writer threads so that redo

log records are written from the log buffer to the system buffers and flushed from the system buffers

to the redo log files by each user thread, which is the behavior prior to the introduction of dedicated

log writer threads. Other redo logging optimizations were implemented, including the removal of an

unnecessary log closer thread that wasted CPU time, and optimizations to remedy too-aggressive

checkpoint activity and excessive flush calls. The issues addressed by this fix also manifested in a LOAD

DATA performance regression. (Bug #30088404, Bug #30003849)

• InnoDB: Restarting the server with an incorrect lower_case_table_names setting after a failure

caused a hang condition. At startup, InnoDB waited for a transaction to roll back, but the rollback thread

was not initiated due to a startup validation failure caused by the incorrect lower_case_table_names

setting. (Bug #29833945)

• Packaging; Group Replication: MySQL Server Docker images did not expose the Group Replication

recommended port (33061). (Bug #31627536)

210

MySQL 8.0 Release Notes

• Packaging: Added a client-plugins RPM that was separated from the client package. It contains

shared plugins for MySQL client applications. (Bug #35162346)

• Replication: You can now set the value of the gtid_purged system variable in a stored procedure,

which was not previously permitted. You cannot set gtid_purged in a stored function. (Bug

#31571427)

• Replication: When a replication source server shuts down and restarts, its MEMORY tables become

empty. To replicate this effect to replicas, the first time that the source uses a given MEMORY table after

startup, it logs an event that notifies replicas that the table must be emptied by writing a statement to

the binary log to that effect. Previously, this was a DELETE statement, but it is now a TRUNCATE TABLE

statement. A replica server also writes this statement to its own binary log when it shuts down and

restarts. The statement is always logged in statement format, even if the binary logging format is set

to ROW, and it is written even if read_only or super_read_only mode is set on the server. (Bug

#29848785, Bug #95496)

• Replication: When the system variable session_track_gtids was set to OWN_GTID on a

multithreaded replica, the replica’s performance would degrade over time and begin to lag behind the

master. The cause was the buildup of the GTIDs recorded by the replica’s worker threads at each

transaction commit, which increased the time taken by the worker threads to insert new ones. Session

state tracking is now disabled for worker threads on a multithreaded replica. Thanks to Facebook for the

contribution. (Bug #29049207, Bug #92964)

• Replication: When using row-based replication, the replica was allowed to use an invisible index when

searching for rows to synchronize. (Bug #96148, Bug #30072179)

• Group Replication: X Plugin could stop unexpectedly if a Group Replication notification was issued

after a new X Protocol connection was made but before the session was created. The dispatcher

thread that handles Group Replication notifications now checks that the session pointer is valid. (Bug

#31742798)

• Group Replication: Group Replication handling of memory allocation issues when adding transaction

write sets has been improved. (Bug #31586243)

• Group Replication: While a remote cloning procedure was taking place on a joining member during

distributed recovery, Group Replication considered the pre-cloning gtid_executed value on the joining

member when identifying the common set of transactions that had been applied on all members. This

meant that garbage collection for applied transactions from the group's set of certification information

(shown as the count_transactions_rows_validating field in the Performance Schema table

replication_group_member_stats) did not take place during the remote cloning procedure. If the

remote cloning procedure took a long time, the certification information could therefore get too large to

transmit to the joining member when it restarted after the remote cloning procedure, in which case an

error was raised and the member was not able to join the group.

To avoid this issue, Group Replication now considers only group members with ONLINE status when

identifying the common set of transactions that have been applied on all members. When a joining

member enters ONLINE state after distributed recovery, its certification information is updated with the

certification information from the donor at the time when the member joined, and garbage collection

takes place for this on future rounds.

As a workaround for this issue in earlier releases, after the remote cloning operation completes, wait two

minutes to allow a round of garbage collection to take place to reduce the size of the group's certification

information. Then issue the following statement on the joining member, so that it stops trying to apply the

previous set of certification information:

RESET SLAVE FOR CHANNEL group_replication_recovery;

211

MySQL 8.0 Release Notes

(Bug #31446381, Bug #99778)

• Group Replication: It was possible for a group member that left the group due to a communication error

to reconnect between auto-rejoin attempts while the auto-rejoin procedure was still ongoing, which left

Group Replication unable to function on the member. Group Replication error management and member

status handling has now been corrected to prevent this situation. (Bug #31401797)

• Microsoft Windows: On Windows, build targets could fail if the build was on a file system root, such as

R:/. (Bug #31315467)

• JSON: JSON_OBJECT() did not always perform proper checking for NULL values. (Bug #31393934)

• The new WITH_SYSTEMD_DEBUG CMake option, if enabled, produces additional systemd debugging

information, for platforms on which systemd is used to run MySQL. The default is OFF. (Bug #31788834)

• For RPM and Debian packages, client-side plugins were moved from the server package to the client

package in MySQL 8.0.21. This could cause failures relating to LDAP authentication plugins when

upgrading from 5.7 packages to 8.0 packages. Packaging adjustments were made to avoid this problem.

(Bug #31782612)

References: This issue is a regression of: Bug #31123564, Bug #31336340.

• The timestamp written for the ts key by the log_sink_json JSON-format error log sink did not have

the same value as other timestamps in the same log message. (Bug #31749103)

• Kerberos authentication for the SASL LDAP authentication plugin incorrectly handled failure to acquire a

ticket-granting ticket. (Bug #31727195)

• For some third-party libraries, enabling link-time optimization caused build failures. (Bug #31701553,

Bug #100410)

• Printing an excessively long diagnostic message could cause the server to exit unexpectedly. (Bug

#31686926)

• A page-compressed table was cloned as an uncompressed table. The associated tablespace object,

which includes a compression flag, was not initialized prior to the cloning operation. (Bug #31677990,

Bug #100243)

• Certain cases of successful LDAP authentication could cause the server to hang. (Bug #31661437)

• During transformation of a grouped query into a derived table, when the WHERE clause and the HAVING

clause became part of the derived table, the condition count was not updated for the derived table. This

resulted in reduced memory allocation while creating keys for ref access. (Bug #31661309)

• When a value was compared using LIKE with a table column not defined as one of the MySQL string

types, the server sometimes did not raise the expected error. (Bug #31659015)

• The acquire_related() service function returned the default service in some cases when it should

have returned an error. (Bug #31655906)

• In bootstrapping mode, certain multiple-statement transactions could cause unexpected server behavior.

(Bug #31650096)

• A remote cloning operation checked for the availability of a plugin on the recipient that was removed

from the donor instance previously. References to the uninstalled plugin had not been released. Error

reporting issues related to plugin mismatches and availability were also addressed. (Bug #31639732,

Bug #100244)

212

MySQL 8.0 Release Notes

• In debug builds, the server attempted to evaluate subqueries while creating a view. (Bug #31590301)

References: This issue is a regression of: Bug #25466100.

• A condition using RAND() was not pushed down even in cases where it was safe to do so, that is when

no windowing function or GROUP BY is in use. (Bug #31587575)

• While pushing conditions down to a derived table, a constant condition such as WHERE FALSE or WHERE

TRUE was pushed down to the first table in the derived table, which is not necessary as the condition has

nothing to do with the derived table. MySQL now avoids pushing constant conditions down to derived

tables in such cases.

In addition used tables are now updated for the condition that needs to be pushed down to the derived

table, following code inspection revealing that this was not done after replacing the columns in the

condition with the derived table expressions. (Bug #31587493)

• A query using WHERE column > (... IN (SELECT ...)) could sometimes trigger an assertion in

the range optimizer. (Bug #31586906)

References: This issue is a regression of: Bug #30473261.

• It was possible for ANALYZE TABLE to fail with Duplicate key error if a row was inserted in

the interval between the check for the existence of the row and the execution of the insert, and the

statistics table was updated concurrently. ANALYZE TABLE now ignores the error in this situation. (Bug

#31582758)

• The range optimizer does not use the correct lock type after cloning the handler needed to perform

merged scans, and instead used a read lock unconditionally. This resulted in various different side

effects for different scenarios.

For example, a SELECT with FOR UPDATE requests a write lock, but after cloning the handler for an

index merge scan, the range optimizer requested a read lock which resulted in a mismatch. Similarly, for

data dictionary tables, the lock type was set to LOCK_NONE due to the special handling required for such

tables.

To prevent this problem from occurring, we now ensure that the original lock type of the handler is

always used in the cloned handler as well. (Bug #31582383)

• In some cases, a query using an ANY subquery gave an incorrect result when the

subquery_to_derived optimizer switch was enabled. (Bug #31566339)

• When FALSE AND condition was simplified as FALSE, temporary table resources allocated for the

condition were not always released afterwards. (Bug #31565009)

• A value equal to ULLONG_MAX could be inserted into a BIT(64) column, but not retrieved. (Bug

#31564742, Bug #100053)

• While removing an unused window definition, a subquery that was part of an ORDER BY was not

removed. The optimizer then tried to optimize the subquery without locking the tables. Now, when

removing an unused window definition, the server cleans up any subqueries present as part of the

definition. (Bug #31518806)

References: This issue is a regression of: Bug #27062031.

• A coding problem introduced in MySQL 8.0.20 could cause client applications to exit unexpectedly

during shutdown. (Bug #31515752)

References: This issue is a regression of: Bug #27045306.

213

MySQL 8.0 Release Notes

• Added a missing error code translation from ICU U_REGEX_NUMBER_TOO_BIG to MySQL

ER_REGEX_NUMBER_TOO_BIG. (Bug #31514995)

• Merging during filesort operations could fail to remove duplicates for queries that used DISTINCT.

(Bug #31498664, Bug #99900)

• MySQL's internal DYNAMIC_STRING class formerly allocated memory in a linear fashion, that is, by

a predetermined number of bytes. The class has been revised such that it now allocates memory

exponentially, which should make operations such as repeated string appends more efficient. (Bug

#31491799)

• LOCK_mutex mishandling could result in a memory leak. (Bug #31491146)

• A newly added collation was not added and could cause an unexpected exit on shutdown. (Bug

#31470422)

• On Windows, file name reuse by the GetTempFileName() function could cause an assertion to be

raised. (Bug #31468590)

• A LATERAL subquery was incorrectly converted into an antijoin. (Bug #31465717)

• NATURAL JOIN evaluation could inadvertently match hidden virtual columns created by functional

indexes. (Bug #31463511, Bug #99807)

• Sort keys for string hash join keys using more than 1024 bytes were not handled correctly by the server.

(Bug #31437753)

• The server attempted to delete from a view whose definition included HAVING when the HAVING clause

was constant and evaluated as true even though a view with HAVING as part of its definition should not

be updatable. (Bug #31429865)

• Privilege requirements were checked incorrectly for the INFORMATION_SCHEMA.USER_ATTRIBUTES

table. (Bug #31427410)

• When the internal function replace_index_subquery() failed, the server still attempted to create

iterators for the affected subquery. Now the function raises a clear error instead. (Bug #31427072)

• A query using WHERE NOT EXISTS (SELECT const FROM table WHERE

column=FROM_UNIXTIME(value) was not handled correctly. (Bug #31425664)

• In some cases, key_hint handling was improperly applied to derived and internal temporary tables.

(Bug #31424455)

• Re-execution of prepared INSERT statements could fail for inserts through a view. (Bug #31417951)

• JSON scalar evaluation could enter an infinite loop. (Bug #31406724)

• The user_attributes column in mysql.user table rows could be affected incorrectly by partial

revokes. (Bug #31405985)

• Improper window function initialization could cause a server exit. (Bug #31389573, Bug #31437834)

• Sensitive LDAP authentication plugin system variables now display as asterisks when retrieved in SQL

statements. (Bug #31388444, Bug #31391864)

• mysql-test-run.pl tests under no-threads connection handling failed with ASAN builds due

to improper resource group initialization. This has been fixed. Thanks to Xiaoyu Wang, Tencent

Technology for the contribution. (Bug #31378900, Bug #99609)

214

MySQL 8.0 Release Notes

• Using the authentication_ldap_simple authentication plugin with SSL could cause a

segmentation fault during shutdown. (Bug #31364927)

• Killing a query could raise spurious assertions in the hash join iterator. (Bug #31361354)

• In some cases, an outer reference that was not LATERAL was not marked as read-only as expected.

(Bug #31359965)

• A failure occurred when upgrading from MySQL 5.7 to MySQL 8.0 due to invalid references to orphaned

events (events for which a database no longer exists). The server now fails with an appropriate error

messages when orphaned events are encountered during upgrade. Error messages for orphaned stored

routines were also revised. (Bug #31335554)

• Enabling the create_admin_listener_thread system variable could cause a server exit during

startup. (Bug #31335279)

• After ALTER TABLE to add an expression default to a column, the first insert inserted a value as if the

expression had been evaluated at alter time and not insert time. (Bug #31330789, Bug #99513)

• The LDAP authentication plugins did not properly compare the user-supplied authentication method

against the permitted methods. (Bug #31320532)

• Certain views could cause a following USE statement to result in an unexpected server exit. (Bug

#31311312)

• When a filesort sorted a buffer and LIMIT was active, it first sorted all rows and then discarded those

that did not fit within the limit, which required sorting many rows that were certain to be discarded later.

Now the optimizer sorts only the rows actually needed. Internal testing shows that this change can speed

up the sort phase for a simple string sorting benchmark (as measured by EXPLAIN ANALYZE) by up to

15%. (Bug #31303537)

• A dynamic range scan runs the range optimizer for each row fetched from the first table in a join to

determine whether a range scan can be picked for the second table using the value available from that

row. If the row contains no usable indexes, a table scan may be chosen instead. For the query giving

rise to this issue, a table scan is chosen once, followed by a range scan on a non-covering index, and

the dynamic range iterator has two read sets which are used for both these cases. One of these, used

for the table scan, includes the base columns of generated columns required for processing the query;

the other read set does not include the base columns in the read set used for range scans. This is

because, for covering indexes, the read set should not include base columns to avoid adding unneeded

columns by hash join or batched key access. The issue arose because the second read set was also

used for a non-covering index, which resulted in an assert.

To prevent this from happening, when initializing a table read set in the dynamic range iterator, we now

make sure that it includes the base columns when the range optimizer picks a non-covering index. (Bug

#31280526)

References: This issue is a regression of: Bug #30417361.

• It was possible to insert an out-of-range value for a TIMESTAMP if it included a timezone offset. (Bug

#31239157)

• The keyring_hashicorp keyring plugin did not limit the size of keys for key operations. (Bug

#31205715)

• Configuring with -DWITH_ZSTD=system failed for older versions of the zstd library. CMake now checks

the zstd version and requires at least 1.0.0 for compilation, 1.2.0 to run compression checks. (Bug

#31174920, Bug #99241)

215

MySQL 8.0 Release Notes

• In some cases, a SELECT that obtained status variable information from Performance Schema tables

and that included a sort by a column containing temporal values was not handled correctly. (Bug

#31168097)

• In some cases, ROUND() and TRUNCATE() did not return the data type of their first arguments as

expected. This fix insures that return types from these functions follow these rules, where the first

argument is of the type shown:

• For any integer type, the return type is BIGINT.

• For any floating-point type or any non-numeric type, the return type is DOUBLE.

• For DECIMAL, the return type is also DECIMAL.

• The type attributes for the return value are also copied from the first argument, except in the case of

DECIMAL, when the second argument is a constant value.

• When the desired number of decimal places is less than the scale of the argument, the scale and the

precision of the result are adjusted accordingly. In addition, for the ROUND() function, the precision is

extended by one place to accomodate rounding that increases the number of significant digits. If the

second argument is negative, the return type is adjusted such that its scale is 0, with a corresponding

precision.

For more information, see the description of the ROUND() function. (Bug #31128028)

• A SELECT ... FOR SHARE statement now only requires the SELECT privilege. Previously, the SELECT

privilege was required with at least one of the DELETE, LOCK TABLES, or UPDATE privileges. (Bug

#31096384, Bug #99101)

• A semijoin strategy was chosen for the join of a correlated subquery having a LIMIT clause and

requiring a row other than the first, which caused the LIMIT clause to be ignored and invalid rows to be

returned. Now, when LIMIT used with this type of join specifies a row other than the first row, or more

than one row, the semijoin strategy is no longer employed. (Bug #31096309)

• After the fix for Bug #81009, privilege checks for truncating Performance Schema tables were too

restrictive when read_only or super_read_only were enabled, causing truncation to fail even for

users with appropriate table privileges. (Bug #31080309, Bug #99072)

References: This issue is a regression of: Bug #81009.

• ORDER BY did not work as expected for queries with ROLLUP in which window functions were also used.

(Bug #31073133)

• Some INSERT statements were not handled correctly. (Bug #31072198)

• Date interval calculations checked for overflow but not underflow. Now they check for both. (Bug

#31054071)

• If an XA prepared transaction rollback XID was incorrectly formatted, the transaction remained in

recovered state for XA COMMIT and XA ROLLBACK statements (or raised an assertion for debug builds)

rather that reporting an error. (Bug #31030205)

• Database-level privileges inherited through a role were not handled properly for database names that

contained wildcard characters. (Bug #31013538, Bug #98876)

• When the --local option was given, mysqlimport mishandled the

MYSQL_OPT_LOAD_DATA_LOCAL_DIR option for mysql_options() so that it had no effect. (Bug

#31001550)

216

MySQL 8.0 Release Notes

• Certain prepared statements could cause an unexpected server exit. (Bug #30943963)

• OPTIMIZE TABLE for MyISAM tables could cause table size to increase and query performance to

decrease. REPAIR TABLE for MyISAM tables could cause the Table is already up to date

status produced by a previous OPTIMIZE TABLE to be lost. (Bug #30869674, Bug #98511, Bug

#29755517)

• mysqlpump object validation included objects in excluded databases. (Bug #30819012)

• Inserting a TIMESTAMP value having a timezone offset which also had a zero for the month, day, or both,

led to an assert. Such a value should be and is now rejected, regardless of the sql_mode setting. (Bug

#30786762)

References: See also: Bug #31239157.

• Privileges granted using roles could be mishandled at the column-privilege level. (Bug #30660403, Bug

#97971)

• Comparison of a TIME value with NULL in some cases raised an assertion. (Bug #30324587)

References: This issue is a regression of: Bug #25949639.

• LDAP authentication plugins enforced CA verification incorrectly, which could result in use of an incorrect

CA. (Bug #30220357)

• ORDER BY queries were not executed correctly when sort_buffer_size and max_sort_length

were set to values which caused the internal limit on the maximum number of keys allowed per sort

buffer to be set to 0. (Bug #30175483)

• A large number of nested arguments in full-text search query caused an error. (Bug #29929684)

• A potential misreporting of memory use by the Performance Schema has been corrected. (Bug

#29912403)

• When explicit_defaults_for_timestamp was disabled and a NULL was inserted into a

generated column declared as TIMESTAMP NOT NULL, the server would attempt to convert the inserted

value to CURRENT_TIMESTAMP. Such an insertion is now rejected with ER_BAD_NULL_ERROR. (Bug

#29449518)

• The SET_VAR hint did not accept a floating point value specified as a system variable setting. (Bug

#29349748)

• Previously, when NULL was used as the format argument to STR_TO_DATE(), irrelevant warnings were

printed. Now, when NULL is passed to it, the function returns NULL. (Bug #27265863)

• In some cases, incorrect use of IS NULL generated multiple warnings about invalid arguments. (Bug

#27264652)

• Resolving an ORDER BY column that referred to a SELECT list column from a derived table was not

performed correctly when executing certain prepared statements. (Bug #26808862)

• When using EXPLAIN on a multi-table UPDATE statement in which a generated column was referenced

in a condition, the output always showed the table containing this column as being updated, whether the

table was actually updated or not. (Bug #22671310)

• An assertion could be raised when the SQL layer passed incorrect information to InnoDB about the type

of operation to be performed on a temporary table. (Bug #22503696)

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MySQL 8.0 Release Notes

• This construct works for base tables to insert a row using all default values but failed for views:

INSERT INTO name () VALUES ();

(Bug #15988466, Bug #67863)

• In some cases, the server issued an error when an invisible index was used in an index hint even when

the use_invisible_indexes optimizer switch was not set to OFF. (Bug #100024, Bug #31550839)

• Regular expression functions such as REGEXP_LIKE() yielded inconsistent results with binary string

arguments. These functions now reject binary strings with an error. (Bug #98950, Bug #98951, Bug

#31031886, Bug #31031888)

• When range values specified in a predicate are not compatible with the data type of the column with

which the values are compared, the range optimizer rounds off the range values and assigns certain

flags so that it does not exclude rows that qualify for the range because of rounding. In the specific

query that triggered the reported issue, a column named id of type INT was tested using id NOT

IN (-0.1, 0.1), and the values being tested are rounded to integers, with the predicate thus being

treated as NOT IN (0,0). The optimizer then treats this as the intervals id < 0 and 0 < id <

0, but in this case it also set a flag to a value that indicated that reads should begin following rows

containing 0 for the value to be compared. Now in such cases, the flag is set in such a way that the

values which have been rounded are treated correctly. (Bug #98826, Bug #30988735)

References: This issue is a regression of: Bug #80244, Bug #22661012.

• For a view based on a join having an updatable part and one that was not, the error message generated

when attempting to update a column of this view that was not updatable referenced the source table

or view instead of the view actually named in the offending UPDATE statement. (Bug #80655, Bug

#22891840)

Changes in MySQL 8.0.21 (2020-07-13, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

In the documentation for MySQL 8.0.21, we have started changing the term “master” to “source”, the

term “slave” to “replica”, the term “whitelist” to “allowlist”, and the term “blacklist” to “blocklist”. There are

currently no changes to the product's syntax, so these terms are still present in the documentation where

the current code requires their use. See the blog post MySQL Terminology Updates for more information.

• Account Management Notes

• C API Notes

• Compilation Notes

• Configuration Notes

• Connection Management Notes

• Deprecation and Removal Notes

• JSON Notes

• Optimizer Notes

• Packaging Notes

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MySQL 8.0 Release Notes

• Pluggable Authentication

• Security Notes

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• You can now set per-user comments and attributes when creating or updating MySQL user accounts.

A user comment consists of arbitrary text passed as the argument to a COMMENT clause used with a

CREATE USER or ALTER USER statement. A user attribute consists of data in the form of a JSON object

passed as the argument to an ATTRIBUTE clause used with either of these two statements. The attribute

can contain any valid key-value pairs in JSON object notation.

For example, the first of the following two statements creates a user account bill@localhost with the

comment text This is Bill's user account. The second statement adds a user attribute to this

account, using the key email, with the value [email protected].

CREATE USER 'bill'@'localhost' COMMENT 'This is Bill\'s user account';

ALTER USER 'mary'@'localhost'

ATTRIBUTE '{"email":"[email protected]"}';

Only one of COMMENT or ATTRIBUTE can be used in the same CREATE USER or ALTER USER

statement.

User comments and user attributes are stored together internally as a JSON object, with the comment

text as the value of an element with the key comment. You can information retrieve user comments and

user attributes from the ATTRIBUTE column of the INFORMATION_SCHEMA.USER_ATTRIBUTES table;

since this data is in JSON format, you can work with it using MySQL's JSON function and operators (see

JSON Functions). Changes to an existing user attribute are merged with its current value, as you had

used JSON_MERGE_PATCH(); new key-value pairs are appended to the attribute, and new values for

existing keys overwrite their previous values.

To remove a given key-value pair from a user attribute, use ALTER USER user ATTRIBUTE

'{"key":null}'.

For more information and examples, see CREATE USER Statement, ALTER USER Statement, and The

INFORMATION_SCHEMA USER_ATTRIBUTES Table. (WL #13562)

References: See also: Bug #31067575.

C API Notes

• Per OpenSSL recommendation, x509_check_host() and X509_check_ip_asc() calls in

the C client library were replaced, respectively, with X509_VERIFY_PARAM_set1_host() and

X509_VERIFY_PARAM_set1_ip_asc() calls. (Bug #29684791)

• The MySQL C API now supports compression for asynchronous functions. This means that the

MYSQL_OPT_COMPRESSION_ALGORITHMS and MYSQL_OPT_ZSTD_COMPRESSION_LEVEL options for

the mysql_options() function now affect asynchronous operations, not just synchronous operations.

See mysql_options().

219

MySQL 8.0 Release Notes

Our thanks to Facebook for the contribution. (Bug #96802, Bug #30284871, WL #13510)

Compilation Notes

• The minimum version of the Boost library for server builds is now 1.72.0. (Bug #30963985)

Configuration Notes

• tcmalloc is no longer a permitted value for the mysqld_safe --malloc-lib option. (Bug

#31372027)

Connection Management Notes

• MySQL Server supports a “main” network interface for ordinary client connections, and optionally

an administrative network interface for administrative client connections. Previously, the main and

administrative interfaces used the same TLS configuration, such as the certificate and key files for

encrypted connections. It is now possible to configure TLS material separately for the administrative

interface:

• There are new configuration parameters that apply specifically to the administrative interface.

• The ALTER INSTANCE RELOAD TLS statement is extended with a FOR CHANNEL clause that

enables specifying the channel (interface) for which to reload the TLS context.

• The new Performance Schema tls_channel_status table exposes TLS context properties for the

main and administrative interfaces.

• For backward compatibility, the administrative interface uses the same TLS context as the main

interface unless some nondefault TLS parameter value is configured for the administrative interface.

For more information, see Administrative Interface Support for Encrypted Connections, ALTER

INSTANCE Statement, and The tls_channel_status Table. (WL #13850)

Deprecation and Removal Notes

• Partitioning: Columns with index prefixes are not supported as part of a table's partitioning key;

previously such columns were simply omitted by the server when referenced in creating, altering, or

upgrading a table that was partitioned by key, with no indication that this omission had taken place,

except when the proposed partitioning function used only columns with prefixes, in which case the

statement failed with an error message that did not identify the actual source of the problem. This

behavior is now deprecated, and subject to removal in a future release in which using any such columns

in the proposed partitioning key will cause the CREATE TABLE or ALTER TABLE statement in which

they occur to be rejected.

When one or more columns using index prefixes are specified as part of the partitioning key, a warning is

now generated for each such column. In addition, when a CREATE TABLE or ALTER TABLE statement

is rejected because all columns specified in the proposed partitioning key employ index prefixes, the

error message returned now makes clear the reason the statement did not succeed. This includes cases

in which the columns proposed the partitioning function are defined implicitly as those in the table's

primary key by employing an empty PARTITION BY KEY() clause.

For more information and examples, see Column index prefixes not supported for key partitioning, and

KEY Partitioning. (Bug #29941932, Bug #29941959, Bug #31100205, WL #13588)

References: See also: Bug #29942014.

220

MySQL 8.0 Release Notes

JSON Notes

• Added the JSON_VALUE() function, which simplifies creating indexes on JSON columns. A call to

JSON_VALUE(json_doc, path RETURNING type) is equivalent to calling CAST( JSON_UNQUOTE(

JSON_EXTRACT(json_doc, path) ) AS type), where json_doc is a JSON document, path

is a JSON path expression pointing to a single value within the document, and type is a data type

compatible with CAST(). RETURNING type is optional; if no return type is specified, JSON_VALUE()

returns VARCHAR(512).

JSON_VALUE() also supports ON EMPTY and ON ERROR clauses similar to those used with

JSON_TABLE().

You can create indexes on a JSON column using JSON_VALUE() as shown here:

CREATE TABLE inventory(

items JSON,

INDEX i1 ( (JSON_VALUE(items, '$.name' RETURNING CHAR(50))) ),

INDEX i2 ( (JSON_VALUE(items, '$.price' RETURNING DECIMAL(5,2))) ),

INDEX i3 ( (JSON_VALUE(items, '$.quantity' RETURNING UNSIGNED)) )

);

Assuming the items column contains values such as '{"name": "hat", "price": "22.95",

"quantity": "17"}', you can issue queries, such as the following, that are able to use these

indexes:

SELECT items->"$.price" FROM inventory

WHERE JSON_VALUE(items, '$.name' RETURNING CHAR(50)) = "hat";

SELECT * FROM inventory

WHERE JSON_VALUE(items, '$.price' RETURNING DECIMAL(5,2)) <= 100.01;

SELECT items->"$.name" AS item, items->"$.price" AS amount

FROM inventory

WHERE JSON_VALUE(items, '$.quantity' RETURNING UNSIGNED) > 500;

For more information and examples, see the description of the JSON_VALUE() function. (WL #12228)

Optimizer Notes

• MySQL attempts to use an ordered index for any ORDER BY or GROUP BY query that has a LIMIT

clause, overriding any other choices made by the optimizer, whenever it determines that this would result

in faster execution. Because the algorithm for making this determination makes certain assumptions

about data distribution and other conditions, it may not always be completely correct, and it is

possible in some cases that choosing a different optimization for such queries can provide better

performance. To handle such occurrences, it is now possible to disable this optimization by setting the

optimizer_switch system variable's prefer_ordering_index flag to off.

For more information about this flag and examples of its use, see Switchable Optimizations, and LIMIT

Query Optimization.

Our thanks to Jeremy Cole for the contribution. (Bug #97001, Bug #30348211, WL #13929)

References: See also: Bug #31686878.

• A single-table UPDATE or DELETE statement that uses a subquery having a [NOT] IN or [NOT]

EXISTS predicate can now in many cases make use of a semijoin transformation or subquery

materialization. This can be done when the statement does not use LIMIT or ORDER BY, and when

semijoin or subquery materialization is allowed by any optimizer hints used in the subquery, or by the

value of the optimizer_switch server system variable.

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MySQL 8.0 Release Notes

You can see when the semijoin optimization or subquery materialization is used for an eligible single-

table DELETE or UPDATE due to the presence of a join_optimization object in the optimizer trace.

You can also see that the conversion is performed by checking the output of EXPLAIN FORMAT=TREE; if

the optimization is not performed, this shows <not executable by iterator executor>, while a

multi-table statement reports a full plan.

As part of this work, semi-consistent reads are now supported by multi-table UPDATE of InnoDB tables,

when the transaction isolation level is weaker than REPEATABLE READ. (Bug #35794, Bug #96423, Bug

#11748293, Bug #30139244, WL #6507)

• Added the optimizer_switch flag subquery_to_derived. When this flag is set to on, the optimizer

transforms eligible scalar subqueries into left outer joins (and in some cases, inner joins) on derived

tables. This optimization can be applied to a subquery which meets the following conditions:

• It uses one or more aggregate functions but no GROUP BY.

• It is part of a SELECT, WHERE, JOIN, or HAVING clause.

• It is not a correlated subquery.

• It does not make use of any nondeterminstic functions.

ANY and ALL subqueries which can be rewritten to use MIN() or MAX() are also not affected.

With subquery_to_derived=on, the optimization can also be applied to a table subquery which is the

argument to IN, NOT IN, EXISTS, or NOT EXISTS, and which does not contain a GROUP BY clause.

The subquery_to_derived flag is set to off by default, since it generally does not improve

performance, and its intended use for the most part is for testing purposes.

For more information, see Switchable Optimizations, for more information and examples. See also

Optimizing Derived Tables, View References, and Common Table Expressions with Merging or

Materialization, and LIMIT Query Optimization. (WL #13851)

• Building on work done in MySQL 8.0.18, the server now performs injection of casts into queries to

avoid mismatches when comparing string data types with those of numeric or temporal types; as

when comparing numeric and temporal types, the optimizer now adds casting operations in the item

tree inside expressions and conditions in which the data type of the argument and the expected data

type do not match. This makes queries in which string types are compared with numeric or temporal

types equivalent to queries which are compliant with the SQL standard, while maintaining backwards

compatibility with previous releases of MySQL. Such casts are now performed whenever string values

are compared to numeric or temporal values using any of the standard numeric comparison operators (=,

>=, >, <, <=, <>/!=, and <=>).

Such implicit casts are now performed between a string type (CHAR, VARCHAR, BINARY, VARBINARY,

BLOB, TEXT, ENUM, or SET) and a numeric type (SMALLINT, TINYINT, MEDIUMINT, INT/INTEGER,

BIGINT; DECIMAL/NUMERIC; FLOAT, DOUBLE, REAL; and BIT) by casting the string value to DOUBLE;

if the numeric value is not already of type DOUBLE, FLOAT, or REAL, it is also cast to DOUBLE. A YEAR

value is also cast to DOUBLE when compared with a string value (as is the string value). For such

comparisons between string types and TIMESTAMP or DATETIME values, the arguments are cast as

DATETIME; when a string type is compared with a DATE value, the string is cast to DATE.

For example, a query such as SELECT * FROM t1 JOIN t2 ON t1.char_col = t2.int_col is

rewritten and executed as SELECT * FROM t1 JOIN t2 ON CAST(t1.char_col AS DOUBLE)

= CAST(t2.int_col AS DOUBLE), and SELECT * FROM t1 JOIN t2 ON t1.varchar_col =

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MySQL 8.0 Release Notes

t2.timestamp_col is transformed to SELECT * FROM t1 JOIN t2 ON CAST(t1.varchar_col

AS DATETIME) = CAST(t2.timestamp_col AS DATETIME) prior to execution.

You can see when casts are injected into a given query by viewing the output of EXPLAIN ANALYZE,

EXPLAIN FORMAT=JSON, or EXPLAIN FORMAT=TREE. EXPLAIN [FORMAT=TRADITIONAL] can also

be used, but in this case it is necessary, following execution of the EXPLAIN statement, to issue SHOW

WARNINGS to view the rewritten query.

This change is not expected to cause any difference in query results or performance. (WL #13456)

Packaging Notes

• For RPM and Debian packages, client-side plugins were moved from the server package to the client

package. Additionally, debug versions of client-side plugins were moved to the test package. (Bug

#31123564, Bug #31336340)

• MSI packages for Windows no longer include the legacy server data component. (Bug #31060177)

• The bundled Protobuf library was upgraded from version 3.6.1 to version 3.11. (Bug #31000511, Bug

#98852)

• The libevent library bundled with MySQL was upgraded to version 2.1.11. In addition, for the

WITH_LIBEVENT CMake option, the following two changes were made:

1. yes is no longer permitted as a synonym for system. Use system instead.

2. If system is specified but no system libevent is found, the bundled version is no longer used in

place of the missing system library, and an error occurs instead.

(Bug #30926742)

• The ICU (International Components for Unicode) library bundled with MySQL has been upgraded to

version 65.1.

Pluggable Authentication

• The MySQL Enterprise Edition authentication_ldap_sasl plugin that implements SASL LDAP

authentication supports multiple authentication methods, but depending on host system configuration,

they might not all be available. The new Authentication_ldap_sasl_supported_methods status

variable provides discoverability for the supported methods. Its value is a string consisting of supported

method names separated by spaces. Example: "SCRAM-SHA1 GSSAPI" (WL #13876)

Security Notes

• Incompatible Change: Access to the INFORMATION_SCHEMA.FILES table now requires the PROCESS

privilege.

This change affects users of the mysqldump command, which accesses tablespace information in the

FILES table, and thus now requires the PROCESS privilege as well. Users who do not need to dump

tablespace information can work around this requirement by invoking mysqldump with the --no-

tablespaces option. (Bug #30350829)

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.1.1g. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/vulnerabilities.html. (Bug

#31296697)

223

MySQL 8.0 Release Notes

• Previously, LOCAL data loading capability for the LOAD DATA statement could be controlled on the

client side only by enabling it for all files accessible to the client, or by disabling it altogether. The new

MYSQL_OPT_LOAD_DATA_LOCAL_DIR option for the mysql_options() C API function enables clients

to restrict LOCAL data loading to files located in a designated directory. See Security Considerations for

LOAD DATA LOCAL. (WL #13168)

Test Suite Notes

• mysql-test-run.pl no longer accepts unique prefixes of command options. Complete option names

must be given. (Bug #31390127)

• MySQL tests were updated to use googletest 1.10.0. (Bug #31364750)

• The innodb.innodb_mysql test case was updated to avoid nondeterminism of output row order.

Thanks to Facebook for the contribution. (Bug #30810572, Bug #98377)

• mysql-test-run.pl now supports an --mtr-port-exclude option for specifying the range of ports

to exclude when searching for available port ranges to use. The MTR_PORT_EXCLUDE environment

variable may also be set to achieve the same effect. Thanks to Facebook for the contribution. (Bug

#30809607)

• In addition to aborting on receipt of CTRL+C (SIGINT), mysql-test-run.pl now also displays a list of

test cases that failed up to that point. (Bug #30407014)

X Plugin Notes

• Where a dollar sign ($) was used to reference an entire document, X Plugin handled the reference

differently depending on the context in which it was used. This has now been standardized. (Bug

#31374713)

• With certain settings for the global SQL mode, X Plugin's authentication process failed to accept a

correct user password. The authentication process now operates independently from the global SQL

mode's setting to ensure consistency. (Bug #31086109)

Functionality Added or Changed

• Important Change; Group Replication: By default, a replication source server writes a checksum for

each event in the binary log, as specified by the system variable binlog_checksum, which defaults

to the setting CRC32. Previously, Group Replication did not support the presence of checksums in the

binary log, so binlog_checksum had to be set to NONE when configuring a server instance that would

become a group member. This requirement is now removed, and the default can be used. The setting for

binlog_checksum does not have to be the same for all members of a group.

Note that Group Replication does not use checksums to verify incoming events on the

group_replication_applier channel, because events are written to that relay log from

multiple sources and before they are actually written to the originating server's binary log, which

is when a checksum is generated. Checksums are used to verify the integrity of events on the

group_replication_recovery channel and on any other replication channels on group members.

(WL #9038)

• Performance: Improved the implementation of the UNHEX() function by introducing a lookup table for

mapping a hexadecimal digit string to its binary representation. This change speeds up execution of the

function by a factor of 8 or more in testing. (Bug #31173103)

• InnoDB: Redo logging can now be enabled and disabled using ALTER INSTANCE {ENABLE|

DISABLE} INNODB REDO_LOG syntax. This functionality is intended for loading data into a new MySQL

instance. Disabling redo logging helps speed up data loading by avoiding redo log writes.

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MySQL 8.0 Release Notes

The new INNODB_REDO_LOG_ENABLE privilege permits enabling and disabling redo logging.

The new Innodb_redo_log_enabled status variable permits monitoring redo logging status.

See Disabling Redo Logging. (WL #13795)

• InnoDB: Truncating an undo tablespace on a busy system could affect performance due to associated

flushing operations that remove old undo tablespace pages from the buffer pool and flush the initial

pages of the new undo tablespace to disk. To address this issue, the flushing operations were removed.

Old undo tablespace pages are now released passively as they become least recently used, or are

removed at the next full checkpoint. The initial pages of the new undo tablespace are now redo logged

instead of flushed to disk during the truncate operation, which also improves durability of the undo

tablespace truncate operation.

To prevent potential issues caused by an excessive number of undo tablespace truncate operations,

truncate operations on the same undo tablespace between checkpoints are now limited to 64. If the limit

is exceeded, an undo tablespace can still be made inactive, but it is not truncated until after the next

checkpoint.

INNODB_METRICS counters associated with defunct undo truncate flushing operations were removed.

Removed counters include: undo_truncate_sweep_count, undo_truncate_sweep_usec,

undo_truncate_flush_count, and undo_truncate_flush_usec.

See Undo Tablespaces. (WL #11819)

• InnoDB: At startup, InnoDB validates the paths of known tablespace files against tablespace file paths

stored in the data dictionary in case tablespace files have been moved to a different location. The new

innodb_validate_tablespace_paths variable permits disabling tablespace path validation. This

feature is intended for environments where tablespaces files are not moved. Disabling tablespace path

validation improves startup time on systems with a large number of tablespace files.

For more information, see Disabling Tablespace Path Validation. (WL #14008)

• InnoDB: Table and table partition data files created outside of the data directory using the DATA

DIRECTORY clause are now restricted to directories known to InnoDB. This change permits database

administrators to control where tablespace data files are created and ensures that the data files can be

found during recovery.

General and file-per-table tablespaces data files (.ibd files) can no longer be created in the undo

tablespace directory (innodb_undo_directory) unless that directly is known to InnoDB.

Known directories are those defined by the datadir, innodb_data_home_dir, and

innodb_directories variables.

Truncating an InnoDB table that resides in a file-per-table tablespace drops the existing tablespace and

creates a new one. As of MySQL 8.0.21, InnoDB creates the new tablespace in the default location

and writes a warning to the error log if the tablespace was created with an earlier version and the

current tablespace directory is unknown. To have TRUNCATE TABLE create the tablespace in its current

location, add the directory to the innodb_directories setting before running TRUNCATE TABLE. (WL

#13065)

• InnoDB: To improve concurrency for operations that require access to lock queues for table and

row resources, the lock system mutex (lock_sys->mutex) was replaced by sharded latches, and

lock queues were grouped into table and page lock queue shards, with each shard protected by a

dedicated mutex. Previously, the single lock system mutex protected all lock queues, which was a point

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MySQL 8.0 Release Notes

of contention on high-concurrency systems. The new sharded implementation permits more granular

access to lock queues.

The lock system mutex (lock_sys->mutex) was replaced by the following sharded latches:

• A global latch (lock_sys->latches.global_latch) consisting of 64 read-write lock objects

(rw_lock_t). Access to an individual lock queue requires a shared global latch and a latch on the

lock queue shard. Operations that require access to all lock queues take an exclusive global latch,

which latches all table and page lock queue shards.

• Table shard latches (lock_sys->latches.table_shards.mutexes), implemented as an array of

512 mutexes, with each mutex dedicated to one of 512 table lock queue shards.

• Page shard latches (lock_sys->latches.page_shards.mutexes), implemented as an array of

512 mutexes, with each mutex dedicated to one of 512 page lock queue shards.

The Performance Schema wait/synch/mutex/innodb/lock_mutex instrument for monitoring the

single lock system mutex was replaced by instruments for monitoring the new global, table shard, and

page shard latches:

• wait/synch/sxlock/innodb/lock_sys_global_rw_lock

• wait/synch/mutex/innodb/lock_sys_table_mutex

• wait/synch/mutex/innodb/lock_sys_page_mutex

(WL #10314)

• Group Replication: Group Replication group members can now advertise a list of IP addresses that

joining members can use to make connections to them for state transfer during distributed recovery.

Previously, the existing member's standard SQL client connection was used for this purpose as well

as for client traffic. Advertising distributed recovery endpoints instead gives you improved control of

distributed recovery traffic (comprising remote cloning operations and state transfer from the binary

log) in your network infrastructure. The list of distributed recovery endpoints for a member is specified

using the new group_replication_advertise_recovery_endpoints system variable, and the

same SSL requirements are applied that would be in place if the SQL client connection was used for

distributed recovery. (WL #13767)

• Group Replication: You can now specify user credentials for distributed recovery on the START

GROUP_REPLICATION statement using the USER, PASSWORD, and DEFAULT_AUTH options. These

credentials are used for distributed recovery on the group_replication_recovery channel. When

you specify user credentials on START GROUP_REPLICATION, the credentials are saved in memory

only, and are removed by a STOP GROUP_REPLICATION statement or server shutdown. These

credentials can replace user credentials set using a CHANGE MASTER TO statement, which are stored

in the replication metadata repositories, and can therefore help to secure the Group Replication servers

against unauthorized access.

The new method of providing user credentials is not compatible with starting Group Replication

automatically on server start. If user credentials have previously been set using a CHANGE MASTER

TO statement, credentials that you specify on START GROUP_REPLICATION take precedence

over these. However, the credentials from the replication metadata repositories are used if START

GROUP_REPLICATION is specified without user credentials, which happens on automatic starts if the

group_replication_start_on_boot system variable is set to ON (including after a remote cloning

operation for distributed recovery). To gain the security benefits of specifying user credentials on START

GROUP_REPLICATION, ensure that group_replication_start_on_boot is set to OFF (the default

226

MySQL 8.0 Release Notes

is ON), and use a CHANGE MASTER TO statement to clear any user credentials previously set for the

group_replication_recovery channel. (WL #13768)

• Group Replication: The minimum setting for the maximum size for the XCom message cache in Group

Replication, specified by the group_replication_message_cache_size system variable, has been

reduced from approximately 1 GB to 134217728 bytes, or approximately 128 MB. Note that this size

limit applies only to the data stored in the cache, and the cache structures require an additional 50 MB

of memory. The same cache size limit should be set on all group members. The default XCom message

cache size of 1 GB, which was formerly also the minimum setting, is unchanged.

The smaller message cache size is provided to enable deployment on a host that has a

restricted amount of available memory and good network connectivity. Having a very low

group_replication_message_cache_size setting is not recommended if the host is on an

unstable network, because a smaller message cache makes it harder for group members to reconnect

after a transient loss of connectivity. If some messages that were exchanged during a member's

temporary absence have been deleted from the other members' XCom message caches because their

maximum size limit was reached, the member cannot reconnect using the message cache. It must leave

the group and rejoin in order to retrieve the transactions through distributed recovery, which is a slower

process than using the message cache, although the member still can rejoin in this way without operator

intervention.

Note that from MySQL 8.0.21, by default an expel timeout of 5 seconds is added before a member is

expelled from the group (specified by the group_replication_member_expel_timeout system

variable). With this default setting the XCom message cache therefore now needs to store the messages

exchanged by the group in a 10-second period (the expel timeout plus the initial 5-second detection

period), rather than in a 5-second period as previously (the initial 5-second detection period only). (WL

#13979)

• Group Replication: group_replication_member_expel_timeout specifies the period of time

in seconds that a Group Replication group member waits after creating a suspicion, before expelling

from the group the member suspected of having failed. The initial 5-second detection period before a

suspicion is created does not count as part of this time.

Previously, the waiting period specified by group_replication_member_expel_timeout defaulted

to 0, meaning that a suspected member was liable for expulsion immediately after the 5-second

detection period ended. Following user feedback, the waiting period now defaults to 5 seconds, giving

a member that loses touch with the group 10 seconds in total to reconnect itself to the group. If the

member does reconnect in this time, it can recover missed messages from the XCom message cache

and return to ONLINE state automatically, rather than being expelled from the group and needing the

auto-rejoin procedure or manual operator intervention to rejoin.

If you previously tuned the size of the XCom message cache with reference to the expected volume of

messages in the previous default time before a member was expelled (the 5-second detection period

only), increase your group_replication_message_cache_size setting to account for the new

expel timeout, which doubles the default time to 10 seconds. With the new default expel timeout you

might start to see warning messages from GCS on active group members, stating that a message that

is likely to be needed for recovery by a member that is currently unreachable has been removed from

the message cache. This message shows that a member has had a need to use the message cache to

reconnect, and that the cache size might not be sufficient to support the current waiting period before a

member is expelled. (WL #13773)

• Group Replication: The Group Replication auto-rejoin feature is now activated by default. The

group_replication_autorejoin_tries system variable, which is available from MySQL 8.0.16,

makes a member that has been expelled or reached its unreachable majority timeout try to rejoin

the group automatically. This system variable, which originally defaulted to 0 so auto-rejoin was not

227

MySQL 8.0 Release Notes

activated, now defaults to 3, meaning that a member makes three attempts to rejoin the group in the

event of its expulsion or unreachable majority timeout. Between each attempt the member waits for 5

minutes. If the specified number of tries is exhausted without the member rejoining or being stopped, the

member proceeds to the action specified by the group_replication_exit_state_action system

variable.

The auto-rejoin feature minimizes the need for manual intervention to bring a member back into the

group, especially where transient network issues are fairly common. During and between auto-rejoin

attempts, a member remains in super read only mode and does not accept writes. However, reads

can still be made on the member, with an increasing likelihood of stale reads over time. If you want to

intervene to take the member offline, the member can be stopped manually at any time by using a STOP

GROUP_REPLICATION statement or shutting down the server. If you cannot tolerate the possibility of

stale reads for any period of time, set the group_replication_autorejoin_tries system variable

to 0, in which case operator intervention is required whenever a member is expelled from the group or

reaches its unreachable majority timeout. (WL #13706)

• Previously, the --disabled-storage-engines option did not ignore spaces around storage engines

listed in the option value. Spaces around engine names are now ignored. (Bug #31373361, Bug #99632)

• The new HANDLE_FATAL_SIGNALS CMake option enables configuring whether Address Sanitizer and

Undefined Behavior Sanitizer builds use the sanitizer runtime library to handle fatal signals rather than

a MySQL-internal function. The option default is ON for non-sanitizer builds, OFF for sanitizer builds. If

the option is OFF, the default action is used for SIGBUS, SIGILL and SIGSEGV, rather than the internal

function. (Bug #31068443)

• Using a column that is repeated twice or more in GROUP BY (through an alias), combined with ROLLUP,

had behavior differing from MySQL 5.7. Example:

SELECT a, b AS a, COUNT(*) FROM t1 GROUP BY a, b WITH ROLLUP;

Behavior of such queries has been changed to better match MySQL 5.7. They should be avoided,

however, because behavior may change again in the future or such queries may become illegal. (Bug

#30921780, Bug #98663)

• comp_err provides better error messages for certain input file issues. Thanks to Facebook for the

contribution. (Bug #30810629, Bug #98390)

• MySQL Server Docker containers now support server restart within a client session (which happens, for

example, when the RESTART statement is executed by a client or during the configuration of an InnoDB

Cluster instance). To enable this important feature, containers should be started with the docker run

option --restart set to the value on-failure. See Starting a MySQL Server Instance for details.

(Bug #30750730)

• EXPLAIN ANALYZE now supports the FORMAT option. Currently, TREE is the only supported format.

(Bug #30315224)

• ALTER INSTANCE ROTATE INNODB MASTER KEY is no longer permitted when read_only or

super_read_only are enabled. (Bug #30274240)

• On storage engines that support atomic DDL, the CREATE TABLE ... SELECT statement is now

logged as one transaction in the binary log when row-based replication is in use. Previously, it was

logged as two transactions, one to create the table, and the other to insert data. With this change,

CREATE TABLE ... SELECT statements are now safe for row-based replication and permitted for use

with GTID-based replication. For more information, see Atomic Data Definition Statement Support. (Bug

#11756034, Bug #47899, WL #13355)

• LOAD XML now supports CDATA sections in the XML file to be imported. (Bug #98199, Bug #30753708)

228

MySQL 8.0 Release Notes

• X Plugin's mysqlx_bind_address system variable now accepts multiple IP addresses like MySQL

Server's bind_address system variable does, enabling X Plugin to listen for TCP/IP connections on

multiple network sockets.

An important difference in behavior is that for MySQL Server, any error in the list of addresses prevents

the server from starting, but X Plugin (which is not a mandatory plugin) does not do this. With X Plugin,

if one of the listed addresses cannot be parsed or if X Plugin cannot bind to it, the address is skipped,

an error message is logged, and X Plugin attempts to bind to each of the remaining addresses. X

Plugin's Mysqlx_address status variable displays only those addresses from the list for which the bind

succeeded. If none of the listed addresses results in a successful bind, X Plugin logs an error message

stating that X Protocol cannot be used. (WL #12715)

• ENGINE_ATTRIBUTE and SECONDARY_ENGINE_ATTRIBUTE options were added to CREATE TABLE,

ALTER TABLE, and CREATE INDEX syntax. The ENGINE_ATTRIBUTE option was also added to

CREATE TABLESPACE and ALTER TABLESPACE syntax. The new options, which permit defining

storage engine attributes for tables, columns, indexes, and tablespaces, are reserved for future use.

The following INFORMATION_SCHEMA tables were added for querying storage engine attributes for

tables, columns, indexes, and tablespaces. Values are stored in the data dictionary. The tables are

reserved for future use.

• INFORMATION_SCHEMA.TABLES_EXTENSIONS

• INFORMATION_SCHEMA.COLUMNS_EXTENSIONS

• INFORMATION_SCHEMA.TABLE_CONSTRAINTS_EXTENSIONS

• INFORMATION_SCHEMA.TABLESPACES_EXTENSIONS

(WL #13341)

• The default logging level for MySQL Server omits informational log messages, which previously

included some significant lifecycle events for Group Replication that were non-error situations, such

as a group membership change. Messages about significant events for a replication group have now

been reclassified as system messages, so they always appear in the server error log regardless of the

server logging level. Operators can therefore review a complete history of the server's membership

in a replication group. In addition, socket bind errors on the group communication layer have been

reclassified from information to error messages. (WL #13769)

Bugs Fixed

• InnoDB: A GROUP BY operation on a JSON array column caused failures in an UBSan build of MySQL

due to incorrect type casting. (Bug #31451475)

• InnoDB: Several InnoDB error log messages were defined without symbolic values. (Bug #31401028)

• InnoDB: The file segment for a single page write was not released after a data file write failure

associated with a doublewrite flush and sync operation. (Bug #31370227)

• InnoDB: Code that was accessed when undo tablespace truncation used the same space ID before and

after a truncate operation was removed. That scenario no longer occurs. The truncated undo tablespace

is replaced by a new undo tablespace datafile with a different space ID. (Bug #31354435)

• InnoDB: The range of reserved space IDs for undo tablespaces was increased from 512 per undo

tablespace to 400000. (Bug #31340834)

229

MySQL 8.0 Release Notes

• InnoDB: An error that occurred while inserting a log into the ddl_log table was not returned making it

appear as though the operation was successful, and a transaction was not registered while performing a

tablespace encryption operation. (Bug #31236217)

• InnoDB: The lob::purge() function did not free LOBs correctly for an undo log record type

(TRX_UNDO_UPD_DEL_REC) that is generated when an insert operation modifies a delete-marked

record. (Bug #31222046, Bug #99339)

• InnoDB: A shutdown error occurred following an attempt to rebuild a discarded partition. (Bug

#31215415)

• InnoDB: The internal get_real_path() function, responsible for retrieving directory or a file path, was

modified to strip trailing separators before determining if a path is a file or directory. Additionally, if a path

does not exist or cannot be identified as a file or subdirectory, the function now assumes the path is a file

if the basename has a three letter suffix. (Bug #31215160)

• InnoDB: Tablespace-related error messages were revised. (Bug #31205520, Bug #31205441)

• InnoDB: To avoid potential compilation issues, __attribute__((const)) and

__attribute__((pure)) attributes were removed from internal InnoDB functions. (Bug #31153123)

• InnoDB: The parallel read thread limit was not observed when spawning read threads for histogram

sampling, causing an assertion failure. (Bug #31151218)

• InnoDB: The transaction read view was not checked when sampling records for generation of histogram

statistics. (Bug #31151077)

• InnoDB: An I/O completion routine was not able acquire an LRU list mutex due to a latch held by

another thread. (Bug #31128739)

• InnoDB: An attachable transaction thread requested an InnoDB ticket that was already reserved by the

main thread, causing a deadlock. Additionally, the server failed to respond to KILL statements in this

deadlock scenario. (Bug #31090777)

• InnoDB: The INNODB_METRICS table AVG_COUNT_RESET value for a counter defined as a module

owner reported NULL. The METRIC_AVG_VALUE_RESET field was incorrectly marked as NULL. Thanks

to Fungo Wang for the contribution. (Bug #31084706, Bug #98990)

• InnoDB: At startup, following an unexpected stoppage during an undo tablespace truncate operation,

some rollback segment header pages were found to be corrupted. Encryption of rollback segment

header pages was initiated while the header pages were being written, resulting in some header pages

not being encrypted, as expected. (Bug #31045160)

• InnoDB: Various aspects of the lock system (lock_sys) code were refactored, and issues with

lock_sys lock_rec_block_validate() and lock_test_prdt_pacge_lock() functions were

fixed. The lock_rec_block_validate() function called another function repeatedly, which could

result in locks not being validated under certain circumstances. The implementation also had a potential

quadratic time complexity. The lock_test_prdt_page_lock() function did not iterate over all locks

as intended. (Bug #31001732)

• InnoDB: Use of memory-mapped files after exceeding the temptable_max_ram threshold caused a

performance degradation. (Bug #30952983, Bug #98739)

• InnoDB: In debug mode, a DROP TABLE operation on a table with an incorrectly defined COMPRESSION

clause caused a failure. InnoDB did not return an error to the caller for proper handling. (Bug

#30899683, Bug #98593)

• InnoDB: Purge thread activity was excessive when the history list length approached zero, wasting CPU

resource and causing mutex contention. (Bug #30875956)

230

MySQL 8.0 Release Notes

• InnoDB: A regression introduced in MySQL 8.0.18 affected INFORMATION_SCHEMA.INNODB_COLUMNS

query performance. Schema and table data dictionary objects were fetched repeatedly to retrieve

partition column information. (Bug #30837086, Bug #98449)

References: This issue is a regression of: Bug #93033, Bug #28869903.

• InnoDB: An ALTER TABLE ... IMPORT TABLESPACE operation with a .cfg file failed with an

“Incorrect key file for table” error. The row_import::m_flags member was not initialized. (Bug

#30830441)

• InnoDB: A DROP TABLE operation performed after discarding a partition did not remove the associated

data files, and DROP DATABASE failed with an error indicating that the database directory could not

be removed. Upgrade from MySQL 5.7 to MySQL 8.0 also failed if a partitioned table with a discarded

partition was present. The DISCARD attribute was applied to the table object instead of the partition

object in the data dictionary, which made it appear that all partitions were discarded. (Bug #30818917)

• InnoDB: The server failed intermittently with an “ibuf cursor restoration fails” error. (Bug #30770380, Bug

#91033)

• InnoDB: An ALTER TABLE operation that copied data from one table to another returned an “Out of

range value for column” error. The counter that tracks the number of AUTO_INCREMENT rows required

for a multi-row insert operation was not always set back to zero after a bulk insert operation. (Bug

#30765952, Bug #98211)

• InnoDB: The internal TempTable records_in_range() handler function contained a DBUG_ABORT()

call that caused assertion failures in debug builds, and empty result sets in regular builds for some

queries. (Bug #30716037)

• InnoDB: The btr_cur_pessimistic_update() function failed to handle a cursor position change

caused by a lob::purge() call. (Bug #30712878)

• InnoDB: A type conversion failure during a DELETE IGNORE operation caused an assertion failure. A

JSON value was not converted to the expected value. (Bug #30664660)

• InnoDB: A purge operation encountered a null LOB reference, causing an assertion failure. (Bug

#30658887)

• InnoDB: Chunk size was not calculated correctly when deallocating memory from the TempTable

storage engine, causing a regression in SELECT DISTINCT query performance. (Bug #30562964)

• InnoDB: A segmentation fault occurred in the TempTable storage engine while using the thread pool

plugin. TempTable thread-local variables were not compatible with the use of different threads for

statements issued by a single client connection. Use of thread local variables also lead to excessive

memory consumption due to the memory used by thread-local variables remaining allocated for the life

of the thread. To address these issues, thread-local variables were replaced by a caching mechanism.

(Bug #30050452, Bug #31116036, Bug #99136)

• InnoDB: A fatal “page still fixed or dirty” error occurred during shutdown. (Bug #29759555, Bug #95285)

References: This issue is a regression of: Bug #29207450.

• Partitioning: A query against a partitioned table, which used an ORDER BY, returned unordered results

under the following conditions:

• The table had a composite index with a prefix on one of the columns.

• The query's WHERE clause contained an equality condition on the prefixed column.

231

MySQL 8.0 Release Notes

• The column with the prefix was the leftmost column in the index.

• The column used in the ORDER BY was the rightmost column in the index.

• The index was used for handling the ORDER BY.

Our thanks to Quanan Han for the suggestion. (Bug #84070, Bug #25207522)

• Replication: If a group's consistency level (set by the group_replication_consistency system

variable) was set to BEFORE or BEFORE_AND_AFTER, it was possible for a deadlock to occur in the

event of a primary failover. The primary failover is now registered differently to avoid this situation. (Bug

#31175066, Bug #98643)

• Replication: When a replication source server shuts down and restarts, its MEMORY tables become

empty. To replicate this effect to replicas, the first time that the source uses a given MEMORY table after

startup, it notifies replicas that the table must be emptied by writing a DELETE statement for that table

to the binary log. Previously, the generated DELETE statement was written to the binary log statement

cache for the current session, which could result in it being logged together with other statements

under the same GTID, or logged without BEGIN and COMMIT statements. Also, in some situations, the

generated DELETE statement could consume the GTID intended for the transaction that triggered it. The

generated DELETE statement is now logged with accompanying BEGIN and COMMIT statements, and the

resulting transaction is flushed to the binary log immediately after it is written to the statement cache, so

that it always receives its own GTID and is kept separate from other transactions. (Bug #30527929, Bug

#25681518, Bug #77729)

• Replication: Following a patch in MySQL 8.0.14, if a function call contained operations on temporary

tables, it could be written to the binary log in statement format when binlog_format = MIXED was

set. This led to CREATE TEMPORARY TABLE statements being incorrectly written to the binary log if they

contained a function call. Following further analysis, operations on temporary tables in stored functions

and triggers are now marked as unsafe for binary logging in statement format, as they have a strong

chance of causing issues with replication. When binlog_format = MIXED is set, these operations are

now logged in row format. (Bug #30395151, Bug #30320009)

• Replication: A fix made in MySQL 8.0.14 and MySQL 5.7.25 for a deadlock scenario

involving the system variables binlog_transaction_dependency_tracking and

binlog_transaction_dependency_history_size had the side effect of leaving the writeset

history used for transaction dependency tracking unprotected from concurrent update. The writeset

history and tracking mode are now locked correctly whenever they are accessed. (Bug #29719364, Bug

#95181)

References: See also: Bug #28511326, Bug #91941.

• Replication: If a CHANGE MASTER TO statement was issued with MASTER_USER specified as empty

(MASTER_USER=''), the statement succeeded and cleared any previously specified user name in the

replication metadata repositories. However, if information was subsequently read from the repositories,

for example during an automatic restart of a Group Replication channel, a default user name could be

substituted for the channel. This issue has now been fixed, so from MySQL 8.0.21, it is a valid approach

to set an empty MASTER_USER user name if you always provide user credentials using the START

SLAVE statement or START GROUP_REPLICATION statement that starts the replication channel. This

approach means that the replication channel always needs operator intervention to restart, but the user

credentials are not recorded in the replication metadata repositories.

The documentation for the CHANGE MASTER TO statement has also been corrected to clarify that it

is possible to specify MASTER_USER='', and the resulting error occurs only if you attempt to start the

replication channel with the empty credentials. (Bug #27357189)

232

MySQL 8.0 Release Notes

• Group Replication: A global value that is set for the group_replication_consistency system

variable, which controls all user connections, is applied on Group Replication's internal connections to

MySQL Server modules using the SQL API, which are handled in a similar way to user connections. This

could sometimes lead to Group Replication reporting the use of group_replication_consistency

as an error, for example when checking the clone plugin status during distributed recovery. Such internal

connections using the SQL API now use consistency level EVENTUAL, which matches the behavior

before group_replication_consistency was available, and does not cause an error message.

(Bug #31303354, Bug #99345)

• Group Replication: On Windows, Group Replication's use of the Windows API function

SleepConditionVariableCS to wait for new write events caused noticeably high CPU usage by this

function after Group Replication had been running for two days or more, which could be corrected by

restarting the MySQL server instance, but then increased again over time as before. This was caused by

the use of two clock functions to calculate the timeout after which the SleepConditionVariableCS function

was called, which drifted relative to each other over time, making the timeout progressively shorter and

the calls to the function more frequent. The issue has been corrected on Windows by using the current

time from a single clock to calculate the timeout. (Bug #31117930)

• Group Replication: If Group Replication was stopped while distributed recovery was in progress,

memory issues could result from an attempt to access the record of the member that was selected as

the donor. This record is now kept locally with the distributed recovery state. (Bug #31069563)

• Group Replication: When distributed recovery for Group Replication involves a remote cloning

operation, the flag set on the server to indicate this remains set until the server instance is restarted.

Previously, if Group Replication was stopped and restarted on the server, that flag caused Group

Replication to purge the relay log files for the group_replication_applier channel, as is required

on starting after a remote cloning operation to ensure that there is no mismatch with the cloned data

tables. If there were any unapplied transactions in the purged relay log files, the member could not

subsequently be used to bootstrap a group, although it could successfully join a group by retrieving the

transactions from another member. Group Replication now ignores the flag on its second or subsequent

starts, and only purges the relay log files the first time it is started after a remote cloning operation. (Bug

#31059680)

• Group Replication: To avoid the possibility of data inconsistency, Group Replication blocks a new

incarnation of the same server (with the same address but a new identifier) from joining the group while

its old incarnation is still listed as a member. Previously, the Group Replication Group Communication

System (GCS) treated the connection to the old incarnation of a server as active while it was attempting

to send messages to the server, and only recognized that the connection was inactive when the socket

returned an error, which might take a significant amount of time. During that period, the new incarnation

of the server was unable to join the group because the existing members did not connect to it, as they

were still waiting on the connection to the old incarnation. Now, GCS only treats a connection to a server

as active while messages can be sent to it successfully. If the socket is no longer writeable, the server

connection is treated as inactive and is proactively closed. The connection close triggers the group

member to attempt reconnection to that server address, upon which a connection is established to the

new incarnation of the server, enabling the new incarnation to join the group. (Bug #30770577)

• Group Replication: Group Replication did not broadcast a notification when switching from single-

primary mode to multi-primary mode. The change is now notified for use in routing. (Bug #30738896)

• Group Replication: Setting the group_replication_force_members system variable to force a

specified membership for a group could fail if another member had already requested the expulsion of

the member that was driving the group_replication_force_members operation. The operation

to implement the configuration specified by the group_replication_force_members system

variable forced any pending group reconfigurations to take place first. If one of those successfully

expelled the member where the system variable had been set, because the expel timeout that was set

on the member had expired, the operation timed out and failed to complete. To avoid this situation,

233

MySQL 8.0 Release Notes

Group Replication now proceeds directly to implementing the new configuration specified by the

group_replication_force_members system variable, and ignores any other pending group

reconfigurations. (Bug #29820966)

• Group Replication: Group Replication tracking of connections to other group members only took into

account the incoming connections, not the outgoing connections. This meant if the outgoing connection

from member A to member B was broken, for example by a firewall configuration issue, but the incoming

connection from member B to member A was intact, member A would display member B's status as

ONLINE, although member A's messages were not reaching member B. Member B would display

member A's status as UNREACHABLE. Now, if a group member starts to receive pings from another

group member to which it has an active connection (in this case, if member A received pings from

member B), this is treated as an indicator of an issue with the connection. If sufficient pings are received,

the connection is shut down by the recipient of the pings (in this case, member A), so that the status of

the connection is consistent for both members. (Bug #25660161, Bug #84796)

• JSON: When the expression and path passed to JSON_TABLE() yielded a JSON null, the function

raised an error instead of returning SQL NULL as required. (Bug #31345503)

• JSON: In MySQL 5.7, and in MySQL 8.0 prior to 8.0.17, the server attempted to convert JSON boolean

values to their SQL counterparts when testing them directly with IS TRUE, as shown here:

mysql> CREATE TABLE test (id INT, col JSON);

mysql> INSERT INTO test VALUES (1, '{"val":true}'), (2, '{"val":false}');

mysql> SELECT id, col, col->"$.val" FROM test WHERE col->"$.val" IS TRUE;

+------+---------------+--------------+

| id | col | col->"$.val" |

+------+---------------+--------------+

| 1 | {"val": true} | true |

+------+---------------+--------------+

As the result of work done in MySQL 8.0.17 to ensure that all predicates in SQL conditions are complete

(that is, a condition of the form WHERE value is rewritten as WHERE value <> 0), and that a NOT

IN or NOT EXISTS condition in a WHERE or ON clause is converted to an antijoin, evaluation of a JSON

value in an SQL boolean context performs an implicit comparison against JSON integer 0. This means

that the query shown previously returns the following result in MySQL 8.0.17 and later:

mysql> SELECT id, col, col->"$.val" FROM test WHERE col->"$.val" IS TRUE;

+------+----------------+--------------+

| id | col | col->"$.val" |

+------+----------------+--------------+

| 1 | {"val": true} | true |

| 2 | {"val": false} | false |

+------+----------------+--------------+

In such cases, the server also now provides a warning: Evaluating a JSON value in SQL

boolean context does an implicit comparison against JSON integer 0; if this

is not what you want, consider converting JSON to a SQL numeric type with

JSON_VALUE RETURNING. Thus, the query can now be rewritten using JSON_VALUE() as shown here:

mysql> SELECT id, col, col->"$.val" FROM test

-> WHERE JSON_VALUE(col, "$.val" RETURNING UNSIGNED) IS TRUE;

+------+---------------+--------------+

| id | col | col->"$.val" |

+------+---------------+--------------+

| 1 | {"val": true} | true |

+------+---------------+--------------+

(Bug #31168181)

234

MySQL 8.0 Release Notes

• JSON: A GROUP BY query against a table having a multi-valued index was not always handled correctly

by the server. (Bug #31152942)

• If log_error_services was persisted, in some cases it could take effect at the wrong time during

startup. (Bug #31464539)

• SHOW CREATE USER after certain manual grant table modifications could cause a server exit. (Bug

#31462844)

• Some in-memory updates of partial revokes could produce incorrect privileges. (Bug #31430086)

• If log_error_verbosity was set using SET PERSIST, it did not take effect early enough during

server startup to affect InnoDB initialization. (Bug #31410674)

• The parser incorrectly raised an assertion before rejecting subqueries in generated column expressions.

(Bug #31396191)

• This release makes the following two micro-optimizations for degenerate hash joins (that is, those with

no join conditions):

1. For a degenerate hash antijoin or semijoin, add LIMIT 1 when building the hash table, since having

more rows than this cannot change the result.

2. For a degenerate hash antijoin with a nonempty hash table, avoid scanning the outer side.

Together, these changes handle a performance regression whereby a rewrite to a hash antijoin caused

a NOT EXISTS query which was not rewritten to be executed by the optimizer and be replaced with

“zero rows found”. To handle the case in which a nested loop is used instead, a non-correlated subquery

inside NOT EXISTS is no longer transformed to an antijoin.

This fix also applies to subqueries using constant NOT IN (non_correlated_subquery). (Bug

#31376809)

• Configuring with -DWITH_EDITLINE=system resulted in compilation failures for older library versions.

(Bug #31366715)

• The upgrade of the bundled libedit library in the previous MySQL distribution caused a problem for

builds using that library such that CTRL+C (SIGINT) in the mysql client required a following Enter to

take effect in some circumstances. (Bug #31360025)

• Columns declared with both AUTO_INCREMENT and DEFAULT value expressions are a nonpermitted

combination, but ALTER TABLE failed to produce an error for SET DEFAULT (expr) operations on

AUTO_INCREMENT columns. (Bug #31331454)

• It was possible to set the protocol_compression_algorithms system variable to the empty string.

This is no longer permitted. (Bug #31326231)

• A lookup function used internally in the MySQL server returns integer -1 when the argument is

ambiguous; this resulted in undefined behavior when this value was converted to an unsigned value prior

to use as an argument in subsequent calculations. Now when the function returns -1, this is handled as

an error and the value is not used further. (Bug #31326120)

• Negation of a signed value in certain cases led to undefined behavior; to prevent this from occurring, the

value to be negated is now treated as unsigned. (Bug #31325602)

• The WEIGHT_STRING() function did not always return the correct result for an integer argument. (Bug

#31321257)

References: This issue is a regression of: Bug #30776132.

235

MySQL 8.0 Release Notes

• Assigning CONCAT('') or CONCAT_WS('') to a variable set the variable to NULL, not the empty string.

(Bug #31320716, Bug #99485, Bug #31413167, Bug #99722)

• Corrected problems where under some circumstances privilege restrictions could be ignored. (Bug

#31306814, Bug #31315692)

• Certain SELECT statement privileges to lock rows were not checked properly and could block other users

incorrectly. (Bug #31293065)

• When performing a filesort, an internal function could sometimes return NULL on failure, even if the

subselect being sorted was not nullable. (Bug #31281602)

• Statement rewriting for the binary log was inefficient on Windows. (Bug #31260698)

References: This issue is a regression of: Bug #30654405.

• An inconsistency in representing anonymous users in memory could cause issues while performing

privilege-granting operations. (Bug #31246179)

• If the administrative connection interface was enabled, a race condition could lead to problems accepting

Unix socket file connections on the main connection interface. (Bug #31241872)

• When a role was granted with WITH ADMIN OPTION, the grantee was able to manage the role only

after activating it. (Bug #31237368)

• Invalid rows in the default_roles or role_edges system tables could cause server misbehavior.

(Bug #31217385)

• Component deinitialization failure at runtime could lead to repeated messages written to the error log at

shutdown. (Bug #31217037)

• The prohibition on granting roles to anonymous users was incompletely enforced. (Bug #31215017)

• A privilege-escalation issue was corrected. (Bug #31210226)

• The keyring_hashicorp keyring plugin did not perform sufficient validity checking on the values of its

configuration parameters. (Bug #31205363)

• The keyring_hashicorp keyring plugin did not permit binary log encryption to be enabled (by setting

the binlog_encryption system variable). (Bug #31204841)

• The keyring_hashicorp keyring plugin did not permit an encryption password to be set by the

audit_log plugin. (Bug #31197670)

• Some queries using REGEXP_SUBSTR() with an ORDER BY clause were not handled correctly by the

server. (Bug #31184858)

• Some instances where pointer arithmetic was applied to nullptr were corrected. (Bug #31172750)

• If the available file descriptors were exhausted, mysql_real_connect() caused the client to exit.

(Bug #31151052)

• Using the killall command to initiate a mysqld shutdown resulted in no message being logged to

indicate the start of shutdown. This has been corrected. (Bug #31121907)

• Calling mysql_real_connect_nonblocking() with an invalid host could cause the client to exit

upon calling mysql_close(). (Bug #31104389, Bug #99112)

• For Debian packages, Python 2 dependencies that could cause installation failures were removed. (Bug

#31099324)

236

MySQL 8.0 Release Notes

• A potential memory leak in lf_hash_insert() was fixed. (Bug #31090258, Bug #99078)

• Within the LDAP SASL authentication plugins, multiple calls to sasl_client_done() could cause

undefined behavior in some cases. (Bug #31088206)

• With the thread pool plugin enabled, high concurrency conditions could cause loss of client context

resulting in a server exit. (Bug #31085322)

• For result sets processed using mysql_use_result(), mysql_fetch_row_nonblocking() did not

increment the number of rows, so that after all the rows were fetched, mysql_num_rows() returned an

incorrect number of rows. (Bug #31082201, Bug #99073)

• Removed an unneeded optimization for EXISTS() that was never actually evaluated. (Bug #31069510)

• For a server started with the --skip-grant-tables option, enabling the partial_revokes system

variable caused a server exit. (Bug #31066069, Bug #31202963)

• Queries that used a recursive common table expression with an outer reference could return incorrect

results. (Bug #31066001, Bug #99025)

• The parser could fail for multibyte character sets with a minimum character length greater than 1 byte.

(Bug #31063981)

• In some cases, the LEAST() function could return NULL for non-nullable input. (Bug #31054254)

References: This issue is a regression of: Bug #25123839.

• mysql_real_connect_nonblocking() blocked if the MYSQL_OPT_CONNECT_TIMEOUT option was

set. (Bug #31049390, Bug #98980)

• The last call to the mysql_fetch_row_nonblocking() C API function to return the null row was

setting an error when it should not have. (Bug #31048553, Bug #98947)

• On Windows, the default connection type uses a named pipe. The nonblocking C API, which is intended

for TCP/SSL connections, did not take that into account and caused the client to exit. It now produces an

error message indicating the problem. (Bug #31047717)

• X Plugin connections that failed to authenticate due to nonexistence of the user modified the global

audit_log_filter_id system variable. (Bug #31025461)

• LOAD DATA did not ignore hidden generated columns when parsing input file rows. (Bug #31024266,

Bug #98925)

• Pinbox exhaustion in the metadata locking subsystem could produce a misleading error message. (Bug

#31019269, Bug #98911)

• CREATE TABLE ... SELECT failed if it included a functional index. (Bug #31017765, Bug #98896)

• For X Protocol connections, checking the global session mutex was improved to eliminate a minor

performance degradation as the number of threads increased. (Bug #31000043)

• In certain cases, executing a query containing multiple subqueries could lead to an unplanned shutdown

of the server. (Bug #30975826)

• SHOW CREATE TRIGGER failed if FLUSH TABLES WITH READ LOCK was in effect. (Bug #30964944)

• Excessive access checks were performed on certain of the data dictionary tables that underlie

INFORMATION_SCHEMA views, resulting in slow SHOW COLUMNS performance. These checks were

reduced to improve performance.

237

MySQL 8.0 Release Notes

In addition, several SHOW statements implemented as INFORMATION_SCHEMA queries were found to

benefit from enabling the derived_merge flag for the optimizer_switch system variable. Such

queries now internally enable that flag temporarily for better performance, regardless of the flag session

value. Affected queries are:

SHOW SCHEMAS

SHOW TABLES

SHOW TABLE STATUS

SHOW COLUMNS

SHOW KEYS

SHOW EVENTS

SHOW TRIGGERS

SHOW PROCEDURE STATUS

SHOW FUNCTION STATUS

SHOW CHARACTER SET

SHOW COLLATION

(Bug #30962261, Bug #98750, Bug #30921214)

• Two otherwise identical queries executed separately returned one row when using a case-sensitive

collation and two rows with a case-insensitive collation. When the same two predicates were combined

in a single query using AND, two rows were returned when only one row should have been. (Bug

#30961924)

• ALTER TABLE on a SET column that had a display width greater than 255 was not done in place, even if

otherwise possible. (Bug #30943642, Bug #98523)

• The server checked whether a number in yottabytes was too large to print by comparing the value as

a double to ULLONG_MAX, which cannot be represented as a double. This caused the double value

immediately above ULLONG_MAX yottabytes to be printed as 0Y, the erroneous conversion being

reported by Clang 10. (Bug #30927590)

• Resource group SQL statements such as CREATE RESOURCE GROUP did not work over connections

that use X Protocol. (Bug #30900411)

• SHOW GRANTS could display function privileges as procedure privileges. (Bug #30896461, Bug #98570)

• The audit_log plugin mishandled connection events when multiple clients connected simultaneously.

(Bug #30893593)

• The LOCK_ORDER tool reported a syntax error for empty dependency graphs. Empty graphs are now

permitted.

The LOCK_ORDER tool could exhibit unexpected behavior due to mishandling thread list maintenance.

(Bug #30889192)

• Upgrades from MySQL 5.7 did not grant the REPLICATION_APPLIER privilege to root. (Bug

#30783149)

• The gen_range() user-defined function could mishandle its arguments, causing a server exit. (Bug

#30763294)

• During UPDATE processing, conversion of an internal in-memory table to InnoDB could result in a key-

length error. (Bug #30674616)

• Attempts to grant dynamic privileges (which are always global) at the procedure or function level did not

produce an error. (Bug #30628160)

238

MySQL 8.0 Release Notes

• Table value constructors ignored the LIMIT clause. The clause is now taken into account. For example:

VALUES ROW(1), ROW(2), ROW(3) LIMIT 2 outputs 1 and 2. (Bug #30602659)

• It is possible to define a column named * (single asterisk character), but SELECT `*` was treated

identically to SELECT *, making it impossible to select only this column in a query; in other words, the

asterisk character was expanded to a list of all table columns even when it was surrounded by backticks.

(Bug #30528450)

• The FROM_DAYS() function could produce results that were out of range (with the year > 9999). (Bug

#30455845, Bug #97340)

• For debug builds, altering the mysql.func table to MyISAM (not a recommended operation in any case)

caused a server exit. Now this operation is prohibited. (Bug #30248138, Bug #96692)

• Queries on the INFORMATION_SCHEMA KEY_COLUMN_USAGE and TABLE_CONSTRAINTS views could

be slow due to UNION use in their definitions. These were rewritten to move the UNION into a LATERAL

table to enable the optimizer to better use indexes. (Bug #30216864, Bug #30766181, Bug #98238)

• In certain cases, a LIMIT clause incorrectly caused the optimizer to estimate that zero rows needed to

be read from a table. (Bug #30204811)

References: This issue is a regression of: Bug #29487181.

• An internal packet-length function returned values of the wrong integer type. (Bug #30139031)

• Calculations by mysqldump for the length of INSERT statements did not take into account the _binary

character set introducer used for VARBINARY strings. (Bug #29998457, Bug #96053)

• The messages printed to the error log during upgrade of partitioned tables defined with prefix keys did

not provide sufficient details. Detailed warnings that indicate the schema, table, column, and prefix

length are now printed. (Bug #29942014)

References: See also: Bug #31100205.

• mysql_store_result() could fail to detect invalid data packets. (Bug #29921423)

• An assertion was raised if creating a child table in a foreign key relation caused an engine substitution.

(Bug #29899151, Bug #95743)

• mysqltest and mysql-test-run.pl no longer support the --sleep command-line option.

mysqltest no longer supports the real_sleep command. (Bug #29770237)

• The server permitted connections for hosts with names longer than the maximum permitted length (255

characters). (Bug #29704941)

• In a multiple-table UPDATE that updated the key of the first table, if a temporary table strategy was used,

duplicate entries could be written to the temporary table, followed by occurrence of a Can't find

record error. (Bug #28716103)

• The server sometimes mistakenly removed a subquery with a GROUP BY when optimizing a query, even

in some cases when this subquery was used by an outer select. This could occur when the subquery

also used an aggregate function. (Bug #28240054)

• Coercibility of the NAME_CONST() function was assessed incorrectly. (Bug #26319675)

• When reading rows from a storage engine, errors other than “no more records” could be ignored, leading

to problems later. (Bug #20162055)

239

MySQL 8.0 Release Notes

• When a multi-table update used a temporary table, this was not shown in the output of EXPLAIN

FORMAT=TREE, even though such use could have an impact on the performance of the UPDATE

statement for which this was done. (Bug #17978975)

• When performing a filesort for removing duplicates, such as when executing SELECT DISTINCT, it may

be necessary to perform another sort afterwards to satisfy an ORDER BY. In cases where such an ORDER

BY had been pushed down into the first table of a join, as opposed to the join as a whole, this final sort

was not actually performed. (Bug #99687, Bug #31397840)

• Refactoring work done in MySQL 8.0.20 caused single-row buffering for GROUP BY of non-nullable

columns not to function correctly, not taking into account that such a column could be the inner table for

an outer join, and thus would have a NULL flag that would need to be copied. In a GROUP BY without a

temporary table, this would cause the NULL flag to come from the next output row instead of the previous

one, and the data returned to be inconsistent. (Bug #99398, Bug #31252625)

References: This issue is a regression of: Bug #30460528.

• A logical error in the constant folding code for the case in which a constant of type DECIMAL or FLOAT

was the left-hand operand and an integer column value was the right-hand operand yielded an incorrect

result. (Bug #99145, Bug #31110614)

• A query whose predicate compared 0 with -0 where at least one of these was a floating-point value

returned incorrect results. (Bug #99122, Bug #31102789)

• Reimplemented rollups without using slices. This fixes the following known issues:

• A repeating column in a GROUP BY ... WITH ROLLUP yielded the wrong result; that is, a GROUP

BY of the form GROUP BY a, b, a WITH ROLLUP erroneously produced NULL for some of the

column names in the result.

• A GROUP BY ... WITH ROLLUP that did not require a temporary table to print the result also

produced an erroneous NULL in place of at least one of the expected column names in the output.

(Bug #98768, Bug #99141, Bug #26227613, Bug #29134467, Bug #30967158, Bug #30969045, Bug

#31110494)

• SELECT DISTINCT( HEX( WEIGHT_STRING(varchar_column) ) ) returned a truncated result.

(Bug #98592, Bug #30898753)

• Problems with error handling in queries with MAX(), MIN(), or both, combined with a GROUP BY clause,

meant that such a query continued executing until it went through all possible iterations even when an

error should have caused it to terminate immediately. (Bug #98242, Bug #30769515)

• After refactoring the type propagation code for LEAST(), GREATEST(), and other functions, as well as

UNION, an adjustment of the result type for data types like ENUM also replaced the calculated integer

data type with a type that could not accommodate both signed and unsigned values. (Bug #95148, Bug

#29698617)

References: This issue is a regression of: Bug #83895, Bug #25123839.

Changes in MySQL 8.0.20 (2020-04-27, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• Compilation Notes

240

MySQL 8.0 Release Notes

• Deprecation and Removal Notes

• JSON Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Pluggable Authentication

• SQL Syntax Notes

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• Previously, for a user to access definitions of routines the user did not define, the user was required

to have the global SELECT privilege, which is very broad. The new SHOW_ROUTINE privilege may be

granted instead as a privilege with a more restricted scope that permits access to routine definitions.

(That is, an administrator can rescind global SELECT from users that do not otherwise require it and

grant SHOW_ROUTINE instead.) This enables an account to back up stored routines without requiring a

broad privilege.

SHOW_ROUTINE provides access to:

• The contents of the INFORMATION_SCHEMA.ROUTINES table.

• The SHOW CREATE FUNCTION and SHOW CREATE PROCEDURE statements.

• The SHOW FUNCTION CODE and SHOW PROCEDURE CODE statements.

• The SHOW FUNCTION STATUS and SHOW PROCEDURE STATUS statements.

For upgrades from an older version of MySQL, any user who has the global SELECT privilege is granted

SHOW_ROUTINE, if there is not already some user who has SHOW_ROUTINE. (WL #9049)

Compilation Notes

• Solaris: Clang and GCC now can be used for compiling MySQL on Solaris, although both are

experimental and cannot currently be used for production code. (Bug #30562248)

• On EL7 and EL8, CMake configuration was adjusted to look for GCC 9 before GCC 8. Because

libmysqlclient ships with MySQL distributions, client applications built against libmysqlclient

on those platforms are affected and may need to be recompiled. (Bug #30722756)

• On Windows, the CMake compiler-version check for Visual Studio was updated to indicate that Visual

Studio 2019 is the currently supported version. (The version check can be bypassed by running CMake

with -DFORCE_UNSUPPORTED_COMPILER=1.) (Bug #30688403)

241

MySQL 8.0 Release Notes

Deprecation and Removal Notes

• JSON: Previously, it was possible to specify ON EMPTY and ON ERROR clauses in either order when

invoking the JSON_TABLE() function. This runs counter to the SQL standard, which stipulates that when

ON EMPTY is specified, it must always come before any ON ERROR clause. For this reason, specifying

ON ERROR before ON EMPTY is now deprecated, and trying to do so causes the server to issue a

warning. Support for the nonstandard syntax will be removed in a future version of MySQL. (WL #13512)

• The max_length_for_sort_data system variable is now deprecated due to optimizer changes that

make it obsolete and of no effect. (WL #13600)

References: See also: Bug #30473261.

• The use of VALUES() to access new row values in INSERT ... ON DUPLICATE KEY UPDATE

statements is now deprecated, and is subject to removal in a future MySQL release. Instead, you should

use aliases for the new row and its columns as implemented in MySQL 8.0.19 and later.

For example, the statement shown here uses VALUES() to access new row values:

INSERT INTO t1 (a,b,c) VALUES (1,2,3),(4,5,6)

ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

Henceforth, you should instead use a statement similar to the following, which uses an alias for the new

row:

INSERT INTO t1 (a,b,c) VALUES (1,2,3),(4,5,6) AS new

ON DUPLICATE KEY UPDATE c = new.a+new.b;

Alternatively, you can employ aliases for both the new row and each of its columns, as shown here:

INSERT INTO t1 (a,b,c) VALUES (1,2,3),(4,5,6) AS new(m,n,p)

ON DUPLICATE KEY UPDATE c = m+n;

For more information and examples, see INSERT ... ON DUPLICATE KEY UPDATE Statement. (WL

#13325)

JSON Notes

• The rapidjson library included with MySQL has been upgraded to the GitHub snapshot of 16 January

2020. A fix for a compiler error encountered when building from the snapshot on Mac OS X has been

added. (Bug #30898701)

Logging Notes

• Sending a SIGHUP signal to the server no longer causes it to write a status report to the error log. Other

actions performed by the server in response to SIGHUP continue to be done. See Unix Signal Handling

in MySQL.

Similarly, mysqladmin debug no longer causes the status report to be written. (Bug #30578923)

• The log_sink_json JSON-format error log sink now includes a ts (timestamp) in log messages. The

value is an integer indicating milliseconds since the epoch ('1970-01-01 00:00:00' UTC). See Error

Log Output Format. (WL #13786)

Optimizer Notes

• Hash joins are now used any time a nested block loop would be employed. This means that hash joins

can be used for the following types of queries:

242

MySQL 8.0 Release Notes

• Inner non-equi-joins

• Semijoins

• Antijoins

• Left outer joins

• Right outer joins

This builds on work done for MySQL 8.0.18, and removes a limitation in the implementation such that a

hash join could be used only with a query having at least one equi-join condition. In addition, both inner

and outer joins (including semijoins and antijoins) can now employ batched key access (BKA), which

allocates join buffer memory incrementally so that individual queries need not use up large amounts of

resources that they do not actually require for resolution. For more information, see Batched Key Access

Joins.

This fix completes the task of replacing the executor used in previous versions of MySQL with the

iterator executor, including replacement of the old index subquery engines that governed queries of the

form WHERE value IN (SELECT column FROM table WHERE condition) for those IN queries

which have not been converted into semijoins, as well as queries materialized into the same form, which

depended on internals from the old executor.

For more information and examples, see Hash Join Optimization. (Bug #30528604, Bug #30473261,

Bug #30912972, WL #13377, WL #13476)

• This release implements several new index-level optimizer hints, which function much like existing index

hints that employ SQL keywords such as FORCE INDEX and IGNORE INDEX. These are intended to

replace the equivalent index hints, which will be deprecated in a future MySQL release (and eventually

removed). The new hints are listed here, along with a brief description of each:

• JOIN_INDEX: Forces MySQL to use the specified index or indexes for any available access method,

such as ref, range, index_merge, and so on. This is equivalent to the FORCE INDEX FOR JOIN

index hint.

NO_JOIN_INDEX: Causes the server to ignore the specified index or indexes for any access method.

The equivalent index hint is IGNORE INDEX FOR JOIN.

• GROUP_INDEX: Makes the server use the specified index or indexes for index scans for GROUP BY

operations. Equivalent to FORCE INDEX FOR GROUP BY.

NO_GROUP_INDEX: Forces MySQL to ignore the specified index or indexes for index scans for GROUP

BY operations. The equivalent index hint is IGNORE INDEX FOR GROUP BY.

• ORDER_INDEX: Causes MySQL to use the specified index or indexes for sorting rows. It is equivalent

to FORCE INDEX FOR ORDER BY.

NO_ORDER_INDEX: Keeps the server from using the specified index or indexes for performing row

sorts. Equivalent to IGNORE INDEX FOR ORDER BY.

• INDEX: Acts as the combination of JOIN_INDEX, GROUP_INDEX, and ORDER_INDEX, forcing the

server to use the specified index or indexes for any and all scopes. Equivalent to FORCE INDEX.

NO_INDEX: Acts as the combination of NO_JOIN_INDEX, NO_GROUP_INDEX, and NO_ORDER_INDEX;

that is, it forces MySQL to ignore the specified index or indexes for any and all scopes. It is equivalent

to the index hint IGNORE INDEX.

243

MySQL 8.0 Release Notes

Consider the following query using index hints on a table having the indicated columns and index:

SELECT a,b FROM t1 USE INDEX FOR ORDER BY (i_ab) ORDER BY a;

Using the index-level optimizer hints introduced in this release, this query can be rewritten as shown

here:

SELECT /*+ ORDER_INDEX(t1 i_ab) */ a,b FROM t1 ORDER BY a;

The new index-level optimizer hints can be used with SELECT, UPDATE, and DELETE statements. (This

is unlike index hints using FORCE INDEX or IGNORE INDEX, which can be used only with SELECT and

UPDATE.) Thus, statements like the following are possible:

UPDATE /*+ INDEX(t1 i_ab) */ t1 SET d = 1

WHERE a = 1 AND b = 2 AND c = 3;

DELETE /*+ INDEX(t1 i_a,i_c) */ FROM t1

WHERE a = 1 AND b = 2 AND c = 3;

Multiple hints can be specified within the same comment, like this:

DELETE /*+ INDEX(t1 i_a) JOIN_INDEX(t1 i_c) */

FROM t1 WHERE a = 1 AND b = 2 AND c = 3;

Index-level optimizer hints can be used concurrently with other optimizer hints. When you do so, the

index-level hints apply first; the effects of any other optimizer hints are limited to the set of indexes

permitted by the index-level hints.

Index-level hints can also be used when creating views, as shown here:

CREATE VIEW v1 AS

SELECT /*+ NO_INDEX(t1 i_a,i_b) */ a FROM t1

WHERE b IN

(SELECT /*+ NO_INDEX(t1 i_ab,i_b) */ a FROM t1 WHERE a > 3)

ORDER BY a;

If these index-level optimizer hints are used in the same statement as index hints, the index hints are

ignored.

The new index-level optimizer hints are equivalent to FORCE INDEX rather than USE INDEX; in other

words, using one or more of the index-level optimizer hints means that a table scan is used only if

there is no way to use one of the named indexes to find rows in the table. To cause MySQL to use

the same index or set of indexes as with a given instance of USE INDEX, you can use NO_INDEX,

NO_JOIN_INDEX, NO_GROUP_INDEX, NO_ORDER_INDEX, or some combination of these.

For more information and examples, see Index-Level Optimizer Hints. (WL #13538)

Packaging Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.69.0. (Bug #30866333)

• For RPM packages, the comp_err utility has been moved to the -test subpackage and marked as a

test component. (Bug #30716034)

• The bundled libedit library was upgraded to version 3.1. (Bug #28939380, Bug #20770875, Bug

#22930525, Bug #22332089, Bug #27433491, Bug #27285445, WL #13534)

244

MySQL 8.0 Release Notes

• The bundled LZ4 library was upgraded to version 1.9.2. This fixes certain issues such as Bug

#30369643 producing a mysqlpump runtime error. (WL #13690)

References: See also: Bug #30369643.

Performance Schema Notes

• The Performance Schema collected session-related statistics for errors that can occur only globally

and not per session. This is no longer done, reducing memory overhead for error instrumentation.

Additionally, rows for global errors are no longer included in error summaries reported per thread,

account, user, or host. (Bug #30311574)

Pluggable Authentication

• An LDAP server can be configured to delegate LDAP searches to another LDAP server, a functionality

known as LDAP referral. However, enabling LDAP referral can cause searches to fail with LDAP

operation errors under certain conditions. To enable the MySQL Enterprise Edition LDAP authentication

plugins to avoid referral errors, the new authentication_ldap_simple_referral and

authentication_ldap_sasl_referral system variables are available. These variables enable

each plugin to control whether the LDAP server should use referral during MySQL authentication. See

LDAP Search Referral. (WL #12888)

• The MySQL Enterprise Edition SASL LDAP authentication plugin now supports GSSAPI/Kerberos as

an authentication method for MySQL clients and servers on Linux. This is useful in Linux environments

where applications access LDAP using Microsoft Active Directory, which has Kerberos enabled by

default. See LDAP Authentication Methods.

This feature is available for all RPM and DEB packages for Linux, but not for the TAR archive packages.

(WL #12888)

SQL Syntax Notes

• Previously, the INTO clause for SELECT statements could appear at either of two positions:

• Before FROM:

SELECT * INTO OUTFILE 'file_name' FROM table_name;

• Before a trailing locking clause:

SELECT * FROM table_name INTO OUTFILE 'file_name' FOR UPDATE;

INTO now can appear in a third position, at the end of SELECT statements:

SELECT * FROM table_name FOR UPDATE INTO OUTFILE 'file_name';

Placing INTO at the end is the preferred position. The position before a locking clause is now deprecated

and support for it will be removed in a future MySQL version. In other words, INTO after FROM but not at

the end of the SELECT produces a warning.

Additionally, some changes have been made for UNION with respect to INTO. These UNION variants

containing INTO are syntactically correct and produce the same result:

... UNION SELECT * FROM table_name INTO OUTFILE 'file_name';

... UNION (SELECT * FROM table_name) INTO OUTFILE 'file_name';

... UNION SELECT * INTO OUTFILE 'file_name' FROM table_name;

... UNION (SELECT * INTO OUTFILE 'file_name' FROM table_name);

245

MySQL 8.0 Release Notes

However, the last two variants are confusing, as if they collect information from the named table rather

than the entire query expression (the UNION). Those two UNION variants containing INTO now are

deprecated and support for them will be removed in a future MySQL version. Thus:

• In the trailing query block of a query expression, use of INTO before FROM produces a warning.

• In a parenthesized trailing block of a query expression, use of INTO (regardless of its position relative

to FROM) produces a warning.

The deprecations apply to all INTO forms: INTO OUTFILE, INTO DUMPFILE, and INTO var_list.

(WL #13559)

Test Suite Notes

• The perfschema.idx_compare_replication_applier_status test case was updated to store

the old value of number of transaction retries and compare it with the new value of number of transaction

retries. Thanks to Facebook for the contribution. (Bug #30810627, Bug #98389)

X Plugin Notes

• If the MySQL Server instance's client connections limit, as specified by the max_connections server

system variable, was reached while X Plugin was starting up, X Plugin was unable to create a session

to get the server configuration, so failed to start. X Plugin now creates an administrative session (using

the mysql_admin_session service) during startup, which is not subject to the client connections limit.

(Bug #30894981)

• When an X Protocol session could not be initialized because there were too many X Protocol

connections already, the error code 5011 Could not open session was returned. The more relevant

error code 1040 Too many connections is now returned in this situation. (Bug #30753637)

• An issue with validating JSON references caused an error when creating a collection with a validation

schema. (Bug #30733330)

• During shutdown of a MySQL Server instance with X Protocol connections to clients, a race condition in

X Plugin could cause invalid client connections to be accepted for processing. Because invalid clients

were ignored for client timeout verification during shutdown, these clients blocked shutdown until the

timeout set by the mysqlx_wait_timeout system variable was reached, which defaults to 8 hours.

To prevent this issue, client timeout verification now includes clients that are in an invalid state. (Bug

#30702685)

• When connecting to a MySQL 8.0 server, X Plugin set a different collation for the session to that used

by the mysql client, which could cause issues with queries that depended on the collation. X Plugin

now uses the utf8mb4_0900_ai_ci collation, which is the default for the utf8mb4 characterset. (Bug

#30516849)

• The worker threads for X Protocol connections were identified as system threads on creation, and

assigned to the SYS_default resource group. This identification meant they could not be assigned to

user resource groups for resource management purposes. They are now identified as user threads and

assigned to the USR_default resource group. Note that X Protocol does not currently support CREATE,

ALTER, DROP, and SET RESOURCE GROUP statements, but these statements can operate on X Protocol

connection threads using classic MySQL protocol connections. (Bug #30059288)

• X Plugin can now access the MySQL system variables as soon as initialization starts, so the plugin

install thread can set up the required connectivity itself rather than starting a separate thread. (Bug

#29127302)

246

MySQL 8.0 Release Notes

Functionality Added or Changed

• Important Change: Previously, including any column of a blob type larger than TINYBLOB or BLOB

as the payload in an ordering operation caused the server to revert to sorting row IDs only, rather than

complete rows; this resulted in a second pass to fetch the rows themselves from disk after the sort was

completed. Since JSON and GEOMETRY columns are implemented internally as LONGBLOB, this caused

the same behavior with these types of columns even though they are almost always much shorter than

the 4GB maximum for LONGBLOB (or even the 16 MB maximum for MEDIUMBLOB). The server now

converts columns of these types into packed addons in such cases, just as it does TINYBLOB and BLOB

columns, which in testing showed a significant performance increase. The handling of MEDIUMBLOB and

LONGBLOB columns in this regard remains unchanged.

One effect of this enhancement is that it is now possible for Out of memory errors to occur when trying

to sort rows containing very large (multi-megabtye) JSON or GEOMETRY column values if the sort buffers

are of insufficient size; this can be compensated for in the usual fashion by increasing the value of the

sort_buffer_size system variable. (Bug #30400985, Bug #30804356)

• InnoDB: The Contention-Aware Transaction Scheduling (CATS) algorithm, which prioritizes transactions

that are waiting for locks, was improved. Transaction scheduling weight computation is now performed a

separate thread entirely, which improves computation performance and accuracy.

The First In First Out (FIFO) algorithm, which had also been used for transaction scheduling, was

removed. The FIFO algorithm was rendered redundant by CATS algorithm enhancements. Transaction

scheduling previously performed by the FIFO algorithm is now performed by the CATS algorithm.

A TRX_SCHEDULE_WEIGHT column was added to the INFORMATION_SCHEMA.INNODB_TRX table,

which permits querying transaction scheduling weights assigned by the CATS algorithm.

The following INNODB_METRICS counters were added for monitoring code-level transaction scheduling

events:

• lock_rec_release_attempts

The number of attempts to release record locks.

• lock_rec_grant_attempts

The number of attempts to grant record locks.

• lock_schedule_refreshes

The number of times the wait-for graph was analyzed to update transaction schedule weights.

(WL #13486)

• InnoDB: The storage area for the doublewrite buffer was moved from the system tablespace to

doublewrite files. Moving the doublewrite buffer storage area out of the system tablespace reduces write

latency, increases throughput, and provides flexibility with respect to placement of doublewrite buffer

pages. The following system variables were introduced for advanced doublewrite buffer configuration:

• innodb_doublewrite_dir

Defines the doublewrite buffer file directory.

• innodb_doublewrite_files

Defines the number of doublewrite files.

247

MySQL 8.0 Release Notes

• innodb_doublewrite_pages

Defines the maximum number of doublewrite pages per thread for a batch write.

• innodb_doublewrite_batch_size

Defines the number of doublewrite pages to write in a batch.

For more information, see Doublewrite Buffer. (WL #5655)

• EXPLAIN ANALYZE can now be stopped during execution using KILL QUERY or CTRL-C. (Bug

#30787515)

• EXPLAIN FORMAT=TREE now displays inversion information for windowing functions. (Bug

#30770631)

• EXPLAIN FORMAT=TREE output has been improved to provide more information about evaluated

window functions, and to match that supplied for regular aggregates. (Bug #30573446, Bug #30582782)

• Configuring with the -DWITH_LTO=1 CMake option now works on macOS. (Bug #30125902)

• You can now enable binary log transaction compression on a MySQL server instance. When binary log

transaction compression is enabled, transaction payloads are compressed using the zstd algorithm,

and then written to the server's binary log file as a single event (a Transaction_payload_event).

Compressed transaction payloads remain in a compressed state while they are sent in the replication

stream to replicas, other Group Replication group members, or clients such as mysqlbinlog. They

are not decompressed by receiver threads, and are written to the relay log still in their compressed

state. Binary log transaction compression therefore saves storage space both on the originator of

the transaction and on the recipient (and for their backups), and saves network bandwidth when the

transactions are sent between server instances.

You can enable binary log transaction compression on a MySQL server instance using the

binlog_transaction_compression system variable, which defaults to OFF. You can also use the

binlog_transaction_compression_level_zstd system variable to set the level for the zstd

algorithm that is used for compression. This value determines the compression effort, from 1 (the lowest

effort) to 22 (the highest effort). (WL #3549)

• A new option for the CHANGE MASTER TO statement, REQUIRE_TABLE_PRIMARY_KEY_CHECK,

enables a replication slave to select its own policy for primary key checks. When the option is set to ON

for a replication channel, the slave always uses the value ON for the sql_require_primary_key

system variable in replication operations, requiring a primary key. When the option is set to OFF, the

slave always uses the value OFF for the sql_require_primary_key system variable in replication

operations, so that a primary key is never required, even if the master required one. When the

REQUIRE_TABLE_PRIMARY_KEY_CHECK option is set to STREAM, which is the default, the slave uses

whatever value is replicated from the master for each transaction.

• For multisource replication, setting REQUIRE_TABLE_PRIMARY_KEY_CHECK to ON or OFF enables

a slave to normalize behavior across the replication channels for different masters, and keep a

consistent setting for the sql_require_primary_key system variable. Using ON safeguards

against the accidental loss of primary keys when multiple masters update the same set of tables.

Using OFF allows masters that can manipulate primary keys to work alongside masters that cannot.

• When PRIVILEGE_CHECKS_USER is set to apply replication privilege checks to the channel, setting

REQUIRE_TABLE_PRIMARY_KEY_CHECK to ON or OFF means that the user account does not need

session administration level privileges to set restricted session variables, which are required to change

the value of sql_require_primary_key to match the master's setting for each transaction.

248

MySQL 8.0 Release Notes

(WL #13239)

• Since MySQL 8.0.19, compression has been supported for messages sent over X Protocol connections.

Connections can be compressed if the server and the client agree on a compression algorithm to use.

By default, the server permits the Deflate, LZ4, and zstd compression algorithms, or you can set the

mysqlx_compression_algorithms system variable to include only the ones you permit. In MySQL

8.0.19, X Protocol uses the library default compression level for each algorithm, and the client cannot

negotiate this.

From MySQL 8.0.20, the client can request a specific compression level during capability

negotiations for an X Protocol connection. X Protocol sets a maximum compression level for

each algorithm, which prevents the server from agreeing to high compression levels that are

requested by clients if that would consume too much resource on the server. The maximum

compression levels are initially set to 5 for Deflate, 8 for LZ4, and 11 for zstd. You can adjust

these settings using the new mysqlx_deflate_max_client_compression_level,

mysqlx_lz4_max_client_compression_level, and

mysqlx_zstd_max_client_compression_level system variables.

New default compression levels for X Protocol have also been selected through performance

testing as being a good trade-off between compression time and network transit time. These

defaults are not necessarily the same as the library default for each algorithm. They are

applied if the client does not request a compression level for the algorithm. The default

compression levels are initially set to 3 for Deflate, 2 for LZ4, and 3 for zstd. You can

adjust these settings using the new mysqlx_deflate_default_compression_level,

mysqlx_lz4_default_compression_level, and mysqlx_zstd_default_compression_level

system variables. (WL #13034)

Bugs Fixed

• Incompatible Change: Some queries that used ST_Contains() did not return any results unless > 0

was added.

Note

For upgrades from earlier versions of MySQL, you should recreate spatial

indexes in tables that have them.

(Bug #30461595, Bug #97347)

• Performance: Certain queries against tables with spatial indexes were not performed as efficiently

following an upgrade from MySQL 5.7 to MySQL 8.0. (Bug #94655, Bug #29488350)

References: See also: Bug #89551, Bug #27499984.

• NDB Cluster: NDB defines one SPJ worker per node owning a primary partition of the root table. If this

table used read from any fragment replica, DBTC put all SPJ workers in the same DBSPJ instance, which

effectively removed the use of some SPJ workers. (Bug #30639165)

• NDB Cluster: Executing the SHOW command using an ndb_mgm client binary from NDB 8.0.16 or earlier

to access a management node running NDB 8.0.17 or later produced the error message Unknown

field: is_single_user. (Bug #30599413)

References: See also: Bug #16275500.

• InnoDB: A CREATE UNDO TABLESPACE operation that specified an undo data file name without

specifying a path removed an existing undo data file of the same name from the directory specified by

249

MySQL 8.0 Release Notes

innodb_undo_directory variable. The file name conflict check was performed on the data directory

instead of the directory specified by the innodb_undo_directory variable. (Bug #30908328, Bug

#98628)

• InnoDB: In debug builds, a regression introduced in MySQL 8.0.19 slowed down mutex and rw-lock

deadlock debug checks. (Bug #30886393)

References: This issue is a regression of: Bug #30628872.

• InnoDB: Valgrind testing raised an error indicating that a conditional jump or move depends on an

uninitialized value. The error was a false-positive due to invalid validation logic. (Bug #30837136)

• InnoDB: Missing barriers in rw_lock_debug_mutex_enter() (in source file sync0debug.cc) could

cause a thread to wait without ever being woken up. (Bug #30819167)

• InnoDB: To improve server initialization speed on Linux, posix_fallocate() is now used to allocate

space for redo log files. (Bug #30804431, Bug #98342)

• InnoDB: A data dictionary table open function was implemented with incorrect lock ordering. (Bug

#30782103, Bug #97825)

• InnoDB: Changes to parallel read threads functionality introduced in MySQL 8.0.17 caused a

degradation in SELECT COUNT(*) performance. Pages were read from disk unnecessarily. (Bug

#30766089)

• InnoDB: DDL logging was not performed for SQL operations executed by the bootstrap thread using

the init_file startup variable, causing files to be left behind that should have been removed during a

post-DDL stage. (Bug #30721214, Bug #98131)

• InnoDB: Adding an index on a column cast as a JSON array on a table with a specific number of

records failed with an “Incorrect key file for table” error. (Bug #30709525, Bug #98098)

• InnoDB: A Valgrind error reported that an uninitialized lock->writer_thread value was used in a

conditional jump. (Bug #30694177)

• InnoDB: An internal buffer pool statistics counter (n_page_gets) was partitioned by page number to

avoid contention when accessed by multiple threads. (Bug #30604841, Bug #97822)

• InnoDB: A tablespace import operation failed with a schema mismatch error due to the .cfg file and the

data dictionary both containing default values for a column that was added using ALGORITHM=INSTANT.

An error should only occur if default values differ. (Bug #30561144)

• InnoDB: A slow shutdown failed to flush some GTIDs, requiring recovery of unflushed GTIDs from the

undo log. (Bug #30548229)

• InnoDB: A broken alignment requirement in the code that allocates a prefix in memory for Performance

Schema memory allocations caused a failure on MySQL builds optimized for macOS and FreeBSD.

(Bug #30530857)

• InnoDB: Adding a virtual column raised an assertion failure due to data that was missing from the new

data dictionary object created for the table. (Bug #30524263)

• InnoDB: A required latch was not taken when checking the mode of an undo tablespace. A required

latch was also not taken when checking whether an undo tablespace is empty. (Bug #30509134)

• InnoDB: Allocating an update undo log segment to an XA transaction for persisting a GTID value before

the transaction performed any data modifications caused a failure. (Bug #30456328)

250

MySQL 8.0 Release Notes

• InnoDB: A query executed on a partitioned table with a discarded tablespace raised an assertion failure.

(Bug #30437407, Bug #97271)

• InnoDB: The row_upd_clust_rec_by_insert function, which marks a clustered index record as

deleted and inserts an updated version of the record into the clustered index, passed an incorrect n_ext

value (the total number of external fields) to lower level functions, causing an assertion failure. (Bug

#30437378)

• InnoDB: During a cloning operation, writes to the data dictionary buffer table at shutdown were too

late, causing a failure. Newly generated dirty pages were not being flushed. (Bug #30427369, Bug

#30405535, Bug #30405535)

• InnoDB: An operation performed with the innodb_buffer_pool_evict debug variable set to

uncompressed caused an assertion failure. (Bug #30405531)

• InnoDB: Read-write lock code (rw_lock_t) that controls ordering of access to the boolean recursive

flag and the writer thread ID using GCC builtins or os_mutex when the builtins are not available, was

revised to use C++ std::atomic in some instances. Thanks to Yibo Cai from ARM for the contribution.

(Bug #30401416, Bug #97150)

• InnoDB: A failure occurred while upgrading from MySQL 5.7 to MySQL 8.0. A server data dictionary

object was missing information about the FTS_DOC_ID column and FTS_DOC_ID_INDEX that remain

after dropping a FULLTEXT index. (Bug #30357954)

• InnoDB: Unnecessary messages about parallel scans were printed to the error log. (Bug #30330448)

• InnoDB: During upgrade from MySQL 5.7 to MySQL 8.0, clustered indexes named GEN_CLUST_INDEX

are renamed to PRIMARY, which resulted in duplicate entries for the clustered indexes being added to

the mysql.innodb_index_stats table. (Bug #30330448)

• InnoDB: Various internal functions computed write event slots in an inconsistent manner. (Bug

#30228108, Bug #96519)

• InnoDB: Under specific circumstances, it was possible that tablespace encryption key information would

not be applied during the redo log apply phase of crash recovery. (Bug #30209760)

• InnoDB: A file operation failure caused the page tracking archiver to fail, which in turn caused the main

thread to hang, resulting in an assertion failure. Also, incorrectly, the page tracking archiver remained

enabled in innodb_read_only mode. (Bug #30202643)

• InnoDB: An index corruption error was reported when attempting to import a tablespace containing

a table column that was added using ALGORITHM=INSTANT. The error was due to missing metadata

associated with the instantly added column. (Bug #30191523, Bug #96477)

• InnoDB: A transaction attempting to fetch an LOB record encountered a null LOB reference, causing an

assertion failure. However, the null LOB reference was valid in this particular scenario because the LOB

value was not yet fully written. (Bug #30144303)

• InnoDB: During a parallel read operation, the rollback of a table load operation while autocommit was

disabled resulted in a server to exit due to assertion code that did not account for the possibility of tree

structure changes during a parallel read. (Bug #30060690)

• InnoDB: The current size value maintained in a rollback segment memory object was found to be

invalid, causing an assertion failure in function trx_purge_free_segment(). A validation routine

(trx_rseg_t::validateCurrSize()) was added to verify the current size value. (Bug #29947027)

• InnoDB: A prepared statement executed with invalid parameter values raised an assertion failure. (Bug

#29880907)

251

MySQL 8.0 Release Notes

• InnoDB: An add column operation caused an assertion failure. The failure was due to a dangling

pointer. (Bug #29866408)

References: This issue is a regression of: Bug #28491099.

• InnoDB: Updating certain InnoDB system variables that take string values raised invalid read errors

during Valgrind testing. (Bug #29717909, Bug #95215)

• InnoDB: Redo log records for modifications to undo tablespaces increased in size in MySQL 8.0 due to

a change in undo tablespace ID values, which required additional bytes. The change in redo log record

size caused a performance regression in workloads with heavy write I/O. To address this issue, the

redo log format was modified to reduce redo log record size for modifications to undo tablespaces. (Bug

#29536710)

• InnoDB: Additional information about InnoDB file writes, including progress data, is now printed to the

error log. (Bug #29472295, Bug #94634)

• InnoDB: An insert statement on a table with a spatial index raised a record type mismatch assertion due

to a tuple corruption. (Bug #29465567)

• InnoDB: A function that calculates undo log record size could calculate an incorrect length value in the

case of a corrupted undo log record, resulting in a malloc failure. Assertion code was added to detect

incorrect calculations. (Bug #29448406, Bug #82734)

• Replication: While an SQL statement was in the process of being rewritten for the binary log so that

sensitive information did not appear in plain text, if a SHOW PROCESSLIST statement was used to

inspect the query, the query could become corrupted when it was written to the binary log, causing

replication to stop. The process of rewriting the query is now kept private, and the query thread is

updated only when rewriting is complete. (Bug #30569003, Bug #97531, Bug #30654405)

• Replication: When a GRANT or REVOKE statement is only partially executed, an incident event is

logged in the binary log, which makes the replication slave's applier thread stop so that the slave can

be reconciled manually with the master. Previously, if a failed GRANT or REVOKE statement was the

first statement executed in the session, no GTID was applied to the incident event (because the cache

manager did not yet exist for the session), causing an error on the replication slave. Also, no incident

event was logged in the situation where a GRANT statement created a user but then failed because the

privileges had been specified incorrectly, again causing an error on the replication slave. Both these

issues have now been fixed. (Bug #30566518, Bug #30324661)

• Replication: Compression is now triggered for the mysql.gtid_executed table when the thread/

sql/compress_gtid_table thread is launched after the server start, and the effects are visible when

the compression process is complete. (Bug #30541799)

• Replication: In the event of an unplanned disconnection of a replication slave from the master, the

reference to the master's dump thread might not be removed from the list of registered slaves, in

which case statements that accessed the list of slaves would fail. The issue has now been fixed. (Bug

#29915479)

• Replication: When a partitioned table was involved, the server did not correctly handle the situation

where a row event could not be written to the binary log due to a lack of cache space. An appropriate

error is now returned in this situation. (Bug #29848931)

• Replication: With the settings binlog_format=MIXED, tx_isolation=READ-COMMITTED, and

binlog_row_image=FULL, an INSERT ... SELECT query involving a transactional storage engine

omitted any columns with a null value from the row image written to the binary log. This happened

because when processing INSERT ... SELECT statements, the columns were marked for inserts

252

MySQL 8.0 Release Notes

before the binary logging format was selected. The issue has now been fixed. (Bug #29110804, Bug

#93423)

• Replication: Under certain conditions, replication of conditional comments could fail. (Bug #28388217)

• Group Replication: The thread used by the Group Replication message service was not correctly

registered by the Performance Schema instrumentation, so the thread actions were not visible in

Performance Schema tables. (Bug #30824676)

• Group Replication: Group Replication initiates and manages cloning operations for distributed

recovery, but group members that have been set up to support cloning may also participate in cloning

operations that a user initiates manually. In releases before MySQL 8.0.20, you could not initiate a

cloning operation manually if the operation involved a group member on which Group Replication was

running. From MySQL 8.0.20, you can do this, provided that the cloning operation does not remove and

replace the data on the recipient. The statement to initiate the cloning operation must therefore include

the DATA DIRECTORY clause if Group Replication is running. (Bug #30798640)

• Group Replication: For Group Replication channels, issuing the CHANGE MASTER TO statement with

the PRIVILEGE_CHECKS_USER option while Group Replication was running caused the channel's relay

log files to be deleted. Transactions that had been received and queued in the relay log, but not yet

applied, could be lost in this situation. The CHANGE MASTER TO statement can now only be issued

when Group Replication is not running. (Bug #30655369)

• Group Replication: The Group Replication failure detection mechanism raises a suspicion if a server

stops sending messages, and the member is eventually expelled provided that a majority of the group

members are still communicating. However, the failure detection mechanism did not take into account

the situation where one or more of the group members in the majority had actually already been marked

for expulsion, but had not yet been removed from the group. Where the network was unstable and

members frequently lost and regained connection to each other in different combinations, it was possible

for a group to end up marking all its members for expulsion, after which the group would cease to exist

and have to be set up again.

The Group Replication Group Communication System (GCS) now tracks the group members that have

been marked for expulsion, and treats them as if they were in the group of suspect members when

deciding if there is a majority. This ensures at least one member remains in the group and the group can

continue to exist. When an expelled member has actually been removed from the group, GCS removes

its record of having marked the member for expulsion, so that the member can rejoin the group if it is

able to. (Bug #30640544)

• Group Replication: Performance Schema tables could not be accessed on a MySQL server with Group

Replication that was running under high load conditions. (Bug #30112711, Bug #30675790)

• Group Replication: Internal queries from Group Replication to the Performance Schema for statistics

on local group members failed if they occurred simultaneously with changes to the group's membership.

Locking for the internal queries has been improved to fix the issue. (Bug #30049349, Bug #30791583,

Bug #30963553)

• Group Replication: During the Group Replication distributed recovery process, if a joining member is

unable to complete a remote cloning operation with any donor from the group, it uses state transfer from

a donor's binary log to retrieve all of the required data. However, if the last attempted remote cloning

operation was interrupted and left the joining member with incomplete or no data, an attempt at state

transfer immediately afterwards could also fail. Before attempting state transfer following a failed remote

cloning operation, Group Replication now checks that the remote cloning operation did not reach the

stage of removing local data from the joining member. If data was removed, the joining member leaves

the group and takes the action specified by the group_replication_exit_state_action system

variable. (Bug #29669099, Bug #29944828)

253

MySQL 8.0 Release Notes

• Group Replication: An earlier change to reduce Performance Schema memory instrumentation

overhead had the unintended effect of causing Group Replication performance degradation. (Bug

#28719976)

References: This issue is a regression of: Bug #27500610.

• Group Replication: Before taking certain actions, Group Replication checks what transactions are

running on the server. Previously, the service used for this check did not count transactions that were in

the commit phase, which could result in the action timing out. Now, transactions that are in the commit

phase are included in the set of currently ongoing transactions. (Bug #28327838)

• JSON: When JSON_TABLE() was used as part of an INSERT statement in strict mode, conversion

errors handled by any ON ERROR clause could cause the INSERT to be rejected. Since errors are

handled by an ON ERROR clause, the statement should not be rejected unless ERROR ON ERROR is

actually specified.

This issue is fixed by ignoring warnings when converting values to the target type if NULL ON ERROR or

DEFAULT ... ON ERROR has been specified or is implied. (Bug #30628330)

• JSON: The output from JSON_TABLE() was not always correct when used in views. This fix corrects

the following issues:

• Column names were not quoted, causing syntax errors when quoting was needed for these.

• Some column types were misreported.

• Some column type attributes such as UNSIGNED were lost.

• Column character set and collation were lost.

(Bug #30263373)

• JSON: The functions JSON_SCHEMA_VALID() and JSON_SCHEMA_VALIDATION_REPORT() formerly

checked to ensure that their arguments were convertible to JSON each time a prepared statement

including these was executed, which was neither efficient nor necessary. Now in such cases, the check

is performed only once, when the statement is prepared. (Bug #97878, Bug #30622327)

• Privilege requirements were checked incorrectly for stored objects with a DEFINER that has the

SYSTEM_USER privilege. (Bug #31077699)

• A number of errors reported by Clang in the documentation generated from the MySQL sources have

been corrected. (Bug #30956093)

• On FreeBSD, the krb5 package is a now a dependency. (Bug #30887620)

• If a query contained multiple references to the same common table expression (CTE) and a pseudo-

comment crossed borders of the CTE definition, the parser failed with confusing syntax error messages.

(Bug #30871301)

• For installation using Debian packages, the /var/run/mysqld directory was not created. (Bug

#30855015, Bug #98484)

• mysqlslap did not shut down its threads properly when SQL statements returned an error. This could

result in attempts to free already freed memory. (Bug #30850310)

• When X Plugin was attempting to add a document to a collection as either an insertion or an update in

the case of a duplicate key, in the case where the document failed a unique key constraint in a field other

254

MySQL 8.0 Release Notes

than the primary key, the error returned by X Plugin did not state that this was the cause of the issue.

The appropriate error is now returned. (Bug #30843865)

• An integer value generated by transformations in the resolver was supplied to a test which expected a

boolean. (Bug #30837240)

• A query using an IN expression that accessed one or more columns holding large string values could

lead to a memory leak. (Bug #30814171)

• Statements did not work properly when the target of a DELETE was a common table expression. (Bug

#30796015, Bug #98330)

• Starting the server with create_admin_listener_thread enabled and without admin_address

enabled caused an abnormal exit during the server shutdown process. (Bug #30785609)

• When a table had both a primary key and a secondary key on the same column, but for different lengths,

the range optimizer chose the wrong key part in the secondary index for comparing range values. (Bug

#30783011)

• In some cases, errors caused when DISTINCT was used with an aggregate function whose argument

was of an incorrect type were not propagated correctly. (Bug #30782687)

• For replication using compression, the slave could raise an assertion if the master was restarted. (Bug

#30774692)

• For debug builds, the server could exit trying to print an optimizer trace. (Bug #30773218, Bug #98258)

• The mysql_real_connect_nonblocking() C API function exhibited blocking behavior. (Bug

#30771233)

• With LOCK TABLES active, while processing INFORMATION_SCHEMA queries, the server could

attempt to lock internal temporary tables (which need no locks), causing an assertion to be raised. (Bug

#30764651, Bug #98221)

• The mysqldump internal network timeout was increased from 700 to 86400 seconds to accommodate

connecting to busy or unresponsive servers. (Bug #30755992, Bug #98203)

• Configuring with -DWITH_SASL=path/to/custom/installation inadvertently caused libsasl to

be linked into the daemon_memcached plugin. (Bug #30755301)

• After deleting the temporary table associated with a window function's frame buffer, the temporary table

parameter for the frame buffer was not cleaned up, causing string buffers associated with copy fields not

to be freed properly. (Bug #30752366)

• The -libs-compat RPM package is now built with system zlib to avoid problems with unrestricted

export of symbols in libmysqlclient.so.18. (Bug #30722389, Bug #98130)

• The server exited histogram sampling prematurely, causing an assertion failure. An unnecessary

boolean variable that marked the completion of a sampling operation was removed. (Bug #30717778)

• When removing a WHERE condition because one of the participating conditions was always false, a

materialized derived table was not cleaned up properly, resulting in a memory leak. (Bug #30712243)

• Multiple comparisons with the same GEOMETRY value were not always handled correctly. (Bug

#30697042)

References: See also: Bug #30306306.

255

MySQL 8.0 Release Notes

• MIN() and MAX() could return an incorrect value for some queries if a WHERE clause containing an IN

() subquery was added. (Bug #30691682, Bug #98047)

• Server startup failed if MySQL Enterprise Firewall was enabled at startup but the whitelist and user

tables were missing. (Bug #30690181)

• For prepared statements, re-execution could cause a server exit if a cleaned-up materialized temporary

table was still being referred to. (Bug #30674598)

• The ER_WARN_DEPRECATED_SQL_CALC_FOUND_ROWS and ER_WARN_DEPRECATED_FOUND_ROWS

error messages were incorrectly categorized in the range of messages meant to be written to the

error log. They are now correctly categorized as messages meant to be sent to clients. The old

errors are now designated as OBSOLETE_ER_WARN_DEPRECATED_SQL_CALC_FOUND_ROWS

and OBSOLETE_ER_WARN_DEPRECATED_FOUND_ROWS in the range of error-log messages. (Bug

#30673043)

• Some joins within subqueries where an outer query used EXISTS or NOT EXISTS were not always

handled correctly. (Bug #30671329)

• Queries using ORDER BY constant are permitted but an ORDER BY clause of this sort should not have

any effect on the result; such queries were not always handled correctly. (Bug #30669493)

• A missing out-of-bounds check in wild_case_match() caused a pointer to read out of bounds. (Bug

#30668886)

• The strconvert() function was not safe for conversions between filename and utf8_general_ci

strings. (Bug #30668847)

• Some filesorts using keys of fixed length were not always handled correctly. (Bug #30665034)

• When performing a hash join on two string columns that were potentially very large (in particular, BLOB

columns with PAD SPACE collations), MySQL stored the entire sort key in the row, which impacted

performance by requiring large amounts of memory. Now only a collation-aware hash is stored, with an

added equality comparison prevent a wrong answer, even in the event of a 64-bit hash collision. (Bug

#30664831)

• When at least two tables were joined to at least two other tables using a semijoin, and the join optimizer

chose to use a loose scan, it was possible to place both of the left tables below the deduplicating nested

loop iterator, leading to excessive deduplication. We fix this by treating a loose scan across multiple

tables as a separate internal structure. (Bug #30659810)

• In unions of a const table and zero or more known-zero expressions, derived tables of exactly one row

could be read incorrectly as having zero rows. (Bug #30655712, Bug #97967)

• A MySQL 8.0.19 patch set an invalid INFORMATION_SCHEMA and data dictionary version number.

Assertion code was added to prevent future version information errors. (Bug #30645158, Bug #97948)

References: This issue is a regression of: Bug #29871530.

• When setting up the iterator tree, the optimizer now filters away and subsequently ignores conditions

which are known to be trivially true. (Bug #30644591)

• Under some conditions, SHOW COLUMNS on a temporary MERGE table could raise an assertion or cause

a server exit. (Bug #30640463)

References: This issue is a regression of: Bug #28811287, Bug #92834.

• The Event Scheduler had a memory leak. (Bug #30628268)

256

MySQL 8.0 Release Notes

• Using the asynchronous C API functions could result in freeing already freed memory. (Bug #30596999,

Bug #97805)

• On tables containing a CHECK constraint, certain simple queries were inefficient due to excessive

memory allocation and Performance Schema calls. (Bug #30594613)

• Under certain circumstances, a memcached command could result in reading an uninitialized memory

buffer, causing a failure. (Bug #30592346)

• A race condition could occur between InnoDB issuing requests for schema and table metadata while

filling INFORMATION_SCHEMA.INNODB_TABLES, and the schema being dropped, leading to user

queries on INNODB_TABLES reporting an error. (Bug #30591967)

• The client library could be induced into an infinite loop by a malicious server. (Bug #30581726)

• Using ALTER USER to reset an account MAX_USER_CONNECTIONS value did not take effect until all

current account connections terminated, if there were any. (Bug #30578217, Bug #97735)

• When the optimizer sets up a weedout, it notifies all tables that are part of the weedout that they should

provide row IDs. For confluent weedouts (weedouts returning at most one row), the optimizer expects

that the executor handles the weedout without row IDs. In the iterator executor, confluent weedouts are

implemented using LIMIT 1; the normal weedout iterator does not handle confluent weedouts, and

thus always expects row IDs. In the case of a confluent weedout on the right side of an outer join, the

confluent weedout was processed as a normal weedout, causing the iterator executor to ask for row IDs

where the tables did not supply them. Now in such cases, the LIMIT 1 optimization is also applied.

(Bug #30566549, Bug #30282693)

• SET PERSIST could fail due to attempting to persist variables to the wrong directory. (Bug #30561982)

• Within a stored program with an error handler defined for the error condition of accessing a nonexistent

table, the handler was not invoked if the table was nonexistent because it was named in a nonexistent

database. (Bug #30561920, Bug #97682)

• The duplicate weedout optimization strategy employed by MySQL (see Optimizing IN and EXISTS

Subquery Predicates with Semijoin Transformations) uses an internal table of row IDs which it

has already seen, with a unique index on the column containing these IDs. When the key for the

unique index became too large, which could happen with very large row IDs, the server reverted to

deduplication by hash key instead, with a separate index (not unique) over the hash field only, as with

other temporary tables. Because the latter index was not properly initialized, affected queries were not

executed properly and could lead to a premature exit. (Bug #30556257)

• For debug builds, under LOCK TABLES, the server could mishandle materialized temporary tables and

raise an assertion. (Bug #30476213, Bug #97404)

• The internal array of materialized query blocks

SELECT_LEX_UNIT::m_query_blocks_to_materialize was not reset between executions, which

meant that it pointed to objects which were no longer valid when a prepared statement was executed a

second time, causing the second execution to fail. (Bug #30438038)

• Altering column collations did not affect unique indexes until a server restart. (Bug #30386119, Bug

#97103)

• When using roles, the EXECUTE privilege for stored functions was treated as a privilege for stored

procedures. As a result, it was not possible to use EXECUTE as a role privilege for functions. (Bug

#30376231)

• A materialized subquery including a condition in which a column value was used as input to a

nondeterministic function produced incorrect results. (Bug #30368937)

257

MySQL 8.0 Release Notes

• Several fixes were applied to the InnoDB memcached plugin. The fixes addressed potential deadlock

issues, issues related to connection list latches, and removal of an obsolete flush mutex. (Bug

#30354225)

• Strings that used the utf8mb4_0900_bin collation could not be compared with utf8mb4 strings that

used a different collation. Now the comparison is done by using utf8mb4_0900_bin for both strings.

(Bug #30350111)

• During optimization, MySQL removes conditions in which all arguments are considered equal; for

example, 1 <> 1 is removed and replaced with false. In doing so, conditions containing non-

deterministic arguments were also removed, which caused a condition such as RAND() < RAND()

to be considered an impossible condition. Now, the optimizer no longer removes conditions containing

nondeterministic arguments. (Bug #30311271)

• Scheduling of events could be disturbed by removing events. (Bug #30301356, Bug #96849)

• The Event Scheduler reported warnings for Valgrind builds. (Bug #30301340)

• Shutting down the server while using the clone plugin raised a Valgrind error. (Bug #30248419)

• If the mysqld-auto.cnf file was malformed, the server did not start (expected), but did not report any

error (unexpected). (Bug #30169731, Bug #96501)

• UPDATE statements could give an inconsistent number of rows matched (found rows) in cases where not

all matched rows were updated, depending on the reason for rows not being updated. For example, rows

not updated due to being updated through a view with a WITH CHECK OPTION clause were not counted

as matching rows, whereas rows not updated due to a failing CHECK CONSTRAINT were counted. For

consistency, rows that fail a WITH CHECK OPTION clause now are counted as matching rows. (Bug

#30158954)

• When restarting the MySQL server on a cloned directory, InnoDB reported an error indicating that it

could not find a tablespace file for a statistics table that was dropped by the server previously. (Bug

#30093799)

• The server did not handle correctly a UNION in which one of the queries contained a subquery that used

ORDER BY. (Bug #29952565)

• For INFORMATION_SCHEMA queries, a race condition could result in multiple attempts to insert a key

when updating the dynamic statistics tables, producing a duplicate-key error. (Bug #29948755, Bug

#95929)

• SHOW CREATE VIEW could fail with an illegal mix of collations for views defined on a function that

returns a string. (Bug #29904087)

• The Performance Schema could fail to remove thread instrumentation when a thread was deleted. (Bug

#29859605)

• A query with a WHERE clause whose predicate contained a numeric value in scientific notation was not

handled correctly.

In addition, attempting to insert a particular integer specified as a string caused a server exit when the

string-to-integer conversion was not successful. (Bug #29723340, Bug #30441969)

• An internal interface was added for retrieving and parsing errors that occur on the donor MySQL server

instance (ER_CLONE_DONOR errors) and for checking if data on the recipient has been dropped. (Bug

#29682642)

• It was not possible to drop any columns from a table when the DEFAULT value. (Bug #29661106)

258

MySQL 8.0 Release Notes

• For the CONNECTION_CONTROL plugin, the Performance Schema instrumentation used keys that were

not discoverable to the Performance Schema unless the associated code actually executed. (Bug

#29539976)

• For a nullable column c, the optimizer now recognizes when the conditions c < c, c > c, and c <> c

are always false and need not be evaluated for every row. Thanks to Daniel Black for the contribution.

(For nonnullable columns, the optimizer already recognized always-false conditions.) (Bug #29115386,

Bug #93642)

• Reinitialization of character sets from Index.xml could cause a use-after-free error. (Bug #28956360,

Bug #93276)

• The sys schema ps_setup_reset_to_default() procedure used MySQL 5.7 defaults, not MySQL

8.0 defaults. (Bug #27636611)

• Some connection encryption ciphers did not work. (Bug #27045306)

•

Previously, mysqlpump read the [mysql_dump] and [client] groups from option files. mysqlpump

now additionally reads the [mysqlpump] group. The [mysql_dump] group is still accepted but is

deprecated. (Bug #24733245, Bug #83144)

• For a query of the form SELECT DISTINCT ... ORDER BY ..., when the ORDER BY was pushed

down onto the first table in the join, the result was not always sorted in the correct order. (Bug #98217,

Bug #30760534)

• The NULL indicator was not properly written for items used as variable-length keys, such that all such

items were assumed to be not NULL, which was considered equal to the empty string when using certain

collations. One visible effect of this issue was that ordering by an expression using a nullable string was

sometimes not performed correctly. An example of such a query, where column c1 contains both NULL

and empty string values, is shown here:

SELECT c1, SUBSTR(c1, 1) AS c2 FROM t ORDER BY c2;

(Bug #98035, Bug #30687020)

• A query returned inaccurate results when an expression in a GROUP BY clause used a column name

differing in case from that used for the name of the column when the table containing this column was

created. An example of this would be when the query used GROUP BY id although the column name as

shown in the original CREATE TABLE statement was ID.

This occurred because, the server performed case-sensitive comparisons of column names in

expressions with names of columns in tables. This issue is fixed by ensuring that such comparisons are

performed in a case-insensitive fashion as expected. (Bug #97628, Bug #98222, Bug #30541701, Bug

#30761372)

• A multi-table UPDATE statement which updated a table joined to a derived table that joined two

other tables was not optimized properly as it had been in MySQL 5.6, instead being treated as if

STRAIGHT_JOIN had been used with the subquery creating the derived table. (Bug #97418, Bug

#30488700)

• EXPLAIN now uses hash join instead of block nested loop, since the latter no longer exists and

is replaced by a hash join in nearly all cases. (Bug #97299, Bug #30444550)

• The execution plan for a query that filtered on the first column of a composite hash index wrongly used

this index, producing erroneous results. (Bug #94737, Bug #29527115)

259

MySQL 8.0 Release Notes

• References to columns from tables of outer query blocks in an ON condition of a JOIN did not work, and

could be used only in a WHERE. The fix for this problem means that a query such as this one now works

correctly:

SELECT o.order_date FROM orders o

WHERE o.order_date IN ( SELECT c.contact_name FROM customers c

INNER JOIN order_details od

ON o.order_id = od.discount );

Previously this had to be rewritten as shown here:

SELECT o.order_date FROM orders o

WHERE o.order_date IN ( SELECT c.contact_name FROM customers c

INNER JOIN order_details od

ON 1

WHERE o.order_id = od.discount );

References to other tables of the same FROM clause as the JOIN, as in the query SELECT * FROM t1

CROSS JOIN (t2 LEFT JOIN t3 ON t1.c=3), are not outer references and remain forbidden. In

this case, a lateral join is required, like this: SELECT * FROM t1 JOIN LATERAL (SELECT * FROM

t2 LEFT JOIN t3 ON t1.c=3). (Bug #35242, Bug #96946, Bug #11748138, Bug #30350696)

• There could be a mismatch between the version of OpenSSL used to build the server and the version

used for other parts of MySQL such as libraries or plugins. This could cause certain features not to

work, such as the LDAP authentication plugins. Now the same version of OpenSSL is used for building

everything. (WL #13759)

• Previous work in MySQL 8.0 to optimize impossible expressions such as a=b AND FALSE as FALSE

could make for less efficient execution when such expressions appeared as outer join conditions, due

to the fact that the join was interpreted as a Cartesian product followed by a filter. (Bug #8202, Bug

#89739, Bug #97552, Bug #11745046, Bug #27581277, Bug #30520749)

References: See also: Bug #98206, Bug #30756135.

Changes in MySQL 8.0.19 (2020-01-13, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Important

There is an issue for MySQL 8.0.19 installed using MySQL Installer that prevents

the server from starting if MySQL Enterprise Firewall is selected during the server

configuration steps. If the server startup operation fails, click Cancel to end the

configuration process and return to the dashboard. You must uninstall the server.

The workaround is to run MySQL Installer without MySQL Enterprise Firewall

selected. Then install MySQL Enterprise Firewall afterward using the instructions for

manual installation (see Installing or Uninstalling MySQL Enterprise Firewall). This

problem is corrected in MySQL 8.0.20.

• Account Management Notes

• Audit Log Notes

• Compilation Notes

• Configuration Notes

260

MySQL 8.0 Release Notes

• Deprecation and Removal Notes

• Error Handling

• SQL Function and Operator Notes

• INFORMATION_SCHEMA Notes

• Keyring Notes

• Logging Notes

• Packaging Notes

• SQL Syntax Notes

• sys Schema Notes

• Thread Pool Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• MySQL now enables administrators to configure user accounts such that too many consecutive

failures and the lock time are configurable per account, using the FAILED_LOGIN_ATTEMPTS and

PASSWORD_LOCK_TIME options of the CREATE USER and ALTER USER statements. See Password

Management. (Bug #27733694, Bug #90169, WL #13515)

Audit Log Notes

• ANALYZE TABLE statements now produce read audit events. (Bug #29625461)

• Audit log connect events now include any connection attributes passed by the client. Connection

attribute logging is supported for new-style XML log file format and JSON format, but not old-style XML

format. See Audit Log File Formats. (WL #11378)

Compilation Notes

• Microsoft Windows: On Windows, the minimum version of CMake for builds from the command line is

now 3.15. (Bug #30332632, Bug #96954)

Configuration Notes

• New FPROFILE_GENERATE and FPROFILE_USE CMake options are available for experimenting with

profile guided optimization (PGO) with GCC. See the cmake/fprofile.cmake in a MySQL source

distribution for information about using them. These options have been tested with GCC 8 and 9, and

with Clang.

Enabling FPROFILE_USE also enables WITH_LTO (link time optimization). (Bug #30089834, Bug

#96314, Bug #30133324, Bug #96410, Bug #30164113, Bug #96486)

• Innodb_system_rows_read, Innodb_system_rows_inserted,

Innodb_system_rows_deleted status variables were added for counting row operations on InnoDB

261

MySQL 8.0 Release Notes

tables that belong to system-created schemas. The new status variables are similar to the existing

Innodb_rows_read, Innodb_rows_inserted, Innodb_rows_deleted status variables, which

count operations on InnoDB tables that belong to both user-created and system-created schemas.

The new status variables are useful in replication environments where relay_log_info_repository

and master_info_repository variables are set to TABLE, resulting in higher row operation counts

on slaves due to operations performed on the slave_master_info, slave_replay_log_info,

and slave_worker_info tables, which belong to the system-created mysql schema. For a valid

comparison of master and slave row operation counts, operations on tables in system-created schemas

can now be excluded using the count data provided by the new status variables.

Thanks to Facebook for the contribution. (Bug #27724674, Bug #90148)

Deprecation and Removal Notes

• The thread_pool plugin used display widths in definitions for integer columns of Performance Schema

tables. This resulted in warnings written to the error log because integer column display widths are now

deprecated. (Bug #30597673)

• Display width specification for integer data types was deprecated in MySQL 8.0.17, and now statements

that include data type definitions in their output no longer show the display width for integer types, with

these exceptions:

• The type is TINYINT(1). MySQL Connectors make the assumption that TINYINT(1) columns

originated as BOOLEAN columns; this exception enables them to continue to make that assumption.

• The type includes the ZEROFILL attribute.

This change applies to tables, views, and stored routines, and affects the output from SHOW CREATE and

DESCRIBE statements, and from INFORMATION_SCHEMA tables.

For DESCRIBE statements and INFORMATION_SCHEMA queries, output is unaffected for objects created

in previous MySQL 8.0 versions because information already stored in the data dictionary remains

unchanged. This exception does not apply for upgrades from MySQL 5.7 to 8.0, for which all data

dictionary information is re-created such that data type definitions do not include display width. (Bug

#30556657, Bug #97680, WL #13528)

• Setting the hash_join optimizer switch (see optimizer_switch system variable) no longer has any

effect. The same applies with respect to the HASH_JOIN and NO_HASH_JOIN optimizer hints. Both the

optimizer switch and the optimizer hint are now deprecated, and subject to removal in a future release of

MySQL.

This also fixes an issue whereby SELECT DISTINCT ... WITH ROLLUP did not always return all

distinct rows. (Bug #27549694, Bug #30471809)

• In MySQL 5.7.14, the mysqlx namespace parameter was introduced for X Protocol's StmtExecute

request, replacing the xplugin parameter, which was therefore deprecated. X Plugin continued

to support the deprecated xplugin namespace for backward compatibility. In MySQL 8.0.19,

the xplugin namespace has now been removed. If the xplugin namespace is used from

this release on, an error message is returned as for an unknown namespace. X Plugin's

Mysqlx_stmt_execute_xplugin status variable, which counted the number of StmtExecute

requests received for the xplugin namespace, is no longer used from MySQL 8.0.19. (WL #13057)

• Support for the YEAR(2) data type was removed in MySQL 5.7.5, leaving only YEAR and YEAR(4)

as valid specifications for year-valued data. Because YEAR and YEAR(4) are semantically identical,

specifying a display width is unnecessary, so YEAR(4) is now deprecated and support for it will be

262

MySQL 8.0 Release Notes

removed in a future MySQL version. Statements that include data type definitions in their output no

longer show the display width for YEAR. This change applies to tables, views, and stored routines, and

affects the output from SHOW CREATE and DESCRIBE statements, and from INFORMATION_SCHEMA

tables.

For DESCRIBE statements and INFORMATION_SCHEMA queries, output is unaffected for objects created

in previous MySQL 8.0 versions because information already stored in the data dictionary remains

unchanged. This exception does not apply for upgrades from MySQL 5.7 to 8.0, for which all data

dictionary information is re-created such that data type definitions do not include display width.

The (undocumented) UNSIGNED attribute for YEAR is also now deprecated and support for it will be

removed in a future MySQL version. (WL #13537)

Error Handling

• Error messages regarding crash recovery for XA were revised to indicate XA context to distinguish them

from non-XA crash recovery messages. (Bug #30578290, Bug #97743)

• Previously, the server returned this error message for attempts to use LOAD DATA LOCAL with LOCAL

capability disabled: The used command is not allowed with this MySQL version. This

was misleading because the error condition is not related to the MySQL version. The server now returns

an error code of ER_CLIENT_LOCAL_FILES_DISABLED and this message: Loading local data

is disabled; this must be enabled on both the client and server side. (Bug

#30375698, Bug #29377985, Bug #94396)

SQL Function and Operator Notes

• Previously, loadable functions took no account of the character set or collation of string arguments

or return values. In effect, string arguments and return values were treated as binary strings, with the

implication that only string arguments containing single-byte characters could be handled reliably.

Loadable function behavior is still the same by default, but the interface for writing loadable functions

has been extended to enable them to determine the character set and collation of string arguments,

and to return strings that have a particular character set and collation. These capabilities are optional

for loadable function writers, who may take advantage of them as desired. See Loadable Function

Character Set Handling

Of the loadable functions distributed with MySQL, those associated with the following features and

extensions have been modified to take advantage of the new capabilities: MySQL Enterprise Audit,

MySQL Enterprise Firewall, MySQL Enterprise Data Masking and De-Identification, MySQL Keyring (the

general-purpose keyring functions only), and Group Replication. The modification applies only where it

make sense. For example, a function that returns encrypted data is intended to return a binary string, not

a character string.

Character-set capabilities for loadable functions are implemented using the mysql_udf_metadata

component service. For information about this service, see the MySQL Server Doxygen documentation,

available at https://dev.mysql.com/doc/index-other.html (search for s_mysql_mysql_udf_metadata

and udf_metadata_imp). Source code for the MySQL Keyring functions is available in Community

source distributions and may be examined as examples for third-party loadable function writers who wish

to modify their own functions to be character set-aware. (WL #12370)

INFORMATION_SCHEMA Notes

• The INFORMATION_SCHEMA contains several new tables that expose role information:

263

MySQL 8.0 Release Notes

• ADMINISTRABLE_ROLE_AUTHORIZATIONS: Roles the current user can grant; see The

INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table.

• APPLICABLE_ROLES: Roles applicable for the current user; see The INFORMATION_SCHEMA

APPLICABLE_ROLES Table.

• ENABLED_ROLES: Roles enabled within the current session; see The INFORMATION_SCHEMA

ENABLED_ROLES Table.

• ROLE_COLUMN_GRANTS: Column privileges for roles for the current user; see The

INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table.

• ROLE_ROUTINE_GRANTS: Routine privileges for roles for the current user; see The

INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table.

• ROLE_TABLE_GRANTS: Table privileges for roles for the current user; see The

INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table.

(WL #10895)

Keyring Notes

• A new SECRET key type is available that is intended for general-purpose storage of sensitive data using

the MySQL keyring. The keyring encrypts and decrypts SECRET data as a byte stream upon storage and

retrieval. The SECRET key type is supported by all keyring plugins. See Supported Keyring Key Types

and Lengths. (WL #12859)

Logging Notes

• The SIGUSR1 signal now causes the server to flush the error log, general query log, and slow query log.

One use for SIGUSR1 is to implement log rotation without having to connect to the server (which to flush

logs requires an account that has the RELOAD privilege). The server response to SIGUSR1 is a subset

of the response to SIGHUP, enabling SIGUSR1 to be used as a more “lightweight” signal that flushes

certain logs without the other SIGHUP effects such as flushing the thread and host caches and writing a

status report to the error log. See Unix Signal Handling in MySQL. (WL #13689)

Packaging Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.66.0. (Bug #30356844)

• The zstd library bundled with MySQL has been upgraded from version 1.3.3 to 1.4.3. MySQL uses the

zstd library to support connection compression. (Bug #30236685)

• For package types for which OpenSSL shared libraries are included, they are now also included under

lib/private if the package has private-to-MySQL libraries located there that need OpenSSL. (Bug

#29966296)

SQL Syntax Notes

• Important Change: MySQL now supports explicit table clauses and table value constructors according

to the SQL standard. These have now been implemented, respectively, as the TABLE statement and the

VALUES statement, each described in brief here:

• TABLE table_name is equivalent to SELECT * FROM table_name, and can be used anywhere

that the equivalent SELECT statement would be accepted; this includes joins, unions, INSERT ...

264

MySQL 8.0 Release Notes

SELECT statements, REPLACE statements, CREATE TABLE ... SELECT statements, and

subqueries.

You can use ORDER BY with TABLE, which also supports LIMIT with optional OFFSET; these clauses

function in the same way in a TABLE statement as they do with SELECT. The following two statements

produce the same result:

TABLE t ORDER BY c LIMIT 10 OFFSET 3;

SELECT * FROM t ORDER BY c LIMIT 10 OFFSET 3;

• VALUES consists of the VALUES keyword followed by a series of row constructors (ROW()), separated

by commas. It can be used to supply row values in an SQL-compliant fashion to an INSERT statement

or REPLACE statement. For example, the following two statements are equivalent:

INSERT INTO t1 VALUES ROW(1,2,3), ROW(4,5,6), ROW(7,8,9);

INSERT INTO t1 VALUES (1,2,3), (4,5,6), (7,8,9);

You can also select from a VALUES table value constructor just as you would a table, bearing in mind

that you must supply a table alias when doing so. Using column aliases, you can also select individual

columns, like this:

mysql> SELECT a,c FROM (VALUES ROW(1,2,3), ROW(4,5,6)) AS t(a,b,c);

+---+---+

| a | c |

+---+---+

| 1 | 3 |

| 4 | 6 |

+---+---+

You can employ such SELECT statements in joins, unions, subqueries, and other constructs in which

you normally expect to be able to use such statements.

For more information and examples, see TABLE Statement, and VALUES Statement, as well as

INSERT ... SELECT Statement, CREATE TABLE ... SELECT Statement, JOIN Clause, UNION Clause,

and Subqueries. (Bug #77639, WL #10358)

• Previously, it was not possible to use LIMIT in the recursive SELECT part of a recursive common table

expression (CTE). LIMIT is now supported in such cases, along with an optional OFFSET clause. An

example of such a recursive CTE is shown here:

WITH RECURSIVE cte AS (

SELECT CAST("x" AS CHAR(100)) AS a FROM DUAL

UNION ALL

SELECT CONCAT("x",cte.a) FROM cte

WHERE LENGTH(cte.a) < 10

LIMIT 3 OFFSET 2

)

SELECT * FROM cte;

This statement produces the following output in the mysql client:

+-------+

| a |

+-------+

| xxx |

| xxxx |

| xxxxx |

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MySQL 8.0 Release Notes

+-------+

Specifying LIMIT in this fashion can make execution of the CTE more efficient than doing so in the

outermost SELECT, since only the requested number of rows is generated.

For more information, see Recursive Common Table Expressions. (Bug #92857, Bug #28816906, WL

#12534)

• When CHECK constraints were implemented in MySQL 8.0.16, ALTER TABLE supported DROP CHECK

and ALTER CHECK syntax as MySQL extensions to standard SQL for modifying check constraints, but

did not support the more general (and SQL standard) DROP CONSTRAINT and ALTER CONSTRAINT

syntax for modifying existing constraints of any type. That syntax is now supported; the constraint type is

determined from the constraint name. (WL #12787)

• MySQL now supports aliases in the VALUES and SET clauses of INSERT INTO ... ON DUPLICATE

KEY UPDATE statement for the row to be inserted and its columns. Consider a statement such as this

one:

INSERT INTO t

VALUES (9,5), (7,7), (11,-1)

ON DUPLICATE KEY UPDATE a = a + VALUES(a) - VALUES(b);

Using the alias new for the inserted row, you can now rewrite the statement, referring back to the row

alias in the ON DUPLICATE KEY UPDATE clause, like this:

INSERT INTO t

VALUES (9,5), (7,7), (11,-1) AS new

ON DUPLICATE KEY UPDATE a = a + new.a - new.b;

Using the same row alias, and, additionally, the column aliases m and n for the columns of the inserted

row, you can omit the row alias and use only the column aliases, as shown here:

INSERT INTO t

VALUES (9,5), (7,7), (11,-1) AS new(m,n)

ON DUPLICATE KEY UPDATE a = a + m - n;

The row alias must be distinct from the table name; column aliases must be distinct from one another.

See INSERT ... ON DUPLICATE KEY UPDATE Statement, for more information and examples. (WL

#6312)

sys Schema Notes

• sys schema objects have been reimplemented not to invoke the deprecated sys.format_bytes(),

sys.format_time(), and sys.ps_thread_id() stored functions. Instead, they invoke the

equivalent built-in SQL functions implemented in MySQL 8.0.16 that format or retrieve Performance

Schema data (see Changes in MySQL 8.0.16 (2019-04-25, General Availability)).

sys.format_bytes(), sys.format_time(), and sys.ps_thread_id() will be removed in a

future MySQL version, so applications that use them should be adjusted to use the built-in functions

instead, keeping in mind some minor differences between the sys functions and the built-in functions.

See Performance Schema Functions. (WL #13439)

Thread Pool Notes

• By default, the thread pool plugin tries to ensure a maximum of one thread executing

in each group at any time. The default algorithm takes stalled threads into account

and may temporarily permit more active threads. The plugin now implements a new

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MySQL 8.0 Release Notes

thread_pool_max_active_query_threads system variable for controlling number of active threads

per group. If thread_pool_max_active_query_threads is 0, the default algorithm applies. If

thread_pool_max_active_query_threads is greater than 0, it places a limit on the number of

active threads per group. See Thread Pool Operation. (WL #12915)

X Plugin Notes

• X Plugin could not be compiled on Debian with GCC 9. The --no-as-needed linker option was added

to provide a workaround for the issue. (Bug #30445201)

• Using X Protocol to query the Information Schema table TRIGGERS could result in errors being returned

or some rows not being returned. (Bug #30318917)

Functionality Added or Changed

• Group Replication: Replication connections to a replication slave, and Group Replication connections

for distributed recovery, now have full client side configuration options for the TLSv1.3 protocol.

In MySQL releases where TLSv1.3 support was available but these configuration options were

not available, if TLSv1.3 was used for these connection types, the client in the connection (the

replication slave or the joining Group Replication member that initiated distributed recovery) could

not be configured. This meant that the server in the connection (the replication master or the Group

Replication existing member that was the donor for distributed recovery) had to permit the use of

at least one TLSv1.3 ciphersuite that is enabled by default. From MySQL 8.0.19, you can use the

configuration options to specify any selection of ciphersuites for these connections, including only non-

default ciphersuites if you want.

The new configuration options are as follows:

• Group Replication system variables group_replication_recovery_tls_version

and group_replication_recovery_tls_ciphersuites.

group_replication_recovery_tls_version specifies a list of permitted TLS protocols

for connection encryption for the client instance (the joining member) in the distributed recovery

connection. group_replication_recovery_tls_ciphersuites specifies a list of permitted

ciphersuites when TLSv1.3 is used for that connection.

• A MASTER_TLS_CIPHERSUITES option on the CHANGE MASTER TO command, to specify a list of

TLSv1.3 ciphersuites permitted by the replication slave for the connection to the replication master.

(The CHANGE MASTER TO command already had a MASTER_TLS_VERSION option to specify the

permitted TLS protocol versions for the connection.)

(Bug #29960735, WL #13392)

• Group Replication: The Group Replication plugin interacts with MySQL Server using internal sessions

to perform SQL API operations. Previously, these sessions counted towards the client connections

limit specified by the max_connections server system variable. If the server had reached this

limit when Group Replication was started or attempted to perform an operation, the operation was

unsuccessful and Group Replication or the server itself might stop. From MySQL 8.0.19, Group

Replication interactions with MySQL Server use a new component service that handles the internal

sessions separately, which means that they do not count towards the max_connections limit and are

not refused if the server has reached this limit. (Bug #29635001, WL #13378)

• Microsoft Windows: Previously, the system (\!) command for the mysql command-line client worked

only for Unix systems. It now works on Windows as well. For example, system cls or \! cls may be

used to clear the screen. (Bug #11765690, Bug #58680, WL #13391)

267

MySQL 8.0 Release Notes

• JSON: When using JSON_SCHEMA_VALID() to specify a CHECK constraint on a table

containing one or more JSON columns and experiencing a validation failure, MySQL

now provides detailed information about the reasons for such failures. A new error

ER_JSON_SCHEMA_VALIDATION_ERROR_WITH_DETAILED_REPORT is implemented containing this

information, which can be viewed in the mysql client by issuing SHOW WARNINGS when an INSERT

statement is rejected by the server.

For more information and examples, see JSON_SCHEMA_VALID() and CHECK constraints. For more

general information, see also CHECK Constraints. (WL #13195)

• Debian packages now contain more general systemd support that better supports manual mysqld

execution. (Bug #29702050, Bug #95163)

• Duplicate key error information was extended to include the table name of the key. Previously,

duplicate key error information included only the key value and key name. Thanks to Facebook for the

contribution. (Bug #28686224, Bug #925308, WL #12589)

• When the mysql client operates in interactive mode, the --binary-as-hex option now is enabled

by default. In addition, output from the status (or \s) command includes this line when the option is

enabled implicitly or explicitly:

Binary data as: Hexadecimal

To disable hexadecimal notation, use --skip-binary-as-hex (Bug #24432545, WL #13038)

• MySQL now supports datetime literals with time zone offsets, such as '2019-12-11

10:40:30-05:00', '2003-04-14 03:30:00+10:00', and '2020-01-01 15:35:45+05:30';

these offsets are respected but not stored when inserting such values into TIMESTAMP and DATETIME

columns; that is, offsets are not displayed when retrieving the values.

The supported range for a timezone offset is -13:59 to +14:00, inclusive. Time zone names such as

'CET' or 'America/Argentina/Buenos_Aires', including the special value 'SYSTEM', are not

supported in datetime literals. In addition, in this context, a leading zero is required for an hour value less

than 10, and MySQL rejects the offset '-00:00' as invalid.

Datetime literals with time zone offsets can also be used as parameter values in prepared statements.

As part of this work, the allowed range of numeric values for the time_zone system variable has been

changed, so that it is now also -13:59 to +14:00, inclusive.

For additional information and examples, see The DATE, DATETIME, and TIMESTAMP Types, and

MySQL Server Time Zone Support. (Bug #83852, Bug #25108148, WL #10828)

• From MySQL 8.0.19, compression is supported for messages sent over X Protocol connections.

Connections can be compressed if the server and the client agree on a compression algorithm to use.

By default, X Protocol announces support for the deflate, lz4, and zstd compression algorithms.

You can disallow any of these algorithms by setting the new mysqlx_compression_algorithms

system variable to include only the ones you permit. X Protocol always allows uncompressed

connections if the client does not request compression during capability negotiation. Note that X

Protocol's list of permitted compression algorithms operates independently of the list of compression

algorithms announced by MySQL Server, and X Protocol does not fall back to using MySQL Server's

compression settings. You can monitor the effects of message compression for X Protocol using new X

Plugin status variables. (WL #9252, WL #13442)

• For multithreaded slaves (replication slaves on which slave_parallel_workers is set to a value

greater than 0), setting slave_preserve_commit_order=1 ensures that transactions are executed

and committed on the slave in the same order as they appear in the slave's relay log, preserving the

268

MySQL 8.0 Release Notes

same transaction history on the slave as on the master. Previously, this setting required binary logging

and slave update logging to be enabled on the slave, with the associated execution costs and disk space

requirements. Now, slave_preserve_commit_order=1 can be set on a slave with no binary log and

no slave update logging. This enables you to preserve commit order on the slave, and avoid gaps in the

sequence of transactions, without the overhead of binary logging.

A limitation to preserving the commit order on the slave can occur if statement-based replication is in

use, and both transactional and non-transactional storage engines participate in a non-XA transaction

that is rolled back on the master. Normally, non-XA transactions that are rolled back on the master

are not replicated to the slave, but in this particular situation, the transaction might be replicated to the

slave. If this does happen, a multithreaded slave without binary logging does not handle the transaction

rollback, so the commit order on the slave diverges from the relay log order of the transactions in that

case. (WL #7846)

• The MySQL 8.0.18 release introduced the ability to specify a PRIVILEGE_CHECKS_USER account for

a replication channel (using a CHANGE MASTER TO statement), against which MySQL makes privilege

checks when replicated transactions are applied. The use of a PRIVILEGE_CHECKS_USER account

helps secure a replication channel against the unauthorized or accidental use of privileged or unwanted

operations. The use of row-based binary logging is strongly recommended when replication channels are

secured with privilege checks.

In MySQL 8.0.19, a new setting REQUIRE_ROW_FORMAT is added for replication channels, which makes

the channel accept only row-based replication events. You can specify REQUIRE_ROW_FORMAT using

a CHANGE MASTER TO statement to enforce row-based binary logging for a replication channel that is

secured with privilege checks, or to increase the security of a channel that is not secured in this way.

By allowing only row-based replication events, REQUIRE_ROW_FORMAT prevents the replication applier

from taking actions such as creating temporary tables and executing LOAD DATA INFILE requests,

which protects the replication channel against some known attack vectors. Row-based binary logging

(binlog_format=ROW) must be used on the replication master when REQUIRE_ROW_FORMAT is set.

Group Replication already requires row-based binary logging, so from MySQL 8.0.19, Group Replication

channels are automatically created with REQUIRE_ROW_FORMAT set, and you cannot change the option

for those channels. The setting is also applied to all Group Replication channels on upgrade.

mysqlbinlog has a new --require-row-format option, which enforces row-based replication

events for mysqlbinlog's output. The stream of events produced with this option would be accepted by

a replication channel that is secured using the REQUIRE_ROW_FORMAT option. (WL #12968)

• MySQL uses delimiter strings when constructing tablespace names and file names for table partitions.

A “#p#” delimiter string precedes partition names, and an “#sp#” delimiter string precedes subpartition

names, as shown:

schema_name.table_name#p#partition_name#sp#subpartition_name

table_name#p#partition_name#sp#subpartition_name.ibd

Historically, delimiter strings have been uppercase (#P# and #SP#) on case-sensitive file systems

such as Linux, and lowercase (#p# and #sp#) on case-insensitive file systems such as Windows. To

avoid issues when migrating data directories between case-sensitive and case-insensitive file systems,

delimiter strings are now lowercase on all file systems. Uppercase delimiter strings are no longer used.

Additionally, partition tablespace names and file names generated based on user-specified partition

or subpartition names, which can be specified in uppercase or lowercase, are now generated (and

stored internally) in lowercase regardless of the lower_case_table_names setting to ensure case-

269

MySQL 8.0 Release Notes

insensitivity. For example, if a table partition is created with the name PART_1, the tablespace name and

file name are generated in lowercase:

schema_name.table_name#p#part_1

table_name#p#part_1.ibd

During upgrade, MySQL now checks and modifies if necessary:

• Partition file names on disk and in the data dictionary to ensure lowercase delimiters and partition

names.

• Partition metadata in the data dictionary for related issues introduced by previous bug fixes.

• InnoDB statistics data for related issues introduced by previous bug fixes.

During tablespace import operations, partition tablespace file names on disk are checked and modified if

necessary to ensure lowercase delimiters and partition names. (WL #13352)

References: See also: Bug #26925260, Bug #29823032, Bug #30012621, Bug #29426720, Bug

#30024653.

• Support was added for efficient sampling of InnoDB data for the purpose of generating histogram

statistics. The default sampling implementation used by MySQL when storage engines do

not provide their own requires a full table scan, which is costly for large tables. The InnoDB

sampling implementation improves sampling performance by avoiding full table scans. The

sampled_pages_read and sampled_pages_skipped INNODB_METRICS counters can be used to

monitor sampling of InnoDB data pages. See Histogram Statistics Analysis. (WL #8777)

Bugs Fixed

• Important Change: Character set resolution has been changed for the following string functions:

• REPLACE(str, from_str, to_str)

• SUBSTRING_INDEX(str, delim, count)

• TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM] str)

Previously, character set information for all arguments to these functions was aggregated, which could

lead to results that were not well formed. This also caused issues with LPAD(), which assumes that both

input and output are well formed. Now each of the three listed functions always uses the character set

employed by str, and converts all other arguments to this character set at execution time; if any such

conversion fails, the function returns an error. (Bug #30114420)

References: This issue is a regression of: Bug #28197977.

• Important Change: Subquery materialization no longer requires strict matching of inner and outer types.

Different types can now be materialized when one of the following conditions is true:

• The inner type is numeric (since there is always a way to cast the outer type to a number)

• The inner type is temporal (since there is always a way to cast the outer type to a temporal)

• Both types are strings

(Bug #13960580)

270

MySQL 8.0 Release Notes

• NDB Cluster: Password masking was incomplete for some NDB logging options. (Bug #97335, Bug

#30453137)

• InnoDB: Initialization of certain internal data structures at startup depend on internal variables derived

from the max_connections setting. InnoDB failed to resize the internal data structures when the

max_connections setting was modified after startup using SET PERSIST. (Bug #30628872)

• InnoDB: os_file_get_parent_dir warnings were encountered when compiling MySQL with GCC

9.2.0. (Bug #30499288, Bug #97466)

• InnoDB: An attempt to access a large object (LOB) value using a null reference raised an assertion

failure. To prevent this issue form occurring, a check was added to determine if LOB references are null

before they are accessed. (Bug #30499064)

• InnoDB: An assertion failure occurred after upgrading the data directory. Prepared XA transaction were

still present, which prevented undo tablespaces from being upgraded. Undo tablespaces containing

prepared transaction changes must remain active until all prepared XA transactions are committed or

rolled back.

Prepared XA transactions also prevented the completion of an explicit undo tablespace truncation

operation after a restart. (Bug #30489497)

• InnoDB: Attempting to upgrade a MySQL 5.7 instance on Linux with uppercase table names

(partitioned or otherwise) to MySQL 8.0 on macOS raised an assertion failure. Partition file format

changes in MySQL 8.0 prevented migration of the data directory to a different platform, and the

lower_case_table_names setting was changed at upgrade time, which can cause an upgrade failure.

Instead of a failure occurring under these circumstances, an error is now reported. (Bug #30450968, Bug

#30450979)

• InnoDB: On macOS, a failure occurred when attempting to upgrade a MySQL 5.7 instance with

uppercase table names to MySQL 8.0. Uppercase table names were not normalized to lowercase. The

following errors were reported: Table is not found in InnoDB dictionary and Error in

fixing SE data errors. (Bug #30450944)

• InnoDB: On Windows, a failure occurred when attempting to upgrade a MySQL 5.7 instance with

uppercase partitioned table names to MySQL 8.0. Opening the table returned a null pointer, which

caused a segmentation fault when closing the table. (Bug #30450918)

• InnoDB: On Windows, a mysqld exception was raised when attempting to upgrade a MySQL 5.7

instance with uppercase partitioned table names to MySQL 8.0. (Bug #30447790)

• InnoDB: On Windows, a failure occurred when attempting to upgrade a MySQL 5.7 instance containing

general tablespace defined with an uppercase name to MySQL 8.0. The following errors were reported:

Error in fixing SE data and Failed to Populate DD. (Bug #30446798)

• InnoDB: Introduction of local minitransactions (mtrs) in LOB-related code resulted in an assertion failure

during recovery. (Bug #30417719)

• InnoDB: A failure occurred when attempting to upgrade a MySQL 5.7 instance on Windows with

uppercase partitioned table names to MySQL 8.0 on Linux. Partition file format changes in MySQL 8.0

prevented migration of the data directory to a different platform. Instead of a failure, an error is now

reported. (Bug #30411118)

• InnoDB: Updating the same compressed LOB data repeatedly caused the tablespace file to increase in

size. (Bug #30353812)

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MySQL 8.0 Release Notes

• InnoDB: When the temptable_max_ram limit was reached, the TempTable storage engine incorrectly

reported an out-of-memory error instead of falling back to disk-based storage. (Bug #30314972, Bug

#96893)

• InnoDB: After importing an encrypted table and restarting the server, the following error was returned

when attempting to access the table: ERROR 3185 (HY000): Can't find master key from

keyring, please check in the server log if a keyring plugin is loaded and

initialized successfully. The tablespace key was not written to disk after it was encrypted with

the destination master key. (Bug #30313734)

• InnoDB: The internal InnoDB dict_create_foreign_constraints() function that parsed

SQL statements and performed foreign key related DDL checks was removed. The function became

redundant with introduction of the data dictionary in MySQL 8.0 and the subsequent relocation of foreign

key related DDL checks to the SQL layer.

Removal of the dict_create_foreign_constraints() function also addressed the following

foreign key issues:

• Spaces around dots (“.”) in a fully qualified referenced table name were not permitted by the InnoDB

parser.

• Adding a foreign key and removing partitioning in the same ALTER TABLE statement was not

permitted. The InnoDB parser did not detect that the new table version was no longer partitioned.

• A foreign key constraint could not reference a table inside a schema named “AUX”. The function that

parsed referenced table names did not recognize that special names such as AUX are encoded.

• Conditional comments in foreign key definitions were ignored.

Additionally, a check was added to the SQL layer to detect attempts to create multiple foreign keys

of the same name on a table at an early stage in the execution of an ALTER TABLE statement. (Bug

#30287895, Bug #22364336, Bug #28486106, Bug #28703793, Bug #16904122, Bug #92567, Bug

#11754659, Bug #46293)

• InnoDB: A comparison function found two records to be equal when attempting to merge non-leaf pages

of a spatial index. The function was unable to handle this unexpected condition, which resulted in a long

semaphore wait and an eventual assertion failure. (Bug #30287668)

• InnoDB: A locally acquired latch required for freeing a large object (LOB) page could have caused

a deadlock if a subsequent caller attempted to acquire a latch for the same page before the page

was freed. Similarly, a latch taken on a compressed or uncompressed LOB during a rollback related

operation could have caused a deadlock due to a latching order issue. (Bug #30258536)

References: This issue is a regression of: Bug #29846292.

• InnoDB: A race condition between a purge thread that was purging a compressed LOB page and an

update thread that is using a delete-marked record caused an assertion failure. (Bug #30197056)

• InnoDB: A tablespace import operation that failed due to the source and destination tables being defined

with different DATA DIRECTORY clauses reported an insufficiently descriptive schema mismatch error.

Moreover, if a .cfg file was not present, the same operation would raise an assertion failure. A more

informative error message is now reported in both cases before the import operation is terminated due to

the data directory mismatch. (Bug #30190199, Bug #30190227, Bug #20644698, Bug #76142)

• InnoDB: A purge operation failed when attempting to purge a LOB value larger than the buffer pool.

(Bug #30183982)

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MySQL 8.0 Release Notes

• InnoDB: Update operations that moved externally stored LOB data to inline storage failed to mark the

old LOB data as purgeable. (Bug #30178056, Bug #96466)

• InnoDB: Index key part sort order information was not stored to the .cfg metadata file used by ALTER

TABLE ... IMPORT TABLESPACE operations. The index key part sort order was therefore assumed

to be ascending, which is the default. As a result, records could be sorted in an unintended order if one

table involved in the import operation is defined with a DESC index key part sort order and the other

table is not. To address this issue, the .cfg file format was updated to include index key part sort order

information. (Bug #30128418)

• InnoDB: Criteria used by the btr_cur_will_modify_tree() function, which detects whether a

modifying record needs a modifying tree structure, was insufficient. (Bug #30113362)

• InnoDB: Startup was slow on instances with a large number of tables due the tablespace file scan

that occurs at startup to retrieve space IDs. A multithreaded scan was only initiated if the number of

tablespace files exceed 50,000, and three tablespace pages were read to retrieve a space ID. To

improve startup times, additional threads are now allocated for the tablespace file scan, and only the

first tablespace page is read to retrieve a space ID. If a space ID is not found on the first page of the

tablespace, three pages are read to determine the space ID, as before. (Bug #30108154, Bug #96340)

• InnoDB: Startup failed on a case insensitive file system with an error indicating that multiple

files were found for the same tablespace ID. A file path comparison did not recognize that

innodb_data_home_dir and datadir paths were the same due to the paths having different

lettercases. (Bug #30040815)

• InnoDB: A storage engine error occurred when accessing the mysql.innodb_index_stats and

mysql.innodb_table_stats persistent optimizer statistics tables after upgrading a MySQL 8.0.13

instance on Linux with partitioned tables and a lower_case_table_names=1 setting to MySQL 8.0.14

or MySQL 8.0.15. The persistent optimizer statistics tables contained duplicate entries. (Bug #30012621)

References: This issue is a regression of: Bug #26925260.

• InnoDB: CREATE TABLESPACE failed with an error indicating that the tablespace already exists. The

error was due to the failure of a preceding CREATE TABLESPACE operation where the DDL failed but

related changes were not rolled back due to rollback being disabled prior to transaction commit. Rollback

is now disabled after the transaction commits successfully. (Bug #29959193, Bug #95994)

• InnoDB: Changed pages belonging to imported tablespaces were not being tracked. (Bug #29917343)

• InnoDB: Renaming of full-text search auxiliary tables during upgrade failed due to a tablespace

name conflict when upgrading from MySQL 5.7 to MySQL 8.0 on a case-insensitive file system. (Bug

#29906115)

• InnoDB: Rollback of an INSERT operation that inserted a LOB value larger than a buffer pool caused a

deadlock. (Bug #29846292, Bug #95572)

• InnoDB: A code regression was addressed by prohibiting unnecessary implicit to explicit secondary

index lock conversions for session temporary tables. (Bug #29718243)

• InnoDB: A tablespace import operation raised an assertion when the cursor was positioned on a

corrupted page while purging delete-marked records. Instead of asserting when encountering a

corrupted page, the import operation is now terminated and an error is reported. (Bug #29454828, Bug

#94541)

• InnoDB: Delete marked rows were able to acquire an external read lock before a partial rollback was

completed. The external read lock prevented conversion of an implicit lock to an explicit lock during the

partial rollback, causing an assertion failure. (Bug #29195848)

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MySQL 8.0 Release Notes

• InnoDB: After a server exit that occurred while an undo tablespace truncation operation was in progress,

warning messages were printed at startup stating that doublewrite pages could not be restored for undo

tablespace pages. The warning messages are no longer printed for undo tablespaces that are being

truncated. (Bug #28590016)

• InnoDB: In read-only mode (innodb_read_only=ON), SHOW CREATE TABLE output did not include

information about foreign key constraints. (Bug #21966795, Bug #78754)

• Partitioning: When upgrading a database with a subpartitioned table from MySQL 8.0.16 or lower and

then executing ALTER TABLE ADD COLUMN, an assertion or error would occur. (Bug #30360695, Bug

#97054)

• Partitioning: During upgrade of partitioned tables from MySQL 5.7 to 8.0, when a prefix key was used

by the partitioning function, the prefix length was ignored, and the full column length was considered

instead. Consequently, the table might incorrectly be rejected from being upgraded because its partition

field length was found to be too large. (Bug #29941988, Bug #95921)

• Partitioning: ALTER TABLE ... EXCHANGE PARTITION could cause indexes to become corrupted.

This was due to the fact that the server assumed that the order in which an index is created in a

partitioned table is the same as that of the table which is not partitioned. This led to the wrong index data

being exchanged. (Bug #29706669)

• Replication: An assertion was raised when privilege checks were carried out for a replication channel if

the slave had more columns in the relevant table than the master. The check now references the number

of columns in the event, rather than in the table definition. (Bug #30343310)

• Replication: Replication connection parameters that are held in the mysql.slave_relay_log_info

table are now preserved in the event of a server crash or deliberate restart after issuing RESET SLAVE

but before issuing START SLAVE. This action applies to the PRIVILEGE_CHECKS_USER account setting

for replication privilege checks (introduced in MySQL 8.0.18) and the REQUIRE_ROW_FORMAT setting

(introduced in MySQL 8.0.19). Note that if relay_log_info_repository=FILE is set on the server

(which is not the default and is deprecated), replication connection parameters are not preserved in this

situation. (Bug #30311908)

• Replication: When a replication channel is secured by specifying a PRIVILEGE_CHECKS_USER

account, which should not have ACL privileges, a GRANT statement that is replicated to the channel

causes the replication applier to stop. In this situation, the behavior was correct but an assertion was

being raised. The assertion has now been removed. (Bug #30273684)

• Replication: For multithreaded replication slaves, setting slave_preserve_commit_order=1 now

preserves the order of statements with an IF EXISTS clause when the object concerned does not exist.

Previously, these updates might have committed before transactions that preceded them in the relay log,

which might have resulted in gaps in the sequence of transactions that have been executed from the

slave's relay log. (Bug #30262096)

• Replication: When privilege checks were carried out for a replication channel, the permissions required

for setting the session value of the sql_require_primary_key system variable were not being

checked. The check is now carried out. (Bug #30254917)

• Replication: A memory leak could occur when a failed replication group member tried to rejoin a

minority group and was disallowed from doing so. (Bug #30162547, Bug #96471)

• Replication: When a group member rejoins a replication group, it begins the distributed recovery

process by checking the relay log for its group_replication_applier channel for any transactions

that it already received from the group, and applying these. The joining member then initiates state

transfer from an existing online member, which might begin with a remote cloning operation. Previously,

the group_replication_applier channel was not explicitly stopped when a remote cloning

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MySQL 8.0 Release Notes

operation was started, so it was possible that the applier might still be applying existing transactions at

that time, which might lead to errors. The group_replication_applier channel is now stopped

before a remote cloning operation is requested, and restarted when the distributed recovery process

moves on to state transfer from a donor's binary log. (Bug #30152028, Bug #96447)

• Replication: If STOP GROUP_REPLICATION was issued while the member's XCom port was blocked,

the XCom thread hung and the shutdown did not complete. XCom is now terminated in this situation.

(Bug #30139794)

• Replication: The slave status logs mysql.slave_relay_log_info (the relay log info log)

and mysql.slave_worker_info (the slave worker log) are now copied from the donor to the

recipient during a local or remote cloning operation. The slave status logs hold information that

can be used to resume replication correctly after the cloning operation, including the relay log

position from which to restart replication, the PRIVILEGE_CHECKS_USER account setting, and the

new REQUIRE_ROW_FORMAT setting. Note that the relay logs themselves are not copied from the

donor to the recipient, only the information about them that is held in these tables. Also note that if

relay_log_info_repository=FILE is set on the server (which is not the default and is deprecated),

the slave status logs are not cloned; they are only cloned if TABLE is set.

Before this patch, the following replication-related behaviors occurred on a replication slave that had

been provisioned by a cloning operation:

• The default replication channel would fail to start if it was the only channel on the slave, because it

was considered to be not initialized due to the missing relay log information.

• Any PRIVILEGE_CHECKS_USER account setting that had been applied to replication channels on the

donor was absent and had to be respecified.

• Replication channels that used GTID auto-positioning (as specified by the MASTER_AUTO_POSITION

option on the CHANGE MASTER TO statement) were able to resume replication automatically.

• Replication channels that used binary log file position based replication (as specified by the

MASTER_LOG_FILE and MASTER_LOG_POS options on the CHANGE MASTER TO statement)

had to have the MASTER_LOG_FILE and MASTER_LOG_POS options reapplied manually before

restarting replication in order to resume correctly. If the channels were configured to start replication

automatically at server startup, without the options reapplied they would attempt to start replication

from the beginning. They were therefore likely to attempt to replicate data that had already been

copied to the slave by the cloning operation, causing replication to stop and possibly corrupting the

data on the slave.

With this change, the following replication-related behaviors now occur on a replication slave that has

been provisioned by a cloning operation:

• The default replication channel can now always start after the cloning operation if it is configured to do

so.

• All channels now have the donor's PRIVILEGE_CHECKS_USER account setting and

REQUIRE_ROW_FORMAT setting.

• Replication channels that use GTID auto-positioning (as specified by the MASTER_AUTO_POSITION

option on the CHANGE MASTER TO statement) are still able to resume replication automatically. For

Group Replication channels, which use GTID auto-positioning, an internal equivalent of the RESET

MASTER statement is now used to ensure that replication resumes optimally.

• Replication channels that use binary log file position based replication now have the correct

MASTER_LOG_FILE and MASTER_LOG_POS options in place after cloning. Because the relay logs

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MySQL 8.0 Release Notes

themselves are not cloned, these channels now attempt to carry out the relay log recovery process,

using the cloned relay log information, before restarting replication. For a single-threaded slave

(slave_parallel_workers is set to 0), relay log recovery should succeed in the absence of

any other issues, enabling the channel to resume replication correctly. For a multithreaded slave

(slave_parallel_workers is greater than 0), relay log recovery is likely to fail because it cannot

usually be completed automatically, but an informative error message is issued, and the data will not

be corrupted.

(Bug #29995256, Bug #30510766)

• Replication: An internal deadlock could occur on a multi-threaded replication slave when the

relay_log_space_limit system variable was set to limit the size of relay logs on the slave, and the

coordinator thread acquired locks related to this limit and to the end position of the log. (Bug #29842426)

• Replication: If a replication slave was set up using a CHANGE MASTER TO statement that did not

specify the master log file name and master log position, then shut down before START SLAVE was

issued, then restarted with the option --relay-log-recovery set, replication did not start. This

happened because the receiver thread had not been started before relay log recovery was attempted,

so no log rotation event was available in the relay log to provide the master log file name and master log

position. In this situation, the slave now skips relay log recovery and logs a warning, then proceeds to

start replication. (Bug #28996606, Bug #93397)

• Group Replication: When a member is joining or rejoining a replication group, if Group Replication

detects an error in the distributed recovery process (during which the joining member receives state

transfer from an existing online member), it automatically switches over to a new donor, and retries

the state transfer. The number of times the joining member retries before giving up is set by the

group_replication_recovery_retry_count system variable. The Performance Schema table

replication_applier_status_by_worker displays the error that caused the last retry. Previously,

this error was only shown if the group member was configured with parallel replication applier threads

(as set by the slave_parallel_workers system variable). If the group member was configured with

a single applier thread, the error was cleared after each retry by an internal RESET SLAVE operation,

so it could not be viewed. This was also the case for the output of the SHOW SLAVE STATUS command

whether there were single or multiple applier threads. The RESET SLAVE operation is now no longer

carried out after retrying distributed recovery, so the error that caused the last retry can always be

viewed. (Bug #30517160, Bug #30517172, Bug #97540)

• Group Replication: When a replication group member leaves a group, either because STOP

GROUP_REPLICATION was issued or due to an error, Group Replication now stops the binary log dump

thread so that the former group member cannot send unwanted binary log data to the members that

have remained in the group. (Bug #30315614)

• Group Replication: When Group Replication was started following either provisioning with a cloning

operation, execution of RESET MASTER, or removal of a partial transaction from the relay log, RESET

SLAVE ALL was used internally to clear any unwanted state on the server. However, in MySQL 8.0.18,

this caused any PRIVILEGE_CHECKS_USER account that was specified for a Group Replication

channel to be removed. RESET SLAVE is now used instead, which does not remove the account. (Bug

#30262225)

• Group Replication: When Group Replication is running in single-primary mode, and a new primary

server is elected, the messages logged at this time now provide the newly elected primary server's

gtid_executed set, and the set of GTIDs retrieved by the replication applier. (Bug #30049310)

• Group Replication: If a replication group member stops unexpectedly and is immediately restarted

(for example, because it was started with mysqld_safe), it automatically attempts to rejoin the

group if group_replication_start_on_boot=on is set. Previously, if the restart and rejoin

attempt took place before the member's previous incarnation had been expelled from the group,

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MySQL 8.0 Release Notes

the member could not rejoin. Now in this scenario, Group Replication automatically uses a Group

Communication System (GCS) feature to retry the rejoin attempt for the member 10 times, with

a 5-second interval between each retry. This should cover most cases and allow enough time for

the previous incarnation to be expelled from the group, letting the member rejoin. Note that if the

group_replication_member_expel_timeout system variable is set to specify a longer waiting

period before the member is expelled, the automatic rejoin attempts might still not succeed. (Bug

#29801773)

• macOS: On macOS, configuring MySQL with -DWITH_SSL=system caused mysql_config output to

incorrectly include internal CMake names for the static SSL libraries. (Bug #30541879, Bug #97632)

• macOS: Builds on macOS with Ninja could fail with an error trying to create a symbolic link multiple

times. (Bug #30368985)

• Microsoft Windows; JSON: On Windows platforms, memory used for a multi-valued index was not

released after the table containing it was dropped. (Bug #30227756)

• Microsoft Windows: On Windows, -DWITH_SSL=system failed to find the installed OpenSSL headers

if Strawberry Perl was installed. (Bug #30359287)

• Microsoft Windows: On Windows, the -DWITH_SSL=system option did not work if the path

name leading to the system OpenSSL libraries contained a space. This is now handled. Also, -

DWITH_SSL=yes is treated like -DWITH_SSL=system, as on other platforms. (Bug #30261942, Bug

#96739)

• Microsoft Windows: MSVC 2019 produced garbled source file names for compilation errors. A

workaround in the CMake configuration was implemented to correct for this. (Bug #30255096, Bug

#96720)

• JSON: Updating a value in a JSON column by replacing a character string element with a binary string

containing the same byte sequence as the utf8mb4 representation of the character string had no effect.

The root cause of this issue was a change in the behavior of comparisons between JSON strings and

JSON opaque values introduced by the implementation of multi-valued indexes in MySQL 8.0.17,

previous to which, JSON strings and JSON opaque values were never considered equal. After the

change, they were considered equal if their binary data matched.

An analysis of this change showed that it was not needed; in addition, the new behavior conflicted with

the existing documentation for comparisons of JSON values. This issue is fixed by restoring the original

behavior. (Bug #30348554)

• JSON: A view that used JSON_TABLE() did not preserve the character set in which JSON path

arguments were encoded. This meant that, if the view was evaluated with a different character set in

effect from the one in which it was defined, it could produce wrong results. This is fixed by ensuring that

JSON_TABLE() preserves the original character set in such cases. (Bug #30310265)

• JSON: Adding a functional index on a JSON column changed the collation used for comparing strings,

causing the result returned by the same query selecting the column to differ from that obtained without

the index. (Bug #29723353)

• JSON: If the first argument to JSON_TABLE() was const during the execution of a stored procedure,

but not during preparation, it was not re-evaluated when a statement was subsequently executed again,

causing an empty result to be returned each time following the first execution of the procedure. (Bug

#97097, Bug #30382156)

• JSON: In some cases, such as when a query uses FORCE INDEX, the cost of reading

the table is DBL_MAX; this was rounded up to 2e308 when printed, which is too large

for the JSON parser, so that it was not possible to extract parts of the optimizer trace

277

MySQL 8.0 Release Notes

using a query such as SELECT JSON_EXTRACT(trace, '$**.table_scan') FROM

INFORMATION_SCHEMA.OPTIMIZER_TRACE. Now in such cases, values greater than 1.5e308 are

rounded down and printed as 1e308 instead. (Bug #96751, Bug #30226767)

• After upgrading from MySQL 5.7 to MySQL 8.0, a CLONE INSTANCE operation failed with the following

error: ERROR 3862 (HY000): Clone Donor Error: 1016 : Can't open file: './

undo001'. The upgrade process left behind orphaned in-memory undo tablespaces. Thanks to Satya

Bodapati for the contribution. (Bug #30602218, Bug #97784, Bug #30239255, Bug #96637)

• The MySQL optimizer's hash join algorithm uses the join buffer to store intermediate results. If this

buffer overflows, the server uses a spill-to-disk algorithm, which writes one of the hash join operands

to a temporary file, to handle this gracefully. If one of the operands was a table that was a member of a

pushed join operation, this strategy conflicted with the pushed join requirement for all child result rows

to use nested-loop reads whenever one of their pushed join ancestors was the current row in the join

evaluation, which could in some cases result in incorrect query results being returned. (Bug #30573733)

• Access to the INFORMATION_SCHEMA.VIEWS table was not properly restricted to the correct user. (Bug

#30542333)

• When creating hash values used for lookups during a hash join, the server did not respect the PAD

SPACE attribute, meaning that 'foo' and 'foo ' did not match when using a PAD SPACE collation.

This is fixed by padding all strings up to the same length as the longest possible string, where the

longest possible string is deduced from the data type length specifier N in CHAR(N) or VARCHAR(N).

(Bug #30535541)

• When retrieving large result sets containing DECIMAL columns from a secondary engine, conversion of

the column values to strings for transport over the text protocol acted as a bottleneck. The performance

of the functions responsible for such conversions has been improved in some cases by as much as 50%,

as reflected in internal testing. (Bug #30528427)

• When the FORMAT_PICO_TIME() function was invoked to process several rows, once a NULL

argument was found in a row, every result after that was set to NULL. (Bug #30525561)

• When a Performance Schema event was timed, the event duration reported in events_xxx tables

could be NULL instead of 0 for events where the timer start and end values are equal. (Bug #30525560)

• Adding a LIMIT clause to a parenthesized query suppressed locking clauses within the parentheses.

For example, this query would not lock the table:

(SELECT ... FOR UPDATE) LIMIT ...;

Adding a LIMIT clause outside of a parenthesized query is intended to override a LIMIT clause within

the parentheses. However, the outer LIMIT suppressed ORDER BY within the parentheses as well. For

example, for this query, the ORDER BY was suppressed:

(SELECT ... ORDER BY ... LIMIT a) LIMIT b;

Now inner locking and ORDER BY clauses are not suppressed by an outer LIMIT clause. (Bug

#30521098, Bug #30521803)

• When optimizer extracts conditions on constant tables for early evaluation, it does not include WHERE

conditions that are expensive to evaluate, including conditions involving stored functions. When the

extracted condition evaluated to true because it involved only const tables, the entire WHERE condition

was incorrectly removed. Now in such cases, a check for expensive conditions is performed prior to any

removal of the WHERE condition. (Bug #30520714)

• When a lateral materialized derived table used DISTINCT, the derived table was not rematerialized for

each outer row as expected. (Bug #30515233)

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MySQL 8.0 Release Notes

• EXPLAIN ANALYZE did not work correctly with a common table expression using WITH RECURSIVE.

(Bug #30509580)

• The GNU gold loader could cause memory exhaustion on some platforms. Now it is used by default

only on Intel 64-bit platforms. (Bug #30504760, Bug #96698)

• Some Linux platforms experienced high overhead with EXPLAIN ANALYZE due to use of a system call

by libstdc++ instead of clock_gettime(). (Bug #30483025)

• On Solaris 11.4, the LDAP authentication plugins could not be built. (Bug #30482553)

• Queries that used the MEMBER OF() operator were not always handled correctly. (Bug #30477993)

• Boost compilation failed under Visual Studio due to a Boost workaround for a VC++ 2013 bug that has

since been fixed. The workaround is now patched for Boost compilation with MySQL. (Bug #30474056,

Bug #97391)

• When retrieving large result sets containing many integers from a secondary engine, conversion of the

integers to strings for sending over the text protocol could act as a bottleneck. To avoid this problem, the

performance of internal functions performing such conversions has been improved. (Bug #30472888)

• Docker packages were missing the LDAP authentication plugins. (Bug #30465247)

• Corrected a typo in a mysys/my_handler_errors.h error message. Thanks to Nikolai Kostrigin for

the contribution. (Bug #30462329, Bug #97361)

• A GTID table update while innodb_force_recovery was enabled caused a debug assertion failure.

(Bug #30449531, Bug #97312)

• MySQL failed to compile against Protobuf 3.10. (Bug #30428543, Bug #97246)

• Buffered log lines during system startup could be lost. (Bug #30422941, Bug #97225)

• If the mysql.user system table was renamed, the server could exit. (Bug #30418070)

• Revoking a role specified with no host name could cause a server exit. (Bug #30416389)

• When determining whether to pull out a semijoin table when other tables inside the semijoin depended

on this table, only those semijoin tables which were base tables were considered; those in nested joins

were ignored. (Bug #30406241)

References: See also: Bug #12714094, Bug #11752543, Bug #43768.

• The AppArmor profile on Ubuntu platforms was not able to read the OpenSSL configuration. (Bug

#30375723)

• Some Fedora 30 packages had missing obsoletes information that could cause problems upgrading an

existing MySQL installation. (Bug #30348549, Bug #96969)

• Altering only the default encryption in an ALTER SCHEMA statement caused the schema default

character set and collation to be reset to the system defaults. (Bug #30344462, Bug #96994)

• Columns declared with both AUTO_INCREMENT and DEFAULT value expressions (a nonpermitted

combination) could raise an assertion or cause a server exit. (Bug #30331053)

• SHOW GRANTS for an anonymous user could result in a server exit under some conditions. (Bug

#30329114)

• GREATEST() and LEAST() did not always handle time values correctly. (Bug #30326848)

References: This issue is a regression of: Bug #25123839.

279

MySQL 8.0 Release Notes

• The list of subpartitions in partition objects was not serialized and therefore not included in serialized

dictionary information (SDI). To address this issue, support was added for serialization and

deserialization of subpartition dictionary information. The patch for this bug also includes minor SDI code

refactoring and format changes. Due to the format changes, the SDI version number was incremented.

(Bug #30326020, Bug #96943)

• Following execution of ANALYZE TABLE, the optimizer trace for a given query differed when another

query was executed previously to it, but also after the ANALYZE TABLE. (Bug #30321546)

• innodb_buffer_pool_instances was not initialized correctly at server startup if it had been set

using SET PERSIST or PERSIST_ONLY. (Bug #30318828)

• A low max_allowed_packet value caused the following error: ERROR 1153 (08S01) at line 1:

Got a packet bigger than 'max_allowed_packet' bytes. The error message was revised to

indicate the minimum required max_allowed_packet value for cloning operations. (Bug #30315486,

Bug #96891)

• An assertion could be raised when server code tried to send to clients an error code intended to be

written to the error log. These instances are fixed by sending a code intended to be sent to clients. (Bug

#30312874)

• CREATE VIEW did not always succeed when the body of the view definition contained a join and multiple

subselects. (Bug #30309982)

References: This issue is a regression of: Bug #25466100.

• Dependency information for SLES 12 RPM packages was incorrect, causing MySQL installation failure.

(Bug #30308305)

• When restoring GEOMETRY data from hash join chunk files to a GEOMETRY column, the server did not

copy the data to the column, but instead stored a pointer to the data, which resided in a temporary

buffer, meaning that the GEOMETRY column pointed to random data as soon as this buffer was reused.

Now, the server always copies the data from this buffer into the GEOMETRY column when executing a

hash join. (Bug #30306279)

• Some ALTER TABLE operations using the COPY algorithm did not handle columns with expression

default values properly. (Bug #30302907, Bug #96864)

• The CONV() function did not always handle returning the proper number of characters correctly. (Bug

#30301543)

• Parser recursion checks were insufficient to prevent stack overflow. (Bug #30299881)

• The removal of a subquery because the condition in which it occurred was always false was expected to

be performed during resolution, but when the subquery did not involve any tables, the server executed

it while resolving it. This resulted in the failure of a subsequent check to confirm that the subquery was

only being resolved and not yet optimized. Now in such cases, the server also checks to see whether the

subquery was already executed. (Bug #30273827)

• For debug builds, attempts to add to an empty temporary table a column with an expression default that

was not valid raised an assertion. (Bug #30271792)

• Construction of the iterator tree may yield a non-hierarchical structure; this can happen when, for

example, b and c from a LEFT JOIN b LEFT JOIN c also make up the right side of a semijoin.

The iterator executor solves this by adding a weedout on top of the entire query, which means that is

also necessary to iterators interacting with row IDs that they need to store and restore them. This was

not done in all such cases, causing wrong results. Now the addition of a top-level weedout is always

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MySQL 8.0 Release Notes

communicated to the iterators as soon as it is known that this is being done, before any affected iterators

are constructed. (Bug #30267889)

• Foreign key-handling code duplication between the SQL layer and the data dictionary was eliminated.

A side effect is that some error messages now are more informative and clear. (Bug #30267236, Bug

#96765)

• During startup, the server could handle incorrect option values for persisted variables improperly,

resulting in a server exit. (Bug #30263773)

• In some queries involving materialized semijoins, when using the iterator executor, conditions were

evaluated outside the materialization, causing inefficient query plans to be used and sometimes also

producing wrong results. (Bug #30250091)

• ALTER TABLE statements that renamed a column used in CHECK constraints could result in an incorrect

error message. (Bug #30239721)

• For SELECT statements, an INTO var_name clause prior to a locking clause is legal but the parser

rejected it. (Bug #30237291, Bug #96677)

• FLUSH TABLES WITH READ LOCK caused a deadlock when a LOCK INSTANCE FOR BACKUP

statement was previously executed within the same session and there was a concurrent ALTER

DATABASE statement running in another session against the same database specified (implicitly or

explicitly) for the FLUSH TABLES WITH READ LOCK statement. (Bug #30226264)

• Slow query logging could result in a server exit for connections that did not use the classic client/server

protocol. (Bug #30221187)

• A statement that added a foreign key without an explicit name failed when re-executed as a prepared

statement or in a stored program with an unwarranted duplicate foreign key name error. (Bug

#30214965, Bug #96611)

References: This issue is a regression of: Bug #30171959.

• With multiple sessions executing concurrent INSERT ... ON DUPLICATE KEY UPDATE statements

into a table with an AUTO_INCREMENT column but not specifying the AUTO_INCREMENT value, inserts

could fail with a unique index violation. (Bug #30194841, Bug #96578)

• Client programs could load authentication plugins from outside the plugin library. (Bug #30191834, Bug

#30644258)

• When switching between table scans and index lookups, AlternativeIterator did not reset the

handler, which could lead to assertion failures. (Bug #30191394)

• Setting open_files_limit to a large value, or setting it when the operating system rlimit had a value

that was large but not equal to RLIM_INF could cause the server to run out of memory. As part of this

fix, the server now caps the effective open_files_limit value to the the maximum unsigned integer

value. (Bug #30183865, Bug #96525)

• References to fully qualified INFORMATION_SCHEMA tables could fail depending on the lettercase in

which INFORMATION_SCHEMA was specified. (Bug #30158484)

• Slow queries with an execution time greater than 35 days could cause corruption of the

mysql.slow_log system table requiring a REPAIR TABLE operation. (Bug #30113119, Bug #96373)

• MySQL did not support sending systemd notification messages to a socket specified using the

NOTIFY_SOCKET environment variable, if the variable named an abstract namespace socket. (Bug

#30102279)

281

MySQL 8.0 Release Notes

• Using SET PERSIST_ONLY to set a boolean system variable to a numeric value resulted in the server

being unable to restart. (Bug #30094645, Bug #30298191, Bug #96848)

• A fix for a previous issue combined two TABLE_LIST constructors in an unfortunate way. One of these

created a TABLE_LIST object from a TABLE object representing a temporary table. Previously, the table

name was made the same as the alias; this was changed to copying the name from the TABLE object.

Due to the fact that, for a temporary table, the table name is a file path, it was possible to exceed the

limit for MDL_key names, leading to a failed assertion. Fixed by reintroducing dedicated constructors

which behave in the manner that they did prior to the fix. (Bug #30083125)

References: This issue is a regression of: Bug #27482976.

• For UNIX_TIMESTAMP() errors occurring within stored functions, the number of fractional seconds for

subsequent function invocations could be incorrect. (Bug #30034972, Bug #96166)

• When a common table expression contained a nondeterministic expression (such one that used

RAND()) and the common table expression was referenced more than once in the outer query, it was

merged in some cases. This caused the common table expression to return a different result for each

reference. Now in such cases, the common table expression is not merged, but rather is materialized

instead. (Bug #30026353)

• In debug build of MySQL started on Linux with a lower_case_table_names=1 setting, discarding

a tablespace for a partitioned table after an in-place upgrade from MySQL 8.0.16 caused a serious

error. The partition tablespace name stored in the data dictionary was invalid, and the metadata

lock key prepared for the partition tablespace in MySQL 8.0.17 did not match the key stored in the

mysql.tablespaces table. (Bug #30024653)

• KILL QUERY could kill the statement subsequent to the one intended. (Bug #29969769)

• With lower_case_table_names=2, SHOW TABLES could fail to display tables with uppercase names.

(Bug #29957361)

• The error message reported for attempts to upgrade tables with invalid expressions for generated

columns did not provide sufficient information. The error message now includes the generated column

name and the expression used to create the generated column. (Bug #29941887, Bug #95918)

• Attempting to display an unresolvable view could result in a server exit rather than an error. (Bug

#29939279)

• Incorrect checking of temporal literals for CREATE TABLE statements could lead to a server exit. (Bug

#29906966, Bug #95794)

• Attempting to spawn a thread for a parallel read operation while system resources were temporary

unavailable raised system error. (Bug #29874480)

• Writing unexpected values to the mysql.global_grants system table could cause a server exit. (Bug

#29873343)

• The LAST_EXECUTED value in the INFORMATION_SCHEMA.EVENTS table was incorrectly reported in

UTC, not in the event time zone. (Bug #29871530, Bug #95649)

• With keyring_encrypted_file_password set on the command line at server startup, the password

value could be visible to system utilities. (Bug #29848634)

• Changing the lower_case_table_names setting when upgrading from MySQL 5.7 to

MySQL 8.0 could cause a failure due to a schema or table name lettercase mismatch. If

lower_case_table_names=1, table and schema names are now checked by the upgrade process

to ensure that all characters are lowercase. If table or schema names are found to contain uppercase

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MySQL 8.0 Release Notes

characters, the upgrade process fails with an error. For related information, see Preparing Your

Installation for Upgrade. (Bug #29842749, Bug #95559)

• With a LOCK TABLES statement in effect, a metadata change for the locked table could cause

Performance Schema or SHOW queries for session variables to hang in the opening_tables state.

(Bug #29836204, Bug #92387)

• A SELECT using a WHERE condition of the form A AND (B OR C [OR ...]) resulting in an impossible

range led to an unplanned exit of the server. (Bug #29770705)

• For JSON-format audit logging, the id field now may contain values larger than 65535. Previously, with

heaving logging activity, more than 65536 queries per second could be executed, exceeding the 16 bits

permitted for id values. (Bug #29661920)

• An incomplete connection packet could cause clients not to properly initialize the authentication plugin

name. (Bug #29630767)

• Out-of-memory errors from the parser could be ignored, resulting in a server exit. (Bug #29614521)

• On Linux, an assertion could be raised when the Performance Schema file instrumentation was disabled

and re-enabled. (Bug #29607570)

• For a column defined as a PRIMARY KEY in a CREATE TABLE statement, a default value given as an

expression was ignored. (Bug #29596969, Bug #94668)

• The TABLE_ENCRYPTION_ADMIN privilege, added in MySQL 8.0.16, was incorrectly granted to the

system-defined mysql.session user during upgrade. (Bug #29596053, Bug #94888)

• For connections encrypted with OpenSSL, network I/O at the socket level was not reported by the

Performance Schema. Also, network I/O performed while the server was in an IDLE state was not

reported by the Performance Schema. (Bug #29205129, Bug #30535558, Bug #97600)

• When a query used a subquery that was merged into the outer query block (due to a semijoin

transformation or merge of a derived table), and the subquery itself contained a subquery with an

aggregate function with an aggregation query block that differed from its base query block, the query

could sometimes fail to return any rows unless executed a second time or preceded with FLUSH

TABLES. This was because, when merging, the information regarded tables used and the aggregation

information for the aggregate function was not updated properly. In the case which raised this bug

report, this meant that the comparison operation containing a scalar subquery was regarded as const-

for-execution and therefore the range optimizer attempted to evaluate it, and the scalar subquery

contained a MIN() function referring to an outer reference which had not yet been read. Thus, when the

aggregator object was populated, it was based on uninitialized data, leading to unpredictable results.

(Bug #28941154)

• Changing the mandatory_roles system variable could cause SHOW GRANTS in concurrent sessions to

produce incorrect results. (Bug #28699403)

• Failure of keyring_aws initialization caused failure of SSL socket initialization. (Bug #28591098)

• Under certain conditions, enabling the read_only or super_read_only system variable did not

block concurrent DDL statements executed by users without the SUPER privilege. (Bug #28438114, Bug

#91852)

• The current GROUP BY plan is improved so that every gap attribute is allowed to have a disjunction of

equality predicates. Predicates from different attributes must still be conjunctive to each other in order to

take advantage of this enhancement.

Our thanks to Facebook for this contribution. (Bug #28056998, Bug #15947433, WL #13066)

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MySQL 8.0 Release Notes

• In some cases, BIGINT arguments to the FLOOR() and CEILING() functions were resolved as the

wrong type. (Bug #27125612)

• mysqlpump exits rather than dumping databases that contain an invalid view, by design, but it also

failed if an invalid view existed but was not in any of the databases to be dumped. (Bug #27096081)

• Foreign key information is now retrieved from the data dictionary, not from InnoDB. (Bug #25583288)

• Foreign key definitions used in CREATE TABLE and ALTER TABLE statements for InnoDB tables were

ignored if the statements were wrapped in conditional comments (such as /*!50101 ... */ or /

*! ... */). (Bug #21919887, Bug #78631)

• The --log-raw option is now available at runtime as the log_raw system variable. The system

variable is set at startup to the option value, and may be set at runtime to change password masking

behavior. (Bug #16636373, Bug #68936)

• EXPLAIN ANALYZE did not execute subqueries in the SELECT list, and thus did not take them into

account in its calculations of time or cost. (Bug #97296, Bug #30444266)

• An inner scalar subquery containing an outer reference did not return the same result using a nested set

of SELECT expressions on the right hand side as when using a single SELECT that was equivalent. (Bug

#97063, Bug #30381092)

• A materialized subquery could yield different results depending on whether it used an index. (Bug

#96823, Bug #30289052)

• When a query terminated due to exceeding the time specified using the MAX_EXECUTION_TIME hint,

the error produced differed depending on the stage of the query. In particular, if the query terminated

during a filesort, the error raised was ER_FILSORT_ABORT, even though in such cases the query should

always exit with ER_QUERY_TIMEOUT. This made it unnecessarily difficult to trap such errors and to

handle them correctly.

This fix removes the error codes ER_FILSORT_ABORT and ER_FILESORT_TERMINATED. (Bug #96537,

Bug #30186874)

• If a stored procedure had a parameter named member or array, and it had been defined without quoting

the parameter names, the database in which it was defined could not be upgraded to 8.0.17 or 8.0.18.

(Bug #96288, Bug #30084237)

References: See also: Bug #96350, Bug #30103640.

• When a function such as COALESCE() or IFNULL() was passed a BIGINT column value, casting a

negative return value from this function to UNSIGNED unexpectedly yielded zero.

Our thanks to Oleksandr Peresypkin for this contribution. (Bug #95954, Bug #29952066)

• EXPLAIN output showed Select tables optimized away for a query using MAX() on an indexed

column, but if MAX() on the same column was called in a user function, it showed Using index

instead. (Bug #94862, Bug #29596977)

Changes in MySQL 8.0.18 (2019-10-14, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• Compilation Notes

284

MySQL 8.0 Release Notes

• Configuration Notes

• Connection Management Notes

• Deprecation and Removal Notes

• Keyring Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Pluggable Authentication

• Security Notes

• Spatial Data Support

• sys Schema Notes

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• The CREATE USER, ALTER USER, and SET PASSWORD statements now have the capability of

generating random passwords for user accounts, as an alternative to requiring explicit administrator-

specified literal passwords. See Password Management. (WL #11772)

Compilation Notes

• Incompatible Change: The my_ulonglong type is no longer used in MySQL source code. Any

third-party code that used this type should use the uint64_t C type instead. Also, it is possible

that printf() format strings will need adjustment if used to print my_ulonglong variables. (Bug

#29453827)

• For building MySQL 8.0, the minimum required version of Protobuf is now 3.0 rather than 2.5. (Bug

#30141272)

• The minimum version of the Boost library for server builds is now 1.70.0. (Bug #29639344)

• A DBUG_TRACE macro is available to assist in writing debug code. It is a convenience that replaces pairs

of enter/leave macros. For example, instead of writing this:

void foo() {

DBUG_ENTER("foo");

bar();

DBUG_VOID_RETURN;

}

Write this instead:

void foo() {

DBUG_TRACE;

285

MySQL 8.0 Release Notes

bar();

}

(Bug #29589102)

Configuration Notes

• CMake now enables use of fastcov if it is available. fastcov is faster than lcov or gcov. This

requires GCC and gcov versions of 9 or higher. (Bug #30011512)

• The DISABLE_SHARED CMake option was unused and has been removed. (Bug #29971049, Bug

#96027)

• The CMake code to find Protobuf executables now works on platforms that split these into multiple

packages. (Bug #29953773)

• The new ADD_GDB_INDEX CMake option determines whether to enable generation of a .gdb_index

section in binaries, which makes loading them in a debugger faster. The option is disabled by default. It

has no effect if a linker other than lld or GNU gold is used. (Bug #29925009, Bug #95857)

• For the INSTALL_LAYOUT CMake option, the SLES and WIN option values were not used and have been

removed. (Bug #29871520, Bug #95654)

• The max_prepared_stmt_count system variable maximum value has been increased from 1 million

(1,048,576) to 4 million (4,194,304). The default value remains unchanged at 16,382. (WL #13342)

• MySQL 8.0 no longer supports building using wolfSSL. All MySQL builds now use OpenSSL. (WL

#13290)

• The RE2 library is no longer used by MySQL. The library is no longer bundled with source distributions

and the WITH_RE2 CMake option is obsolete.

Connection Management Notes

• MySQL now provides more control over the use of compression to minimize the number of bytes sent

over connections to the server. Previously, a given connection was either uncompressed or used the

zlib compression algorithm. Now, it is also possible to use the zstd algorithm (zstd 1.3), and to select

a compression level for zstd connections. The permitted compression algorithms can be configured

on the server side, as well as on the connection-origination side for connections by client programs

and by servers participating in master/slave replication or Group Replication. For more information, see

Connection Compression Control.

Connection compression using the zstd algorithm requires that the server be built with zstd library

support. The new WITH_ZSTD CMake option indicates whether to use the bundled or system zstd

library.

Legacy compression-control parameters, such as the --compress client option, are deprecated and will

be removed in a future MySQL version.

Thanks to Facebook for the contribution on which some of this work was based. (WL #12039, WL

#12475)

Deprecation and Removal Notes

• Use of the MYSQL_PWD environment variable to specify a MySQL password is considered insecure

because its value may be visible to other system users. MYSQL_PWD is now deprecated and will be

removed in a future MySQL version. (WL #13449)

286

MySQL 8.0 Release Notes

• The relay_log_info_file system variable and --master-info-file option are now

deprecated and will be removed in a future MySQL version. These were used to specify the name

of the relay log info log and master info log when relay_log_info_repository=FILE and

master_info_repository=FILE were set, but those settings have been deprecated. The use of files

for the relay log info log and master info log has been superseded by crash-safe slave tables, which are

the default in MySQL 8.0. (WL #11031)

• The slave_rows_search_algorithms system variable is now deprecated and will be removed

in a future MySQL version. This variable was used to control how rows were searched for matches

when preparing batches of rows for row-based logging and replication. The default setting

INDEX_SCAN,HASH_SCAN has been found to be optimal for performance and works correctly in all

scenarios. (WL #12892)

• The log_bin_use_v1_row_events system variable is now deprecated and will be removed in a

future MySQL version. When set to ON, the variable made mysqld write the binary log using Version

1 binary log row events, instead of Version 2 binary log row events which are the default from MySQL

5.6. (The default is OFF.) The use of Version 1 binary log row events enabled row-based replication with

slaves running MySQL Server 5.5 and earlier, which could not use Version 2 binary log row events. (WL

#12926)

• The WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS() function is now deprecated, and the

WAIT_FOR_EXECUTED_GTID_SET() function should be used instead. Both functions wait until all

of the specified transactions have been applied, or until the optional timeout has elapsed. However,

WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS() applied to a specific replication channel, and stopped

only after the transactions had been applied on that channel, for which the applier had to be running. In

contrast, WAIT_FOR_EXECUTED_GTID_SET() stops after the specified transactions have been applied

on the server, regardless of how they were applied (on any replication channel or from any user client),

and whether or not any replication channels are running. WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS()

could hang indefinitely if an expected transaction arrived on a different replication channel or from a user

client, for example in a failover or manual recovery situation, and no timeout was set. (WL #13178)

Keyring Notes

• MySQL Enterprise Edition now includes a keyring_hashicorp plugin that uses HashiCorp Vault as a

back end for keyring storage. For more information, see The MySQL Keyring. (WL #12522)

Logging Notes

• Log buffering during server startup was adjusted for less delay in the appearance of output in the error

log. (Bug #30019632)

Optimizer Notes

• Queries involving first match split jump operations were handled wrongly in the iterator executor. They

are now rewritten to weedout. (Bug #30220791)

• Hash joins have been implemented as a way of executing inner equi-joins in MySQL. For example, a

query such as this one can be executed as a hash join beginning with this release:

SELECT *

FROM t1

JOIN t2

ON t1.c1 = t2.c1;

Multi-table joins using equi-joins can also take advantage of this optimization.

287

MySQL 8.0 Release Notes

A hash join requires no index for execution. In most cases, a hash join is more efficient than the block-

nested loop algorithm previously used for equi-joins without indexes.

By default, beginning with this release, a hash join is used whenever a join includes at least one equi-

join condition, and no indexes can be applied to the join condition. (A hash join can still be used where

there are indexes applying to single-table predicates only.) This preference can be overridden by setting

the hash_join optimizer switch to off, or by using the NO_HASH_JOIN optimizer hint. In addition, you

can control the amount of memory used by a hash join by setting join_buffer_size. A join whose

memory requirement exceeds this amount is executed on disk; an on-disk hash join uses a number of

disk files and may not be executable if this number exceeds open_files_limit.

A hash join cannot be employed if the join conditions for any pair of joined tables do not include at least

one equi-join condition among all join conditions used. A hash join is used for a Cartesian product—that

is, a join that specifies no join conditions at all.

You can see whether hash joins have been used to optimize a query in the output of EXPLAIN

FORMAT=TREE or EXPLAIN ANALYZE.

In addition, inner joins using hash joins can now also take advantage of Batched Key Access (BKA).

Outer joins still allocate the entire join buffer.

For more information, see Hash Join Optimization. (WL #2241, WL #13002)

• Added EXPLAIN ANALYZE, which provides iterator-based timing, cost, and other information about

queries in TREE format. This statement produces output similar to that of EXPLAIN, but with additional

information about how optimizer estimates match actual execution. (WL #4168)

• MySQL now performs injection of casts into queries to avoid certain data type mismatches; that is, the

optimizer now adds casting operations in the item tree inside expressions and conditions in which the

data type of the argument and the expected data type do not match. This makes the query as executed

equivalent to one which is compliant with the SQL standard while maintaining backwards compatibility

with previous releases of MySQL.

Such implicit casts are now performed between temporal types and numeric types by casting both

arguments as DOUBLE whenever they are compared using any of the standard numeric comparison

operators. They are also now performed for such comparisons between DATE or TIME values and

DATETIME values, in which case the arguments are cast as DATETIME.

For example, a query such as SELECT * FROM t1 JOIN t2 ON t1.int_col = t2.date_col

is rewritten and executed as SELECT * FROM t1 JOIN t2 ON CAST(t1.int_col AS DOUBLE)

= CAST(t2.date_col AS DOUBLE), and SELECT * FROM t1 JOIN t2 ON t1.time_col

= t2.date_col is transformed to SELECT * FROM t1 JOIN t2 ON CAST(t1.time_col AS

DATETIME) = CAST(t2.date_col AS DATETIME) prior to execution.

It is possible to see when casts are injected into a given query by viewing the output of EXPLAIN

ANALYZE, EXPLAIN FORMAT=JSON, or EXPLAIN FORMAT=TREE. EXPLAIN can also be used, but in

this case it is also necessary to issue SHOW WARNINGS afterwards.

This change is not expected to cause any difference in query results or performance. (WL #12108)

Packaging Notes

• The component_test_page_track_component.so test plugin has been moved to -test

packages. (Bug #30199634)

288

MySQL 8.0 Release Notes

• Binary packages that include curl rather than linking to the system curl library have been upgraded to

use curl 7.65.3. (Bug #30015512)

Pluggable Authentication

• To assist in debugging failed connections for accounts that use an LDAP authentication plugin, the

authentication_ldap_simple_log_status and authentication_ldap_sasl_log_status

system variables now accept a maximum value of 6 (formerly 5). Setting either variable to 6 causes

debugging messages from the LDAP library to be written to the error log for the corresponding plugin.

(Bug #29771393)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.1.1c. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl111.txt and https://www.openssl.org/news/vulnerabilities.html. (Bug

#29868818)

Spatial Data Support

• Previously, for geometry arguments in a geographic SRS, ST_Distance() supported only argument

types of Point and Point, or Point and MultiPoint. ST_Distance() now supports distance

calculations for geographic SRS arguments of all geometry types. For more information, see Spatial

Relation Functions That Use Object Shapes. (WL #12216)

sys Schema Notes

• The sys.schema_unused_indexes view now filters out unique indexes. Thanks to Gillian Gunson for

the contribution. (Bug #24798995, Bug #83257)

• The sys.ps_is_consumer_enabled() function now produces an error rather than returning NULL if

the argument is an unknown non-NULL consumer name. (Bug #24760317)

• Previously, sys schema sources were maintained in a separate Git repository. sys schema

sources now are included with and maintained within MySQL source distributions (under scripts/

sys_schema). As a consequence of this change, to simplify maintenance of sys schema scripts going

forward, the acceptable format of statements in the file named by the init_file system variable has

been expanded. For details, see the description of that variable in Server System Variables.

The sys.version view is deprecated and will be removed in a future MySQL version. Affected

applications should be adjusted to use an alternative instead. For example, use the VERSION() function

to retrieve the MySQL server version. (WL #12673)

Test Suite Notes

• MySQL tests were updated to use the latest version of googletest. (Bug #30079649)

X Plugin Notes

• X Protocol did not correctly display large numbers of warning messages that were issued for the same

query. (Bug #30055869)

• When the NO_BACKSLASH_ESCAPES SQL mode was enabled, X Plugin incorrectly reported collections

as tables. (Bug #28208285)

289

MySQL 8.0 Release Notes

Functionality Added or Changed

• Replication; Group Replication: By default, MySQL replication (including Group Replication) does not

carry out privilege checks when transactions that were already accepted by another server are applied

on a replication slave or group member. From MySQL 8.0.18, you can create a user account with the

appropriate privileges to apply the transactions that are normally replicated on a channel, and specify

this as the PRIVILEGE_CHECKS_USER account for the replication applier. MySQL then checks each

transaction against the user account's privileges to verify that you have authorized the operation for

that channel. The account can also be safely used by an administrator to apply or reapply transactions

from mysqlbinlog output, for example to recover from a replication error on the channel. The use of

a PRIVILEGE_CHECKS_USER account helps secure a replication channel against the unauthorized or

accidental use of privileged or unwanted operations.

You grant the REPLICATION_APPLIER privilege to enable a user account to appear as the

PRIVILEGE_CHECKS_USER for a replication applier thread, and to execute the internal-use BINLOG

statements used by mysqlbinlog. After setting up the user account, use the GRANT statement to grant

additional privileges to enable the user account to make the database changes that you expect the

applier thread to carry out, such as updating specific tables held on the server. These same privileges

enable an administrator to use the account if they need to execute any of those transactions manually

on the replication channel. If an unexpected operation is attempted for which you did not grant the

appropriate privileges, the operation is disallowed and the replication applier thread stops with an error.

(WL #12966)

• Group Replication: For group communication connections, Group Replication now supports the

TLSv1.3 protocol, which was supported by MySQL Server from 8.0.16. To use the TLSv1.3 protocol,

MySQL Server must be compiled using OpenSSL 1.1.1 or higher. For information on configuring

encrypted connections for Group Replication, see Securing Group Communication Connections with

Secure Socket Layer (SSL). (WL #12990)

• Group Replication: A new option OFFLINE_MODE is available for the

group_replication_exit_state_action system variable, which specifies how Group Replication

behaves when a server instance leaves the group unintentionally, for example after encountering an

applier error, or in the case of a loss of majority, or when another member of the group expels it due to a

suspicion timing out.

When OFFLINE_MODE is specified as the exit action, Group Replication switches MySQL to offline mode

by setting the system variable offline_mode to ON. When the member is in offline mode, connected

client users are disconnected on their next request and connections are no longer accepted, with the

exception of client users that have the CONNECTION_ADMIN or SUPER privilege. Group Replication also

sets the system variable super_read_only to ON, so clients cannot make any updates, even if they

have connected with the SUPER privilege.

The OFFLINE_MODE exit action prevents updates like the default READ_ONLY exit action does, but

also prevents stale reads (with the exception of reads by client users with the stated privileges), and

enables proxy tools such as MySQL Router to recognize that the server is unavailable and redirect client

connections. It also leaves the instance running so that an administrator can attempt to resolve the issue

without shutting down MySQL, unlike the existing alternative ABORT_SERVER exit action, which shuts

down the instance. (WL #12895)

• Group Replication: An internal message service has been added to Group Replication. MySQL

modules can use the service to transmit generic messages with an identifying tag to all group members,

using Group Replication's existing group communication connections. (WL #12896)

290

MySQL 8.0 Release Notes

• When the server is run with --initialize, there is no reason to load non-early plugins. The server

now logs a warning and ignores any --plugin-load or --plugin-load-add options given with --

initialize. (Bug #29622406)

• The number of diagnostic messages relating to INFORMATION_SCHEMA upgrade during server startup

has been reduced. (Bug #29440725, Bug #94559)

• Prior to MySQL 8.0, REVOKE produced an error for attempts to revoke an unknown privilege. In MySQL

8.0, an account can possess a privilege that is currently unknown to the server if it is a dynamic

account that was granted while the component or plugin that registers the privilege was installed. If

that component or plugin is subsequently uninstalled, the privilege becomes unregistered, although

accounts that possess the privilege still possess it. Revoking such a privilege cannot be distinguished

from revoking a privilege that actually is invalid, so REVOKE no longer produces an error for attempts to

revoke an unknown privilege. However, to indicate that the privilege is currently unknown, REVOKE now

produces a warning. (Bug #29395197)

• The new innodb_idle_flush_pct variable permits placing a limit on page flushing during idle

periods, which can help extend the life of solid state storage devices. See Limiting Buffer Flushing

During Idle Periods.

Thanks to Facebook for the contribution. (Bug #27147088, Bug #88566, WL #13115)

• mysqld invoked with the --help option no longer aborts if the secure_file_priv argument does not

exist. (Bug #26336130)

• The Protobuf libraries are now dynamically linked. Their default locations are /usr/lib64/mysql/

private/ for RPMs, /usr/lib/mysql/private/ for DEBs, and /lib/private/ for TAR builds. A

new INSTALL_PRIV_LIBDIR CMake variable controls the location. (WL #13126)

Bugs Fixed

• NDB Cluster: A query handled using a pushed condition produced incorrect results when it included an

ORDER BY clause. (Bug #29595346)

References: This issue is a regression of: Bug #28672214.

• NDB Cluster: The NDB transporter layer limits the size of messages to 32768 bytes; send buffers place

additional (and stricter) limitations on message size. Whenever a message is appended to a send buffer,

page checks are performed to ensure that the message fits in the available space; if not, a new page

is used. The current issue arose on account of the fact that no check was performed to make sure that

this message could fit in the empty page; when the size of the message exceeded the empty page,

this resulted in a buffer overwrite and in the overwriting of the next page in memory. For data nodes

the largest message supported by the send buffer (thr_send_page) is 32756 bytes; for API and

management nodes, this maximum is 32752 bytes. (Signals sent within an individual data node are not

subject to these limitations since no send or transporter buffers are used in this case). Now, when a new

page is used, the size of the message is checked against that which is available in a new page.

As part of the work done to fix the problem just described, three new DUMP commands are added

to facilitate related testing and debugging: DUMP 103003 (CmvmiRelayDumpStateOrd) sends

a DUMP command using another node; DUMP 103004 (CmvmiDummySignal) and DUMP 103005

(CmvmiSendDummySignal) can be used to send long messages. (Bug #29024275)

• NDB Cluster: EXPLAIN FORMAT=TREE did not provide proper explanations of conditions and joins

pushed down to the NDBCLUSTER storage engine. Issues included the following:

• Pushed conditions were not shown.

291

MySQL 8.0 Release Notes

• The root of a pushed join was not shown.

• The child of a pushed join did not include any reference to its parent operation.

• InnoDB: An internal function (btr_push_update_extern_fields()) used to fetch newly added

externally stored fields and update them during a pessimistic update or when going back to a previous

version of a record was no longer required. Newly added externally stored fields are updated by a

different function. Also, the method used to determine the number of externally stored fields was

corrected. (Bug #30342846)

• InnoDB: An DROP UNDO TABLESPACE operation on an undo tablespace with a missing data file caused

a segmentation fault. (Bug #30155290)

• InnoDB: An error in the internal trx_rseg_add_rollback_segments function was corrected. (Bug

#30114226, Bug #96372)

• InnoDB: Problematic assertion code in the Contention-Aware Transaction Scheduling (CATS) code was

revised. (Bug #30086559)

• InnoDB: Arguments passed to a derived class in calls from the ib::fatal and

ib::fatal_or_error constructors could be ignored, resulting in invalid error messages. Additionally,

in the case of a fatal error, the ib::fatal_or_error destructor could cause a server exit before

printing a message. (Bug #30071930)

• InnoDB: It was possible for a corrupted table to be removed from the table cache before the reference

count for the table reached zero. (Bug #30065947, Bug #96224)

• InnoDB: A code path for the internal row_update_inplace_for_intrinsic() function did not

include a required mini-transaction (mtr) commit, causing a debug assertion failure. (Bug #30065518)

• InnoDB: The internal fsp_srv_undo_tablespace_fixup() function did not take an

undo::ddl_mutex lock when called during startup, which could lead to an assertion failure under

certain circumstances. (Bug #30029433, Bug #30461911, Bug #97356)

• InnoDB: Inspection of rename_tablespace_name() function showed that if old_shard-

>get_space_by_id(space_id) did not find the tablespace ID, it would return without calling

old_shard->mutex_release(). (Bug #30027771)

• InnoDB: A tablespace with “FTS” in its name was incorrectly determined to be the tablespace of a

full-text index table and not registered with the data dictionary during upgrade, causing the upgrade

operation to fail. (Bug #29992589)

• InnoDB: The ibuf_merge_or_delete_for_page() function, responsible for merging and deleting

pages in the change buffer, is no longer called for undo tablespaces and temporary tablespaces. The

change buffer does not contain entries for those tablespace types. (Bug #29960394, Bug #95989)

• InnoDB: Some combinations of buffer pool size variables (--innodb-buffer-pool-instances, --

innodb-buffer-pool-size, and --innodb-buffer-pool-chunk-size) lead to a chunk size

that is 0, 1, or a value that is not a multiple of the page size, and so on, causing errors during buffer pool

creation and sizing. (Bug #29951982)

• InnoDB: A server exit while an undo tablespace was being truncated caused the following error when

a clone operation was rolled forward after restarting the server: [ERROR] [MY-011825] [InnoDB]

[FATAL] Clone File Roll Forward: Invalid File State: 0. (Bug #29949917)

• InnoDB: An ALTER TABLE ... DISCARD TABLESPACE operation caused a hang condition. (Bug

#29942556, Bug #30324703)

292

MySQL 8.0 Release Notes

• InnoDB: Cloning operations failed with the following error after an archive thread failure: ERROR 3862

(HY000): Clone Donor Error: 1317 : Query execution was interrupted. (Bug

#29930839)

• InnoDB: A clone related regression caused a minor drop in performance for index and non-index update

operations. (Bug #29925409)

• InnoDB: InnoDB now ignores hidden directories and files during the tablespace discovery scan that

occurs at startup. Hidden directories and files include those beginning with "." and hidden and system

directories and files on Windows that are identified by attributes. (Bug #29900671, Bug #95071, Bug

#30068072)

• InnoDB: To improve deadlock detection, the task of detecting a deadlock cycle among data locks was

moved from the transaction thread to a dedicated background thread. (Bug #29882690)

• InnoDB: Updating the mysql.gtid_executed table during mysqld initialization caused the following

warning to be printed to the error log: [Warning] [MY-010015] [Repl] Gtid table is not

ready to be used. Table 'mysql.gtid_executed' cannot be opened. The update and

associated warning no longer occur. (Bug #29871809)

• InnoDB: The LATEST DETECTED DEADLOCK section in InnoDB Standard Monitor output (also printed

by SHOW ENGINE INNODB STATUS) was extended to include additional information about transactions

that participate in a deadlock cycle. (Bug #29871641)

• InnoDB: An incorrect argument was used to compare serialized dictionary information (SDI) input and

output values when checking the size of the buffer used to store SDI. (Bug #29871525, Bug #95606)

• InnoDB: An undo tablespace file was overwritten during a cloning operation when undo tablespaces

files with the same name were copied from different directories on the donor to the same directory on the

recipient. A cloning operation now reports an error if duplicate undo tablespace names are encountered.

When data is cloned to the recipient, undo tablespace files are cloned to the directory defined by the

innodb_undo_directory variable. Because the files are cloned to the same directory, duplicate undo

tablespace file names are not permitted. (Bug #29837617)

• InnoDB: A cloning operation generated a large number of redo log files when cloning from a MySQL

server instance with a small redo log file size and a large number of transactions. The large number of

redo log files sometimes caused startup to hang or assert. Otherwise, startup was permitted proceed

without cleaning up the excessive number of redo log files. (Bug #29837490)

• InnoDB: During recovery, missing table errors that occur when applying redo logs to encrypted tables

could be ignored, permitting startup to proceed. Startup should be halted in this case. (Bug #29820184,

Bug #95183)

• InnoDB: The wrong redo log file size was printed to the server error log at startup. (Bug #29818711)

• InnoDB: A restriction that prevented reuse of lock objects (lock_t structs) in the lock queue when

waiting record lock requests were present was removed. (Bug #29814308)

• InnoDB: When converting a long partitioned table name to a file name, the buffer that holds the file

name did not have enough space, causing an assertion failure. (Bug #29813582)

• InnoDB: Some transaction lock structure fields (trx->lock) were not properly mutex protected. (Bug

#29809137)

• InnoDB: An empty undo segment update during recovery raised an assertion. (Bug #29802703)

• InnoDB: A cloning operation failed when attempting to drop data on the recipient if the recipient data

included a table with a full-text index. (Bug #29796507)

293

MySQL 8.0 Release Notes

• InnoDB: After a file-per-table tablespace was discarded, an error was reported when the old table

was renamed and a new table was created with the same name. The error was due to stale file path

information. (Bug #29793800)

• InnoDB: A test case that attempts to open a file in read-only mode while the server is in a disk-full state

caused a debug assertion failure. The assertion was removed to permit the server to retry opening the

file, and to report an error if unsuccessful after a number of attempts. (Bug #29692250, Bug #95128)

• InnoDB: Foreign-key-related tables constructed during a RENAME TABLE operation contained the old

table name. (Bug #29686796)

• InnoDB: The server passed a NULL value for a column with a non-zero data length. (Bug #29654465)

• InnoDB: Importing a partitioned table from a MySQL 8.0.13 instance (or earlier) to a MySQL 8.0.14,

8.0.15, or 8.0.16 instance failed with a “tablespace is missing” error for source and target instances

defined with lower_case_table_names=1. The tablespace file and the metadata file used by the

import operation could not be found due to a file name case mismatch. (Bug #29627690, Bug #94850)

References: This issue is a regression of: Bug #26925260.

• InnoDB: The read set (TABLE::read_set) was not set properly for handler method calls in

QUICK_SKIP_SCAN_SELECT::get_next(), causing an assertion failure. (Bug #29602393)

• InnoDB: An exclusive backup lock is now used to block tablespace truncate operations during master

key rotation. Previously, metadata locks on undo tablespace names were used to synchronize the

operations. This patch also addresses a deadlock that could occur between master key rotation and drop

undo tablespace operations. (Bug #29549938, Bug #30461225, Bug #97352)

• InnoDB: An unnecessary next key lock was taken when performing a SELECT...FOR [SHARE|

UPDATE] query with a WHERE condition that specifies a range, causing one too many rows to be locked.

The most common occurrences of this issue have been addressed so that only rows and gaps that

intersect the searched range are locked. (Bug #29508068)

• InnoDB: Adding a virtual column in the first position together with a normal column raised an assertion

failure. (Bug #29501324)

• InnoDB: The shutdown process did not wait for InnoDB background threads to exit, which could cause

shutdown to stall, waiting for background threads to remove transactions from the MySQL transaction

list. A check now occurs to ensure that InnoDB background threads have exited properly. Also, an

intermediate shutdown state was added to improve shutdown timing for the InnoDB master thread. (Bug

#29417503)

• InnoDB: A memory leak occurred during TempTable storage engine operation due a failure to

deallocate that last block of allocated memory, which TempTable holds in thread-local storage until

thread exit. (Bug #29300927)

• InnoDB: Throughput stalled under a heavy workload with a small innodb_io_capacity_max setting,

a single page cleaner thread, and multiple buffer pool instances. (Bug #29029294)

• InnoDB: A long running ALTER TABLE ... ADD INDEX operation with concurrent inserts caused

semaphore waits. Thanks to Satya Bodapati for the patch. (Bug #29008298)

• InnoDB: The INFORMATION_SCHEMA.INNODB_COLUMNS table did not display partitioned table

columns after upgrading from MySQL 5.7 to MySQL 8.0. For partitioned tables created on the MySQL

8.0 release, INFORMATION_SCHEMA.INNODB_COLUMNS only displayed columns for the first table

partition. (Bug #28869903, Bug #93033)

294

MySQL 8.0 Release Notes

• InnoDB: The internal rtr_page_split_and_insert() function is called recursively. An inner call

to the function released an object still being used by an outer call to the same function, causing an

assertion failure. (Bug #28569379)

• InnoDB: Under specific circumstances, setting the innodb_limit_optimistic_insert_debug

variable to 2 raised a debug assertion when it should have reported an error. (Bug #28552330, Bug

#92187)

• InnoDB: A deadlock was possible when a transaction tries to upgrade a record lock to a next key lock.

(Bug #23755664, Bug #82127)

• InnoDB: The INFORMATION_SCHEMA.INNODB_METRICS lock_deadlocks counter did not count all

deadlocks. Thanks to Laurynas Biveinis for the contribution. (Bug #21278148, Bug #77399)

• InnoDB: An error reported during a read operation did not identify the name of the file that was read.

(Bug #21120885, Bug #76020)

• Replication: If the group_replication_set_communication_protocol() function was used to

set a communication protocol version that some group members did not support, the protocol change

procedure was not stopped correctly. The issue has now been fixed. (Bug #30209596)

• Replication: The session value of the default_table_encryption system variable is replicated,

so that replication slaves preserve the correct encryption setting for databases and tablespaces. For

a replication channel where the table_encryption_privilege_check system variable is set to

ON, the TABLE_ENCRYPTION_ADMIN privilege is required to apply events where the session value of

default_table_encryption is changed. If this privilege had not been granted on the replication

slave, replication stopped with an error in some situations where the required encryption setting for the

event was actually the same as the slave's own default encryption setting, so the action ought to have

worked. It was also possible for a statement with a different encryption setting from the slave to succeed

when it ought not to have worked. The behaviors have now been corrected so that a replication slave

without the TABLE_ENCRYPTION_ADMIN privilege is permitted to apply events that match its own default

encryption setting, and is not requested to set the encryption setting unnecessarily, but is still subject to

appropriate privilege checks if the event requires a different encryption setting. (Bug #29818605)

• Replication: The timeout in seconds specified by the

group_replication_unreachable_majority_timeout system variable was only checked every

two seconds. The timeout is now checked every second so that odd-numbered values are respected.

(Bug #29762005)

• Replication: A deadlock involving three threads could occur if a START SLAVE statement was issued

to start the SQL thread on a slave while the SQL thread was still in the process of being stopped, and a

request for the slave status was made at the same time. The issue has now been fixed by releasing a

lock earlier while the SQL thread is being stopped. (Bug #29697588, Bug #95115)

• Replication: A locking issue in the WAIT_FOR_EXECUTED_GTID_SET() function could cause the

server to hang in certain circumstances. The issue has now been corrected. (Bug #29550513)

• Replication: A deadlock could occur if the value of the binlog_encryption system variable was

changed while a START SLAVE statement was being executed. (Bug #29515210)

• Replication: The heartbeat interval for a replication slave, which is controlled by the

MASTER_HEARTBEAT_PERIOD option of the CHANGE MASTER TO statement, can be specified with a

resolution in milliseconds. Previously, the master's binary log dump thread used a granularity of seconds

to calculate whether a heartbeat signal should be sent to the slave, causing excessive heartbeat activity

in the case of multiple skipped events. To remove this issue, all heartbeat-related calculations by the

master and slave are now carried out using a granularity of nanoseconds for precision. Thanks to

Facebook for the contribution. (Bug #29363787, Bug #94356)

295

MySQL 8.0 Release Notes

• Replication: Creation of a table with functional index creates a hidden generated column on the table,

but this column did not always appear in the same position in the table, which meant that later adding a

column (or columns) to the table might leave the hidden column in a different position as compared to an

otherwise identical table already having the additional column or columns in a single CREATE TABLE

statement. For example, this difference could be evident between two tables t1 and t2, with t1 created

and then altered by the two statements CREATE TABLE t (a INT, INDEX ((a+1))) and ALTER

TABLE t ADD COLUMN b INT, and t2 created using CREATE TABLE t2 (a INT, b INT, INDEX

((a+1))), even though SHOW CREATE TABLE t1 and SHOW CREATE TABLE t2 produced identical

results (other than for the names of the tables).

The issue just described could become problematic due to the fact that the internal definitions for the

tables as described by Table_map_log_events in the binary log would differ. This meant that, if

such a table was created using CREATE TABLE followed by ALTER TABLE on the master, and then a

slave was deployed using mysqldump, the slave's version of the table would be created using a single

CREATE TABLE statement, and subsequent replication of row events would then fail with an error due to

mismatching types.

This issue is fixed by forcing all hidden generated columns always to be located at the end of the list

of columns, with multiple generated columns sorted by column name. If a new functional index part

is added to the table, the new hidden column is inserted according to this rule. In addition, if the user

creates a new column that is not a generated column, the column is always added before the first hidden

column.

Note

The structure of tables affected by this change is not changed automatically

during upgrade; this must done explicitly by executing ALTER TABLE.

(Bug #29317684)

• Replication: If a RESET MASTER statement was stopped during its execution, the binary log was not

available for writes afterwards. (Bug #29125121)

• Replication: On a multi-threaded slave with GTIDs in use and MASTER_AUTO_POSITION set to ON,

following an unexpected halt the slave would attempt relay log recovery, which failed if relay logs had

been lost, preventing replication from starting. However, this step was unnecessary as GTID auto-

positioning can be used to restore any missing transactions. In a recovery situation, the slave now

checks first whether MASTER_AUTO_POSITION is set to ON, and if it is, omits the step of calculating

the transactions that should be skipped or not skipped, so that the old relay logs are not needed and

recovery can proceed without them. (Bug #28830834, Bug #92882)

• Group Replication: If the TCP connections used by Group Replication time out due to a lengthy

network error, the group communication engine (XCom) cannot re-establish its local connection,

requiring a restart of Group Replication on the instance (see Bug #25656508). Previously, attempting to

stop Group Replication in this situation caused XCom to hang, preventing the restart. This issue has now

been fixed so that XCom terminates correctly and Group Replication can be restarted to re-establish the

local connection. (Bug #30132500)

References: See also: Bug #22158368.

• Group Replication: When the ANSI_QUOTES SQL mode was enabled, Group Replication returned

an error when checking for the presence of MySQL Server's clone plugin to perform remote cloning

operations for distributed recovery. The issue has now been fixed. (Bug #30099796)

296

MySQL 8.0 Release Notes

• Group Replication: default_table_encryption could be changed while Group Replication was

running by issuing SET PERSIST, even though this variable should never be settable insuch cases.

(Bug #30031228, Bug #96158)

• Group Replication: If group_replication_local_address was changed for a member which

then rejoined the group, copies of the old local address were retained in some locations by the Group

Communication System (GCS). To fix this, we now fetch the local address when needed, and no longer

obtain it from the cache. (Bug #29910699)

• Group Replication: When a remote cloning operation was used to provide transactions to a joining

member and the joining member was stopped during the operation, it did not shut down cleanly. (Bug

#29902389)

• Group Replication: The input channel introduced in this release uses a shared memory queue instead

of a TCP socket for communication between the Group Communication System (GCS) component

of Group Replication and the local group communication engine (XCom) instance. This input channel

could not be established on SELinux installations, which meant members upgraded to MySQL 8.0.14

or later were unable to rejoin the group. When Group Replication was started, the XCom instance

temporarily opened a port from the ephemeral port range to allow GCS to establish a connection for

the input channel, but on SELinux the mysqld process did not have permission to connect to this

port. A workaround was to amend the SELinux policy to allow MySQL to connect to any port, but this

reduced security. This issue is now fixed; XCom and GCS no longer use an ephemeral port to establish

a connection for the input channel, but instead use the Group Replication communication port set by

group_replication_local_address. This action must be permitted by SELinux (see Frequently

Asked Questions). (Bug #29742219, Bug #30087757)

• Group Replication: Server certificates whose Common Name value used a wildcard were incorrectly

rejected. (Bug #29683275, Bug #95068)

• Group Replication: It was possible for the Group Communication System (GCS) to deliver messages

from a member after STOP GROUP_REPLICATION had been issued and the member's status was

OFFLINE, resulting in an error. GCS now verifies that the member belongs to a group before delivering

any such messages. (Bug #29620900)

• Group Replication: Some threads that executed transient or minor tasks, such as the delayed plugin

initialization thread, were not visible in the Performance Schema threads table. (Bug #28930537, Bug

#93212)

• Group Replication: The implementation for the process of a member leaving the group due to an error

has been standardized across components. This ensures that the member carries out exactly the same

actions and issues the same error messages consistently, regardless of the original reason for leaving

the group. (Bug #28866495, Bug #93027)

• For XA COMMIT statements, invocation order of the plugins involved in statement execution was

nondeterministic, which could lead to replication problems. Thanks to Dennis Gao for contributing a fix.

(Bug #31082237, Bug #99051)

• The keyring_aws plugin was not included in Commercial Docker RPM packages. (Bug #30199423)

• When generating C source from SQL scripts, Some utf8-encoded characters were split across lines.

Thanks to Przemysław Skibiński for the patch. (Bug #30152555, Bug #96449)

• The ARRAY reserved word was listed as unreserved in the INFORMATION_SCHEMA.KEYWORDS table.

(Bug #30134275, Bug #96416)

• Some statements containing || produced a parse error even with the PIPES_AS_CONCAT SQL mode

enabled. (Bug #30131161, Bug #96405)

297

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #29305022.

• LOAD DATA statements incorrectly ignored the NO_AUTO_VALUE_ON_ZERO SQL mode if a SET clause

was present. (Bug #30126375)

• Automatic upgrades failed with a server exit if the thread_pool plugin was enabled. (Bug #30121742)

• When determining whether to recalculate a materialized derived table for each execution, the

uncacheability of the parent query block was used instead of the rematerialize flag on the table (currently

only true for JSON_TABLE()). This could cause unneeded rematerializations, especially when making

queries against non-merged views, leading to reduced performance. (Bug #30110851)

• With an IGNORE clause, LOAD DATA should skip rows that produced a CHECK constraint violation and

continue with the following rows, but it stopped with an error. (Bug #30084966, Bug #96296)

• With sql_require_primary_key enabled, clone plugin initialization failed because it created two

dynamic Performance Schema tables, which do not support indexes or primary keys. The effect of

sql_require_primary_key is now limited to storage engines that can participate in replication

(currently all storage engines except the Performance Schema) (Bug #30083300, Bug #96281)

• Protobuf compilation failed on macOS. (Bug #30079536, Bug #96263)

• For automatic upgrades, the audit_log plugin was not reloaded, causing auditing to start in legacy

mode. (Bug #30068110)

• In order to remove duplicate rows, the weedout optimization needs a unique identifier for each row,

which is provided by the storage engine by calling handler::position(), but this function was not

always called at the correct time, or was sometimes called when not needed. Issues regarding how and

when to place such calls were the source of many bugs in optimizations. This fix moves the responsibility

of calling handler::position() to the iterators, whose default implementations usually handle this

task adequately on their own. (Bug #30060691)

References: See also: Bug #29693294, Bug #30049217, Bug #30153695.

• The server could exit due to mishandling a COM_PROCESS_INFO command. (Bug #30032302)

• Warnings are normally generated when deprecated system variables are assigned a value, but this did

not occur when persisted system variables were processed during server startup. (Bug #30030648)

• With bind_address set to a value containing multiple addresses, setting host_cache_size=0

caused a server exit at client connect time. (Bug #30018958)

• On Windows, Protobuf compilation failed for the Ninja build type. (Bug #30018894)

• SHOW PROCESSLIST output could include statements that had completed and were no longer in

process. (Bug #29999818)

• A mysqldump error-message buffer was too small, potentially leading to message truncation. (Bug

#29999782, Bug #96074)

• Last used auto-increment values instead of “next to be used” auto-increment values were cached while

importing tables from MySQL 5.7 to MySQL 8.0 during an in-place upgrade, which resulted in any tables

read from the table cache after upgrade having incorrect auto-increment values. (Bug #29996434)

• When executing a prepared statement that used constant folding, it was possible to register a location

for rollback which was not allocated on the MEMROOT, but rather on the stack, and so was no longer in

scope. (Bug #29990693)

298

MySQL 8.0 Release Notes

References: See also: Bug #29939331.

• A warning about ZEROFILL being deprecated was produced for CREATE TABLE ... AS and CREATE

TABLE ... LIKE statements that created tables that contained a YEAR column. This could be

confusing because the ZEROFILL attribute may only have been added implicitly to the YEAR column. To

avoid confusion, the warning is no longer raised for such statements. (Bug #29961060)

• A query using bitwise operators, such as in WHERE text_col < (int_col & int_col) AND

int_col = -1, failed to return any rows as expected. (Bug #29957969)

• Malformed resource group names in optimizer hints could lead to unexpected server behavior. (Bug

#29955732)

• EXPLAIN, when using FORMAT=TREE, did not show the same costs as with FORMAT=JSON. In particular,

when using FORMAT=TREE, the cost calculated took into account eval_cost for joins, but not for base

tables. (Bug #29953579)

• For Solaris, mysqld.cc contained a prototype for memcntl() that is no longer needed. The prototype

has been removed. (Bug #29953495, Bug #95971)

• For Solaris, -DWITH_SSL=system did not work when compiling with GCC. (Bug #29953460, Bug

#95970)

• MySQL builds configured with -DWITHOUT_SERVER=1 failed. (Bug #29948728, Bug #95740)

• The internal method Field_tiny::pack() did not always perform bounds checking as expected.

(Bug #29948029)

References: See also: Bug #31591391.

• Improper handling of plugin unloading could cause a server exit. (Bug #29941948)

• The internal MEM_ROOT class did not handle all out-of-memory errors correctly. (Bug #29940846)

• JSON_SCHEMA_VALIDATION_REPORT() did not distinguish between a JSON document that did not

validate according to a JSON schema and a JSON document which was too deeply nested, which

resulted in wrong behavior in some cases. (Bug #29940833)

• Use of the <=> operator could yield incorrect results for comparisons involving very large constants.

(Bug #29939331, Bug #95908)

• For the keyring_aws plugin, some valid region values for the keyring_aws_region system variable

were rejected. (Bug #29933758)

• For debug builds, an assertion could be raised during UNION queries when computing the combined

data type of a GEOMETRY column and SELECT * FROM (SELECT NULL). (Bug #29916900, Bug

#95827)

• For columns defined with the binary character set, SHOW CREATE TABLE could generate CREATE

TABLE statements that produced a syntax error when executed. (Bug #29909573, Bug #95801)

• Data dictionary APIs were added for fetching table names in a schema that use a specific storage

engine, and for fetching table names in a schema that are created and hidden by the storage engine.

The former is required by NDB, and the latter is required for DROP DATABASE operations. (Bug

#29906844, Bug #95792)

• mysqldump leaked memory when run with the --order-by-primary option. (Bug #29906736)

299

MySQL 8.0 Release Notes

• For queries involving functional indexes, EXPLAIN FORMAT=TREE printed the hidden column name

instead of the indexed expression. (Bug #29904996)

• For debug builds, CREATE TABLE ... IGNORE SELECT ... statements did not properly clean up

the table state when the last row to be inserted was skipped due to a failed CHECK constraint. This could

cause the next statement using the table to raise an assertion. (Bug #29903865)

• MySQL did not handle execution of a recursive common table expression (CTE) correctly when the

termination condition of the recursive query for this CTE had an IN predicate using another recursive

CTE. (Bug #29899614)

• Deserialization of serialized dictionary information (SDI) failed for a table with partitions residing in

different tablespace files. (Bug #29898965)

• For authentication using an LDAP authentication plugin, if the user DN portion was empty and group

mapping was configured, authentication assigned an incorrect user DN and skipped the user search.

(Bug #29897624)

• Constraints defined without a name could in some cases cause a server exit. (Bug #29892876)

• An in-place upgrade from MySQL 5.7 to MySQL 8.0 failed due a missing NDB tablespace. (Bug

#29889869, Bug #30113440)

• mysqlpump produced an error when run against a server older than MySQL 5.7. (Bug #29889253)

• When Boost was downloaded, CMake configuration logic for determining the size of the downloaded file

was incorrect, and could remove that file after a successful download operation. (Bug #29881279)

• A possible integer overflow due to unsigned integer type casting could lead to later buffer overflow due to

arbitrary size memory allocation. (Bug #29878914)

• When the client character set was other than latin1, the server converted the string representation

of a DECIMAL value from latin1 to the client character set. This conversion was not necessary, since

all supported client character sets encode numbers in the same way as latin1, and so is no longer

performed. (Bug #29875672)

• The vio_description() debugging function was called in nondebug builds. (Bug #29871361)

• The fix for a previous issue in MySQL 8.0.3 changed a test for whether an expression over constant

DATE values could be cached from allowing any expressions except global variables to a blanket denial

of all functions, regardless of whether they were over constants or not, which significantly impacted

performance of related queries in which the optimizer needed to perform conversion of a string to a DATE

value. This test has been reverted to its original form. (Bug #29871018)

References: This issue is a regression of: Bug #85471, Bug #28576018.

• The INFORMATION_SCHEMA can fetch dynamic table statistics from storage engines, but this did not

work for partitioned tables. (Bug #29870919, Bug #95641)

• Retrying a failed access-control statement could permit another thread to acquire a lock on the access-

control cache during a window when metadata locks where released and reacquired, resulting in a

deadlock. The locks are now not released during the retry operation. (Bug #29870899, Bug #95612)

• An assertion could be raised if a user without the proper privilege attempted to enable the

offline_mode system variable. (Bug #29849046)

• Fedora packaging configuration put debug information for mysql_config_editor in the wrong

package. (Bug #29841342)

300

MySQL 8.0 Release Notes

• Attempted use of a freed object during MeCab plugin initialization caused a segmentation fault. (Bug

#29832534)

• The function used to generate entropy for random passwords could sometimes not provide much

entropy. (Bug #29808492)

• With super_read_only enabled, the server could process DROP TABLESPACE improperly. (Bug

#29802833)

• The server did not handle a query with a left join containing a materialized semijoin correctly. (Bug

#29800741)

• For MySQL installed using RPM packages, an initialization script that tested server connectivity

misbehaved if the client account authenticated using an LDAP authentication plugin. (Bug #29786782)

• Improper locking during storage engine initialization could cause a server exit. (Bug #29782379)

• On a GTID-enabled server, concurrent execution of DROP USER and a prepared statement that

accessed a view could deadlock. (Bug #29772622)

• When performing EXPLAIN FORMAT=JSON on a query of the form SELECT WHERE NOT EXISTS

(SELECT FROM (derived_table) WHERE false_condition) involving an antijoin

transformation, the subquery was eliminated but its own subqueries were moved up instead of being

eliminated along with it. (Bug #29759277)

References: See also: Bug #30017509.

• An interrupted tablespace encryption operation caused a discrepancy between data dictionary and

storage engine metadata, resulting in an assertion failure on a subsequent attempt to access the

tablespace. (Bug #29756808)

• Simultaneous execution of the event scheduler and DROP EVENT could result in lock acquisition hanging

until lock wait timeout. (Bug #29742901, Bug #95223)

• CHECK constraints were not enforced when a column took its default value from an expression. (Bug

#29706689, Bug #95192)

• When performing two sorts on the same table with no temporary table, both sorts tried to use the same

buffer, resulting in a read out of bounds. This could occur when the same query used both DISTINCT

and ORDER BY. (Bug #29699759)

• When performing a weedout involving a sorted table, sorting was not done by row IDs. (Bug #29693294)

• VS2019 produced compilation errors with debug compilation selected due to use of the /ZI flag. Now /

Z7 is used instead. (Bug #29691691, Bug #95125)

• In source distributions, these changes were made in relation to the DBUG package, to clean up old and

unmaintained code in the dbug directory:

• Moved dbug.cc to the mysys directory, removed the dbug library.

• Removed unused functions in dbug.cc.

• Removed the DBUG_LEAVE macro; no longer needed.

• Wrapped the body of the DBUG_LOG macro in if _db_enabled_(), to avoid formatting of strings

that likely will not be printed anyway.

• Removed the dbug directory.

301

MySQL 8.0 Release Notes

(Bug #29680868, Bug #95082)

• While allocating the reference item array, the count for any window functions was not taken into

consideration. As a result, when expressions having window functions were split, the extra space

needed to store the new item references was not properly allocated. (Bug #29672621)

• Setting the collation of a user variable did not work correctly in all cases. (Bug #29665165)

• Processing of WHERE clauses in SHOW statements was not performed consistently. (Bug #29664758)

• If clauses to drop and add constraints were specified within the same ALTER TABLE statement, they

were executed in incorrect order. (Bug #29652464)

• EXPLAIN now shows when a result is being sorted by row ID. (Bug #29634196)

• Unnecessary materialization is no longer performed in either of the following cases:

• When performing a sort at the end of a join, such as for grouping, and the sorting does not make use

of row IDs.

• When materializing a derived table which is not to be read from more than once.

(Bug #29634179)

• CAST(arg AS FLOAT) did not returned the expected out-of-range error when arg was too small to be

represented as a FLOAT value. (Bug #29621333)

• Internal conversion of FLOAT values sometimes occurred at the wrong time, which could lead to excess

precision in results. Consider the table created and populated as shown here:

CREATE TABLE t(f FLOAT);

INSERT INTO t VALUES (2.3);

Prior to the fix, the query SELECT f, IF(f > 0, f, 0) FROM t against this table returned (2.3,

2.299999952316284) instead of (2.3, 2.3) as expected. (Bug #29621062)

• log0meb.cc failed to compile with some build options. (Bug #29616525)

• The client library could dereference a null pointer while fetching result set metadata from the server.

(Bug #29597896, Bug #30689251)

• A runtime error could occur for interval value checks when summing date and interval values. (Bug

#29587536)

• In builds with Undefined Behavior Sanitizer enabled, multiplication with -9223372036854775808 could

produce warnings and incorrect results. (Bug #29581610)

• During startup, the server attempted to write operations to the binary log that should not have been

logged. (Bug #29557747, Bug #94835)

• A statement of the form CREATE VIEW v1 AS SELECT * FROM table WHERE (constant IN

(SELECT constant) IS UNKNOWN) led to an assertion. (Bug #29525304)

References: This issue is a regression of: Bug #25466100.

• On EL6, if a FIPS-enabled OpenSSL library was not available, attempting to enable FIPS mode could

cause a server malfunction. (Bug #29519794)

302

MySQL 8.0 Release Notes

• SET PERSIST_ONLY can be used to persist some system variables that SET PERSIST cannot (due to

the way variable settings occur). If such a variable is found in mysqld-auto.cnf at startup, the server

now issues a warning and ignores the setting. (Bug #29511118)

• The server did not properly aggregate a partial revoke and a schema-level privilege in some cases. (Bug

#29484519)

• For debug builds, ENUM or SET columns defined with a DEFAULT clause raised an assertion. (Bug

#29480711)

• MySQL Installer did not install OpenSSL DLL dependencies if the Development component was not

selected. (Bug #29423421, Bug #94168, Bug #30199579, Bug #96573)

• In READ UNCOMMITTED isolation level, a segmentation fault occurred under heavy load from

memcached clients. An externally stored BLOB column that was being updated by one transaction was

read by another transaction as having a NULL value and a non-zero data length. (Bug #29396364, Bug

#93961)

• On systems with working IPv6 address resolution, IPv6 socket creation failure at connect time resulted in

a memory leak. (Bug #29374606, Bug #94384)

• In replication scenarios, if multiple clients concurrently executed XA COMMIT or XA ROLLBACK

statements that used the same XID value, replication inconsistency could occur. (Bug #29293279, Bug

#94130)

• Arguments for the TIMESTAMPADD() function could be reversed for prepared statements. (Bug

#29268394)

• The DEFAULT ROLE option for CREATE USER statements was not written to the binary log. (Bug

#28948915, Bug #93252)

• Starting the server from the command line with invalid memcached plugin variable settings caused the

server to exit. (Bug #28575863)

• The SET clause for LOAD DATA did not work to set GEOMETRY NOT NULL columns. (Bug #28460369,

Bug #91893)

• On Windows 8 and higher, the keyring_aws plugin was not able to communicate with Amazon KMS

servers. (Bug #28377961)

• INFORMATION_SCHEMA tables and SHOW COLUMNS could produce incorrect view column types when a

query on the view had multiple query blocks combined with the UNION operator. (Bug #28278220, Bug

#91486)

• On Debian, long InnoDB recovery times at startup could cause systemd service startup failure. The

default systemd service timeout is now disabled (consistent with RHEL) to prevent this from happening.

(Bug #28246585, Bug #91423)

• With the thread_pool plugin enabled, the sys.processlist and sys.session views displayed a

thread name rather than the actual user name. (Bug #25906021, Bug #85976)

• The delete_latency column in the sys.schema_index_statistics view

incorrectly referred to the SUM_TIMER_INSERT column of the Performance Schema

table_io_waits_summary_by_index_usage table rather than the SUM_TIMER_DELETE column.

(Bug #25521928)

• In output from the sys.diagnostics() procedure, the latency column for the

user_summary_by_file_io_type view was incorrectly displayed in raw picoseconds rather than as

a formatted value. (Bug #25287996)

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MySQL 8.0 Release Notes

• MySQL Enterprise Encryption functions could apply Diffie-Hellman (DH) methods to non-DH keys,

resulting in unpredictable results or server exit. (Bug #22839007)

• Password masking was incomplete for SHOW PROCESSLIST and some INFORMATION_SCHEMA and

Performance Schema tables. (Bug #20712046)

• With strict SQL mode enabled, the STR_TO_DATE() function did not properly handle values with time

parts only. Thanks to Daniel Black for the contribution. (Bug #18090591, Bug #71386)

• A query using GREATEST() in the WHERE clause could, in certain cases, fail to return a row where one

was expected or raise a spurious error. (Bug #96012, Bug #29963278)

• Explicitly setting sort_buffer_size to its maximum value or close to it caused some queries to fail

with an out of memory error. (Bug #95969, Bug #29952775)

References: See also: Bug #22594514.

• Late NULL filtering, to avoid index lookups if the lookup key contains at least one NULL, was not

performed for backwards index scans, although it was for forward index scans. (Bug #95967, Bug

#29954680)

• Using a function such as IFNULL() or ABS() in a functional index led to the error Value is out of

range for functional index... when an UNSIGNED column used as an argument to such a

function contained a value exceeding that of the corresponding signed integer type. (Bug #95881, Bug

#29934661)

• The resolution procedure for the IFNULL() function differed from that for all other functions derived from

CASE operations, including COALESCE(), which caused incorrect length information to be generated for

certain numeric expressions. (Bug #94614, Bug #29463760)

• Queries using UNION ALL ... LIMIT 1 evaluated an excessive number of rows as shown by

Handler_read_key and Handler_read_next. (Bug #79340, Bug #22292995)

References: See also: Bug #79040, Bug #22158368, Bug #92994, Bug #28866942.

• The -DWITH_EXAMPLE_STORAGE_ENGINE=1 CMake option was ignored but should not have been. If -

DWITH_EXAMPLE_STORAGE_ENGINE=0 is given, the EXAMPLE storage engine is built as a plugin. (Bug

#70859, Bug #17772560, Bug #30133062)

References: See also: Bug #18324650.

Changes in MySQL 8.0.17 (2019-07-22, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Audit Log Notes

• C API Notes

• Character Set Support

• Component Notes

• Configuration Notes

• Debugging Notes

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MySQL 8.0 Release Notes

• Deprecation and Removal Notes

• Installation Notes

• Keyring Notes

• Packaging Notes

• Performance Schema Notes

• Plugin Notes

• Security Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• Encryption and decryption operations for encrypted MySQL Enterprise Audit log files use a

password stored in the MySQL keyring. Previously, only a single password was stored. Generating

a new password made the old password inaccessible, rendering MySQL Enterprise Audit unable

to read log files encrypted with the old password. MySQL Enterprise Audit now implements

password history in the keyring, which includes password archiving and expiration capabilities.

The audit log plugin includes in each encrypted log file name the ID of the password required to

read the file. To enable expiration and removal of old archived passwords in the keyring, the new

audit_log_password_history_keep_days system variable is available. See Configuring Audit

Logging Characteristics. (WL #11246)

C API Notes

• These C API changes were made:

• HOSTNAME_LENGTH was changed from 60 to 255 and moved from include/mysql_com.h to

include/my_hostname.h.

• USER_HOST_BUFF_SIZE was moved from include/mysql_com.h to sql/auth/

auth_common.h.

(Bug #29590300)

Character Set Support

• The utf8mb4 character set has a new binary collation, utf8mb4_0900_bin, which differs from the

existing utf8mb4_bin binary collation as follows:

• For collating weights, utf8mb4_bin uses code points, possibly with leading zero bytes added,

whereas utf8mb4_0900_bin uses the utf8mb4 encoding bytes. The sort order is the same for both

collations, but sorting for utf8mb4_0900_bin is much faster.

• The pad attribute for utf8mb4_bin is PAD SPACE, whereas for utf8mb4_0900_bin it is NO PAD.

Consequently, operations involving utf8mb4_0900_bin do not add trailing spaces, and comparisons

involving strings with trailing spaces may differ for the two collations.

305

MySQL 8.0 Release Notes

For more information, see Unicode Character Sets. (WL #10354)

Component Notes

• A new mysql_current_thread_reader component service is available to enable components to

obtain a handle to the current thread. For example, the service enables components to access properties

of the current session by passing its thread handle to other services. For information about this service,

see the Component Subsystem section of the MySQL Server Doxygen documentation, available at

https://dev.mysql.com/doc/index-other.html. (WL #12727)

Configuration Notes

• The source files in the mysys_ssl directory have been moved to the mysys directory and the

mysys_ssl library is no longer built. (Bug #29488066)

• MySQL configuration now requires a minimum CMake version of 3.5.1. (Bug #29337090)

• The maximum permitted length of host names throughout MySQL has been raised to 255 ASCII

characters, up from the previous limit of 60 characters. This applies to, for example, host name-related

columns in the data dictionary, mysql system schema, Performance Schema, INFORMATION_SCHEMA,

and sys schema; the MASTER_HOST value for the CHANGE MASTER TO statement; the Host column

in SHOW PROCESSLIST statement output; host names in account names (such as used in account-

management statements and in DEFINER attributes); and host name-related command options and

system variables.

Caveats:

• The increase in permitted host name length can affect tables with indexes on host name columns.

For example, tables in the mysql system schema that index host names now have an explicit

ROW_FORMAT attribute of DYNAMIC to accommodate longer index values.

• Some file name-valued configuration settings might be constructed based on the server host name.

The permitted values are constrained by the underlying operating system, which may not permit file

names long enough to include 255-character host names. This affects the general_log_file,

log_error, pid_file, relay_log, and slow_query_log_file system variables and

corresponding options. If host name-based values are too long for the OS, explicit shorter values must

be provided.

• Although the server now supports 255-character host names, connections to the server established

using the --ssl-mode=VERIFY_IDENTITY option are constrained by maximum host name length

supported by OpenSSL. Host name matches pertain to two fields of SSL certificates, which have

maximum lengths as follows: Common Name: maximum length 64; Subject Alternative Name:

maximum length as per RFC#1034.

Applications that expect host names to be a maximum of 60 characters should be adjusted to account

for this change. (Bug #13548245, Bug #63814, Bug #27925782, Bug #90601, Bug #27955121, Bug

#29584642, Bug #29602081, Bug #94907, WL #12571)

Debugging Notes

• The MySQL server is a multithreaded application that uses numerous internal locking primitives such

as mutexes. To enable detection of lock-acquisition deadlocks and enforcement that runtime execution

is free of them, MySQL now supports LOCK_ORDER tooling. This enables a lock-order dependency

graph to be defined as part of server design, and server runtime checking to ensure that lock acquisition

is acyclic and that execution paths comply with the graph. LOCK_ORDER support includes:

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MySQL 8.0 Release Notes

• A lock_order_dependencies.txt file that defines the server lock-order dependency graph.

• A WITH_LOCK_ORDER CMake option that configures whether MySQL is built with LOCK_ORDER

tooling.

• A set of system variables that configure LOCK_ORDER tool operation during server execution.

• A --lock-order option for mysql-test-run.pl that controls whether to enable the

LOCK_ORDER tool during test case execution.

To use the LOCK_ORDER tool, you must build MySQL from source with tooling enabled. See The

LOCK_ORDER Tool. It is intended for debugging the server, not for production use.

Deprecation and Removal Notes

• X DevAPI: For Collection objects, the following methods have been deprecated and are scheduled to

be removed in a future release:

• Collection.find().where()

• Collection.modify().where()

• Collection.remove().where()

Any Collection code relying on the .where() method should be updated and the expression in

the .where() method should be provided directly in the appropriate .find(), .remove(), and

.modify() method. (WL #12902)

• A mysql_upgrade_info file created by the mysql_upgrade program during a previous upgrade

could only be modified the operating system user that executed the mysql_upgrade program, causing

an upgrade error. A warning is now issued instead of an error, which permits the upgrade operation to

proceed. The mysql_upgrade_info file is deprecated and will be removed in a future MySQL version.

(Bug #29702060, Bug #95165)

• FLOAT(M,D) and DOUBLE(M,D) syntax to specify the number of digits for columns of type FLOAT and

DOUBLE (and any synonyms) is a nonstandard MySQL extension. This syntax is deprecated and support

for it will be removed in a future MySQL version. (Bug #25328973, Bug #84363, WL #12575)

• For string data types, the BINARY attribute is a nonstandard MySQL extension that is shorthand for

specifying the binary (_bin) collation of the column character set (or of the table default character set

if no column character set is specified). In MySQL 8.0, this nonstandard use of BINARY is ambiguous

because the utf8mb4 character set has multiple _bin collations, so the BINARY attribute is deprecated

and support for it will be removed in a future MySQL version. Applications should be adjusted to use an

explicit _bin collation instead.

The use of BINARY to specify a data type or character set remains unchanged. (WL #13068)

• The nonstandard C-style &&, ||, and ! operators that are synonyms for the standard SQL AND, OR,

and NOT operators, respectively, are deprecated and support for them will be removed in a future

MySQL version. Applications that use the nonstandard operators should be adjusted to use the standard

operators.

Note

Use of || is deprecated unless the PIPES_AS_CONCAT SQL mode is enabled. In

that case, || signifies the SQL-standard string concatenation operator).

307

MySQL 8.0 Release Notes

(WL #13070)

• The ZEROFILL attribute is deprecated for numeric data types, as is the display width attribute for integer

data types. Support for ZEROFILL and display widths for integer data types will be removed in a future

MySQL version. Consider using an alternative means of producing the effect of these attributes. For

example, applications could use the LPAD() function to zero-pad numbers up to the desired width, or

they could store the formatted numbers in CHAR columns. (WL #13127)

• The UNSIGNED attribute is deprecated for columns of type FLOAT, DOUBLE, and DECIMAL (and any

synonyms) and support for it will be removed in a future MySQL version. Consider using a simple CHECK

constraint instead for such columns. (WL #12391)

• AUTO_INCREMENT support is deprecated for columns of type FLOAT and DOUBLE (and any synonyms)

and will be removed in a future MySQL version. Consider removing the AUTO_INCREMENT attribute from

such columns, or convert them to an integer type. (WL #12595)

• The SQL_CALC_FOUND_ROWS query modifier and accompanying FOUND_ROWS() function are now

deprecated and will be removed in a future MySQL version. As a replacement, considering executing

your query with LIMIT, and then a second query with COUNT(*) and without LIMIT to determine

whether there are additional rows. For example, instead of these queries:

SELECT SQL_CALC_FOUND_ROWS * FROM tbl_name WHERE id > 100 LIMIT 10;

SELECT FOUND_ROWS();

Use these queries instead:

SELECT * FROM tbl_name WHERE id > 100 LIMIT 10;

SELECT COUNT(*) WHERE id > 100;

COUNT(*) is subject to certain optimizations. SQL_CALC_FOUND_ROWS causes some optimizations to

be disabled. (WL #12615)

Installation Notes

• An automatic upgrade at server startup can take some time to complete. For better status notification

in systemd environments, the server now sends messages to the system notification socket when

upgrades start and end. (Status can be monitored with server mysqld status.) (Bug #29493201)

Keyring Notes

• The keyring_aws plugin has been updated to use the latest AWS Encryption SDK and so that it works

with OpenSSL 1.1.

The keyring_aws_region variable supports the additional AWS regions supported by the new SDK.

Refer to the variable description for a list of supported AWS regions. (WL #12886)

Packaging Notes

• To reduce the download size and disk footprint of mysql-community-server Linux packages, debug

binaries and plugins have been moved to separate packages for these platforms:

• EL8, Fedora: The mysql-community-server package with debug binaries and associated plugins

is now split into a mysql-community-server package without debug binaries or plugins and a

mysql-community-server-debug package with debug binaries and plugins.

• Debian: The mysql-community-server package with debug binaries and associated plugins is

now split into a mysql-community-server package without debug binaries or plugins, a mysql-

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MySQL 8.0 Release Notes

community-server-debug package with debug binaries, and a mysql-community-test-debug

package with debug plugins.

In all cases, the debug packages are dependent on the corresponding mysql-community-server

package. (Bug #29769061, Bug #28647754, Bug #92415, Bug #29702765, Bug #95169, Bug

#29681301)

Performance Schema Notes

• Performance Schema version checking at compile time was improved to prevent incompatibilities with

the server version. (Bug #29550156)

• Previously, the Performance Schema instrumentation for RWLOCK named priority read/write locks as

rwlock (thus failing to distinguish plain from priority locks) and did not collect information about the

kind of unlock operation performed. Priority read/write locks now are named prlock, so that events for

them begin with wait/synch/prlock. Also, information about unlock operations is provided. (Bug

#29270712)

Plugin Notes

• Not all plugins can operate properly if loaded “early” in the server startup sequence using the --early-

plugin-load option (that is, before InnoDB is initialized). However, InnoDB requires keyring backend

plugins to operate on encrypted tables. To enable plugins to indicate to the server whether they can be

loaded early, a new PLUGIN_OPT_ALLOW_EARLY flag is available for use in the plugin descriptor. See

Server Plugin Library and Plugin Descriptors. Keyring plugins included in MySQL distributions now have

the PLUGIN_OPT_ALLOW_EARLY flag enabled because InnoDB requires them, but the flag is not limited

to keyring plugins. It can be set for other plugins that are able to initialize successfully early in the server

startup sequence.

This flag has no effect on whether a plugin can be loaded at server startup with the --plugin-load or

--plugin-load-add option, or at runtime with the INSTALL PLUGIN statement.

All plugins compiled using MySQL distributions prior to 8.0.17 do not have this flag set. When loading

these into pre-8.0.17 servers this does not matter, but attempts to use --early-plugin-load to load

plugin binaries compiled using pre-8.0.17 MySQL distributions into a 8.0.17 or higher server will fail.

The plugins must be recompiled against MySQL 8.0.17 or higher. (Bug #29040456, Bug #93550, WL

#12935)

Security Notes

• For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server

has been updated to version 1.0.2s. Issues fixed in the new OpenSSL version are described at

https://www.openssl.org/news/cl102.txt and https://www.openssl.org/news/vulnerabilities.html. (Bug

#29881152)

X Plugin Notes

• The createIndex() method did not support the DOUBLE(M,D) syntax for specifying double-precision

values due to a regression in MySQL 8.0.16. (Bug #29748841)

• X Protocol's handling of messages with arguments encoded as octets was corrected to support non-

scalar data such as an array of strings. (Bug #29721046)

• When host name identity verification was active for SSL connections (--ssl-

mode=VERIFY_IDENTITY), X Protocol did not check for matches to Subject Alternative Names (SANs)

in the server Certificate Authority (CA) certificate. This could lead to connection requests being rejected

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MySQL 8.0 Release Notes

unnecessarily because they used a valid host name that was specified as an SAN rather than as the

certificate's Common Name value. (Bug #29691694)

• When prepared statements were used with X Plugin, using IN or NOT IN in a modify or find operation

produced invalid JSON, resulting in an error. (Bug #29259501)

• On Windows, X Plugin logged some messages that were unnecessary or insufficiently informative. The

messages have been removed or improved as appropriate. (Bug #27839153)

• X Plugin's list of SQL functions was out of date, and has been updated to add new functions and remove

functions that are no longer available. (Bug #26574971)

Functionality Added or Changed

• InnoDB; JSON: InnoDB now supports multi-valued indexes on JSON arrays. A multi-valued index is an

index in which multiple index records can point to the same data record. This can be useful for indexing

JSON documents such as {"user":"Bob","zipcode":[94477,94536]} in which, if we wish to

search all zip codes, it is necessary to have two index records for each zip code in the document. We

can create such an index on the zipcode array using a CREATE INDEX statement such as this one:

CREATE INDEX zips ON t1( (CAST(data->'$.zipcode' AS UNSIGNED ARRAY)) )

Effectively, this is a functional index using the CAST() function, which has been extended with the

ARRAY keyword to enable casting of JSON arrays to SQL data type arrays. The expression must be a

valid JSON expression, and must point to an array in the JSON document in order to be effective. All

type specifiers supported by CAST() can be used except for BINARY and JSON. Such usage of the

CAST() function is supported only by InnoDB, and only for creating multi-valued indexes on JSON

arrays.

As part of this work, MySQL adds a new function JSON_OVERLAPS() as well as a new MEMBER OF()

operator for working with JSON documents, as described here:

• JSON_OVERLAPS() compares two JSON documents. If they contain any key-value pairs or array

elements in common, the function returns TRUE (1); otherwise it returns FALSE (0). If both values are

scalars, the function performs a simple test for equality. If one argument is a JSON array and the other

is a scalar, the scalar is treated as an array element. Thus, JSON_OVERLAPS() acts as a complement

to JSON_CONTAINS(), which indicates whether all key-value pairs or array elements are present in

both JSON documents.

• MEMBER OF() tests whether the first operand (a scalar or JSON document) is a member of the JSON

array passed as the second operand, returning TRUE (1) if it is, and FALSE (0) if it is not. No type

conversion of the operand is performed.

The MySQL optimizer uses multi-valued indexes automatically for any suitable query—that is, a query

using in its WHERE clause any of JSON_CONTAINS(), JSON_OVERLAPS(), or MEMBER OF() on an

array within a JSON column. You can see whether such an index is actually used by checking the output

of EXPLAIN for the given query.

Multi-Valued Indexes, provides more detailed information about multi-valued indexes, including

examples. For more information about JSON_OVERLAPS() and MEMBER OF(), with examples of use,

see Functions That Search JSON Values.

Note

ARRAY and MEMBER now are reserved words and cannot be used as identifiers

without identifier quoting.

310

MySQL 8.0 Release Notes

(WL #8955, WL #8763)

• Group Replication: It is now possible to use a remote cloning operation for state transfer to

a joining member during distributed recovery. The remote cloning operation lets you add new

members to the group without transferring the group's data to the server manually beforehand. To

use this functionality, you must install the Clone plugin on the donor and joining member, grant

the BACKUP_ADMIN permission to the replication user for distributed recovery, and set the new

group_replication_clone_threshold system variable to an appropriate level. Required Clone

plugin settings are now made and the remote cloning operation is now handled automatically. When

cloning is complete and the joining member has restarted, any transactions that the group applied while

the remote cloning operation was in progress are transferred to the joining member by replication from a

donor's binary log to complete distributed recovery. (WL #12827)

• Microsoft Windows: A new warning message now reminds DBAs that connections made using the

MySQL named pipe on Windows has limited the permissions a connector can request on the named

pipe.

Previously, the named_pipe_full_access_group system variable was set to a value that maps to

the built-in Windows Everyone group (SID S-1-1-0) by default. However, this group is not ideal and

should be replaced with a group that restricts its membership for connectors that are unable to request

fewer permissions on the MySQL named pipe.

The new warning is written to the error log at startup if the string value assigned to

named_pipe_full_access_group is '*everyone*' (or the Windows System Language equivalent)

and named pipes are enabled. In addition, the warning is written to the error log and raised to the client if

the system variable is reset to the Everyone group at runtime. (WL #12670)

• JSON: MySQL now supports JSON schema validation using two functions JSON_SCHEMA_VALID()

and JSON_SCHEMA_VALIDATION_REPORT(), both of which validate a JSON document

against a JSON schema conforming to Draft 4 of the JSON Schema specification.

JSON_SCHEMA_VALID() returns true if the document validates against the schema and false if it does

not. JSON_SCHEMA_VALIDATION_REPORT() returns a JSON document containing detailed information

about the results of the validation.

For both of these functions, the following statements apply:

• required attributes are supported.

• Regular expressions are supported (invalid expressions are silently ignored).

• External resources in schemas and the $ref keyword are not supported.

For more information, including examples, see JSON Schema Validation Functions. (WL #11999, WL

#13005)

• The time_zone session variable is now hintable using the SET_VAR optimizer hint. (Bug #29776464)

• The minor version of the libmysqlclient.so C client library has been increased to 1 (21.0 to 21.1),

to signal that new symbols have been added. This was done to correct an oversight in the MySQL 8.0.16

release. To address compatibility concerns, the version of all symbols is unchanged. This means the

filename of the library is libmysqlclient.so.21.1.17, whereas all symbols inside the library are

tagged as 21_0 (unchanged from the 8.0.16 release). (Bug #29584073, Bug #29642146)

• Thanks to Josh Braden, Daniël van Eeden, Simon Mudd, and Zhou Mengkang, who contributed

corrections to comments and messages in the MySQL source code. (Bug #29403708, Bug #94464, Bug

#29428435, Bug #94527, Bug #29262200, Bug #94049, Bug #29468128, Bug #94625)

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MySQL 8.0 Release Notes

• The mysql client program now sends os_user and os_sudouser connection attributes, when

available, to indicate the name of the operating system user running the program and the value of the

SUDO_USER environment variable, respectively. For general information about connection attributes, see

Performance Schema Connection Attribute Tables. Thanks to Daniël van Eeden for the contribution on

which this feature was based. (Bug #29210935, Bug #93916, WL #12955)

• The optimizer now transforms a WHERE condition having NOT IN (subquery), NOT EXISTS

(subquery), IN (subquery) IS NOT TRUE, or EXISTS (subquery) IS NOT TRUE internally

into an antijoin, thus removing the subquery. This is similar to the existing IS NULL (Not exists) outer

join optimization; see EXPLAIN Extra Information, for further information.

In addition, the semijoin materialization can now be used for a WHERE condition having IN (subquery)

IS TRUE, or EXISTS (subquery) IS TRUE, or when the IN condition belongs to a left join such as

SELECT * FROM t1 LEFT JOIN t2 ON t2.x IN (SELECT * FROM t3). See Optimizing IN and

EXISTS Subquery Predicates with Semijoin Transformations.

Also as a result of this work, MySQL is now able to simplify a condition of the form (x IS TRUE) IS

FALSE as x IS NOT TRUE, which can be tested more quickly and optimized more easily than the

condition as originally written. (Bug #29027883, WL #4245)

• Password hash values displayed in the IDENTIFIED WITH clause of output from SHOW CREATE

USER may contain unprintable characters that have adverse effects on terminal displays and in other

environments. Enabling the new print_identified_with_as_hex system variable causes SHOW

CREATE USER to display such hash values as hexadecimal strings rather than as regular string literals.

Hash values that do not contain unprintable characters still display as regular string literals, even with

this variable enabled. For compatibility with this change, CREATE USER and ALTER USER now accept

hash values specified either as regular string literals or as hexadecimal strings. (Bug #28053446, Bug

#90947, WL #12803)

• In MySQL 8.0, the lower_case_table_names variable can only be configured when the MySQL

server is initialized. Because a MySQL server installation on Debian and Ubuntu performed using APT

initializes the MySQL server for you, there was no opportunity to enable lower_case_table_names.

To work around this issue, you can now use the debconf-set-selection utility to enable

lower_case_table_names (set lower_case_table_names=1) prior to installing MySQL using

APT.

To enable lower_case_table_names prior to installing MySQL using APT, execute the following

command:

shell> sudo debconf-set-selections <<< "mysql-server mysql-server/lowercase-table-names select Enabled

(Bug #27948395, Bug #90695)

• The server now checks the SSL server certificate better at startup and writes a warning to the error log if

it finds a problem. (Bug #25945005)

• The umask for files created using SELECT ... INTO OUTFILE or SELECT ... INTO DUMPFILE

was changed from 0666 to 0640. The LOAD_FILE() function no longer requires files to be world-

readable, just readable by the server. (Bug #24513720)

• The mysqldump option --set-gtid-purged controls whether or not a SET

@@GLOBAL.gtid_purged statement is added to the mysqldump output. The statement updates the

value of gtid_purged on a server where the dump file is reloaded, to add the GTID set from the

source server's gtid_executed system variable. A new choice --set-gtid-purged=COMMENTED

is now available. When this value is set, if GTIDs are enabled on the server you are backing up,

SET @@GLOBAL.gtid_purged is added to the output (unless gtid_executed is empty), but it is

commented out. This means that the value of gtid_executed is available in the output, but no action

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MySQL 8.0 Release Notes

is taken automatically when the dump file is reloaded. With COMMENTED, you can control the use of the

gtid_executed set manually or through automation. For example, you might prefer to do this if you are

migrating data to another server that already has different active databases. Thanks to Facebook for this

contribution. (Bug #94332, Bug #29357665, WL #12959)

• MySQL now supports explicit casts to DOUBLE, FLOAT, and REAL using either of the functions CAST()

or CONVERT(). For more information, see Cast Functions and Operators. (Bug #30524, Bug #11747058,

WL #529)

• InnoDB now supports redo log archiving. Backup utilities that copy redo log records may sometimes fail

to keep pace with redo log generation while a backup operation is in progress, resulting in lost redo log

records due to those records being overwritten. The redo log archiving feature addresses this issue by

sequentially writing redo log records to an archive file. Backup utilities can copy redo log records from

the archive file as necessary, thereby avoiding the potential loss of data.

For more information, see Redo Log Archiving. (WL #12009, WL #12329, WL #12348)

• To provide additional indexing options for JSON data, InnoDB now supports multi-valued indexes. A

multi-valued index is a secondary index defined on a column that contains an array of values. (WL

#8763)

• MySQL now provides a clone plugin that permits cloning InnoDB data locally or from a remote MySQL

server instance. A local cloning operation stores cloned data on the same server or node where the

MySQL instance runs. A remote cloning operation transfers cloned data over the network from a donor

MySQL server instance to the recipient server or node where the cloning operation was initiated.

The clone plugin supports replication. In addition to cloning data, a cloning operation extracts and

transfers replication coordinates from the donor and applies them on the recipient, which enables

using the clone plugin for provisioning Group Replication members and replication slaves. Using the

clone plugin for provisioning is considerably faster and more efficient than replicating a large number

of transactions. Group Replication members can also be configured to use the clone plugin as an

alternative method of recovery, so that members automatically choose the most efficient way to retrieve

group data from seed members.

For more information, see The Clone Plugin, and Cloning for Distributed Recovery. (WL #9209, WL

#9210, WL #9211, WL #9212, WL #11636, WL #9682)

• Compatibility policies for member versions in groups now consider member's MySQL release version.

Previously, only the minor version was considered. Using the release version means Group Replication

can better maintain replication safety for mixed version groups during group reconfigurations and

upgrade procedures.

The compatibility policies are applied when a member joins the group, either for the first time or following

its upgrade, when a donor is selected for state transfer, and when a primary member election takes

place. Members running MySQL 8.0.16 or earlier take into account only the major version in these

situations. For primary member election, so that all members come to the same decision, members

running MySQL 8.0.17 or later adjust their policies to match members running lower releases if any are

in the group.

In a multi-primary mode group where members running multiple MySQL Server versions are online,

for example during a rolling online upgrade procedure, Group Replication now automatically manages

the read-write and read-only status of members running releases. If a member leaves the group, the

members running the version that is now the lowest are automatically set to read-write mode. When you

change a mixed version group that was running in single-primary mode to run in multi-primary mode,

using the group_replication_switch_to_multi_primary_mode() function, members are set

automatically to read-write or read-only mode depending on their MySQL server versions.

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MySQL 8.0 Release Notes

These improved compatibility policies influence the behavior of group members during an online upgrade

procedure from one patch version to another, in the same ways as the behavior during upgrades from

one major version to another was influenced previously. For a multi-primary mode group, the number

of members in read-write mode is reduced during the upgrade procedure; their read-write status is now

handled automaticaly when the upgrade is otherwise complete. For a single-primary mode group, if you

want the primary to remain as the primary, it must be upgraded last. (WL #12826)

• Data that is held in the binary log transaction and statement caches during a transaction is in

unencrypted format in the memory buffer that stores the cache. The data is written to a temporary file

on disk if it exceeds the space available in the memory buffer. From MySQL 8.0.17, when binary log

encryption is active on the server (binlog_encryption=ON), the temporary files used for the binary

log cache are now encrypted using AES-CTR (AES Counter mode) for stream encryption. Because the

temporary files are volatile and tied to a single process, they are encrypted using single-tier encryption,

using a randomly generated file password and initialization vector that exist only in memory and are

never stored on disk or in the keyring. After each transaction is committed, the binary log cache is reset:

the memory buffer is cleared, any temporary file used to hold the binary log cache is truncated, and a

new file password and initialization vector are randomly generated for use with the next transaction. This

reset also takes place when the server is restarted after a normal shutdown or an unexpected halt. (WL

#12079)

• An incomplete SQL predicate has the form WHERE value, in which value is a column name or

constant expression and no comparison operator is used. MySQL now rewrites any predicate of this type

internally as WHERE value <> 0 during the contextualization phase, so that the query resolver, query

optimizer, and query executor need work only with complete predicates. The principal visible effect of

this change is that, for Boolean values, EXPLAIN output now shows true and false, rather than 1 and

0. (WL #12358)

• InnoDB parallel read thread performance for large data sets was improved through better utilization

of read threads, through a reduction in read thread I/O for prefetch activity that occurs during parallel

scans, and through support for parallel scanning of partitions.

The parallel read thread feature is controlled by the innodb_parallel_read_threads variable. The

maximum setting is now 256, which is the total number of threads for all client connections. If the thread

limit is reached, connections fall back to using a single thread. (WL #12978)

• mysqlbinlog now supports the --compress (or -C) option to enable compression in the client/server

protocol. (WL #2726)

Bugs Fixed

• NDB Cluster: Compile times for NDB Cluster using the included compile_cluster build script have

been improved by removing options for software components not strictly necessary for running MySQL

Cluster. (Bug #29355872)

• NDB Cluster: Attempting to change an NDB table's column properties (such as COLUMN_FORMAT) using

ALTER TABLE ALGORITHM=INPLACE was rejected, which is correct behavior, but which raised a

misleading error message. (Bug #28929906, Bug #27645777)

• InnoDB: A failure occurred when attempting to kill a process that was executing a row count. (Bug

#29939617)

• InnoDB: Due to a regression introduced in MySQL 8.0.14, in-place upgrade on a case sensitive file

system from MySQL 5.7 or a MySQL 8.0 release prior to MySQL 8.0.14 to MySQL 8.0.16 failed for

instances with partitioned tables and lower_case_table_names=1. The failure was caused by a

case mismatch issue related to partitioned table file names. The fix that introduced the regression was

314

MySQL 8.0 Release Notes

reverted, which permits upgrades to MySQL 8.0.17 from MySQL 5.7 or MySQL 8.0 releases prior to

MySQL 8.0.14 to function as normal. However, the regression is still present in the MySQL 8.0.14,

8.0.15, and 8.0.16 releases.

In-place upgrade on a case sensitive file system from MySQL 8.0.14, 8.0.15, or 8.0.16 to MySQL 8.0.17

fails with the following error when starting the server after upgrading binaries or packages to MySQL

8.0.17 if partitioned tables are present and lower_case_table_names=1:

Upgrading from server version version_number with

partitioned tables and lower_case_table_names == 1 on a case sensitive file

system may cause issues, and is therefore prohibited. To upgrade anyway,

restart the new server version with the command line option 'upgrade=FORCE'.

When upgrade is completed, please execute 'RENAME TABLE part_table_name

TO new_table_name; RENAME TABLE new_table_name

TO part_table_name;' for each of the partitioned tables.

Please see the documentation for further information.

If you encounter this error when upgrading to MySQL 8.0.17, perform the following workaround:

1. Restart the server with --upgrade=FORCE to force the upgrade operation to proceed.

2. Identify partitioned table file names with lowercase partition name delimiters (#p# or #sp#):

SELECT FILE_NAME FROM INFORMATION_SCHEMA.FILES

WHERE FILE_NAME LIKE '%#p#%' OR FILE_NAME LIKE '%#sp#%';

3. For each file identified, rename the associated table using a temporary name, then rename the table

back to its original name.

mysql> RENAME TABLE table_name TO temporary_table_name;

mysql> RENAME TABLE temporary_table_name TO table_name;

4. Verify that there are no partitioned table file names with lowercase partition name delimiters (an

empty result set should be returned).

mysql> SELECT FILE_NAME FROM INFORMATION_SCHEMA.FILES

-> WHERE FILE_NAME LIKE '%#p#%' OR FILE_NAME LIKE '%#sp#%';

Empty set (0.00 sec)

5. Run ANALYZE TABLE on each renamed table to update the optimizer statistics in the

mysql.innodb_index_stats and mysql.innodb_table_stats tables.

Because of the regression still present in the MySQL 8.0.14, 8.0.15, and 8.0.16 releases, importing

partitioned tables from MySQL 8.0.14, 8.0.15, or 8.0.16 to MySQL 8.0.17 is not supported on case

sensitive file systems where lower_case_table_names=1. Attempting to do so results in a

“Tablespace is missing for table” error. (Bug #29823032, Bug #29917793, Bug #95834)

References: This issue is a regression of: Bug #26925260.

• InnoDB: lock_sys mutex contention caused by lock-wait functions (lock_wait_suspend_thread()

and lock_wait_table_release_slot()) was reduced. (Bug #29814339)

• InnoDB: The fseg_n_reserved_pages_low() function, which determines the number of pages

reserved by a segment, did not validate results read from the segment inode. (Bug #29761998)

• InnoDB: Creation of the transaction rollback list (hit_list) was decoupled from lock acquisition calls

(lock_rec_lock calls) to permit the use of different latching schemes. (Bug #29753800)

• InnoDB: Disabling Performance Schema consumers caused an ALTER TABLESPACE ...

ENCRYPTION operation to assert. (Bug #29646974, Bug #95005)

315

MySQL 8.0 Release Notes

• InnoDB: Error messages were revised to remove references to .frm files, which are not used in MySQL

8.0. (Bug #29639655)

• InnoDB: It was possible for a background thread to check the encryption status of an undo tablespace

before the undo tablespace was fully initialized and the encryption flag set. (Bug #29600309)

• InnoDB: A table name parsing function call returned false when parsing serialized dictionary information

(SDI) tables names, which are not formatted to include a database name. The buffer that holds the

database name remained uninitialized, causing Valgrind errors. (Bug #29550527)

• InnoDB: The space reserved in the mini-transaction (mtr) log buffer for dynamic metadata logging was

insufficient. (Bug #29524260)

• InnoDB: Inaccuracies in the Contention-Aware Transaction Scheduling (CATS) implementation raised a

signed integer overflow error in an UBSan build of MySQL. (Bug #29508517, Bug #91959)

• InnoDB: Insufficient memory barriers in the rw-lock implementation caused deadlocks on ARM.

Thanks to Yibo Cai from Arm Technology for the contribution. (Bug #29508001, Bug #94699)

• InnoDB: The INFORMATION_SCHEMA.INNODB_TABLESPACES ENCRYPTION column was not updated

after enabling undo tablespace encryption. (Bug #29492911, Bug #94665)

• InnoDB: A relocated table could not be accessed due to incorrect parsing of a schema or table name

that included a forward slash character (/), which the server incorrectly interpreted as a directory

separator. (Bug #29492113)

• InnoDB: Various fixes and revisions were applied to the InnoDB memcached source code. (Bug

#29485891)

• InnoDB: To enable global access, the value of innodb_directories variable is now stored internally

as a global variable instead of a static variable. (Bug #29471990)

• InnoDB: In debug builds, the thd_innodb_tmpdir() function did not accept a NULL argument. (Bug

#29471846)

• InnoDB: A subtraction operation in the file space allocation code incorrectly stored the result as an

unsigned variable, which raised an assertion failure. (Bug #29466680)

• InnoDB: After moving or deleting default undo tablespaces and restarting the server with a new

innodb_undo_directory value, MySQL recreated the undo tablespaces in the new location but failed

to update the undo directory path in the data dictionary. (Bug #29461900)

• InnoDB: A previously freed LOB page was accessed while rolling back a transaction during recovery.

(Bug #29440408)

• InnoDB: A request was issued during recovery to read pages into the buffer pool when there were no

pages to be read. A check was added to avoid the unnecessary read request. (Bug #29440208)

• InnoDB: A regression introduced in MySQL 8.0.14 caused a “Invalid (old?) table or database name”

error when creating a partitioned table on a MySQL instance with lower_case_table_names=1. The

change that caused the regression has been reverted. (Bug #29426720, Bug #94519)

References: This issue is a regression of: Bug #26925260.

• InnoDB: A FULLTEXT index table created in MySQL 5.6 in a database with a hyphen in its name caused

a startup failure after upgrading from MySQL 5.7 to MySQL 8.0. Tablespace file paths for FULLTEXT

auxiliary tables were not found in the data dictionary, and the hyphen in the database name was not

handled correctly in subsequently generated file paths. (Bug #29411899, Bug #94431)

316

MySQL 8.0 Release Notes

• InnoDB: There was potential for data loss to occur if the redo log was not logically empty and comprised

a single block, and the server exited during recovery after an insert buffer merge generated new redo

records but before the new records could be flushed to disk. (Bug #29411832, Bug #94448)

• InnoDB: InnoDB returned an unknown generic error when attempting to create a tablespace for

which the path and file name exceeded the MAX_PATH limit on Windows. InnoDB now returns a more

meaningful error. (Bug #29341634)

• InnoDB: An undo tablespace file was not found after being moved to a different directory. (Bug

#29328158)

• InnoDB: The server failed to start with an innodb_buffer_pool_size=default setting. The default

value was not checked for compatibility with dependent system variable settings. (Bug #29267814, Bug

#94065)

• InnoDB: The CREATE TABLESPACE ... ADD DATAFILE clause no longer permits circular directory

references. For example, the circular directory reference (/../) in the following statement is not

permitted:

CREATE TABLESPACE ts1 ADD DATAFILE ts1.ibd 'any_directory/../ts1.ibd';

An exception to this restriction exists on Linux, where a circular directory reference is permitted if the

preceding directory is a symbolic link. For example, the data file path in the example above is permitted if

any_directory is a symbolic link. (It is still permitted for data file paths to begin with '../'.)

To avoid upgrade issues, remove any circular directory references from tablespace data file

paths before upgrading to MySQL 8.0.17 or higher. To inspect tablespace paths, query the

INFORMATION_SCHEMA.INNODB_DATAFILES table. (Bug #29157265)

• InnoDB: Manually changing the system time while the MySQL server was running caused page cleaner

thread delays. (Bug #29138644, Bug #93708)

• InnoDB: UPDATE statements did not always disable semi-consistent reads properly when encountering

errors, which could lead to assertion errors in debug mode. (Bug #29047894)

• InnoDB: When purging a deleted row, the logic that governs lock inheritance did not correctly determine

the type of lock that should be inherited to satisfy constraint checks by active transactions. (Bug

#29004362)

• InnoDB: An unnecessary read lock was taken on implicitly opened data dictionary tables when

executing a prepared statement in LOCK TABLES mode. (Bug #28875646)

• InnoDB: During log application, after an OPTIMIZE TABLE operation, InnoDB did not populate virtual

columns before checking for virtual column index updates. (Bug #28834208)

• InnoDB: An operation that copied data from the clustered index was performed incorrectly, causing

spatial indexes to use spatial rows with stale pointers to the clustered index. (Bug #28758961)

• InnoDB: An INSERT operation involving a generated virtual BLOB column resulted a secondary index

being updated with an incorrect value. (Bug #28652826)

• InnoDB: Configuring innodb_data_file_path and innodb_temp_data_file_path using SET

PERSIST_ONLY = default incorrectly set the variable values to NULL. (Bug #28590014)

• InnoDB: A CREATE TABLE ... REPLACE SELECT operation raised a

lock_rec_get_rec_not_gap(lock) assertion failure. The operation set a flag on the transaction

object indicating that a REPLACE operation was requested, but did not clear the flag before updating

dependent views, causing a subsequent INSERT operation to be interpreted as a REPLACE operation,

leading to the wrong row locks being taken. (Bug #28523025, Bug #92068)

317

MySQL 8.0 Release Notes

• InnoDB: With super_read_only enabled, an attempted RENAME TABLE operation on a temporary

table raised an assertion instead of returning an error. (Bug #28490368, Bug #91975)

• InnoDB: Valgrind errors were reported due to uninitialized bytes read during a virtual index prefix

search. (Bug #28184025)

• InnoDB: InnoDB initialization failed when attempting to create an system tablespace greater than 2GB

in size. (Bug #27538464)

• InnoDB: A full-text cache lock taken when data is synchronized was not released if the full-text cache

size exceeded the full-text cache size limit. (Bug #25289359)

• InnoDB: The INNODB_METRICS metadata_table_reference_count counter reported a negative

value. (Bug #20584149, Bug #75966)

• InnoDB: Client sessions using different auto_increment_increment values while performing

concurrent insert operations could cause a duplicate key error. (Bug #15851528, Bug #67526)

References: Reverted patches: Bug #14049391, Bug #65225.

• Partitioning: For partitioned tables, an ALTER TABLE statement could cause incorrect query results

under these conditions:

• The statement swapped columns by renaming them, either directly with RENAME COLUMN or by

replacement with DROP COLUMN/ADD COLUMN.

• A swapped column was used in a partitioning expression.

• The alteration was performed as an in-place operation that did not redistribute rows between

partitions.

Such column renames are now prohibited unless the same ALTER TABLE statement satisfies one of

these conditions:

• The statement makes the table nonpartitioned.

• The statement redefines the table partitioning or partitioning expression (which causes a table rebuild

that redistributes rows). This enables supporting existing scenarios in which partitioning expressions

are updated to follow column renaming.

• Partitioning is specified using PARTITION BY KEY() with an empty column list. This partitions using

the primary key, which tracks column renaming.

(Bug #29541665, Bug #94792)

• Partitioning: ALTER TABLE ... EXCHANGE PARTITION failed with the error Non matching

attribute 'ROW_FORMAT' between partition and table when the partitioned table had

partitions using different row formats, even when the partition to be exchanged used the same row

format as the non-partitioned table. (Bug #28687608)

• Replication: When events generated by one MySQL server instance were written to the binary log

of another instance, the second server implicitly assumed that the first server supported the same

number of binary log event types as itself. Where this was not the case, the event header was handled

incorrectly. The issue has now been fixed. Thanks to Facebook for the contribution. (Bug #29417234,

Bug #94500)

• Replication: If a LOCK INSTANCE FOR BACKUP statement was used to acquire an instance-level

backup lock, then a STOP SLAVE statement was issued, a deadlock could be created with the SQL

318

MySQL 8.0 Release Notes

thread waiting on the backup lock and the STOP SLAVE statement waiting on the SQL thread to

complete its current action. To prevent this situation, the STOP SLAVE process now tries to acquire the

backup lock before proceeding, and returns an error if the lock cannot be acquired. (Bug #29386503,

Bug #93649)

• Replication: From MySQL 8.0.13, if any replication channel has open temporary tables, the

binary logging format cannot be changed using SET @@global.binlog_format or SET

@@persist.binlog_format. Previously, if this operation was attempted after the new restriction

was implemented, the wrong error message was returned to the client (referencing a running replication

channel applier as the issue, rather than an open temporary table). The appropriate error message is

now returned. (Bug #29370024, Bug #94340)

• Replication: Binary log checksums were handled incorrectly when de-serializing a format description

event. (Bug #29355110)

• Replication: With row-based replication in use, when the replication applier thread unpacked a row

change event, index values for any functional indexes were calculated for both the “before” image and

the “after” image. In the case of the “before” image, the values were not necessary. This calculation has

therefore been removed for the before image in order to optimize row unpacking. (Bug #29304076)

• Replication: When a MEMORY table is implicitly deleted on a master following a server restart, the

master writes a DELETE statement to the binary log so that slaves also empty the table. This generated

event now includes a comment in the binary log so that the reason for the DELETE statement is easy to

identify. Thanks to Daniël van Eeden for the contribution. (Bug #29157796, Bug #93771)

• Replication: If an invalid starting offset was provided in a SHOW BINLOG EVENTS FROM statement,

the invalid offset was returned in place of the correct starting position for the first returned event. (Bug

#29039732, Bug #93544)

• Replication: Replication could stop with a “record not found” error when the

value INDEX_SCAN,HASH_SCAN (the default in MySQL 8.0) was set for the

slave_rows_search_algorithms system variable, and an update event contained two updates to

the same row in a table that did not have a unique key, meaning that the hash scan was used. In this

situation, the second update was missed by the hash scan due to the row change. Now, after updating

a row, the hash scan operation searches for the updated row in the hash map, and applies any further

update.

When the value TABLE_SCAN,HASH_SCAN is set for the slave_rows_search_algorithms system

variable, so that the search cannot use an index, the “record not found” error can occur in the above

situation whether or not the table has a unique key. Also, with this setting, when a hash scan is used

on a table that has a unique key, in the case of an update event containing two row updates that

are order-dependent, the updates might be applied out of order, causing replication to stop with a

duplicate key error. To avoid these issues, the documentation has been updated to state that the value

TABLE_SCAN,HASH_SCAN should not be used. (Bug #28846386)

• Replication: When binary logging is enabled on a replication slave, the combination of the --

replicate-same-server-id and --log-slave-updates options on the slave can cause infinite

loops in replication if the server is part of a circular replication topology. (In MySQL 8.0, binary logging is

enabled by default, and slave update logging is the default when binary logging is enabled.) However,

the use of global transaction identifiers (GTIDs) prevents this situation by skipping the execution

of transactions that have already been applied. The restriction on this combination of options has

therefore now been removed when gtid_mode=ON is set. With any other GTID mode, the server still

does not start with this combination of options. As a safeguard against creating the problem situation

after the server has started, you now cannot change the GTID mode to anything other than ON on a

running server that has this combination of options set. Thanks to Facebook for the contribution. (Bug

#28782370, Bug #92754)

319

MySQL 8.0 Release Notes

• Replication: In query log events in the binary log, the thread ID used for the execution of DROP TABLE

and DELETE statements was identified incorrectly or not at all. On a multi-threaded replication slave,

where temporary tables were involved (which require the correct thread ID as they are session specific),

this omission resulted in errors when using mysqlbinlog to replay the binary log for point-in-time

recovery. The thread ID is now set correctly. (Bug #28642318, Bug #92398)

• Replication: When a trigger invoked an INSERT or UPDATE statement that set a column to its default

value, and the DEFAULT expression of that column was non-deterministic, the expected warning was not

raised when the trigger fired under statement-based replication. In addition, if the binary logging format

was MIXED, the non-deterministic statements were logged in the format used for STATEMENT rather than

that used for ROW.

The statement that causes the trigger to fire checks at resolution time whether any of the triggered

statements are non-deterministic. At this time, the triggered statements have been parsed, but not

resolved, so the only check that can be performed is whether the triggered statements directly reference

any non-deterministic operators. When the non-deterministic operator is used by a DEFAULT expression,

the non-determinism is not visible until the triggered statement has been resolved, which happens when

the trigger fires.

This is fixed by adding an extra check when determining the logging format, where a statement

is flagged as unsafe if any of its substatements can write to a table that has a column with a non-

deterministic DEFAULT expression. Since it is not yet known at this point whether the DEFAULT

expression will be used by the substatement, this check flags the statement as unsafe even if the

substatement provides an explicit value for the column with a non-deterministic DEFAULT expression.

(Bug #28297486)

• Replication: When a slave server logs master status and connection information to a

table (master_info_repository=TABLE), which is the default in MySQL 8.0, the

mysql.slave_master_info table was not being updated on shutdown if the server was in super read

only mode (super_read_only=ON). No error was written to the error log at this time, but replication

failed after server startup because the master log file and master log position information was out of

date. The thread that updates the master info log at shutdown is now excluded from read-only checks

like other replication threads are, so it can update the table even if the server is in super read only mode.

Error handling for a slave that is shutting down has also been improved so that any failure to write to the

slave status logs results in an error in the error log. (Bug #27675107, Bug #89987)

• Replication: If a replication slave tried to connect to the master using an incorrect user name, host,

or port, the original error message specifying the reason for the connection failure was overwritten

with a generic message. The issue has now been corrected in the output from the SHOW SLAVE

STATUS statement and in the Performance Schema table replication_connection_status. (Bug

#26580064)

• Group Replication: When message fragmentation is in use for large Group Replication messages

(which is available, and the default, from MySQL 8.0.16), if a fragmented message sent by the group

member with the highest node identifier in XCom was partially delivered, and one or more members

then left the group prior to the delivery of the remaining message fragments, reassembly of the message

caused Group Replication to stop working. The loss of members meant that the node identifier of the

original sender was no longer valid in the new view of the group. To correct this issue, reassembly of

fragmented messages now uses the delivery information from the last fragment that was delivered,

which reflects the new situation after the view change, rather than from the first fragment that was

delivered, which reflects the old situation before the view change. (Bug #29716639)

• Group Replication: The error message that is issued for a discrepancy between the

number of group members and the auto-increment interval incorrectly referred to the

group_replication_auto_increment_increment system variable, instead of the

auto_increment_increment system variable. The value of auto_increment_increment is

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MySQL 8.0 Release Notes

changed to the value specified by group_replication_auto_increment_increment when

Group Replication starts, but only if auto_increment_increment and auto_increment_offset

have their default values, and from MySQL 8.0, only in multi-primary mode. The value of

auto_increment_increment was always the value that was checked for the error message, and it

has now been corrected to give the accurate system variable name. (Bug #29542425)

• Group Replication: Group Replication cannot be started following a MySQL Server upgrade that uses

the MINIMAL option (--upgrade=MINIMAL), which does not upgrade system tables on which this

feature depends. Previously, in this situation, the server waited indefinitely for Group Replication to

start. This is now handled correctly by unblocking the waiting thread and issuing the expected error

ER_GRP_RPL_START_GRP_RPL_FAILED. (Bug #29423358, Bug #94515)

• Group Replication: A change in the processing of suspicions by a member that is leaving the group

meant that recovery failed because due to a circular dependency between the recovery failure and the

view change notification. Now, if an error makes recovery impossible, the Group Communication System

handles this as follows:

1. The member leaves the group

2. the view change is applied

3. The recovery thread is terminated.

(Bug #29417365, Bug #29628909)

• Group Replication: In Group Replication, joining members could wrongly identify themselves as

incompatible with an existing replication group even if there were members at the same version already

in the group, because they checked against all other members, including the member at the highest

version. Joining members also included their own version in the compatibility check. Now, joining

members only compare themselves with the existing group member at the lowest version, and do not

count their own version. (Bug #29390946, Bug #94429)

• Group Replication: Functions for configuring an online group sometimes did not return an error when

an issue arose during execution. These functions also now check whether the Group Replication plugin

is stopping before they start to initialize. (Bug #28978767, Bug #93372)

• Group Replication: The XCom group communication engine did not handle out of memory errors in

an appropriate way. If memory could not be allocated to make a copy of the payload for a message,

an error was logged but the message was still sent, with a null payload. The Group Communication

System (GCS) on the receiving member discarded the message as empty, and the XCom instance

on the receiving member accepted this action and did not retry, resulting in the message effectively

being skipped. This caused the GTID set on the receiving member to diverge from the group, leading to

replication errors. XCom now terminates gracefully if it experiences an out of memory error, so that this

situation cannot occur. (Bug #28702320)

321

MySQL 8.0 Release Notes

• macOS: For macOS installations performed using DMG packages, launchd operation was problematic:

• Previously, SHUTDOWN caused a restart if MySQL was configured to start at boot time via the

preference pane. This also affected the mysqladmin shutdown command. Server shutdown

initiated in these ways now works correctly.

• Previously, RESTART did not work. It now works correctly.

• Previously, unexpected server exits did not cause automatic restart if the server was not configured to

start at boot time. Exits with a nonzero exit status now cause a restart regardless of boot-time startup

configuration.

(Bug #29789857)

• JSON: MAX() and MIN() used on expressions returning JSON data sometimes compared these values

as strings rather than JSON values, which caused unexpected results; this was particularly evident when

the JSON values were numbers.

This was due to the fact that GROUP BY when using temporary tables with indexes did not compare

JSON values correctly. (Bug #28947381)

• JSON: JSON_TABLE() returned the error Unknown database '' when executed from a stored

function.

The root cause of this issue was that, when merging tables from a select that used JSON_TABLE(),

MySQL checked only for derived tables. This caused the result table returned by JSON_TABLE() to

be noted as a regular table, so that when attempting to execute the query, the server failed to open it.

Now MySQL checks whether the table to be added is not an internal table, that is, not a derived table, a

JSON_TABLE() result table, or a reference to a recursive common table expression. (Bug #92976, Bug

#28851656)

• The WITH ADMIN option for GRANT statements sometimes was not handled properly. (Bug #29900772)

• Some foreign key error messages could differ depending on whether the user had the GRANT OPTION

privilege. (Bug #29868844)

• During upgrade operations, upgrades of the help tables failed if autocommit was disabled. (Bug

#29865428, Bug #95620)

• Fetching dynamically allocated dictionary objects into a vector during upgrade while operating with a

small table_open_cache size caused data dictionary tables to be reopened, triggering a garbage

collection mechanism that incorrectly freed collected objects. Subsequent attempts to access the freed

objects caused a segmentation fault. (Bug #29823053)

• For upgrades from MySQL 5.7 to 8.0, the upgrade process did not close the

innodb_*_stats_backup57.ibd files in the mysql system schema before removing them, resulting

in errors for subsequent file system operations. (Bug #29791350)

• mysqld --initialize would fail if the file system was mounted at the data directory mount point and

a lost+found file or directory was present. The lost+found file or directory is now ignored during

data directory initialization. (Bug #29780434)

• MySQL upgrades did not assign the AUDIT_ADMIN privilege to accounts that had the SUPER privilege.

(Bug #29770732)

• The REGEXP_REPLACE() function did not handle empty strings correctly in all cases. (Bug #29763554)

322

MySQL 8.0 Release Notes

• An overly strict assertion could be raised during sorting of stored program local objects. (Bug

#29759547, Bug #95062)

• The group_replication_get_communication_protocol() function, which is used to query

the group's communication protocol version, failed if any group members were in RECOVERING state,

which was an unnecessary restriction. The function can now be used provided that the member where it

runs is in ONLINE state, and is in contact with a majority of the group. (Bug #29754967, Bug #95306)

• For some arguments to REPEAT(), maximum length calculations were not always handled correctly.

(Bug #29739778)

• UPDATE statements for tables with CHECK constraints could fail to enforce the constraints. (Bug

#29706621, Bug #95189)

• For installation from RPM or Debian packages, if the mysql_upgrade_info file in the data directory

is found to exist but is owned by root, it is now changed to the same owner as the data directory. The

correct SELinux file context is also set. (Bug #29704041)

• Installing from RPM packages could result in an error log with incorrect permissions. (Bug #29702462)

• A replication group member that was unable to contact a majority of the group before the

group_replication_unreachable_majority_timeout setting was reached, and then exhausted

the number of auto-rejoin attempts specified by the group_replication_autorejoin_tries

system variable without successfully rejoining, was sometimes unable to carry out the action specified by

the group_replication_exit_state_action system variable. The member tries to carry out the

action using the current session, which sometimes failed. The member now ensures that the session is

initialized before using it to connect to the server to carry out the exit state action. (Bug #29698754, Bug

#95151)

• When performing a upgrade, server-side SQL statements that update data dictionary tables used a non-

default collation, causing an upgrade failure. (Bug #29697670, Bug #95144)

• Starting the server with --skip-grant-tables and invoking ROLES_GRAPHML() could lead to a

server exit. (Bug #29681975)

• SELECT DISTINCT when using fixed-length keys did not deduplicate records properly in all cases. (Bug

#29628699)

• Client programs that used asynchronous C API functions could access freed memory after occurrence of

a fatal error such as connection failure or receipt of a too-large packet. (Bug #29596244)

• The ST_AsWKB() function could fail to perform proper error checking. (Bug #29594287)

• For failed data directory initialization, the server could produce a message indicating that the directory

could be removed, even if the server itself did not create it. The message now indicates that only files in

the directory created by the server can be removed. (Bug #29594082, Bug #94880)

• In MySQL 8.0, the keyring_encypted_file plugin could not read a file created by a MySQL 5.7

keyring_encypted_file plugin. (Bug #29588345)

• In builds with Undefined Behavior Sanitizer enabled, runtime errors occurred in my_strtoll10_mb2()

and val_decimal(). (Bug #29585648, Bug #29594951)

• Some diagnostics produced by the server while checking grant table structure at startup were written as

errors rather than warnings. (Bug #29558993)

• The comp_err utility could read uninitialized data. (Bug #29550442)

• Enabling audit log encryption could cause a server exit. (Bug #29549327)

323

MySQL 8.0 Release Notes

• RPM package obsoletes were updated to enable successful upgrades from MariaDB to MySQL on EL8.

(Bug #29549127, Bug #29623146, Bug #29623201, Bug #29659212)

• In a join of the form LEFT JOIN t ON column WHERE t.x=0 IS NOT TRUE, MySQL evaluated

IS NOT TRUE as FALSE for a NULL argument in a null-complemented row, and rejected it. This caused

an invalid conversion of the left join to an inner join, so that there were missing rows in the result. The

same issue affected joins of the same form but having IS NOT FALSE in the WHERE condition. (Bug

#29540230)

• If the read_only system variable was enabled, its value improperly was applied against updates to the

character set and collation data dictionary tables. (Bug #29533590, Bug #94769)

• The functions STATEMENT_DIGEST() and STATEMENT_DIGEST_TEXT() used

character_set_client while parsing the function's argument instead of the character set of the

argument. (Bug #29526571)

• The server now tracks data dictionary upgrades to ensure that INFORMATION_SCHEMA views are

recreated when data dictionary tables are changed. (Bug #29513265)

• Execution of STATEMENT_DIGEST() or STATEMENT_DIGEST_TEXT() could have unintended side

effects on data in the performance_schema.events_statements_summary_by_digest table.

(Bug #29512067)

• The implementation for CREATE TABLE did not provide the table a clearly defined starting cursor when

no seeks or writes were performed. (Bug #29511318)

• When a table is const optimized, any predicate terms in the join's ON condition should also be

evaluated on the tables marked as const to make sure that the row qualifies for the ON condition.

The optimizer failed to mark a table as const when it was handled as having an impossible ON

condition, in which case the resulting row from this table is a NULL extended row.

This fix sets the const_table flag for the table and marks the row as a NULL row. It also changes

EXPLAIN output for a table optimized as having an impossible ON condition, where the resulting NULL

values from this row are now propagated into the rows column values, as with other const rows. (Bug

#29493830)

• A query containing an IN subquery could return superfluous rows when optimizer_switch did not

include firstmatch=on. (Bug #29493026)

• RPM package detection of whether the operating system is EL6 or EL7 failed on some systems. (Bug

#29492896)

• SQL layer validation of keys stored in storage-engine-private data fields in the data dictionary was

disabled to permit storage engines to add new keys as required. Storage engines are now responsible

for key validation. (Bug #29491593, Bug #94667)

• Checks for NULL returned an incorrect result for some expressions comparing rows. (Bug #29491083)

• When optimizing a table join which included ORDER BY and LIMIT, the optimizer modified the select

limit on the first table by taking the fanout of the entire join into consideration. The fanout was calculated

using the filter_effect for each table, which can be set to COND_FILTER_STALE (-1) to indicate

an unknown value. This value was not actually checked for by the optimizer, which could result in a

negative fanout, leading to an unexpected rows value of 0 in the EXPLAIN output for the query.

Now COND_FILTER_STALE (filter_effect unknown) is specifically checked for, and, if it is found,

the fanout is also assumed to be unknown, and the number of rows to be selected from the first table is

thus not modified by the fanout for the entire join. (Bug #29487181, Bug #29531472)

324

MySQL 8.0 Release Notes

• An implicit assumption was made for the LEAST() and GREATEST() functions that arguments to either

of these were all signed or all unsigned values. (Bug #29467577)

• Some arguments for the BIT_OR() function were not always handled correctly. (Bug #29459549)

• For debug builds, mishandling of the user_attributes column of the mysql.user system table

could cause a server exit. (Bug #29451897)

• MySQL Cluster-specific Debian debug packages had an incorrect path to the debug symbols. (Bug

#29446947)

• Compilation failure occurred when building with Protobuf 3.7.0. (Bug #29436791, Bug #94543)

• On Debian and Ubuntu, MySQL packages did not enable mysql.service after upgrades from native

MySQL packages. (Bug #29435592)

• The server did not properly close shared-memory connections when an error occurred, which could

result in unexpected server behavior. (Bug #29435426)

• The internal JOIN_CACHE::join_record() method attempted to leave all tables on which it operated

in the same state with regard to the has_row and null_row flags by saving the state upon entry and

restoring the appropriate flags when on completion.

The issue addressed here arose after these flags had been restored, due to the fact that

restore_last_record() was also called to restore any records that had been processed, which

could lead to setting back a null_row flag that had just been restored based on the saved state. This

is fixed by calling restore_last_record() before the saved states are restored, rather than after,

as well as making sure that reset_null_row() is also called if the saved state indicates that the

null_row flag was not set at the beginning. (Bug #29435133)

• Some ALTER TABLE statements using ADD COLUMN did not perform as expected. (Bug #29428288)

References: This issue is a regression of: Bug #28333657.

• An incorrect error message was reported during upgrade from MySQL 5.7 to MySQL 8.0

when a non-natively partitioned table was encountered. The error message referenced the -

DWITH_PARTITION_STORAGE_ENGINE CMake build option, which is not supported in MySQL 8.0. (Bug

#29426632, Bug #94518)

• At startup, the server did not properly check the length of user and host names in persisted variables.

(Bug #29420141)

• The parser could leak memory for certain multiple-statement queries. (Bug #29419820)

• Installing MySQL on EL8 from RPM packages caused a conflict with the installed MeCab library. (Bug

#29413115)

• On FreeBSD, stack traces dumped for fatal signals did not work correctly. (Bug #29408039)

• With the derived_merge switch disabled in the value of the optimizer_switch system variable,

information retrieved for base tables from INFORMATION_SCHEMA.TABLES displayed inappropriate

information in the TABLE_COMMENT column. (Bug #29406053, Bug #94468)

• In certain cases, use of ORDER BY in a subselect did not produce the expected result. (Bug #29402943)

• ROLLUP queries with wildcards (and probably also certain other wildcard queries) could cause assertion

errors. (Bug #29396628)

325

MySQL 8.0 Release Notes

• A condition inside an IF function having a constant evaluating to TRUE was not always handled

correctly. (Bug #29394833)

• A code change in MySQL 8.0.13 related to full-text search caused a segmentation fault. (Bug

#29393105)

• mysqlpump did not check whether the argument to --result-file was opened correctly and exited

unexpectedly if an error occurred. (Bug #29389828)

• In queries without joins, batch mode was not enabled until after initialization was complete, so that

OFFSET rows were read outside of batch mode. This negated any performance benefit to be had from

batch mode. (Bug #29373972)

• When renaming a functional index, the server did not check for a possible duplicate index name. (Bug

#29360763)

• The system variable service did not check the input buffer size for some operations. (Bug #29343505)

• For mysql system schema dumps, mysqlpump dumped certain tables by row rather than as account-

management statements. (Bug #29343073)

• Creation of a functional index on a UNION subquery led to an assertion in debug builds. (Bug

#29342245)

• Non-numeric arguments to AVG() were not always handled correctly. (Bug #29321764)

• Result sets with a very large number of columns could cause client programs to use all available

memory. Now the client library allocates no more than max_allowed_packet bytes for result set

metadata, returning an out-of-memory error if this limit is exceeded. If this error occurs, it is fatal and the

client should disconnect. (Bug #29316814)

• A call to mysql_shutdown() could cause the client to exit when the server and client were from

different MySQL series, due to return packet payload misinterpretation. (Bug #29315393)

• Client programs could fail while reading result set metadata if communicating with the server using the

pre-MySQL 4.1 protocol. (Bug #29304864)

• HANDLER statements did not always work correctly with tables having generated columns. (Bug

#29300049)

• Session-tracking information in the client/server protocol could be mishandled. (Bug #29297652)

• Client programs that used the libmysqlclient C client library could exit upon receipt of an OK packet

containing malformed session-tracking information. (Bug #29297620, Bug #29630735)

• With the PAD_CHAR_TO_FULL_LENGTH SQL mode enabled, password changes failed, with no warning

or error reported. (Bug #29287785)

• Initialization code of loadable functions for the keyring_aws plugin did not properly check whether the

plugin had been initialized. (Bug #29278153)

• Scalar subqueries were not always identified and handled correctly when compared with aggregate or

window functions. (Bug #29276063)

• Ubuntu packages did not disable binary logging for initialization scripts. (Bug #29263771)

• The internal collation map could become corrupted by use of invalid collation names. (Bug #29258979)

• Single-table UPDATE and DELETE statements that used indexed expressions could cause the server to

exit when executed as prepared statements. (Bug #29257254)

326

MySQL 8.0 Release Notes

• The audit_log plugin did not log UNINSTALL PLUGIN audit_log statements. (Bug #29248047)

• MySQL now uses open(O_TMPFILE) whenever applicable when creating a temporary file that is

immediately unlinked. This is more efficient than previously and avoids the small possibility of a race

condition. Thanks to Daniel Black for the contribution. (Bug #29215177, Bug #93937)

• audit_log filtering operations could leak memory. (Bug #29201747)

• The GRANT OPTION privilege could be mishandled in some cases. (Bug #29179334)

• Previously, LIKE comparisons could be incorrect if either of the _ or % SQL wildcard characters was

used as the ESCAPE character. These characters can now be used. (Bug #29175461, Bug #93811)

• The component_sys_variable service could fail to read certain system variables, causing a server

exit. (Bug #29162657)

• Multiple-table UPDATE statements could search for incorrect generated-column values when determining

which row to update. (Bug #29154379)

• If the server was started with Performance Schema parameters that caused an out-of-memory condition,

startup failed. (Bug #29140212, Bug #93726)

• For consistency and compliance with standard SQL, the ISNULL() function is now printed as IS NULL

in warnings generated by EXPLAIN statements. (Bug #29119455)

• Some supplemental Unicode characters could incorrectly be flagged with a warning message as invalid.

(Bug #29110613, Bug #93626)

• For upgrades from MySQL 5.7 to 8.0, the root user was not given all dynamic privileges. (Bug

#29043233)

• When using subpartitioning, table serialized dictionary information (SDI) was not stored in any

tablespace file. (Bug #29020745, Bug #93499)

• Privileges for dropping some Performance Schema tables were checked incorrectly. (Bug #29010031)

• mysqldump failed to wrap SET NAMES utf8mb4 and SET character_set_client = utf8mb4

statements within version-specific comments, which could cause compatibility problems. (Bug

#29007506, Bug #93450)

• For a unique index created on one or more columns defined as NULL, the optimizer failed to handle joins

using that index as eq_ref.

As part of this fix, late NULL filtering is now also performed to avoid treating comparisons with NULL as

potential equality matches. (Bug #28965762, Bug #29337233)

• For debug builds, an assertion could be raised by string comparisons for which the expected and actual

collation differed. (Bug #28960901)

• The server did not handle correctly a subquery which, prior to conversion to a semijoin, contained a

merged derived table or common table expression which in turn had a WHERE clause with an outer

reference against an indexed column. (Bug #28955216)

• A query that employed a derived table which included an ORDER BY was not always handled correctly.

(Bug #28942965)

• When clients were terminated for inactivity exceeding the wait_timeout value, the message written to

the error log was unclear. Now ER_NET_WAIT_ERROR is written, which is more specific about the cause

of the problem. Thanks to Mattias Jonsson for the contribution. (Bug #28940167, Bug #93240)

327

MySQL 8.0 Release Notes

• Concurrent execution of FLUSH PRIVILEGES along with CREATE USER or ALTER USER could cause

the server to stall. (Bug #28937018, Bug #93085)

• CASE statement comparisons that relied on index prefix values could produce incorrect results. (Bug

#28934315, Bug #93215)

• When adjusting the query cost after sort elimination to compensate for sorts that had not been

considered in the original cost estimate, and the estimates could sometimes be too low, or even

negative.

The sort cost is added to the total cost in Optimize_table_order::consider_plan(), and

subtracted from the total cost in JOIN::optimize() if it is found that sorting is not needed.

If consider_plan() finds that sorting is not needed, it does not add the sort cost to the total cost, but

still records a sort cost in JOIN::sort_cost(), and this is set to the sort cost of the candidate plan

considered previously. Later, JOIN::optimize() saw that the JOIN object had an associated sort

cost, and subtracted that cost from the total cost, since it also sees that no sort is needed. Since the sort

cost came from a candidate plan that was not the same as the chosen plan, the estimate was incorrect.

The fix is to make consider_plan() set JOIN::sort_cost to 0 if no sort cost is added to the

total cost, so that the mistaken adjustment of the cost in JOIN::optimize() is not performed. (Bug

#28884359)

• Some GIS code failed to compile under Visual Studio 2017 15.5.6. (Bug #28861188)

References: This issue is a regression of: Bug #28842878.

• Stored generated column values and indexes on virtual generated columns were not correctly updated

after columns on which these generated columns depended were swapped using ALTER TABLE with

RENAME COLUMN or CHANGE COLUMN.

Renaming of base columns for generated columns, generated defaults, and functional indexes is now

prohibited unless the same ALTER TABLE statement satisfies one of these conditions:

• The statement removes the generated column, generated default, or functional index.

• The statement updates the dependent expression in question. This enables supporting existing

scenarios in which generation expressions are updated to follow base column renaming.

Restrictions on dropping columns on which generated columns, generated defaults, or functional indexes

depend were relaxed in a similar way. (Bug #28772251, Bug #92727)

• Base columns were not excluded from index-only access by a generated column. (Bug #28652733)

References: See also: Bug #29664369. This issue is a regression of: Bug #23169112.

• SET PERSIST_ONLY did not properly handle the version_tokens_session system variable. (Bug

#28542569)

• For debug builds, improper error checking for CREATE TABLE statements could cause an assertion to

be raised. (Bug #28490361, Bug #91976)

• MySQL 5.7 supported foreign keys on InnoDB tables with a parent key for which part of the referenced

columns were hidden, but MySQL 8.0 did not. MySQL 8.0 now supports this capability. (Bug #28480149,

Bug #91952)

• INSERT ... ON DUPLICATE KEY UPDATE did not consider privileges granted by active roles. (Bug

#28395115)

328

MySQL 8.0 Release Notes

• For unloaded components, component options specified at startup with a --loose- prefix were not

processed if the component was later loaded at runtime. (Bug #28341329)

• Long passwords solicited interactively by client programs could fail to be null-terminated. (Bug

#28121400)

• When building MySQL, CMake begins the process of downloading Boost by creating a zero-length

tarball in the destination directory, which is removed when the download is complete. If the download

was interrupted or timed out, the presence of this file prevented CMake from attempting to perform the

download the time it was run. Now the zero-length tarball, if present, is removed before the download is

started. (Bug #28089173)

• A thread pool group could be blocked when a thread process tick time exceeded the maximum permitted

value. The tick time now uses a larger data type to permit larger values. (Bug #28072609)

• Privileges were not checked correctly for ALTER USER ... IDENTIFIED WITH ... BY. (Bug

#27923149, Bug #29882299)

• MySQL does not support OpenSSL session tickets, but did not set the SSL_OP_NO_TICKET flag to

inform OpenSSL of that. The flag is now set. (Bug #27655493)

• The audit_null plugin did not properly check for a null event record. (Bug #27638290)

• UpdateXML() did not always free memory properly in certain cases. (Bug #27312862)

• Empty values in the name column of the mysql.plugin system table caused the server to exit during

startup. (Bug #27302459)

• The server did not properly check privileges for CACHE INDEX statements. (Bug #26173827)

• With the thread_pool plugin enabled, the Performance Schema status_by_thread table contained

no data. (Bug #25933891)

• The GRANT OPTION privilege was treated as related to database operations. (Bug #25203933, Bug

#34159579)

• REPAIR TABLE for ARCHIVE tables could result in a server exit. (Bug #23304911)

• If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it

caused the server to hang (or to raise an assertion in debug builds). (Bug #14653594, Bug #23080148,

Bug #27167197)

• Logging to the mysql.slow_log system table could fail when values were to large for table columns.

Now logging proceeds on a best-effort basis, writing what information can be provided. Otherwise, the

row is discarded and a message is written to the error log. (Bug #11748692, Bug #37132)

• A query using WHERE date_column LIKE 'year_value' failed with error 1525 Incorrect DATE

value on Windows platforms. (Bug #95780, Bug #29904751)

References: This issue is a regression of: Bug #29368521.

• A fix for a previous issue caused YEAR values to be treated as unsigned, but this did not allow for

possible negative values arising during calculations involving subtraction, which could lead to data

truncation errors. (Bug #95045, Bug #29668676)

References: This issue is a regression of: Bug #92209, Bug #28562930.

• When working with derived tables with an aggregation which had zero input rows, the results of the

aggregate functions were not properly copied into the temporary table. This caused incorrect results

329

MySQL 8.0 Release Notes

in cases where the derived table was evaluated multiple times, such as when performing a lateral join.

(Bug #94721, Bug #29514504)

• A window without a frame specification inheriting from a window with an ORDER BY yielded an incorrect

result. (Bug #94251, Bug #29328529)

• The results returned by the functions REGEXP_REPLACE() and REGEXP_SUBSTR() used UTF-16

rather than the character set and collation of the expression searched for matches. (Bug #94203, Bug

#29308212)

• A UNION ALL query with SUM(constant) was processed very slowly compared to the same query

using SUM(column) instead. (Bug #93922, Bug #29227464)

• JSON_OBJECTAGG() is non-deterministic in the presence of duplicate keys unless the window has

ordering on the key, which is expected behavior, but a key-value pair that was no longer in the window

frame still appeared in the result. (Bug #93822, Bug #29175262)

• LIMIT was applied before HAVING in queries with subselects. (Bug #93214, Bug #28934388)

References: This issue is a regression of: Bug #25466100.

• A query involving GROUP BY on a TIMESTAMP column resulted in a duplicate entry for key

(ER_DUP_ENTRY) error. This problem arose when TIMESTAMP values were inserted into a table using a

given setting for the time zone and these values were later fetched after the time zone setting had been

changed, such that at least some of the inserted TIMESTAMP values occurred during the hour that the

time changed from standard to daylight time (DST) in the new time zone, during which time the same

TIMESTAMP value can exist twice. Now, when the server would otherwise return the error DUPLICATE

ENTRY FOR KEY 'group_key', if the grouping involves a TIMESTAMP column, it instead raises

the error Grouping on temporal is non-deterministic for time zones having DST.

Please consider switching to UTC for this query.

In addition, it is suggested to set explicit_defaults_for_timestamp to ON as well as one or more

of MODE_NO_ZERO_IN_DATE, MODE_NO_ZERO_DATE, or MODE_INVALID_DATES as part of the server

SQL mode to help avoid this issue. (Bug #90398, Bug #27970159)

Changes in MySQL 8.0.16 (2019-04-25, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• C API Notes

• Character Set Support

• Compilation Notes

• Configuration Notes

• Deprecation and Removal Notes

• Installation Notes

• Packaging Notes

• Parser Notes

• Performance Schema Notes

330

MySQL 8.0 Release Notes

• Plugin Notes

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• sys Schema Notes

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• Previously, users who had the DROP ROLE privilege could use the DROP ROLE statement to drop locked

or unlocked accounts. Now, users who have the DROP ROLE privilege can use DROP ROLE only to

drop accounts that are locked (unlocked accounts are presumably user accounts used to log in to the

server and not just as roles). Users who have the CREATE USER privilege can use DROP ROLE to drop

accounts that are locked or unlocked. (Bug #28953158, Bug #93263)

• Several changes have been made to MySQL account-management capabilities:

• MySQL now incorporates the concept of user account categories, with system and regular users

distinguished according to whether they have the new SYSTEM_USER privilege:

• System users are users who possess the SYSTEM_USER privilege. A system user can perform

operations on both system and regular accounts.

• Regular users are ordinary users who do not possess the SYSTEM_USER privilege. A regular user

can perform operations on regular accounts, but not system accounts.

If a user has the appropriate privileges to perform a given operation on regular accounts,

SYSTEM_USER enables the user to also perform the operation on system accounts. SYSTEM_USER

does not imply any other privilege, so the ability to perform a given account operation remains

predicated on possession of any other required privileges. For example, if a user can grant the

SELECT and UPDATE privileges to regular accounts, then with SYSTEM_USER the user can also grant

SELECT and UPDATE to system accounts.

The distinction between system and regular accounts enables better control over certain account

administration issues by protecting accounts that have the SYSTEM_USER privilege from accounts

that do not have the privilege. For example, the CREATE USER privilege enables not only creation of

new accounts, but modification and removal of existing accounts. Without the system user concept, a

user who has the CREATE USER privilege can modify or drop any existing account, including the root

account. The concept of system user enables restricting modifications to the root account (itself a

system account) so they can be made only by system users. Regular users with the CREATE USER

privilege can still modify or drop existing accounts, but only regular accounts.

Other operational implications of the SYSTEM_USER privilege:

• A session that has the SYSTEM_USER privilege can be killed only by users who have the

SYSTEM_USER privilege, in addition to any other required privileges.

331

MySQL 8.0 Release Notes

• An account that has the SYSTEM_USER privilege can be specified as the DEFINER for a stored

object only by users who have the SYSTEM_USER privilege, in addition to any other required

privileges.

• A role that has the SYSTEM_USER privilege cannot be listed in the value of the mandatory_roles

system variable.

For more information, see Account Categories.

• Previously, it was not possible to grant privileges that apply globally except for certain schemas. This

is now possible if the new partial_revokes system variable is enabled. For example, the following

statements enable an account to select from or insert into any table except those in the mysql system

schema:

SET PERSIST partial_revokes = ON;

GRANT SELECT, INSERT ON *.* TO u1;

REVOKE SELECT, INSERT ON mysql.* FROM u1;

The server records partial revokes by adding a Restrictions attribute to the User_attributes

column of the mysql.user system table. SHOW GRANTS includes REVOKE statements in its output to

indicate partial revokes.

Note

Enabling partial_revokes causes MySQL to treat unescaped _ and %

SQL wildcard characters in schema names as literal characters, just as if they

had been escaped as \_ and \%. Because this changes the interpretation

of privilege assignments, it may be advisable to avoid unescaped wildcard

characters in schema privilege assignments for MySQL installations where

partial_revokes may be enabled.

For more information, see Privilege Restriction Using Partial Revokes.

• The GRANT statement has a new AS user [WITH ROLE] clause that specifies additional information

about the privilege context to use for statement execution. This syntax is visible at the SQL level,

although its primary purpose is to enable uniform replication across all nodes of grantor privilege

restrictions imposed by partial revokes, by causing those restrictions to appear in the binary log.

For more information, see GRANT Statement.

(WL #12098, WL #12364, WL #12820)

C API Notes

• The MySQL C API now supports asynchronous functions for nonblocking communication with the

MySQL server:

• mysql_real_connect_nonblocking()

• mysql_real_query_nonblocking()

• mysql_store_result_nonblocking()

• mysql_next_result_nonblocking()

• mysql_fetch_row_nonblocking()

332

MySQL 8.0 Release Notes

• mysql_free_result_nonblocking()

Each function is the asynchronous counterpart to a synchronous function that has the same name

without a _nonblocking suffix. The synchronous functions block if reads from or writes to the server

connection must wait. The asynchronous functions enable an application to check whether work on the

server connection is ready to proceed. If not, the application can perform other work before checking

again later. See C API Asynchronous Interface. (WL #11381)

Character Set Support

• MySQL now supports a new Chinese collation, utf8mb4_zh_0900_as_cs, for the utf8mb4 Unicode

character set. utf8mb4_zh_0900_as_cs is the first Chinese language-specific collation available for

Unicode in MySQL. This collation is accent sensitive and case sensitive. Its characteristics are similar

to utf8mb4_0900_as_cs except that language-specific rules take precedence where applicable. For

more information, see Unicode Character Sets. (WL #11825)

Compilation Notes

• CMake now causes the build process to link with the llvm lld linker for Clang if it is available and

not explicitly disabled. To disable use of this linker, specify the -DUSE_LD_LLD=OFF option. (Bug

#29264211)

• Builds on EL6 and EL7 now try to use the compiler in devtoolset-8 rather than devtoolset-7. (Bug

#29198846)

• The minimum version of the Boost library for server builds is now 1.69.0. (Bug #29114233)

• The configuration-time check for Visual Studio 2017 was not specific enough. The check for MySQL

compilation now requires at least Visual Studio update 15.8, which is version number 1915. (Bug

#28970895)

• MySQL now can be compiled using C++14. The following minimum version requirements apply for

compiler support:

• GCC 5.3 (Linux)

• Clang 4.0 (FreeBSD)

• XCode 9 (macOS)

• Developer Studio 12.6 (Solaris)

• Visual Studio 2017 (Windows)

(WL #12424)

Configuration Notes

• MySQL configuration now requires a minimum CMake version of 3.4.3. This requires the use of cmake3

rather than cmake on some Red Hat and Oracle Linux platforms. (Bug #29246216)

• The WITH_LZMA CMake option was removed. (Bug #29153932, Bug #93755)

• The EXCLUDE_FROM_ALL option is now used in CMake configuration as appropriate so that libraries are

built only if they are actually used by any executable. (Bug #29052599)

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MySQL 8.0 Release Notes

• The new WITH_JEMALLOC CMake option indicates whether to link with -ljemalloc. If enabled, built-

in malloc(), calloc(), realloc(), and free() routines are disabled. The default is OFF. (Bug

#29027974)

• The new WITH_LSAN CMake option indicates whether to run LeakSanitizer, without AddressSanitizer.

The default is OFF. (Bug #28936574)

• The new WITH_ROUTER CMake option indicates whether to build MySQL Router. The default is ON. (Bug

#28759234)

• MySQL Server now supports a --validate-config option that enables the startup configuration to be

checked for problems without running the server in normal operational mode. For more information, see

Server Configuration Validation. (WL #12360)

Deprecation and Removal Notes

• The TempTable storage engine now always uses InnoDB to manage internal temporary tables on

disk, and the choice of storage engine employed for this task is no longer user-configurable. The

internal_tmp_disk_storage_engine system variable has been removed. (Bug #91377, Bug

#28234637, WL #11974)

References: See also: Bug #28081038, Bug #82556, Bug #27408352.

Installation Notes

• Previously, after installation of a new version of MySQL, the MySQL server automatically upgraded the

data dictionary tables at the next startup, after which the DBA was expected to invoke mysql_upgrade

manually to upgrade the system tables in the mysql schema, as well as objects in other schemas such

as the sys schema and user schemas.

The server now performs the tasks previously handled by mysql_upgrade. After installation of a

new MySQL version, the server now automatically performs all necessary upgrade tasks at the next

startup and is not dependent on the DBA invoking mysql_upgrade. In addition, the server updates the

contents of the help tables (something mysql_upgrade did not do). A new --upgrade server option

provides control over how the server performs automatic data dictionary and server upgrade operations.

For more information, see Upgrading MySQL.

This change to the upgrade procedure results in some deprecations:

• mysql_upgrade is deprecated because it is no longer necessary.

• The --no-dd-upgrade server option is deprecated because the --upgrade option supersedes it.

mysql_upgrade and the --no-dd-upgrade option will be removed in a future MySQL version. (Bug

#28146052, Bug #28162609, Bug #91205, Bug #29185739, Bug #27740692, Bug #28547424, Bug

#91961, WL #12413, WL #12918)

Packaging Notes

• The Docker image for MySQL Cluster 8.0 is now available for download. (Bug #30010921, Bug #96084)

• Binary packages that include curl rather than linking to the system curl library now use curl 7.64.0.

(Bug #29357198)

• The Henry Spencer regex library (extra/regex) is no longer used by MySQL 8.0 and is no longer

present in source distributions. (Bug #29192306)

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MySQL 8.0 Release Notes

• RPM packages now have dependencies on libtirpc and rpcgen because newer versions of glibc

do not include Sun RPC. (Bug #28995257)

• The support-files/magic file was removed from the MySQL source tree. Most MySQL file formats

are covered by operating system file type capabilities. (Bug #18335080, Bug #71898)

• MySQL now provides “Minimal Install” Linux generic binary download packages for MySQL Server and

the Test Suite. Minimal install packages exclude debug binaries and are stripped of debug symbols,

making them significantly smaller than the regular Linux generic binary packages. Downloads are

available at https://dev.mysql.com/downloads/.

• The Docker image for MySQL Enterprise Edition is now available for download from My Oracle Support.

Parser Notes

• The parser no longer accepts the undocumented and nonstandard = alias_name syntax for specifying

table aliases. (Bug #29205289)

• The parser is now permits several additional nonreserved keywords to be used as labels within stored

programs that previously were restricted from such use: ACCOUNT, ALWAYS, BACKUP, CLOSE, FORMAT,

GROUP_REPLICATION, HOST, INVISIBLE, OPEN, OPTIONS, OWNER, PARSER, PORT, REMOVE,

RESTORE, ROLE, SECONDARY, SECONDARY_ENGINE, SECONDARY_LOAD, SECONDARY_UNLOAD,

SECURITY, SERVER, SOCKET, SONAME, UPGRADE, VISIBLE, WRAPPER. (Bug #29033659)

• The parser accepted ODBC escape syntax for outer joins ({ OJ outer_join }), but also accepted

identifiers other than OJ. The parser now accepts only OJ.

Note

OJ now is a nonreserved keyword.

(Bug #22320942)

Performance Schema Notes

• The new Performance Schema keyring_keys table exposes metadata for keys in the MySQL Keyring.

Key metadata includes key IDs, key owners, and backend key IDs. The keyring_keys table does not

expose any sensitive keyring data such as key contents. See The keyring_keys table. (WL #11543)

Plugin Notes

• MySQL now includes a ddl_rewriter plugin that modifies CREATE TABLE statements received by

the server before it parses and executes them. The plugin removes ENCRYPTION, DATA DIRECTORY,

and INDEX DIRECTORY clauses, which may be helpful when restoring tables from SQL dump files

created from databases that are encrypted or that have their tables stored outside the data directory.

For example, the plugin may enable restoring such dump files into an unencrypted instance or in

an environment where the paths outside the data directory are not accessible. When installed,

ddl_rewriter exposes the Performance Schema memory/rewriter/ddl_rewriter instrument for

tracking plugin memory use. For more information, see The ddl_rewriter Plugin. (WL #12668)

Security Notes

• Previously, if the grant tables were corrupted, the MySQL server wrote a message to the error log but

continued as if the --skip-grant-tables option had been specified. This resulted in the server

operating in an unexpected state unless --skip-grant-tables had in fact been specified. Now,

the server stops after writing a message to the error log unless started with --skip-grant-tables.

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MySQL 8.0 Release Notes

(Starting the server with that option enables you to connect to perform diagnostic operations.) (Bug

#29394501, Bug #94394, WL #12971)

• The OpenSSL libraries bundled with MySQL on some platforms (Windows, macOS, and Generic

Linux) have been upgraded to version 1.0.2r. On all other platforms, MySQL uses the system installed

OpenSSL. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html. (Bug #28988091)

• Granting roles to anonymous users is no longer supported because such roles caused problematic

behavior. (Bug #28910120)

• OpenSSL 1.1.1 supports the TLS v1.3 protocol for encrypted connections, and MySQL now supports

TLS v1.3 as well, if both the server and client are compiled using OpenSSL 1.1.1 or higher:

• Some TLSv1.3 ciphersuites are enabled by default. The tls_ciphersuites system variable

enables explicitly specifying which TLSv1.3 ciphersuites the server permits.

• The --tls-ciphersuites client option specifies which TLSv1.3 ciphersuites a client

permits. This option applies to these programs: mysql, mysqladmin, mysqlbinlog,

mysqlcheck, mysqldump, mysqlimport, mysqlpump, mysqlshow, mysqlslap, mysqltest,

mysql_secure_installation, and mysql_upgrade.

• The mysql_options() C API function has a new MYSQL_OPT_TLS_CIPHERSUITES option that

specifies from within the client library which TLSv1.3 ciphersuites a client program permits.

For more information, see Encrypted Connection TLS Protocols and Ciphers.

Note

Group Replication does not support TLSv1.3.

(WL #12361)

• The TLS context the server uses for new connections now is reconfigurable at runtime. This capability

may be useful, for example, to avoid restarting a MySQL server that has been running so long that its

SSL certificate has expired. Dynamic SSL reconfigurability is based on these changes:

• The system variables that define the TLS context are dynamic and can be changed at runtime:

ssl_ca, ssl_capath, ssl_cert, ssl_cipher, ssl_crl, ssl_crlpath, ssl_key,

tls_ciphersuites. tls_version.

• The ALTER INSTANCE statement supports a RELOAD TLS action that reconfigures the TLS context

from the current values of the system variables that define the context.

• These status variables reflect the TLS context the server uses for new connections:

Current_tls_ca, Current_tls_capath, Current_tls_cert, Current_tls_cipher,

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MySQL 8.0 Release Notes

Current_tls_ciphersuites, Current_tls_crl, Current_tls_crlpath,

Current_tls_key, Current_tls_version.

ALTER INSTANCE RELOAD TLS updates those status variables from the corresponding system

variable values when it reconfigures the TLS context.

For more information, see Server-Side Runtime Configuration and Monitoring for Encrypted

Connections.

Thanks to Facebook for submitting code for a similar feature (although the code was not used). (WL

#11541)

References: See also: Bug #27980097.

• In MySQL 8.0, the default authentication plugin was changed from mysql_native_password

to caching_sha2_password. Because caching_sha2_password provides a superset of

the capabilities of the sha256_password authentication plugin, sha256_password is now

deprecated and will be removed in a future MySQL version. MySQL accounts that authenticate using

sha256_password should be migrated to use caching_sha2_password instead. (WL #12694)

Spatial Data Support

• The ST_Length() function now takes an optional second argument enabling the unit for the

return value to be specified. Permitted units are those listed in the new INFORMATION_SCHEMA

ST_UNITS_OF_MEASURE table. See LineString and MultiLineString Property Functions, and The

INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table. (WL #12657)

SQL Syntax Notes

• Incompatible Change: In MySQL 5.7, specifying a FOREIGN KEY definition for an InnoDB table

without a CONSTRAINT symbol clause, or specifying the CONSTRAINT keyword without a symbol,

causes InnoDB to use a generated constraint name. That behavior changed in MySQL 8.0, with InnoDB

using the FOREIGN KEY index_name value instead of a generated name. Because constraint names

must be unique per schema (database), the change caused errors due to foreign key index names

that were not unique per schema. To avoid such errors, the new constraint naming behavior has been

reverted, and InnoDB once again uses a generated constraint name.

For consistency with InnoDB, the NDB storage engine now uses a generated constraint name if the

CONSTRAINT symbol clause is not specified, or the CONSTRAINT keyword is specified without a

symbol. In NDB releases based on MySQL 5.7 and earlier MySQL 8.0 releases, NDB used the FOREIGN

KEY index_name value.

The changes described above may introduce incompatibilities for applications that depend on the

previous foreign key constraint naming behavior. (Bug #29173134)

• Previously, MySQL permitted a limited form of CHECK constraint syntax, but parsed and ignored it.

MySQL now implements the core features of table and column CHECK constraints, for all storage

engines. Constraints are defined using CREATE TABLE and ALTER TABLE statements. The new

INFORMATION_SCHEMA.CHECK_CONSTRAINTS table provides information about CHECK constraints

defined on tables. For more information, see CHECK Constraints. (Bug #11744849, Bug #3464, Bug

#3465, Bug #11746042, Bug #22759, WL #929)

sys Schema Notes

• MySQL now includes built-in SQL functions that format or retrieve Performance Schema data, and that

may be used as equivalents for existing sys schema stored functions:

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MySQL 8.0 Release Notes

• FORMAT_BYTES(): Converts a byte count to a value with units. Similar to sys.format_bytes().

• FORMAT_PICO_TIME(): Converts a time in picoseconds to a value with units. Similar to

sys.format_time().

• PS_THREAD_ID(): Returns the Performance Schema thread ID for a given thread. Similar to

sys.ps_thread_id() invoked with a non-NULL argument.

• PS_CURRENT_THREAD_ID(): Returns the Performance Schema thread ID for the current thread.

Shortcut for sys.ps_thread_id() invoked with a NULL argument.

The built-in functions can be invoked in any schema and require no qualifier, unlike the sys functions,

which require either a sys. schema qualifier or that sys be the current schema.

The built-in functions supersede the corresponding sys functions, which now are deprecated and will be

removed in a future MySQL version. Applications that use the sys functions should be adjusted to use

the built-in functions instead, keeping in mind some minor differences between the sys functions and the

built-in functions. See Performance Schema Functions. (WL #7803)

Test Suite Notes

• mysql-test-run.pl now supports the MTR_UNIQUE_IDS_DIR environment variable, which may be

set to specify a unique-IDs directory to be used as the common location for all chroot environments by

multiple simultaneous mysql-test-run.pl instances. This enables those instances to avoid conflicts

when reserving port numbers. Thanks to Facebook for the contribution. (Bug #29221085, Bug #93950)

• The my_safe_process program was renamed to mysqltest_safe_process and now is installed

with other binaries such as mysqltest rather than with test suite files. (Bug #29198969)

• These changes to the all_persisted_variables test were implemented:

• It limits the number of hardcoded values in the test output by putting them into local variables. New

patches that are then rebased on top that add new system variables do not need to change as many

lines of the original test case, making it easier on the rebase process.

• It removes entries for bugs that were fixed and modifies the queries to include the system variables

that were not tested due to open bugs.

Thanks to the Facebook team for the contribution. (Bug #29013375, Bug #93478)

X Plugin Notes

• X Plugin previously returned a StmtExecuteOk message to the client after query cleanup had ended

and the session had been deactivated. The message is now returned as soon as the result is known and

before query cleanup, which gives a noticeable improvement in performance. (Bug #28997370)

• X Plugin logged the system message "X Plugin ready for connections" when user connections

were not available because preparation of I/O interfaces had failed. (Bug #28906360)

• Some items in the X Plugin code were not instrumented for the Performance Schema by default. (Bug

#28898155)

• X Protocol now supports the COM_RESET_CONNECTION utility command to reset the session state

without re-authenticating or closing the connection. (Bug #28732455)

• X Plugin produced compilation warnings when the MySQL Server source code was built using the Clang

8 compiler. (Bug #28732158)

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MySQL 8.0 Release Notes

Functionality Added or Changed

• InnoDB: When the amount of memory occupied by the TempTable storage engine exceeds the limit

defined by the temptable_max_ram variable, the TempTable storage engine allocates space for

internal in-memory temporary tables as memory-mapped temporary files. This behavior is now controlled

by the temptable_use_mmap variable, which can be disabled to have the TempTable storage engine

use InnoDB on-disk internal temporary tables instead. For more information, see Internal Temporary

Table Use in MySQL. (Bug #28944457)

• InnoDB: undo and purge subsystem counters were added for monitoring background

activities associated with undo log truncation. For counter names and descriptions, query the

INFORMATION_SCHEMA.INNODB_METRICS table.

SELECT NAME, SUBSYSTEM, COMMENT FROM INFORMATION_SCHEMA.INNODB_METRICS WHERE NAME LIKE '%truncate%';

For information about enabling counters and querying counter data, see InnoDB

INFORMATION_SCHEMA Metrics Table. (Bug #28813526, WL #12600)

• InnoDB: The new innodb_spin_wait_pause_multiplier variable provides greater control over

the duration of spin-lock polling delays that occur when a thread waits to acquire a mutex or rw-lock.

Delays can now be tuned more finely to account for differences in PAUSE instruction duration on

different processor architectures. For more information, see Configuring Spin Lock Polling. (WL #12616)

• InnoDB: An internal service interface was added to support tracking of modified pages. (WL #11082)

• InnoDB: The InnoDB data-at-rest encryption feature now supports encryption of the mysql system

tablespace. The mysql system tablespace contains the mysql system database and the MySQL data

dictionary tables. (WL #12063)

• Group Replication: The group communication engine (XCom) includes a cache for messages (and their

metadata) that are exchanged between the group members as a part of the consensus protocol. Among

other functions, the message cache is used for recovery by members that return to the group after a

period where they were unable to communicate with the other group members.

Previously, the size limit for the message cache was fixed at 1GB of memory,

and the maximum number of messages in the cache was also fixed. Now that the

group_replication_member_expel_timeout system variable (introduced in MySQL 8.0.13) can

be set to allow up to an hour for members to return to the group rather than being expelled, having a

fixed 1GB limit on the size of the cache could cause such nodes to be unable to recover the messages

they missed on re-establishing communication.

For this reason, beginning with this release, the XCom message cache has no fixed limit on the number

of messages it can contain, and is bounded only by the limit set for the amount of memory it can

use. The cache size limit can be set using the new group_replication_message_cache_size

system variable, which has a default and minimum setting of 1GB, as used in previous MySQL Server

versions. If the cache size limit is reached, XCom removes the oldest entries that have been decided

and delivered. The cache size limit can be increased or reduced dynamically at runtime. If you reduce

the cache size limit, XCom removes the oldest entries that have been decided and delivered until the

current size is below the limit. The Group Replication Group Communication System (GCS) issues

a warning when a message likely to be needed for recovery by a currently unreachable member is

removed from the message cache. (Bug #26482507, WL #11615)

• Group Replication: Large messages sent between Group Replication group members can now be split

into multiple messages when they exceed a user-defined threshold size. Sending an abnormally large

message can result in some group members being reported as failed and expelled from the group. This

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MySQL 8.0 Release Notes

is because the single thread used by the group communication engine (XCom) is occupied processing

the message for too long, so some of the group members might report the receiver as failed.

A new system variable group_replication_communication_max_message_size specifies the

maximum message size for Group Replication communications. Messages greater than this size are

automatically split into fragments that are sent separately and reassembled by the recipients. Message

delivery for a fragmented message is considered complete when all the fragments of the message have

been received and reassembled by all the group members. Fragmentation is applied by default, and can

be switched off by specifying a zero value for the system variable.

Because older MySQL Server releases do not support message fragmentation, in order to ensure

backward compatibility, Group Replication now has the concept of a communication protocol for the

group. The communication protocol version is set to accommodate the oldest MySQL Server version that

you want the group to support. A MySQL server at version X can only join and reach ONLINE status in a

replication group if the group's communication protocol version is less than or equal to X.

You can inspect the communication protocol in use by a group by using the new

group_replication_get_communication_protocol() function, which returns the oldest MySQL

Server version that the group supports. When a new member joins a replication group, it checks the

communication protocol version that is announced by the existing members of the group. If the joining

member supports that version, it joins the group and uses the communication protocol that the group has

announced, even if the member supports additional communication capabilities. If the joining member

does not support the communication protocol version, it is expelled from the group.

If you need to change the communication protocol version of a group so that members at earlier releases

can join, use the new group_replication_set_communication_protocol() function to specify

the MySQL Server version of the oldest member that you want to allow. This makes the group fall

back to a compatible communication protocol version if possible. If you upgrade all the members of a

replication group to a new MySQL Server release, the group's communication protocol version is not

automatically upgraded to match. If you no longer need to support members from earlier releases, use

the group_replication_set_communication_protocol() function to set the communication

protocol version to the new MySQL Server version to which you have upgraded the members. (Bug

#26438884, Bug #23240361, Bug #28474580, Bug #91830, Bug #28642504, Bug #26941977, Bug

#29240931, WL #11610)

• Group Replication: A new system variable group_replication_autorejoin_tries

lets you specify the number of tries that a member makes to automatically rejoin the

group if it is expelled, or if it is unable to contact a majority of the group before the

group_replication_unreachable_majority_timeout setting is reached. 0, the default,

means that the member does not try to rejoin, and proceeds to the action specified by the

group_replication_exit_state_action system variable.

Activate auto-rejoin if you can tolerate the possibility of stale reads and want to minimize the

need for manual intervention, especially where transient network issues fairly often result in the

expulsion of members. If you specify a number of tries, when the member's expulsion or unreachable

majority timeout is reached, it makes an attempt to rejoin (using the current plugin option values),

then continues to make further auto-rejoin attempts up to the specified number of tries. After an

unsuccessful auto-rejoin attempt, the member waits 5 minutes before the next try. During the auto-

rejoin procedure, the member remains in super read only mode and displays an ERROR state on its

view of the replication group. The member can be stopped manually at any time by using a STOP

GROUP_REPLICATION statement or shutting down the server. If the specified number of tries is

exhausted without the member rejoining or being stopped, the member proceeds to the action specified

by group_replication_exit_state_action. (Bug #25673350, Bug #84784, Bug #28732174, WL

#11284)

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MySQL 8.0 Release Notes

• Group Replication: The default for group_replication_exit_state_action has been changed

from ABORT_SERVER to READ_ONLY. (WL #12659)

• Some InnoDB memory allocation functions that previously were evaluated at runtime now are evaluated

at compile time, resulting in performance improvements. (Bug #29370811, Bug #94380)

• The semijoin optimizations for IN subqueries have been extended to work with EXISTS subqueries

as well; these can now be handled with the same semijoin strategies as IN subqueries, including first-

match, materialization, duplicate weedout and loose index scan.

In addition, the optimizer decorrelates trivially-correlated equality predicates in the WHERE condition

attached to the subquery, so that they can be treated similarly to expressions in IN subqueries. The

decorrelation is now also performed for IN subqueries as well as EXISTS subqueries.

All hints and optimizer switches applicable to IN subqueries which are transformed into semijoin

operations are also applicable to transformed EXISTS subqueries. All limitations on such optimization of

IN subqueries also apply to transformed EXISTS subqueries, so that, for example, aggregate EXISTS

subqueries cannot be transformed.

For more information, see Optimizing IN and EXISTS Subquery Predicates with Semijoin

Transformations. (Bug #28805105, Bug #28857990, WL #4389)

• For consistency with the SQL standard and other RDBMS, table aliases are now supported in single-

table as well as multi-table DELETE statements. (Bug #27455809)

• WHERE conditions making comparisons between constants and column values in which the constant

value is out of range or of the wrong type with respect to the column type are now handled during

optimization rather than during execution. For example, given a table t with a column c whose type

is TINYINT UNSIGNED, the condition in the query SELECT * FROM t WHERE c < 256 can be

folded to SELECT * FROM t WHERE TRUE because 256 is out of range for a column of this type.

Comparisons with NULL columns can also be optimized; if the column c is nullable, the same query can

be optimized as SELECT * FROM t WHERE c IS NOT NULL.

The comparisons that can be treated in this manner are >, >=, <, <=, =, <>/!=, and <=>. (BETWEEN and

IN are not currently supported.) Types for which comparisons can be folded based on range and type

include integer, floating-point, and fixed-point numeric types. BIT is not supported by this optimization,

nor are columns of date and time types.

For more information, see Constant-Folding Optimization. (Bug #90100, Bug #25484743, Bug

#29048682, Bug #27703371, WL #11935)

References: See also: Bug #28172538, Bug #29699347.

• Added an experimental tree format for EXPLAIN output, which prints the generated iterator tree, and

is intended to help users understand how execution was actually set up. EXPLAIN FORMAT=TREE is

currently unsupported in production and both its syntax and output are subject to change in subsequent

versions of MySQL. (WL #12074)

• When binary log and relay log encryption is in use on a MySQL server (binlog_encryption=ON),

you can now rotate the binary log master key at any time while the server is running by issuing ALTER

INSTANCE ROTATE BINLOG MASTER KEY. You can do this on a regular basis to comply with your

organization's security policy, and also if you suspect that the current or any of the previous binary log

master keys might have been compromised.

When you rotate the binary log master key, the new master key is used to encrypt the file passwords

for the new binary log and relay log files, and subsequent files until the key is changed again. The file

passwords for existing encrypted binary log files and relay log files on the server are also re-encrypted

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MySQL 8.0 Release Notes

in turn using the new binary log master key, starting with the most recent files. Any unencrypted files

are skipped. Finally, all binary log encryption keys that no longer apply to any retained binary log files or

relay log files are cleaned up from the keyring. (WL #12080)

• Table encryption can now be managed globally by defining and enforcing encryption defaults. The

default_table_encryption variable defines an encryption default for newly created schemas

and general tablespaces. The encryption default for a schema can also be defined using the DEFAULT

ENCRYPTION clause when creating a schema. By default, a table inherits the encryption of the schema

or general tablespace it is created in.

Encryption defaults are enforced by enabling the table_encryption_privilege_check variable.

The privilege check occurs when creating or altering a schema or general tablespace with an encryption

setting that differs from the default_table_encryption setting, or when creating or altering a table

with an encryption setting that differs from the default schema encryption.

The TABLE_ENCRYPTION_ADMIN privilege permits overriding default encryption settings when

table_encryption_privilege_check is enabled.

For more information, see Defining an Encryption Default for Schemas and General Tablespaces. (WL

#12261)

• When insertions, deletions, or updates are made to partitioned tables, the binary log now records

information about the partition and (if any) the subpartition in which the row event took place. A new

row event is created for a modification that takes place in a different partition or subpartition, even if the

table involved is the same. So if a transaction involves three partitions or subpartitions, three row events

are generated. For an update event, the partition information is recorded for both the “before” image

and the “after” image. The partition information is displayed if you specify the -v or --verbose option

when viewing the binary log using mysqlbinlog. Partition information is only recorded when row-based

logging is in use (binlog_format=ROW). (WL #12168)

Bugs Fixed

• NDB Cluster: EXPLAIN of a query executed with table access type eq_ref could also show a condition

being pushed down, even when condition pushdown was not supported for the query. Now the access

type is checked before NDB checks the condition for a possible pushdown optimization.

This fix does not affect handling of tables which are part of a pushed join, for which NDB continues to

support pushed conditions as before. (Bug #27429615)

References: See also: Bug #27397802, Bug #27808758, Bug #90301.

• InnoDB: Undo tablespaces remained unencrypted after enabling undo tablespace encryption at startup.

(Bug #29477795)

• InnoDB: Problematic macros introduced with undo tablespace DDL support in MySQL 8.0.14 were

revised. (Bug #29324132, Bug #94243)

• InnoDB: Static thread local variables defined at the wrong scope were not released at thread exit. (Bug

#29305186)

• InnoDB: The performance_schema.data_locks LOCK_DATA column only showed the secondary

index values of the locked record for a lock placed on a unique secondary index, which was not sufficient

to ensure the uniqueness of identified records. The clustered index column values of the locked record

are now appended. (Bug #29296645)

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MySQL 8.0 Release Notes

• InnoDB: An incorrect count of transactions using a rollback segment for recovery of an XA transaction

prevented an undo tablespace truncation operation from proceeding and left the purge thread busy

checking for the undo tablespace to become empty. (Bug #29273194)

References: This issue is a regression of: Bug #29273194.

• InnoDB: Invalid assertions were raised at startup after a failure to retrieve the space ID of a compressed

file-per-table tablespace. The invalid assertion code was removed. (Bug #29221385, Bug #93760)

• InnoDB: Optimized InnoDB internal temporary tables did not support in-place UPDATE operations,

which caused the number of delete-marked records to increase continuously. The large number of

delete-marked records could cause longer than expected query execution times. (Bug #29207450)

• InnoDB: The std::sort function in the Contention-Aware Transaction Scheduling (CATS) algorithm

was replaced by the std::stable_sort function to preserve the original FIFO order for transactions of

equal weight. (Bug #29058967)

• InnoDB: Write-ahead did not work as expected due to an incorrectly initialized variable.

Thanks to Yuhui Wang for the contribution. (Bug #29028838, Bug #93442)

• InnoDB: The base column information for a generated column was not stored. (Bug #29021730)

• InnoDB: An implicit lock check on secondary indexes needlessly compared columns using collation

rules. (Bug #29010725)

• InnoDB: Assertion code related to the innodb_flush_method O_DIRECT_NO_FSYNC setting was no

longer valid due to a recent modification to that setting. Assertion code was revised. (Bug #29007731)

References: See also: Bug #27309336.

• InnoDB: When starting the server with undo log encryption enabled, the master key for newly

created undo tablespaces was generated without a server UUID. Undo tablespaces should use the

DefaultMasterKey if the server UUID is not yet generated. (Bug #29006275)

• InnoDB: Data dictionary code did not check for a returned data dictionary object, which could potentially

cause the server to exit due to a null pointer access. (Bug #28977444, Bug #93362)

• InnoDB: An undo tablespace file was left behind by a failed CREATE UNDO TABLESPACE operation.

(Bug #28966457)

• InnoDB: A CREATE UNDO TABLESPACE statement failed on Windows due to an invalid character in

the file name. The failure resulted in a hang condition due to a missing OS_FILE_ON_ERROR_NO_EXIT

attribute in the call that creates the undo tablespace file. (Bug #28955676)

• InnoDB: Modifying the value of the innodb_undo_log_encrypt variable was not a blocking

operation, which could lead to the modification being reverted by a background thread after the operation

appeared to have been completed successfully. (Bug #28952870)

• InnoDB: An invalid debug assertion was removed from the

temptable::Handler::primary_key_is_clustered function. (Bug #28949332)

• InnoDB: An ALTER TABLE ... EXCHANGE PARTITION operation did not properly update column

table_id values in the data dictionary. (Bug #28927005)

• InnoDB: Memory leaks discovered in the innochecksum utility were removed. (Bug #28917614, Bug

#93164)

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MySQL 8.0 Release Notes

• InnoDB: A DDL operation that followed a failed attempt to create an index on a virtual column resulted in

an assertion failure. (Bug #28825718)

• InnoDB: A performance regression was observed for partial update operations on compressed BLOBs

less than or equal to 128KB in size. (Bug #28784301)

• InnoDB: Running aggregated queries raised Valgrind warnings. (Bug #28711717)

• InnoDB: A CHECK TABLE operation raised an assertion failure. A pointer to a local call stack variable

was not set back to null before a function exit. (Bug #28525110)

• InnoDB: DDL log functions were modified to handle ER_TOO_MANY_CONCURRENT_TRXS errors. (Bug

#28523127, Bug #92071)

• InnoDB: The purge thread failed to free LOB data pages. (Bug #28510599)

• InnoDB: Some DDL log table transactions were not rolled back prior to DDL log recovery. (Bug

#28494969)

• InnoDB: A function invoked during SHOW CREATE TRIGGER processing that retrieves the table name

did not perform the expected lowercase conversion. (Bug #28351038)

• InnoDB: The INFORMATION_SCHEMA.INNODB_FOREIGN TYPE column reported incorrect values. (Bug

#28315651, Bug #91577)

• InnoDB: A Linux AIO handler function failed to check if completed I/O events succeeded. Thanks to Wei

Zhao for the contribution. (Bug #27850600, Bug #90402)

• InnoDB: An assertion failure was raised in a check that determines if a transaction holds an implicit

lock on a secondary index. A transaction that does not change the columns of a secondary index that

includes virtual columns could be incorrectly determined to hold an implicit lock. (Bug #27491839)

• InnoDB: A function called by a CREATE TABLE thread attempted to access a table object after it was

freed by a background thread.

Thanks to Yan Huang for the patch. (Bug #27373959, Bug #89126)

• InnoDB: Two sessions concurrently executing an INSERT ... ON DUPLICATE KEY UPDATE

operation generated a deadlock. During partial rollback of a tuple, another session could update it. The

fix for this bug reverts fixes for Bug #11758237, Bug #17604730, and Bug #20040791. (Bug #25966845)

• InnoDB: When the method used to access a joined table was const, InnoDB attempted to unlock the

matching row multiple times. (Bug #20939184)

• InnoDB: The INDEX_LENGTH value in INFORMATION_SCHEMA.TABLES was not updated when adding

an index. (Bug #19811005)

• Partitioning: Some partitioning DDL statements were improperly rejected due to name validation checks

which used the wrong table identifier. (Bug #29317007)

• Partitioning: While rolling back ALTER TABLE ... COALESCE PARTITION, the server sometimes

attempted to lock and close partitions which had been dropped as a result of this statement. (Bug

#28517446)

• Partitioning: An AUTO_INCREMENT key added to a partitioned table by an ALTER TABLE statement

using ALGORITHM=INPLACE restarted on each partition. (Bug #92241, Bug #28573894)

• Replication: If the WAIT_FOR_EXECUTED_GTID_SET() function was used with a timeout value

including a fractional part (for example, 1.5), an error in the casting logic meant that the timeout was

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MySQL 8.0 Release Notes

rounded down to the nearest whole second, and to zero for values less than 1 second (for example,

0.1). The casting logic has now been corrected so that the timeout value is applied as originally

specified with no rounding. Thanks to Dirkjan Bussink for the contribution. (Bug #29324564, Bug

#94247)

• Replication: The consistency level AFTER for the system variable

group_replication_consistency did not include the consistency guarantees provided by

BEFORE_ON_PRIMARY_FAILOVER. These consistency guarantees, which were already implicitly

present with the BEFORE and BEFORE_AND_AFTER consistency levels, are now provided with AFTER.

(Bug #29315752, Bug #94213)

• Replication: On Debian-based platforms (such as Ubuntu), if the hostname resolved to 127.0.1.1 -

which is the default on these platforms - it was not possible to create a cluster using the default settings.

Now, in such situations a proper validation of the instance is performed before creating a cluster and

adding instances to it. (Bug #29246110)

• Replication: In a blocked group, if you set an invalid value for group_replication_force_members

and then issued STOP GROUP_REPLICATION, the server could stop unexpectedly. (Bug #29119961)

• Replication: MySQL Server's behavior when the mysql.gtid_executed table cannot be accessed

has been refactored to provide appropriate error responses and actions. The MySQL server now

ensures that writes are permitted to the mysql.gtid_executed table when the server is in read

only or super read only mode, so that the binary log file can still be rotated in these modes. If the

mysql.gtid_executed table cannot be accessed for writes, and the binary log file is rotated for

any reason other than reaching the maximum file size (max_binlog_size), the current binary log

file continues to be used. An error message is returned to the client that requested the rotation, and a

warning is logged on the server. If the mysql.gtid_executed table cannot be accessed for writes

and max_binlog_size is reached, the server responds according to its binlog_error_action

setting. If IGNORE_ERROR is set, an error is logged on the server and binary logging is halted, or if

ABORT_SERVER is set, the server shuts down. (Bug #29111514)

• Replication: When issuing STOP GROUP_REPLICATION while the member was trying to assess

whether or not it had lost majority, the server could stop unexpectedly. (Bug #29053128)

• Replication: When a RESET MASTER TO statement is used to specify the starting index number

for binary log files, the maximum number that you can specify has been reduced from the maximum

integer value to 2000000000. If the maximum integer value was specified, the server was not able to

start up because no further binary log files could be created. The server also previously experienced a

segmentation fault in that situation. (Bug #28980788, Bug #28995220)

• Replication: On a replication slave with GTIDs in use and binary logging disabled, an assertion was

raised in debug mode when a DDL statement was filtered out by a table filter. (Bug #28965972)

• Replication: Two issues with the deserialization of statement based replication events in the binary log

were corrected. (Bug #28889181, Bug #29028491)

• Replication: If an applier thread was stopped while it was in the process of opening a table, no error

was set, which could result in a segmentation fault or assertion depending on the build type. Error

handling is now correctly activated in this situation. (Bug #28864557)

• Replication: With GTIDs in use on the server, the master info log on a replication slave was being

synchronized every time the master skipped a transaction using the auto-skip function. The process

ends with a dummy heartbeat which is sent to the slave and caused a forced flush to the log, and this

could have a large cumulative impact on the write load on the slave. The same issue could occur in a

circular replication topology with events that originated from the same server and were therefore ignored,

which were also handled by the slave with a forced flush to the log. The slave handling code has now

been changed to remove the forced flush for heartbeat events and for ignored events received through

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MySQL 8.0 Release Notes

circular replication, so that the master info log is only synchronized when appropriate (for example, when

a CHANGE MASTER statement is issued, or the binary log is rotated). (Bug #28815555, Bug #85158)

• Replication: When an ALTER TABLE statement is used with a DEFAULT clause to specify an

expression default value for a new column, and the expression default value refers to a nondeterministic

function, the statement is unsafe for statement-based replication. Previously, such statements were

also evaluated in terms of GTID consistency, which was not the appropriate check as the statements

do not impact GTID consistency. Now, these statements are evaluated only for binary logging and are

handled depending on the binary logging format in use. When binlog_format is set to STATEMENT,

the statement is logged but a warning message is written to the error log. When binlog_format is set

to MIXED or ROW, the statement is not executed and an error message is written to the error log. (Bug

#28799939)

• Replication: In a replication group configured in single-primary mode

(group_replication_single_primary_mode=ON, which is the default), if severe network delays

affected the group, it was possible for the primary and the secondaries to reach different decisions on a

transaction, which could lead to divergence in the gtid_executed sets on the members. The issue has

now been fixed. (Bug #28768550, Bug #28966455, Bug #92690)

• Replication: When you use the group_replication_force_members system variable to force a

new configuration for a group, the group communication engine (XCom) now checks that you have not

included any group members that are currently unreachable. If any are found, the reconfiguration is

disallowed and an error is returned. (Bug #28678845)

• Replication: GRANT statements that were written to the binary log were logged incorrectly in some

cases, which could result in a GRANT statement that executed successfully on the master causing an

error on the replication slave. (Bug #28643405, Bug #29155451, Bug #93750)

• Replication: If a storage engine has the capability to log in STATEMENT format but not in ROW format,

when binlog_format is set to STATEMENT, an unsafe SQL statement should be logged and a warning

message should be written to the error log. However, such statements were instead not executed and an

error message was written to the error log, which is the correct behavior when binlog_format is set to

MIXED or ROW. The issue has now been corrected so that unsafe statements are logged with a warning

as expected when binlog_format is set to STATEMENT. (Bug #28429993, Bug #73936)

• Replication: It is possible for a replication group member to go offline briefly, then attempt to rejoin

the replication group again before the group has detected its failure and been reconfigured to remove

the member. Previously, in this situation, the rejoining member could participate in XCom's consensus

protocol if it received and processed messages intended for its pre-crash incarnation. This could cause

XCom to deliver different values for the same consensus round, because the rejoining member could

make a different decision before and after failure. To prevent this situation, a rejoining member now

ignores messages intended for its pre-crash incarnation. (Bug #27383487)

• Replication: On overloaded servers there was a possibility that when a member joined the group,

the VIEW_CHANGE_LOG_EVENT event which marks that point was not logged in the correct place.

This could lead to errors in the data transfer to the newly joining server and data divergence. Now, the

VIEW_CHANGE_LOG_EVENT event is logged in the correct place in the binary log. In addition, warnings

are logged about the delay in logging the event. (Bug #93347, Bug #28971594)

• Replication: When a member joined a group on server start, if the join process failed, for example

because the server was incompatible with the group, there was a possibility that the offline member

could still see another member as being online. Now, in such a situation the information shown in the

performance_schema.replication_group_members table is restricted to the local member when

it is OFFLINE. (Bug #92110, Bug #28533993)

• Replication: In the event of the recovery channel failing, unprocessed relay logs were being erased.

(Bug #90671, Bug #27940732)

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MySQL 8.0 Release Notes

• Group Replication: START GROUP REPLICATION did not function properly when the port specified for

the member's local address was busy. (Bug #29347285)

• Group Replication: When a host name was specified in the IP address whitelist for Group Replication

(group_replication_ip_whitelist),IPv6 addresses were used for name resolution and whitelist

comparison when an IPv4 address was also available. An IPv4 address should always be preferred for

Group Replication connections. Now, if the host name resolves to an IPv4 address, any IPv6 addresses

are not considered for comparison to the whitelist. (Bug #28841543)

• Group Replication: Previously, relay logs could not be rotated manually for the Group

Replication group_replication_applier channel using the FLUSH RELAY LOGS statement.

Due to this restriction, when encryption was enabled for binary log files and relay log files

(binlog_encryption=ON), as available beginning with MySQL 8.0.14, the relay log file in use on

that channel could not be rotated immediately if encryption was disabled again. The restriction had a

similar impact on binary log master key rotation, as available from MySQL 8.0.16. The restriction has

now been removed, and the FLUSH RELAY LOGS statement and corresponding internal requests now

operate on the group_replication_applier channel as for any other channel, with the exception

that if the request is received while a transaction is being applied, the request is performed after the

transaction ends. The requester must wait while the transaction is completed and the rotation takes

place. This behavior prevents transactions from being split, which is not permitted for Group Replication.

(Bug #28684376)

• Group Replication: A replication group member could trigger a local view after being expelled from

the group due to a loss of majority. This resulted in a message incorrectly stating that the member had

resumed regular operation after the expulsion. Group Replication now checks before delivering a local

view that the member has not been expelled. (Bug #27349236)

• Group Replication: If an invalid value was specified for

group_replication_communication_debug_options, the Group Communication System set

its corresponding internal variable to GCS_DEBUG_NONE, and the server returned the invalid value for a

SHOW VARIABLES query. The value of this system variable is now checked during server initialization,

and if an invalid value was specified, an error message is logged and Group Replication does not start

automatically. (Bug #26729404)

• macOS: CMake 3.12.4 or higher (which forces UseModernBuildSystem = NO) is now required on

macOS if building with Xcode rather than Makefiles. (Bug #28893131)

• Microsoft Windows: Validity testing for the named_pipe_full_access_group system variable did

not account for NULL values. (Bug #29256690)

• Microsoft Windows: When multiple instances of mysqld were started with the --no-monitor option

on the same host for same user, the SHUTDOWN command shut down the wrong server process. This fix

creates a unique shutdown event name for use with --no-monitor by appending the process ID of the

process. (Bug #28723675)

• JSON: The JSON path parser now propagates errors in the same way as most other components of the

MySQL server, returning true on error and false on success. (Bug #28851426)

• JSON: Removed an unneeded type lookup in Json_wrapper::get_datetime(). (Bug #28851324)

• The authentication_ldap_simple plugin could enforce authentication incorrectly. (Bug

#29637712)

• RPM package obsoletes were updated to enable successful upgrades from MariaDB to MySQL on EL8.

(Bug #29413354)

• It was possible for the result of an outer join to contain a non-NULL row where a NULL extended row was

expected. (Bug #29402481)

347

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #27808758.

• SET PASSWORD FOR ... could not be executed as a prepared statement. (Bug #29387041, Bug

#94416)

• Builds under Visual Studio could fail while building MySQL Router libraries. (Bug #29382197)

References: This issue is a regression of: Bug #29361890.

• Imported foreign keys did not work if defined before the referenced table. (Bug #29379078, Bug #94400)

References: This issue is a regression of: Bug #28493257.

• When an error was raised while evaluating the ESCAPE clause of a LIKE expression at resolve time, the

error status was not propagated to the caller. (Bug #29368521)

• Tablespace files for the innodb_table_stats_backup and innodb_index_stats_backup

metadata backup tables were not removed after an in-place upgrade from MySQL 5.7 to MySQL 8.0.

(Bug #29365552)

• While flattening a subquery, if a predicate which was always false was present, the MySQL Optimizer

did not perform any kind of transformation, resulting in a subquery that was not prepared, and which

asserted later when it was executed. To resolve this issue, when such a predicate is present in a

subquery, the subquery's query expression is now unlinked from the query block. (Bug #29356132)

• Upgrade from MySQL 8.0.11, 8.0.12, or 8.0.13 to MySQL 8.0.14 or 8.0.15 failed if an event, routine, or

trigger was defined with the ALLOW_INVALID_DATES SQL mode. The SQL mode identifier in the data

dictionary was changed in MySQL 8.0.14, causing a migration failure. (Bug #29350955)

• RPM builds ignored the WITH_SSL configuration setting. (Bug #29347534)

• Length metadata for the TO_SECONDS() function was not always calculated correctly. (Bug #29321387)

• Conditions using windowing functions removed due to being always true or false were not always

handled correctly. (Bug #29320484)

• SET ROLE statements could leak memory. (Bug #29304583)

• Upgrading from MySQL 5.7 to MySQL 8.0 on Windows failed with “Error 197 from SE while migrating

tablespaces”. The error was due to an access share violation that occurred when attempting to open a

tablespace file. (Bug #29292860)

References: This issue is a regression of: Bug #28642608.

• The COMPILATION_COMMENT_SERVER value could be incorrect in RPM packages. (Bug #29284651)

• CREATE TABLE IF NOT EXISTS failed even if the table already exists if the new table definition had

no primary key and the sql_require_primary_key system variable was enabled. (Bug #29283055,

Bug #94134)

• A delete from a partitioned table from which all partitions had been pruned away was not always handled

correctly. (Bug #29280186)

• The CMake check for the GNU gold linker could fail with Clang. (Bug #29278244)

• The data dictionary version was incremented for the MySQL 8.0.16 release. (Bug #29278241)

• An argument of the wrong type to a function used with DISTINCT was not always handled correctly.

(Bug #29277571)

348

MySQL 8.0 Release Notes

• Length metadata for the QUOTE() function was not always calculated correctly. (Bug #29276074)

• When evaluating GREATEST() or LEAST(), MySQL checked for correct signedness of the return value

before checking it for NULL. (Bug #29275835)

• When strict SQL mode was not in effect, the values of some string functions returning NULL to indicate a

result greater than max_allowed_packet were handled inconsistently behaviour, which could result in

incorrectly sorted output and possibly other misbehaviors. (Bug #29272683)

References: See also: Bug #97301, Bug #29133127.

• Logic that checks if upgrade is supported to a particular server version was inverted to check for server

versions from which upgrade is not supported. (Bug #29270297)

• Event creation could store an incorrect repetition interval. (Bug #29269819, Bug #94085)

• A WHERE condition containing a view reference or an item created by a transformation was not always

handled correctly. (Bug #29268867, Bug #29268698, Bug #28723669, Bug #29244238)

• mysql_ssl_rsa_setup failed to compile using GCC 9. (Bug #29245251)

• If CMake finds a libtirpc library that is too old to work with MySQL, it tries to use Sun RPC from

glibc instead. (Bug #29240701)

• The server could fail to write slow queries to the slow query log due to incorrect calculation of query

execution time. (Bug #29232684, Bug #93963)

• MySQL regular expression functions using positions employed internal indexes based on 16-bit chunks,

rather than on codepoint positions. (Bug #29231490)

• On Windows, the MySQL MSI installer could fail to correctly detect whether the Visual Studio 2015

Redistributable was installed. (Bug #29227209)

• SDI JSON files did not include the m_hidden field of Index_impl objects. This made it hard to use the

SDI JSON to recreate the CREATE statement for the table because InnoDB adds a number of hidden

indexes. The SDI JSON now includes the m_hidden field. This changes SDI format, so the SDI version

number was increased to the current server version number. (Bug #29210646, Bug #93914)

• The position hint for the last row in a range frame was updated to be one row past the actual last row in

the frame. (Bug #29201831)

• In a column definition, multiple constraint definitions were not accepted when the first was a CHECK

constraint. (Bug #29191994)

• Error log information buffered during startup could be buffered too long if the server was performing an

upgrade. (Bug #29189532)

• For nullable columns, if we find an expression that is always true except when the column is NULL, the

expression is folded to column IS NOT NULL. When such an expression was nested, this caused

NULL rows to be selected in error. To prevent this from happening, such an expressions when nested is

now instead folded to IF(column IS NULL, NULL, TRUE). (Bug #29179604)

• PERIOD_ADD() did not handle values greater than 32 bits in length for the period argument correctly

on Windows platforms. (Bug #29175262)

• When sql_auto_is_null is enabled, a WHERE clause of the form WHERE auto_increment_col

IS NULL is rewritten as WHERE auto_increment_col = LAST_INSERT_ID(). This transformation

was only performed once per auto-incremented value, which made it difficult to know in advance whether

349

MySQL 8.0 Release Notes

the transformation would be performed. Now the transformation is performed unconditionally whenever

sql_auto_is_null is enabled.

In addition, the value returned by LAST_INSERT_ID() is now treated as unsigned, fixing a failure to

match an auto-incremented value outside the range of a signed BIGINT. (Bug #29171668)

• On Debian and Ubuntu, installation operations in noninteractive mode ignored the root password,

resulting in the auth_socket authentication plugin being installed by default. (Bug #29165407)

• The harness_plugin_eventlog declaration caused compilation errors in some build environments.

(Bug #29160214)

• The logic for truncating or extending a decimal constant to the desired number of fractional digits during

constant folding was lacking. Extra trailing zeros in the fraction could trigger an attempt to widen the

faction, since the decision to widen was based on the number of non-zero fractional digits, rather

than on total number of fractional digits, leading to an assert (in debug builds) in the internal function

widen_fraction(). This issue is fixed by identifying where it is possible merely to truncate excess

trailing zeroes. In this case, it is not necessary to adjust the comparison operator, and the constant can

be replaced by one having fewer trailing zeroes instead. (Bug #29155439)

• On Windows, the internal function get_mysql_time_from_str_no_warn() did not always perform

proper error checking. (Bug #29155126)

References: See also: Bug #29175262.

• Under certain conditions, RENAME TABLE statements that renamed the same table multiple times could

raise an assertion or cause a server exit. (Bug #29140407)

• For debug builds, starting the server with --event-scheduler=DISABLED could result in an assertion

being raised for certain events. (Bug #29140298, Bug #93719)

• In debug builds, When strict SQL mode was not in effect, the CONCAT() and CONCAT_WS() functions

raised an assertion if the result was longer than max_allowed_packet. (Bug #29133127)

• An out-of-range fractional part could produce incorrect timestamps in SET SESSION timestamp

statements. (Bug #29120569, Bug #93600)

• The mysql_service_component_sys_variable service could access component system variables

but not server or plugin system variables. (Bug #29113463)

• ALTER TABLE ... CONVERT TO CHARACTER SET could produce a memory-access error. (Bug

#29058369, Bug #93603)

• The mysql.tablespaces.name column limit was 259 bytes, which was less than required for

permitted identifier lengths. The column limit was raised to 268 bytes. (Bug #29053560, Bug #93587)

• For debug builds, for spatial computations that raised an assertion, partition-handling code ignored the

error, resulting in a server exit. (Bug #29047811)

• A zero length LOB that was stored externally caused an assertion failure. (Bug #29047795)

• Handling of the COMPILE_DEFINITIONS and COMPILE_FLAGS CMake options was adjusted to avoid

cross-compiling failures. (Bug #29041100)

• The server could try to read the first diagnostics area message even when the max_error_count

system variable was set to zero, resulting in a memory-access error. (Bug #29031684)

• When comparing DATE values with constant strings, MySQL first tries to convert the string to a DATE and

then to perform the comparison. When the conversion failed, MySQL executed the comparison treating

350

MySQL 8.0 Release Notes

the DATE as a string, which could lead to unpredictable behavior. Now in such cases, if the conversion of

the string to a DATE fails, the comparison fails with ER_WRONG_VALUE. (Bug #29025656)

References: See also: Bug #95466, Bug #29812087.

• With the --users option, mysqlpump wrote CREATE USER and GRANT statements to the output, but

too late to apply to the other objects created by the dump. Consequently, restoring the dump file created

the user accounts too late to apply to other objects created by the file. mysqlpump now writes user

accounts to the dump file before other objects. (Bug #29023216)

• For syntax errors at the position of the WITH keyword, the parser error message identified the problem at

the incorrect location. (Bug #29022263)

• MySQL builds using recent versions of the International Components for Unicode (ICU) now return

ER_REGEXP_ILLEGAL_ARGUMENT rather than the generic error ER_REGEXP_ERROR for malformed

regular expressions. (Bug #29016798)

• On Windows, the LDAP library could not be found if the file system was case sensitive. (Bug #29016220)

• Values selected from the TABLE_COMMENT column of the INFORMATION_SCHEMA.TABLES table could

be truncated. (Bug #29014272, Bug #93451)

• Data layer memory leaks related to unfreed schemas were discovered in ASAN and Valgrind builds.

(Bug #29008688)

• A GROUP BY query with ROLLUP incorrectly raised ER_WRONG_FIELD_WITH_GROUP when used with an

ORDER BY clause that contained an expression.

The same issue also led to incorrect ordering of the result from a GROUP BY query with ROLLUP when

ordering on a function. (Bug #29006668, Bug #29054096)

• The parser accepted multiple COLLATE clauses in generated column definitions. It now accepts a single

COLLATE clause. (Bug #28997518)

• INSERT ... ON DUPLICATE KEY UPDATE could perform incorrect updates. (Bug #28995498, Bug

#93410)

References: This issue is a regression of: Bug #26188578.

• A damaged mysql.user table could cause a server exit. (Bug #28986737)

• Reading rows from the Performance Schema data_locks or data_lock_waits table could return an

unbounded number of rows during a scan, resulting in a server exit due to excessive memory allocation.

This situation now produces an error. (Bug #28977428, Bug #87748)

• Calculating the cost of materialization for a LATERAL join on an empty table led to an assertion. Now in

such cases, the query cost is reported as zero. (Bug #28976533)

• For debug builds, an invalid utf8 character in the comment string for a column type in CREATE or

ALTER DDL statements raised an assertion. (Bug #28972424, Bug #93321)

• The CMake check for tirpc headers now falls back to using pkgconfig, to enable finding the headers

on more Linux platforms. This requires that pkgconfig be installed. (Bug #28970313, Bug #93341, Bug

#28997093)

• mysqld could undergo an unplanned shutdown when a component in the WHERE clause of a subquery

was non-deterministic, in this particular case due to referencing a user variable that was also set in the

same statement. This issue is fixed by ignoring predicates having non-deterministic components.

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MySQL 8.0 Release Notes

In addition, since non-deterministic subqueries as a general rule should be evaluated per outer row,

these should not be targets for materialization strategy. This is prevented by not decorrelating the

non-deterministic predicates. When possible, the same strategy selection for non-semijoin and non-

deterministic subqueries is also now enforced. (Bug #28970261)

• ALTER TABLE statements to change a table storage engine could hang when user-level locks and

explicit table locks had been acquired earlier. (Bug #28966941)

• COUNT() with LIMIT ... OFFSET returned a different result from that obtained with other aggregate

functions used with this clause. (Bug #28961843)

• Extracting the value of the MYSQL_HOME environment variable could change the value of the variable

stored following MYSQL_HOME in the environment. (Bug #28960613)

• Item_subselect::walk_body() now walks FROM clauses. (Bug #28955358)

• An issue was uncovered in query plan for a query with the following two IN subqueries:

• A subquery with a derived table containing an outer reference to the topmost query

• A subquery with a derived table, which was not outer-correlated, was semijoined, and was not lateral.

For the second subquery: calculation of the map of dependencies neglected to exclude irrelevant lateral

tables, and wrongly included dependencies of the derived table in the first subquery. (Bug #28954838)

• An error generated while evaluating a constant expression in certain GROUP BY queries was not

checked for in a timely fashion. (Bug #28949452)

• When comparing a DATE or DATETIME value with a string MySQL first tries to convert the string to the

same type (DATE or DATETIME) and then to compare the two as values of that type. If this conversion

fails, MySQL raises an Incorrect date value warning and then falls back to comparing the values

as strings, which is the expected behavior. In some cases, even though the converted string did not

reflect a valid DATE or DATETIME value, no warning was issued so and it was compared with the DATE

or DATETIME value as a value of that type. Now in such cases, the converted string is always checked

for validity as a DATE or DATETIME before being compared, unless the ALLOW_INVALID_DATES server

SQL mode has been set explicitly. (Bug #28940878)

• Long client host names could cause unexpected server behavior. (Bug #28936359)

• Substitution of a large number of parameters in a single prepared statement could lead to excessive and

unnecessary reallocation of memory. This is fixed by having String::replace() use exponential

buffer growth as String::append() does. (Bug #28929977)

• The data dictionary cache could become out of sync with data dictionary contents due to failure to check

the result of a transaction-related operation. (Bug #28923782, Bug #93196)

• Determination of the number of online CPUs available to the mysqld process is now more accurate.

Thanks to Daniel Black for the contribution. (Bug #28907677, Bug #93144)

• The INFORMATION_SCHEMA.TABLES TABLE_COMMENT column reported the wrong error message due

to an invalid view. (Bug #28901919)

• After upgrading, the INFORMATION_SCHEMA.TABLES view reported “View 'view_name' references

invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them” for several

sys schema views. The upgrade process did not update the referencing view state. (Bug #28901821)

• Creating histograms for large tables (millions of rows) having many distinct column values took an

excessive amount of time.

352

MySQL 8.0 Release Notes

The fix make this process marginally slower for data sets with few distinct values and consumes slightly

more memory than previously, but for large data sets with many distinct values it is significantly faster.

(Bug #28888936)

• Upgrade from MySQL 5.7 to MySQL 8.0 failed for instances with a an InnoDB 4K page size due a key

length error that should be suppressed during upgrade. (Bug #28884503)

• An incorrectly configured keyring plugin could cause a server exit. (Bug #28876033)

• Two issues were found in cases involving use of the COUNT() function:

• When the argument passed to COUNT() was a nullable expression, it was possible for the function to

return an incorrect result.

• A query using COUNT() together with an EXISTS subquery returned an incorrect result.

(Bug #28857990, Bug #29240516)

• Commands for invoking ccache during MySQL builds were generated incorrectly. (Bug #28841612, Bug

#92927)

• Previously, for INSERT statements that listed insert column names multiple times, only the first

duplicated name was reported. Now, all duplicated names are reported. (Bug #28836669)

• When using ROLLUP, the GROUP BY may yield NULL in some rows. Expressions referencing any of

these rows could lose the NULL, producing an incorrect result. (Bug #28836345)

• After a failed attempt to open a table, attempts to discover the table from the storage engine did not

check for an error return, which could cause the server to hang if an error occurred. (Bug #28828450)

• The server could exit when trying to drop a user who had been granted a particular role. (Bug

#28817441)

• MySQL Router compilation failed if MySQL was configured with -DWITH_MYSQLX=0. (Bug #28811356)

• A function called during data dictionary upgrade temporarily modified the avoid_temporal_upgrade

parameter so that a check for old temporal types is always performed. Because multiple threads could

call the function concurrently, a check was added to ensure that the parameter value could be safely

modified during data dictionary upgrade. (Bug #28805429)

• An EXISTS subquery is converted to a semijoin operation. The optimizer chooses a materialization

lookup strategy for this semijoin, but because the subquery is not correlated with the outer query block,

there were no keys to use for the lookup, which caused the parent query to fail. To solve this issue, we

use two equal constant items as keys, to ensure that the materialized query gets the constant as a key

(and so that the materialized table consists of at most one row). (Bug #28805105)

• The Last_query_cost status variable now shows the cost of queries which contain multiple blocks

such as subqueries or unions. (Previously, this variable was set only for simple queries consisting of a

single query block.) (Bug #28786951)

• The message displayed by mysqld when a fatal signal occurred has been simplified and made more

informative. It also does not display the calculation of memory usage, which had become out of date and

inaccurate. (Bug #28773322, Bug #92731)

• The skip_name_resolve system variable could be persisted using SET PERSIST_ONLY to enable it,

but not to disable it. (Bug #28749668)

353

MySQL 8.0 Release Notes

• Removed obsolete and unnecessary condition pushdown handling in iterators except where required by

single table update and delete queries. (Bug #28745859)

• IS NOT NULL predicates are added as part of early filtering of NULL for ref access performed by the

Optimizer. For queries having a star-join topology, redundant duplicates of these predicates were added,

which made evaluation of affected WHERE conditions less efficient. (Bug #28727717)

• CMake could generate an incorrect order of system includes when MySQL was configured to use the

bundled version of a system library. (Bug #28727631, Bug #92615)

• Some numeric operations involving double to long long conversions could return different results on

Windows and Linux. (Bug #28706832)

• An attempt to access a null pointer could occur during prepared statement execution. (Bug #28692136)

• FROM_UNIXTIME() returned an out-of-range value if passed an argument that, when rounded up,

exceeded the epoch value. Now it returns NULL as for other out-of-range values. (Bug #28671811, Bug

#92501)

• A replicated DDL operation could result in a 'duplicate entry on primary key' error during recovery on

servers started with the slave_parallel_workers system variable. (Bug #28670843)

• Empty host names in accounts could cause the server to misbehave. (Bug #28653104)

• The MySQL 5.7 to MySQL 8.0 upgrade process did not check for the existence of tablespace files, which

could result in an inconsistent data dictionary. (Bug #28642608)

• Type casting of ENUM behaved differently in subqueries than not in subqueries. (Bug #28547906, Bug

#92173)

• Statements that caused truncation of floating-point values could be executed as prepared statements

even when the server SQL mode included STRICT_TRANS_TABLES. In addition, if the binary logging

mode was MIXED, such statements were propagated to the slave, where they caused errors. (Bug

#28546855)

• Reducing the value of thread_cache_size at runtime did not reduce the size of the thread cache.

(Bug #28508923, Bug #92024)

• Some error messages still referred to the PASSWORD() function, which has been removed. (Bug

#28498714)

• The Aborted_connects status variable was not incremented for unsuccessful connection attempts, if

connections were managed by the thread_pool plugin. (Bug #28490126)

• mysqladmin shutdown did not wait for mysqld to shut down. (Bug #28466137, Bug #91803)

References: This issue is a regression of: Bug #25364806.

• Specifying CURRENT_USER as the user in GRANT statements could fail. (Bug #28454014)

• Repeated invocations of stored procedures which executed queries undergoing short-circuit evaluation

were not always handled correctly. (Bug #28379655)

• Keyring migration should require only read access to the source keyring, but failed unless the user had

write access. (Bug #28339014)

• If a user performing a keyring migration did not have write access to the keyring file, the migration failed

but reported success in its final error log message. (Bug #28330922)

354

MySQL 8.0 Release Notes

• During FLUSH STATUS execution, the Performance Schema unnecessarily aggregated session status to

global status, causing double counts for some status variables. (Bug #28291258, Bug #91541)

• mysql_secure_installation no longer attempts to read a password from the .mysql_secret file.

This was created by mysql_install_db, a program that has been removed. (Bug #28235716, Bug

#91270)

• Some status variable values could temporarily increase before returning to their original value. (Bug

#27839644, Bug #90351)

• Client programs did not exit if --ssl-fips-mode was given but FIPS mode could not be set to the

specified option value. (Bug #27809371)

• Executing ALTER INSTANCE ROTATE INNODB MASTER KEY and migrating keys from the

keyring_file plugin to the keyring_encrypted_file plugin could make encrypted tables

unusable. (Bug #27760952)

• When upgrading from MySQL Community to Commercial, the root password prompt was shown even

when the data directory existed. (Bug #27741998)

• In the client/server protocol, malformed packets for prepared statements could go undetected and cause

an assertion to be raised. (Bug #27627731)

• Changes were made in session connect and disconnect handling for threads in order to speed up

query throughput when using the X Plugin. Previously, a session (Srv_session) was attached to and

detached from the current thread with every command; now, this thread switch takes place only when

disconnecting the current session, or when the current thread and the thread being attached to belong to

different plugins. (Bug #27463277)

• The PERSIST and PERSIST_ONLY keywords were reserved by mistake. They are now nonreserved

keywords. (Bug #25220656)

• Installing and uninstalling a plugin concurrently with client connection activity could cause a server exit.

(Bug #22980441)

• The LOAD_FILE() function could fail for files for which stat() should be considered only advisory,

such as files under /proc. (Bug #18394503, Bug #72027)

• A query using an ORDER BY clause failed silently when the table being queried had an implicit full-

text index and the sort buffer was of insufficient size to contain the sorted keys. (Bug #93241, Bug

#28940361)

• A loadable function returning a string value now sets an explicit return type. Depending on the

arguments passed to the function, this is one of VARCHAR, MEDIUMBLOB, or LONGBLOB. (Bug #92890,

Bug #28828169)

• Made a comparison in the internal method Item_result::item_cmp_type() more efficient. Our

thanks to Daniel Black for the contribution. (Bug #92784, Bug #28796107)

• A windowing function employed in an arithmetic expression produced an incorrect result when the query

containing it used DISTINCT. (Bug #92503, Bug #28672483)

• Some queries involving complex joins leaked file handles. (Bug #90902, Bug #28039829)

• Fedora packaging now supports Fedora 30.

• Ubuntu 14.04 and SLES 11 are EOL, and no longer supported.

355

MySQL 8.0 Release Notes

Changes in MySQL 8.0.15 (2019-02-01, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Bugs Fixed

• InnoDB: After a checkpoint operation persisted modifications to data dictionary metadata, there was

potential for new metadata changes to be lost under certain circumstances. (Bug #29120297)

• Group Replication: Group Replication was unable to function in MySQL 8.0.14 if IPv6 support was

disabled at the operating system level, even if the replication group did not use any IPv6 addresses.

(Bug #29249542, Bug #94004)

• If MySQL was running on the host system and within Docker, it was not possible to update or remove

MySQL on the host system. (Bug #28244773, Bug #91405)

Changes in MySQL 8.0.14 (2019-01-21, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• Audit Log Notes

• Compilation Notes

• Component Notes

• Configuration Notes

• Deprecation and Removal Notes

• SQL Function and Operator Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Pluggable Authentication

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• Thread Pool Notes

• X Plugin Notes

• Functionality Added or Changed

356

MySQL 8.0 Release Notes

• Bugs Fixed

Account Management Notes

• Previously, each MySQL user account was permitted to have a single password. MySQL now permits

an account to have dual passwords, designated as primary and secondary passwords. This capability

enables phased password changes to be performed seamlessly in complex multiple-server systems,

without downtime. To support dual-password capability, the ALTER USER and SET PASSWORD

statements now have a RETAIN CURRENT PASSWORD clause that saves the current password as the

secondary password when you assign an account a new primary password. ALTER USER also has

a DISCARD OLD PASSWORD clause to discard a secondary password that is no longer needed. See

Password Management.

Important

The implementation of dual-password capability involves a change to the

structure of the mysql.user system table. If you upgrade to this MySQL release

from an earlier version, you must run mysql_upgrade (and restart the server) to

incorporate this system database change. Until this is done, password changes

are not possible.

(WL #11540)

Audit Log Notes

• The audit API now enables applications to add their own message events to the audit log using the new

audit_api_message_emit component, which includes an audit_api_message_emit_udf()

loadable function. See The Audit Message Component. (WL #11542)

Compilation Notes

• The minimum version of the Boost library for server builds is now 1.68.0. (Bug #28478497)

Component Notes

• A new host_application_signal component service is available to enable components to deliver

signals to the host application. For example, the service enables replication components to send a

shutdown signal to the server. (WL #12003)

Configuration Notes

• Previously, the COMPILATION_COMMENT CMake option was used by the server (for example, to set

the version_comment system variable) and by other programs. However, when the value contained

the word “server”, it was inappropriate for use by other programs. The server now uses the new

COMPILATION_COMMENT_SERVER option. Other programs continue to use COMPILATION_COMMENT.

(Bug #28888510)

• The content of the .gitignore file has been cleaned up. Much of this file was inherited from its

.bzrignore predecessor and was not relevant. One implication of this cleanup is that in-source builds

are disallowed. (Bug #28341794, Bug #91626)

• MySQL Server now permits a TCP/IP port to be configured specifically for administrative connections.

This provides an alternative to the single administrative connection that is permitted on the network

interfaces used for ordinary connections even when max_connections connections are already

established. The administrative network interface has these characteristics:

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MySQL 8.0 Release Notes

• The interface is enabled only if the admin_address system variable is set at startup to indicate the IP

address for it. If admin_address is not set, the server maintains no administrative interface.

• The admin_port system variable specifies the interface TCP/IP port number (default 33062).

• There is no limit on the number of administrative connections, but connections are permitted only for

users who have the SERVICE_CONNECTION_ADMIN privilege.

• The create_admin_listener_thread system variable enables DBAs to choose at startup

whether the administrative interface has its own separate thread. The default is OFF; that is, the

manager thread for ordinary connections on the main interface also handles connections for the

administrative interface.

Thanks to Facebook for suggesting the idea (and for contributing code, although it was not used). (Bug

#27847672, Bug #90395, WL #12138)

Deprecation and Removal Notes

• The deprecated resolveip and resolve_stack_dump utilities have been removed and are

no longer included in MySQL distributions. nslookup, host, or dig can be used instead of

resolveip. Stack traces from official MySQL builds are always symbolized, so there is no need to use

resolve_stack_dump. (WL #12619, WL #12620)

SQL Function and Operator Notes

• The JSON_ARRAYAGG() and JSON_OBJECTAGG() aggregate functions now can be used as window

functions, if an OVER clause is present. See Aggregate Function Descriptions. (WL #11574)

Logging Notes

• A new system variable, log_slow_extra, if enabled, causes the server to write additional fields to slow

query log lines that provide information about slow statements. In addition, SET lines written to the log to

indicate statement timestamps now use the time from the beginning of statement execution, rather than

the time at the end of execution. See The Slow Query Log. Thanks to Facebook for the contribution on

which this feature is based. (Bug #27535580, Bug #89637, WL #12393)

• Binary log files and relay log files can now be encrypted, helping to protect these files and the potentially

sensitive data contained in them from being misused by outside attackers, and also from unauthorized

viewing by users of the operating system where they are stored.

You enable encryption on a MySQL server by setting the new binlog_encryption system variable

to ON. OFF is the default. The system variable sets encryption on for binary log files and relay log files.

When you first start the server with encryption enabled, a new binary log encryption key is generated

before the binary log and relay logs are initialized. This key is used to encrypt a file password for each

binary log file (if the server has binary logging enabled) and relay log file (if the server has replication

channels), and further keys generated from the file passwords are used to encrypt the data in the files.

If you activate encryption while the server is running, a new binary log encryption key is generated at

that time, and the binary log files and relay log files are rotated so that the new and subsequent files

are encrypted. If you deactivate encryption by changing the binlog_encryption system variable

to OFF, the binary log file and relay log files are rotated immediately and all subsequent logging is

unencrypted. Previously encrypted files are not automatically decrypted, but the server is still able to

read them. (The SHOW BINARY LOGS statement now shows whether each binary log file is encrypted

or unencrypted.) SUPER privileges or the new BINLOG_ENCRYPTION_ADMIN privilege are required to

activate or deactivate encryption while the server is running.

358

MySQL 8.0 Release Notes

The encryption algorithm used for the files, the AES (Advanced Encryption Standard) cipher algorithm, is

built in to MySQL Server and cannot be configured. The binary log encryption keys used to encrypt the

file passwords for the log files are 256-bit keys that are generated specifically for each MySQL server

instance using MySQL Server's built-in keyring service. The binary log encryption key that is currently in

use on the server is called the binary log master key.

The new binlog_rotate_encryption_master_key_at_startup system variable controls

whether the binary log master key is automatically rotated when the server is restarted. If this system

variable is set to ON, a new binary log encryption key is generated and used as the new binary log

master key whenever the server is restarted. If it is set to OFF, which is the default, the existing binary

log master key is used again after the restart.

Note that when encryption is active for a MySQL server instance, only the data at rest that is written to

the binary log files and relay log files is encrypted. The data in motion in the replication event stream,

which is sent to MySQL clients including mysqlbinlog, is always in unencrypted format, so it must be

protected in transit by the use of connection encryption. The data in use that is held in the binary log

transaction and statement caches during a transaction, and any data that exceeds the space available

in those caches and is therefore stored in a temporary file on disk, is also in unencrypted format. The

temporary files and caches are deleted when the thread that handles the transaction ends. (WL #10957)

• Server logging behavior has changed with respect to error log messages generated prior to processing

startup options that specify logging configuration. Previously, the server generated messages with the

default timestamp, format, and verbosity level; buffered them; and then flushed them after the error log

configuration became known. Because these early messages used the default logging configuration,

they could differ from what is specified by the startup options.

Now, the server buffers log events rather than formatted log messages. This enables it to retroactively

apply configuration settings to those events after the settings are known, with the result that flushed

messages use the configured settings, not the defaults. For more information, see Error Log Output

Format. (WL #11875)

Optimizer Notes

• Previously, derived tables and common table expressions could not contain outer references. Outer

references are now permitted. (WL #461)

Packaging Notes

• Ubuntu 18.10 and Fedora 29 install OpenSSL 1.1.1 by default, but OpenSSL 1.1.1 is not fully supported

by MySQL. To install MySQL, the OpenSSL 1.0.2 compatibility package must be installed. (Bug

#28981868)

Performance Schema Notes

• The Performance Schema statement event tables (events_statements_current,

events_statements_history, and events_statements_history_long) now have a

STATEMENT_ID column that indicates the query ID maintained by the server at the SQL level. Column

values are unique for the server instance because they are generated using a global counter that is

incremented atomically. (WL #12165)

Pluggable Authentication

• If the LDAP port number is configured as 636 or 3269, the plugin now uses LDAPS (LDAP over SSL)

instead of LDAP. The port number is settable using the authentication_ldap_sasl_server_port

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MySQL 8.0 Release Notes

or authentication_ldap_simple_server_port system variable. (LDAPS differs from startTLS.)

(Bug #28743563)

• Previously, for LDAP authentication with proxying, LDAP authentication plugins used the first group

name returned by the LDAP server as the MySQL proxied user account name. The authentication

string for a MySQL account now can specify a list of groups to match, in preference order, and can

optionally map the matching group name to a specified MySQL proxied user name. See LDAP Pluggable

Authentication. (WL #12005)

Security Notes

• The OpenSSL libraries bundled with MySQL on some platforms (Windows, macOS, and Generic

Linux) have been upgraded to version 1.0.2q. On all other platforms, MySQL uses the system installed

OpenSSL. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html. (Bug #28988091)

• To affect subsequent server restarts, the SET PERSIST and SET PERSIST_ONLY statements enable

system variables to be persisted to the mysqld-auto.cnf option file in the data directory. However,

some system variables cannot be persisted (for example, because they involve sensitive data).

Consequently, they cannot be set at runtime from within a session conducted by a remote administrator,

and thus require the administrator to log into the server host and directly modify a my.cnf option file.

MySQL now permits users to perform runtime administration of many previously nonpersistible system

variables, so that they can be persisted under certain restrictive conditions. To enable this capability,

designate an SSL certificate X.509 Subject value that signifies the ability to persist these restricted

system variables, and set the new persist_only_admin_x509_subject system variable to that

Subject value. Users who connect to the server using an encrypted connection and supply an SSL

certificate with the designated Subject value then can use SET PERSIST_ONLY to persist persist-

restricted system variables. For more information, see Nonpersistible and Persist-Restricted System

Variables. (WL #12086)

• For most system variables, setting the session value requires no special privileges and can be done by

any user to affect the current session. For some system variables, setting the session value can have

effects outside the current session and thus is a restricted operation that can be done only by users

who have a special privilege. Previously, either SYSTEM_VARIABLES_ADMIN or SUPER qualified as

such a privilege, but both privileges also permit operations other than setting session variables. The new

SESSION_VARIABLES_ADMIN privilege makes it possible to grant users only the ability to set restricted

session variables without also enabling other operations.

Any operation permitted by SESSION_VARIABLES_ADMIN is also permitted by

SYSTEM_VARIABLES_ADMIN or SUPER, so any user who already has one of the latter

privileges effectively has SESSION_VARIABLES_ADMIN by implication and need not be

granted SESSION_VARIABLES_ADMIN explicitly. However, if a user has been granted

SYSTEM_VARIABLES_ADMIN or SUPER only for the purpose of enabling that user to modify restricted

session system variables, an administrator can reduce the user's privilege footprint by revoking

SYSTEM_VARIABLES_ADMIN and SUPER, and granting SESSION_VARIABLES_ADMIN instead. For

instructions, see System Variable Privileges.

These previously restricted session variables required SYSTEM_VARIABLES_ADMIN or SUPER but now

can also be set with SESSION_VARIABLES_ADMIN:

binlog_format

binlog_row_image

binlog_row_value_options

binlog_rows_query_log_events

debug

debug_sync

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MySQL 8.0 Release Notes

default_collation_for_utf8mb4

explicit_defaults_for_timestamp

gtid_next

histogram_generation_max_mem_size

original_commit_timestamp

sql_log_bin

sql_log_off

sql_require_primary_key

These previously unrestricted session variables now are restricted and setting them requires at least

SESSION_VARIABLES_ADMIN (they can also be set by users who have SYSTEM_VARIABLES_ADMIN

or SUPER):

auto_increment_increment

auto_increment_offset

binlog_direct_non_transactional_updates

bulk_insert_buffer_size

character_set_filesystem

character_set_database

collation_database

pseudo_slave_mode

pseudo_thread_id

rbr_exec_mode

transaction_write_set_extraction

(WL #12217)

Spatial Data Support

• The ST_Distance() function now takes an optional third argument enabling the unit for the

return value to be specified. Permitted units are those listed in the new INFORMATION_SCHEMA

ST_UNITS_OF_MEASURE table. See Spatial Relation Functions That Use Object Shapes, and The

INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table. (WL #11000)

SQL Syntax Notes

• A derived table now may be preceded by the LATERAL keyword to specify that it is permitted to refer

to (depend on) columns of preceding tables in the same FROM clause. A derived table specified with

LATERAL can occur only in a FROM clause, either in a list of tables separated with commas or in a join

specification (JOIN, INNER JOIN, CROSS JOIN, LEFT [OUTER] JOIN, or RIGHT [OUTER] JOIN).

Lateral derived tables make possible certain SQL operations that cannot be done with nonlateral derived

tables or that require less-efficient workarounds. See Lateral Derived Tables.

Note

LATERAL now is a reserved word and cannot be used as an identifier without

identifier quoting.

(WL #8652)

Thread Pool Notes

• The INFORMATION_SCHEMA tables that accompany the thread pool plugin have been migrated to be

available as Performance Schema tables. The INFORMATION_SCHEMA tables now are deprecated and

will be removed in a future MySQL version. Applications should transition away from the old tables to the

new tables. For example, if an application uses this query:

SELECT * FROM INFORMATION_SCHEMA.TP_THREAD_STATE;

The application should use this query instead:

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MySQL 8.0 Release Notes

SELECT * FROM performance_schema.tp_thread_state;

For more information, see Performance Schema Thread Pool Tables. (WL #11547)

X Plugin Notes

• X Plugin now includes the 5-digit SQLSTATE error code in its error handling class. Previously, the

SQLSTATE error code was returned to clients for SQL errors, but only the MySQL-specific error number

was exposed. (Bug #28735058)

• When querying collections of documents, if boolean values were used as arguments for a placeholder in

an SQL query, unexpected results were returned. A new translation specialization has now been added

for boolean values so that they are handled correctly in this situation. (Bug #28227037)

• X Protocol now always converts retrieved data to the utf8mb4 character set (using the

utf8mb4_general_ci collation) before returning it. (Bug #28180155)

• X Protocol now supports SQL prepare functionality. (WL #9270)

Functionality Added or Changed

• InnoDB: Disabling the innodb_buffer_pool_in_core_file variable reduces the size of core files

by excluding InnoDB buffer pool pages. To use this variable, the core_file variable must be enabled

and the operating system must support the MADV_DONTDUMP non-POSIX extension to madvise(),

which is supported in Linux 3.4 and later. For more information, see Excluding Buffer Pool Pages from

Core Files.

Thanks to Facebook for the contribution. (Bug #27724476, Bug #90144)

• InnoDB: By default, undo logs reside in two undo tablespaces that are created when the MySQL

instance is initialized.

Additional undo tablespaces can be created in a chosen location at runtime using CREATE UNDO

TABLESPACE syntax.

CREATE UNDO TABLESPACE tablespace_name ADD DATAFILE 'file_name.ibu';

Undo tablespaces created using CREATE UNDO TABLESPACE syntax can be dropped at runtime using

DROP UNDO TABLESPACE syntax.

DROP UNDO TABLESPACE tablespace_name;

ALTER UNDO TABLESPACE syntax can be used to mark an undo tablespace as active or inactive.

ALTER UNDO TABLESPACE tablespace_name SET {ACTIVE|INACTIVE};

A STATE column that shows the state of a tablespace was added to the

INFORMATION_SCHEMA.INNODB_TABLESPACES table. An undo tablespace must be in an empty state

before it can be dropped.

The previously deprecated innodb_undo_tablespaces variable is no longer configurable and will be

removed in a future MySQL version.

For more information, see Undo Tablespaces. (WL #9508)

• InnoDB: InnoDB now supports parallel clustered index reads, which can improve

CHECK TABLE performance. This feature does not apply to secondary index scans. The

362

MySQL 8.0 Release Notes

innodb_parallel_read_threads session variable must be set to a value greater than 1 for parallel

clustered index reads to occur. The default value is 4. The actual number of threads used to perform a

parallel clustered index read is determined by the innodb_parallel_read_threads setting or the

number of index subtrees to scan, whichever is smaller. (WL #11720)

• InnoDB: The ADD DATAFILE clause of the CREATE TABLESPACE statement is now optional, which

permits users without the FILE privilege to create tablespaces. A CREATE TABLESPACE statement

executed without an ADD DATAFILE clause implicitly creates a tablespace data file with a unique file

name. (WL #12236)

• InnoDB: When the innodb_dedicated_server variable is enabled, the size and number of log files

are now configured according to the automatically configured buffer pool size. Previously, log file size

was configured according to the amount of memory detected on the server, and the number of log files

was not configured automatically. See Enabling Automatic Configuration for a Dedicated MySQL Server.

(WL #12300)

• Replication: Two new session variables have been added for internal use by replication.

original_server_version and immediate_server_version support cross-version replication

by transmitting the MySQL server release numbers associated with a transaction through the replication

topology. original_server_version holds the MySQL Server release number of the server where

a transaction was originally committed (for example, 80014 for a MySQL 8.0.14 server instance).

immediate_server_version holds the MySQL Server release number of the server that is the

immediate master in a replication topology. If either of those servers, or another intervening server in the

replication topology, is at an older release that does not support these session system variables, their

values are set to 0.

With this information the slave can correctly process data originating from a master at an older release,

by recognizing where syntax changes or semantic changes have occurred between the releases

involved and handling these appropriately. The information can also be used in a Group Replication

environment where one or more members of the replication group is at a newer release than the

others. The value of the variable can be viewed in the binary log for each transaction (as part of the

Gtid_log_event, or Anonymous_gtid_log_event if GTIDs are not in use on the server), and could

be helpful in debugging cross-version replication issues. (WL #11879)

• Replication: When running a group in single-primary mode, in the event of a new primary being

elected while there were transactions held in the backlog to be applied, there was a chance

that a read operation against the new primary could return a stale value. Now, you can use the

group_replication_consistency variable to control how a group behaves in this situation. When

group_replication_consistency is set to EVENTUAL, a new primary responds to read requests

even when there is a backlog which has not yet been applied, which matches the previous behavior

and comes with the risk that a client could read old values while any backlog is being applied. Writes

to the new primary fail during this period because it is has super_read_only mode enabled. When

group_replication_consistency is set to BEFORE_ON_PRIMARY_FAILOVER, any new read or

write queries against a newly elected primary that is applying backlog from the old primary are held until

the backlog is applied. This ensures that clients always read the newest value which they have written,

but also means that clients might have to wait until the backlog has been applied before they can read

from the new primary. (WL #11123)

References: See also: Bug #26004894.

• Group Replication: The Group Communication System (GCS) and group communication engine

(XCom, a Paxos variant) for Group Replication now provide full support for IPv6, so replication

group members can use IPv6 addresses as an alternative to IPv4 addresses for internal group

communications. The localhost address for IPv6, and the private subnetwork addresses for IPv6

(unique-local addresses and link-local unicast addresses), are added to the automatic whitelist for Group

Replication for use if no manual whitelist is specified.

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MySQL 8.0 Release Notes

If all members of a replication group are at a MySQL server version that supports the use of IPv6

addresses for Group Replication, the group can contain a mix of members using IPv6 addresses and

members using IPv4 addresses. Joining members must provide whitelisted IP addresses or host names

that match the protocols offered by the seed members for connection, but the joining member's main

identifying address or host name (group_replication_local_address) can use either protocol.

If a member uses a host name that resolves to both an IPv4 and an IPv6 address, the IPv4 address is

always used for Group Replication connections.

If any or all existing members of a replication group use an older MySQL Server version without support

for the use of IPv6 addresses for Group Replication, joining members must present an IPv4 address

for group communications in the group_replication_local_address option. When every group

member has been upgraded, the group can be migrated to IPv6 addresses. (Bug #26088469, Bug

#27757729, Bug #90217, WL #11926)

• Group Replication: MySQL Group Replication can now communicate using a dedicated input channel

as an alternative to using a TCP socket. The new input channel uses shared memory for communication

between the Group Replication logic and the local instance of the underlying group communication

engine (XCom, a Paxos variant).

Previously, communication with the local XCom instance always took place using a TCP socket, namely

the network address that is specified by the group_replication_local_address system variable

for each group member. This incurred overheads that were unnecessary for local communication,

such as memory copying through the network protocol stack and data serialization. A TCP socket

(group_replication_local_address) is still required for each group member to communicate with

remote XCom instances. The Group Communication System (GCS) component of Group Replication

now selects the most appropriate communication method for each Group Replication task, either the

input channel or TCP. For example, the process of joining a group requires communication with a remote

XCom instance, so TCP must be used. However, the process of removing a member from a group only

requires communication with the local XCom instance, so the input channel is used. The input channel is

selected wherever possible to minimize the overheads associated with communication using networking

mechanisms. (WL #9850)

• Microsoft Windows: The access control granted to clients on the named pipe created by the MySQL

server now is set to the minimum necessary for successful communication on Windows. Newer MySQL

client software can open named pipe connections without any additional configuration. If older client

software cannot be upgraded immediately, the new named_pipe_full_access_group server

system variable can be used to give a Windows group the necessary permissions to open a named pipe

connection. Membership in the full-access group should be restricted and temporary. (WL #12445)

• The minimal server RPM is mostly used for Docker images. For better Docker compatibility, the log-

error line has been removed from the rpm-docker configuration file. This way, logging goes to

stdout/stderr, enabling use of Docker's own interface. (Bug #28692675)

• Error messages relating to creating and dropping foreign keys were improved to be more specific and

informative. (Bug #28526309, Bug #92087)

• The error message for ALTER TABLE statements that attempted character set conversion but failed was

improved to indicate which column produced the error. (Bug #27546306, Bug #88738)

• Previously, for command options that take a numeric value, the value could be given with a suffix of K,

M, or G to indicate a multiplier of 1024, 1024

or 1024

. Now a suffix can also be T, P, and E to indicate a

multiplier of 1024

, 1024

or 1024

. Thanks to Daniel Black for the patch. (Bug #27306931, Bug #89017)

• Resource group locking was revised to improve scalability and performance. (Bug #27148580)

364

MySQL 8.0 Release Notes

• The startup option --binlog-row-event-max-size now has a corresponding system variable

binlog_row_event_max_size. The startup option and system variable set a soft limit on the

maximum size of a row-based binary log event, with a default setting of 8192 bytes. Where possible,

rows stored in the binary log are grouped into events with a size not exceeding the value of this setting. If

an event cannot be split, the maximum size can be exceeded.

The binlog_row_event_max_size global system variable is read-only and can be set only at

server startup. Its value can therefore only be modified by using the PERSIST_ONLY keyword or the

@@persist_only qualifier with the SET statement. The addition of a system variable means that

this setting can be viewed using the Performance Schema tables or a SHOW VARIABLES or SELECT

statement. (Bug #19985377, Bug #74728, WL #12385)

• ALTER TABLE now can be used to change a column character set in place (without a table rebuild),

when these conditions apply:

• The column data type is CHAR, VARCHAR, a TEXT type, or ENUM.

• The character set change is from utf8mb3 to utf8mb4, or any character set to binary.

• There is no index on the column.

(WL #11605)

• The new -DFORCE_INSOURCE_BUILD CMake option defines whether to force an in-source build. Out-of-

source builds are recommended, as they permit multiple builds from the same source, and cleanup can

be performed quickly by removing the build directory. To force an in-source build, invoke CMake with -

DFORCE_INSOURCE_BUILD=ON.

Bugs Fixed

• Important Change: Importing a dump from a MySQL 5.7 server to a server running MySQL 8.0 often

failed with ER_WRONG_VALUE_FOR_VAR when an SQL mode not supported by the 8.0 server was used.

This could happen frequently due to the fact that NO_AUTO_CREATE_USER is enabled by default in

MySQL 5.7 but not supported in MySQL 8.0.

The behavior of the server in such circumstances now depends on the setting of the

pseudo_slave_mode system variable. If this is false, the server rejects the mode setting with

ER_UNSUPPORTED_SQL_MODE. If pseudo_slave_mode is true, the server ignores the unsupported

mode and gives a warning. Note that mysqlbinlog sets pseudo_slave_mode to true prior to

executing any SQL. (Bug #90337, Bug #27828236)

• InnoDB: Global and backup metadata locks were not released after the background purge thread

truncated undo logs. (Bug #29215254, Bug #93901)

• InnoDB: MySQL would not start on Solaris X86. The static thread-local 'tables' variable in the

TempTable storage engine was not properly initialized. (Bug #28987365)

• InnoDB: Latching logic used during deadlock detection was simplified. (Bug #28904966)

• InnoDB: An invalid record offset for an old version of a clustered index record raised a debug assertion.

(Bug #28825617)

References: This issue is a regression of: Bug #25540277.

• InnoDB: The minimum DML delay imposed when the length of the history list exceeds

innodb_max_purge_lag was decreased from 5000 microseconds to 5 microseconds. (Bug

#28813453)

365

MySQL 8.0 Release Notes

• InnoDB: An incorrect lock order caused a deadlock when one thread attempted to drop a table while

another created an encrypted tablespace. (Bug #28774259)

• InnoDB: ALTER TABLESPACE failed to ignore unsupported tablespace attributes. (Bug #28656611)

• InnoDB: Implicit to explicit lock conversion logic was simplified and optimized. (Bug #28637472)

• InnoDB: A fragment page allocation failure raised an assertion. (Bug #28615893)

• InnoDB: Incorrectly placed debug points caused flushed LOB pages to be considered corrupt. (Bug

#28607368)

• InnoDB: The TempTable storage engine incorrectly created temporary files in the system temporary

directory instead of the directory defined by the tmpdir variable. (Bug #28598943)

• InnoDB: Attempting to drop a table with a name similar to that of a full-text search auxiliary table caused

an assertion failure. (Bug #28577083)

• InnoDB: A function called by an UPDATE query did not account for virtual columns. (Bug #28560650)

• InnoDB: An incorrect key was defined for the buffer pool zip hash mutex. (Bug #28556539)

• InnoDB: Deadlock handling for background transactions that involve the

mysql.innodb_table_stats and mysql.innodb_index_stats tables was modified. The tables

were incorrectly included in an assertion that is triggered when internal tables are included in a deadlock

cycle. (Bug #28523042, Bug #92069)

• InnoDB: Setting innodb_spin_wait_delay to a high value caused an assertion failure

when attempting to shut down the server. To prevent this failure from occurring, the

innodb_spin_wait_delay maximum value was reduced to 1000. (Bug #28489407, Bug #91973)

• InnoDB: An ON DELETE CASCADE operation on table with a foreign key constraint and an indexed

virtual column caused the server to exit. (Bug #28470805)

• InnoDB: An incorrectly written DML log involving a virtual column value raised an assertion. (Bug

#28448853)

• InnoDB: A RENAME TABLE operation failed when run on a table created outside of the MySQL data

directory using the DATA DIRECTORY clause. (Bug #28341514)

• InnoDB: ALTER TABLE ... EXCHANGE PARTITION permitted partitions with different virtual column

definitions to be exchanged, which resulted in an assertion when InnoDB later attempted to read from a

nonexistent virtual column. (Bug #28235668)

• InnoDB: A counter was added for redo log write and flush requests that occur during transaction

commit. The counter is used by the log writer thread to compute the average time between consecutive

requests. When the average time is greater than 100 microseconds, log writer threads do not use spin

delay and instead wait on request events with a 10 microsecond timeout limit.

A log writer thread implementation issue that could cause a hang was also fixed. (Bug #28062382, Bug

#28444247, Bug #28616442, Bug #90890)

• InnoDB: An assertion was raised when attempting to add rollback segments to newly added undo

tablespace that was not fully initialized. (Bug #27914054)

• InnoDB: Foreign key constraints were ignored after a RENAME TABLE operation. (Bug #27453180, Bug

#89441)

• InnoDB: Using the O_DIRECT_NO_FSYNC innodb_flush_method setting could cause the system

to hang due to file system metadata becoming unsynchronized. To prevent this issue from occurring in

366

MySQL 8.0 Release Notes

O_DIRECT_NO_FSYNC mode, InnoDB now calls fsync() after creating a new file, after increasing file

size, and after closing a file. The fsync() system call is still skipped after each write operation. (Bug

#27309336)

• InnoDB: Specifying the CREATE TABLE or ALTER TABLE ENCRYPTION option with an empty string

failed to raise an error and was interpreted as a default setting, which is ENCRYPTION='N'. Specifying

an empty string is now treated as invalid and raises an error. (Bug #27177845)

• InnoDB: Partitioned table name delimiters (the #P# or #SP# part of a partitioned table name) were not

converted to lowercase when moving tablespace data files from a MySQL instance on Windows to a

MySQL instance on Linux where the lower_case_table_names variable was enabled. Failure to fully

convert names to lowercase caused errors such as “'InnoDB error' from storage engine” when attempting

to alter, rename, or optimize the tables. (Bug #26925260)

• InnoDB: An assertion was raised when attempting to write to a tablespace file greater than 4GB in size

on a 64-bit Windows system. The failure was due to a narrowing cast. (Bug #26636815, Bug #87423)

• InnoDB: After attempting to create a table with a foreign key constraint that referenced a partitioned

table, which is an unsupported operation, SHOW ENGINE INNODB STATUS output incorrectly reported

a foreign key error indicating that the referenced table name could not be resolved. This error no longer

appears, and the error message returned to the client now states that foreign keys are not yet supported

in conjunction with partitioning. (Bug #25319071, Bug #84331)

• InnoDB: Misleading error messages were reported for unsupported foreign key operations, including

creating a foreign key that referenced a partitioned table, and referencing a table that uses a storage

engine that does not support foreign keys. The error messages are now more informative. (Bug

#11747571, Bug #33027)

• Partitioning: Trying to perform an instant add column on a discarded tablespace led to an assert. An

error is now returned in such cases. (Bug #28517843)

• Partitioning: Repeated ALTER TABLE statements on partitioned tables containing BLOB or TEXT

columns were not always handled correctly. (Bug #28491099)

• Partitioning: ALTER TABLE ... EXCHANGE PARTITION did not work when the partitioned table had

one or more partition definitions using the DATA DIRECTORY option. This fix supports partitioned tables

using the InnoDB storage engine only. (Bug #19730200)

• Replication: Depending on the value of group_replication_exit_state_action,

the behavior of members exiting a group was not consistent. To harmonize the behavior

of members exiting the group regardless of the error scenario, now when a member with

group_replication_exit_state_action=READ_ONLY exits the group unintentionally, the

super_read_only mode that the member had when started is restored. This makes the behavior

consistent with that of a member with group_replication_exit_state_action=ABORT_SERVER.

(Bug #28971639, Bug #28526591)

• Replication: The metadata written to the binary log for CREATE TABLE statements includes character

set information for the character columns in the table. Previously, when the mysqlbinlog option --

print-table-metadata was specified, a default character set was printed for the table. This default

character set was the character set that appeared most frequently in the table columns, and might

not match the default character set that had been specified for the table. mysqlbinlog now prints

the character set for each column individually. The columns are also printed on separate lines. (Bug

#28774144)

• Replication: Character set information was not written to the binary log as part of the table metadata

for ENUM and SET columns. This information is now added when binlog_row_metadata=FULL is set,

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MySQL 8.0 Release Notes

which produces extended metadata. (For character columns, character set information is also added

with binlog_row_metadata=MINIMAL.) (Bug #28706307)

• Replication: A patch to correct the handling of quotes for identifiers in ROLLBACK TO SAVEPOINT

statements in the binary log was not correctly applied to subsequent MySQL versions. (Bug #28569645)

• Replication: Following a patch in MySQL 5.7.23, LOAD DATA statements stopped statement-based

replication from a MySQL 5.7.22 master to a replication slave at a later release. The problem has now

been fixed. (Bug #28541204, Bug #92132)

• Replication: In some circumstances, the CHANGE MASTER TO statement could not

be used on a replication slave if the master info log had been changed from a table

(master_info_repository=TABLE) into a file (master_info_repository=FILE). (Bug

#28529558)

• Replication: mysqlbinlog incorrectly added statements to set the sql_require_primary_key

system variable (which was introduced in MySQL 8.0.13) to ON for events involving DML SQL

statements. The check carried out when the system variable is set to ON is only relevant for DDL SQL

statements that create new tables or alter the structure of existing tables. (Bug #28524803)

• Replication: When the system variables binlog_transaction_dependency_tracking and

binlog_transaction_dependency_history_size were set or read, the types of lock that were

required could result in a deadlock scenario, because the same locks were also required for working with

the active binary logs. A new lock type is now used instead for access to the transaction dependency

tracking system variables, so that this deadlock cannot occur. (Bug #28511326, Bug #91941, Bug

#28537209, Bug #92108)

• Replication: An assertion was raised in debug builds if an implicit commit was

attempted when the GTID value for the next transaction had not yet been determined

(gtid_next=NOT_YET_DETERMINED). The gtid_next system variable has this value

immediately after the internal-use statement BINLOG has been issued by mysqlbinlog

to execute a format description event. If a statement with an implicit commit was attempted

next (such as a CREATE TABLE statement), the gtid_next setting did not transition to

AUTOMATIC state, and was left in an unacceptable state. If autocommit was on, the error

ER_CANT_SET_GTID_NEXT_TO_ANONYMOUS_WHEN_GTID_MODE_IS_ON was also logged when the

statement was attempted.

To fix this issue, the use of the BINLOG statement is now prevented during transactions if it would

change the state of gtid_next. The error ER_VARIABLE_NOT_SETTABLE_IN_TRANSACTION

is returned if this is attempted. Also, when GTIDs are in use and the value of

gtid_next is NOT_YET_DETERMINED, the next statement must either explicitly set

gtid_next to a valid value or leave the GTID state unaffected. Otherwise the error

ER_CANT_SET_GTID_NEXT_TO_ANONYMOUS_WHEN_GTID_MODE_IS_ON is returned. (Bug #28490793,

Bug #91980)

• Replication: The PURGE BINARY LOGS TO 'log_name' statement failed for binary log files that had

been moved to another location using mysqlbinlogmove. Such files are still listed in the binary log

index file, but they are listed using an absolute path, rather than a path relative to the directory where

the binary log files are normally stored. MySQL Server can now locate and purge moved binary log files

successfully. (Bug #28284624)

• Replication: When binlog_format is set to MIXED, if a function contained DML statements that

applied to a temporary table, and also a DROP TEMPORARY TABLE statement, the function call was not

written to the binary log, which caused replication errors. The function call is now written to the binary

(Bug #28258992)

368

MySQL 8.0 Release Notes

• Replication: If autocommit was set to 0 for a replication slave or Group Replication group member

where GTIDs were in use and super_read_only=ON was set, server shutdown was prevented

by a transaction that did not complete. The transaction was attempting to save GTIDs to the

mysql.gtid_executed table, but the update failed because super_read_only=ON was set. (With

autocommit set to 1, the transaction would complete in this situation, and the mysql.gtid_executed

table would instead be updated at server startup.) Now, the check for the super_read_only setting is

skipped for this task, so the transaction is able to save the GTIDs to the mysql.gtid_executed table

and complete regardless of the combination of super_read_only and autocommit settings. (Bug

#28183718)

• Replication: An assertion was raised in debug builds if an XA ROLLBACK statement was issued for an

unknown transaction identifier when the gtid_next value had been set manually. The server now does

not attempt to update the GTID state if an XA ROLLBACK statement fails with an error. (Bug #27928837,

Bug #90640)

• Replication: An assertion was raised in debug builds if a SELECT... FOR UPDATE statement

was issued immediately after a transaction was committed or rolled back, and the transaction had

been assigned a GTID manually using the gtid_next session system variable. After gtid_next has

been used to set a GTID for a transaction, and the transaction has been committed or rolled back,

another explicit SET GTID_NEXT statement must be issued before any other statement, otherwise

the gtid_next value is left undefined. The SELECT... FOR UPDATE statement caused a GTID

consistency violation in this situation because it acquired write locks, although it did not make any

changes. SELECT... FOR UPDATE statements that acquire write locks now return an error in this

situation. (Bug #27903848, Bug #90547)

• Replication: Under heavy loads, a race condition in binary log group commit could cause the server to

stop unexpectedly. The tracking of transaction commits has been changed to prevent this situation. (Bug

#27556117)

• Replication: The value returned by a SHOW SLAVE STATUS statement for the total combined size of

all existing relay log files (Relay_Log_Space) could become much larger than the actual disk space

used by the relay log files. The I/O thread did not lock the variable while it updated the value, so the SQL

thread could automatically delete a relay log file and write a reduced value before the I/O thread finished

updating the value. The I/O thread then wrote its original size calculation, ignoring the SQL thread's

update and so adding back the space for the deleted file. The Relay_Log_Space value is now locked

during updates to prevent concurrent updates and ensure an accurate calculation. (Bug #26997096, Bug

#87832)

• Replication: If the relay log index file was temporarily locked for viewing by a backup process for a

replication slave, and MySQL Server also attempted to access the file at that time for rename or delete

operations, the backup completed with warnings, but MySQL Server experienced an unexpected halt.

MySQL Server now retries the file access operation a number of times in case this or a similar scenario

is the explanation and the file becomes available again before long. (Bug #25839610)

• Replication: With sync_binlog=1 set, if the binary log was rotated during a commit before the binary

log end position was updated, replication stopped on the slave because the server attempted to use the

old binary log end position with the new binary log file. The server now compares the binary log file name

with the active binary log file when updating the binary log end position, so that the issue does not occur.

(Bug #22252394, Bug #25524203, Bug #84752)

• Replication: When adding a new member to a group, if the certification information was too big to

transmit, an event was generated that caused failures in all group members. To avoid this situation, now

if the certification information is too large an error is generated which makes the joining member leave

the group. (Bug #93130, Bug #91870, Bug #28900691, Bug #28443958)

369

MySQL 8.0 Release Notes

• Replication: When you used group_replication_switch_to_single_primary_mode(),

if a member which also had an asynchronous channel encountered an error, the asynchronous

replication channel was not stopped correctly, and the server could stop unexpectedly. (Bug #91747,

Bug #28382590)

• Replication: It was possible to use the group coordinator based functions which configure a group,

such as group_replication_switch_to_single_primary_mode, while members were in the

UNREACHABLE or RECOVERING state, and this caused the operation to wait until all members became

ONLINE. This could result in the group coordinator operation never completing successfully. Now, if

you invoke any of these functions on a group in this state, an error is returned. Ensure all members are

ONLINE before attempting to configure the group using the functions. (Bug #91537, Bug #28284355)

• Replication: When a member joined a group that had a constant peak load, the member might not be

able to move from the RECOVERING to the ONLINE state. The cause was that:

• the member was waiting in a loop for the complete queue of transactions that arrived during recovery

to be applied, while new transactions were still arriving.

• even when the complete queue had been applied, the member was also checking that the applier was

paused, which is unlikely to happen in a continuous peak workload.

Now, when the recovery completion policy is waiting for transactions to be applied, the member first

waits until one of the following conditions is fulfilled:

• the transactions to apply fit within the flow control configuration. In other words, the transactions to be

applied can be applied during the next flow control iteration;

• no transactions are being queued or applied, in the case of an empty recovery queue.

Then, the member waits for the currently queued transactions in the group_replication_applier

channel to be applied, before the member state changes to ONLINE. (Bug #89582, Bug #27511404)

• Group Replication: The maximum timeout setting for the waiting period before expelling a suspect

Group Replication group member has been reduced to 3600 seconds (one hour). Previously, the

group_replication_member_expel_timeout system variable could be set to a value of up to

31536000 seconds. The new upper limit provides a more reasonable maximum for the removal of

inactive members from the group. The default setting for the timeout is zero, meaning that inactive

members are liable for expulsion immediately after the 5-second detection period ends. Specifying a

timeout value is useful to avoid unnecessary expulsions on slower networks, or in the case of expected

transient network failures or machine slowdowns. (Bug #28656750)

• Group Replication: On systems where the Group Communication System (GCS) used the systemd-

resolved service for network name resolution, if the host name could not be resolved, GCS kept trying

indefinitely. Now, if a retry message is returned from any name resolution service, GCS makes a limited

number of retries, then concludes that the host name is unresolvable. (Bug #28177861)

• Group Replication: When a group was being reconfigured online, for example

using group_replication_switch_to_multi_primary_mode or

group_replication_set_as_primary, there was a chance that stopping a member could result

in an unexpected stop. Now, when you issue STOP GROUP_REPLICATION, if the member is part of

an online group that is being reconfigured, the group coordinator is informed that Group Replication is

stopping. The member waits for the online configuration process to complete any ongoing actions, but

any subsequent actions are cancelled. (Bug #92829, Bug #28807260)

• Group Replication: When stopping group replication, any channels with pending transactions could

cause a deadlock. (Bug #92376, Bug #28636768, Bug #28365855)

370

MySQL 8.0 Release Notes

• Group Replication: When group_replication_exit_state_action is set to ABORT_SERVER,

the Group Replication plugin now uses the new component service added by WL#12003 to shut down

MySQL. (Bug #91793, Bug #28401703)

• Microsoft Windows: MySQL Installer could fail after failure to remove an existing MySQL service. This

is now treated as nonfatal so that installation operations can continue, but might require a system restart

to permit service cleanup. (Bug #29016677, Bug #93048)

• Microsoft Windows: When multiple instances of mysqld were started with the --no-monitor option

on the same host for same user, the SHUTDOWN command shut down the wrong server process. This fix

creates a unique shutdown event name for use with --no-monitor by appending the process ID of the

process. (Bug #28723675)

• X DevAPI: When using the X Protocol, a stored procedure called with a user variable as an OUT

parameter did not set the variable's value. (Bug #91907, Bug #28458752)

• JSON: Iteration over JSON objects resulted in unnecessary allocation of strings. (Bug #28975640)

• JSON: Conversion of JSON values to text caused linear growth of the destination string, resulting in

an unnecessarily high number of reallocations. Now this process uses exponential growth instead, to

reduce the number of allocations required. (Bug #28949700)

References: See also: Bug #103790, Bug #32919524.

• JSON: YEAR values were stored as opaque data in JSON; when JSON documents containing YEAR

values were converted to text, the YEAR values were shown as base64-encoded strings. To resolve this

issue, YEAR values are now stored as unsigned integers, which are shown as numbers when converted

to text. An additional benefit of this fix is that less storage space is now required for YEAR values within

JSON documents. (Bug #28947107)

• JSON: Hit an assert when attempting to execute UPDATE or DELETE on an ARCHIVE table containing a

JSON column. (Bug #28923281)

• JSON: When trying to select from a JSON column of a FEDERATED table, the server returned

ER_INVALID_JSON_PATH_CHARSET Cannot create a JSON value from a string with

CHARACTER SET 'binary'.

In addition, neither DELETE or UPDATE had any effect on a FEDERATED table containing a JSON column.

(Bug #28877215)

• JSON: A query of the form SELECT jt.* FROM t1, JSON_TABLE(t1.c, '$[*]' COLUMNS (num

INT PATH '$[0]')) AS jt failed due a permissions error even though the user executing the query

had the SELECT privilege on column c. (Bug #23254268)

• The code contributed by Facebook for the feature implemented by Bug#27855592 was updated. (Bug

#28950397)

References: See also: Bug #27855592.

• On SuSE Linux, spurious EBUSY return values from pthread_mutex_destroy() were not handled.

(Bug #28948462)

• mysqld_safe and mysqld_multi were incorrectly included in client-only packages. (Bug #28942508)

• Mishandling of host cache locking could cause a server exit. (Bug #28936159)

• MySQL Enterprise Firewall did not work well if the audit_log plugin was installed. (Bug #28930885,

Bug #93184)

371

MySQL 8.0 Release Notes

• Corrections were made to enable successful builds under Visual Studio on Windows. (Bug #28892711,

Bug #93077)

• The server permitted creation of databases with the same name as redo log files, which could result in

unexpected server behavior. Such names are no longer permitted as database names. (Bug #28867993)

• mysqld_multi could fail to pass the correct datadir value to mysqld. (Bug #28866662, Bug #90801)

• A debug assertion that checks parameter schema names during MDL key creation for routines, events,

and triggers to ensure that names are lowercase failed when encountering a schema name that included

multi-byte character. (Bug #28864244)

• The format specifiers for some error messages were improved to avoid displaying incorrect numeric

values. (Bug #28860795)

• For debug builds on Windows, unused memory leak checks were enabled and could slow down the

shutdown process. These checks are now enabled only for specialized builds. (Bug #28857626)

• mysql_upgrade could fail to upgrade certain system tables if the sql_require_primary_key

system variable was enabled. (Bug #28855207, Bug #92988)

• Builds configured with -DWITH_LIBWRAP=ON did not compile. (Bug #28853650, Bug #92983)

• For InnoDB tables, the values of stored or indexed virtual generated columns that depended on the

DEFAULT() function were not correctly updated by ALTER TABLE, if the default for a column referenced

in this function was changed by making column nullable. (Bug #28848265)

• Corrections were made to enable successful builds under Visual Studio on Windows with the /

permissive flag turned on. (Bug #28842878, Bug #92943)

• Builds configured with -DCMAKE_BUILD_TYPE=Release did not compile. (Bug #28841366, Bug

#92945)

• ALTER TABLE now can use the INPLACE algorithm when these conditions apply:

• For InnoDB tables, statements that modify generated stored columns but do not change their type,

expression, or nullability.

• For non-InnoDB tables, statements that modify generated stored or virtual columns but do not change

their type, expression, or nullability.

An example of such a change is a change to the column comment. (Bug #28836543)

• Plugin system variables that had been persisted were not applied when the plugin was reinstalled. (Bug

#28823972)

• EXPLAIN ... FOR CONNECTION could modify another connection's SQL mode. (Bug #28786981)

• Removal of Sun RPC and XDR from glibc into a separate libtirpc library caused problems with

libasan on some platforms. (Bug #28785835, Bug #92762, Bug #28897799, Bug #93116)

• It was possible to hit an assert when comparing two ENUM values while processing a query of the form

SELECT a FROM table WHERE b = value and there was an index on column b. (Bug #28769996)

• Concurrent read and write access to the offline_mode system variable could result in deadlock. (Bug

#28761869)

• Triggers were loaded into memory in an incorrect order when upgrading from MySQL 5.7 to MySQL 8.0,

causing an assertion failure. (Bug #28760011, Bug #92609)

372

MySQL 8.0 Release Notes

• Joins involving the Performance Schema data_locks table could produce incorrect results. (Bug

#28733170)

• Some multiply-nested subqueries involving the use of scalar subqueries were not handled correctly.

(Bug #28723670)

• On Ubuntu, the installed /etc/mysql/mysql.conf.d/default-auth-override.cnf file was

mistakenly created with executable mode. Thanks to Evgeniy Patlan for the correction contribution. (Bug

#28714840, Bug #92587)

• A memory leak was caused by GET_LOCK() calls with a zero timeout that failed due to concurrent

connections holding the same user-level lock. (Bug #28714367)

• Heap corruption and a server exit could occur when a server hosting a large number of tables was

started and stopped repeatedly. (Bug #28705511, Bug #92572)

• MySQL Router was missing from MySQL Server MSI packages. (Bug #28685556)

• The example stored function GTID_SUBTRACT_UUID has been corrected in the code to match the

documented version. (Bug #28670170)

• CAP_SYS_NICE capability is no longer enabled for mysqld by MySQL package installers for Linux.

(This was done to facilitate use of resource groups thread priorities.) For Linux deployments that

require access to thread priorities, consult the MySQL Reference Manual instructions for enabling

CAP_SYS_NICE capability at Resource Group Restrictions. (Bug #28670160)

• The internal implementation of the <=> operator was simplified. (Bug #28660232)

• After a STOP GROUP_REPLICATION statement was issued to remove a server instance from a

group, multiple instances of the error message "[GCS] Error pushing message into group

communication engine" were logged on the server instance. The error is now ignored when a server

is in the process of leaving a group or is no longer a member of a group. (Bug #28658228, Bug #92454)

• If the CHARACTER SET attribute of some column was implicit in JSON_TABLE(... COLUMNS ...), the

resulting column used the global character_set_results as the default character set. The column

now uses the session character_set_connection and collation_connection values. (Bug

#28643862)

• Adding a functional index on an expression that produced a row value raised an assertion; now it results

in an error instead. (Bug #28643252)

• In debug builds, creating a trigger after setting sql-mode to TIME_TRUNCATE_FRACTIONAL caused

an assertion failure. The SQL mode was not present in the sql_mode column of the mysql.triggers

data dictionary table. (Bug #28642918)

• When using --log-timestamps=SYSTEM, ISO 8601 timestamps in log messages did not take account

of daylight saving time. (Bug #28632725, Bug #32893161)

• The arguments for error ER_IB_MSG_720 were computed incorrectly. (Bug #28629175)

• The server could exit at startup if the option for specifying a socket file was not specified correctly. (Bug

#28609181)

• It was possible to create an inconsistent foreign key by adding a parent table with a different storage

engine from the child table, then changing the parent table to the same storage engine as the child table.

(Bug #28608460, Bug #92317)

• When a server is joining a replication group, it attempts to connect to the first seed member listed in

its group_replication_group_seeds system variable. If the connection is refused, the joining

373

MySQL 8.0 Release Notes

member tries to connect to each of the other seed members in the list in order. Previously, If the joining

member connected to a seed member but did not get added to the replication group as a result, the

joining member did not make any further connection attempts. This situation could occur if the seed

member failed after the connection was made, or if the seed member did not have the joining member's

address in its whitelist and closed the connection, or if the seed member rejected the joining member's

request to join the group. Now, if the joining member connects to a seed member but does not manage

to join the group, the joining member continues to try the remaining seed members in the list in order.

(Bug #28602835)

• Given certain patterns of allocations, copies with rebinds of the allocator, and deallocations, it was

possible for temptable::Allocator to reuse a freed memory block. This led to failures in the test

suite on Windows platforms. (Bug #28595557)

• Setting time_zone to a negative offset and timestamp to a low value triggered an assertion when

altering routines and views. (Bug #28590623, Bug #92273)

• Persisting the pid_file system variable to DEFAULT could result in a value of NULL for subsequent

server startups. (Bug #28589736)

• Incorrect privilege checking could produce an error for SELECT ... FOR UPDATE statements that

executed successfully in MySQL 5.7. (Bug #28581664, Bug #92254)

• Attempting to rename the parent column of a foreign key with ALTER TABLE could fail. (Bug #28581468)

• Privileges for RESET PERSIST were not checked correctly. (Bug #28564239)

• An overflow occurred when calculating AVG(YEAR(datetime_column)). (Bug #28562930)

• After a server restart, path names of persisted system variables in the Performance Schema

variables_info table could be calculated incorrectly. (Bug #28561584)

• A partitioned table name check raised an invalid assertion. (Bug #28556942)

• The handler::create() function could be called with an error in the condition list, which could

prevent an error in the handler::create() function from being reported properly. (Bug #28556264)

• For ALTER TABLE, ALGORITHM=INSTANT was incorrectly rejected on tables created in a MySQL

version prior to 8.0.12. (Bug #28554157, Bug #92194)

• mysqlpump did not free all allocated resources when it encountered an error, resulting in memory leaks.

(Bug #28538971, Bug #92131)

• The COLLATE attribute was rejected for data types in the COLUMNS clause of the JSON_TABLE()

function. (Bug #28538315)

• For debug builds, the server could exit when attempting to roll back CREATE USER statements. (Bug

#28536312)

• Plugin variables with signed values were displayed incorrectly. (Bug #28534414, Bug #92107)

• Mishandling of deprecated system variables could cause output from queries on the Performance

Schema variables_by_thread table to be incorrect. (Bug #28515475, Bug #92049)

• Data races discovered by Thread Sanitizer in Event_queue::lock_data and the SAFE_MUTEX

implementation were fixed. (Bug #28510721, Bug #92041, Bug #28510691, Bug #92040)

• No ER_NEED_REPREPARE diagnostic was pushed to the diagnostics area when a reprepare failed for

prepared statements. (Bug #28509306, Bug #92029)

374

MySQL 8.0 Release Notes

• When a subquery contained a UNION, the count of the number of subquery columns was calculated

incorrectly. (Bug #28499924)

• When evaluating an expression using WITH ROLLUP, we now write the result of the expression into a

temporary table only when it has a temporary table column. (Bug #28493849, Bug #28523014)

• For debug builds, incorrect foreign key error checking for ALTER TABLE on a TEMPORARY table could

result in a server exit. (Bug #28493257, Bug #91990)

• For some system variables, SET PERSIST persisted the default value rather than the specified value.

(Bug #28466045)

• SET RESOURCE GROUP could not be executed as a prepared statement. (Bug #28448258, Bug #91876)

• Restored a call to Item_field::fix_fields() that was inadvertently removed during work done to

implement window functions. (Bug #28431783)

• Data races reported by Thread Sanitizer during X Plugin startup and shutdown were corrected. (Bug

#28407294)

• Creating a table with a partition description containing illegal utf8 characters raised an assertion. (Bug

#28387488, Bug #91763)

• mysqldump output could include SQL mode values that have been removed. (Bug #28373001, Bug

#91714)

• A potential lock order cycle was corrected. (Bug #28366531)

• On a GTID-enabled server, concurrent statements on the INFORMATION_SCHEMA.COLUMNS table could

deadlock. (Bug #28293047, Bug #91548)

• CREATE TABLE statements for tables with the utf32 table character set and literal strings in the table

definition raised an assertion. (Bug #28275881)

• Internal functions were added to support updating the server version number upon the successful

completion of a server upgrade. (Bug #28211486, Bug #91323)

• Comparing log file names as strings using the memcmp() function resulted in uninitialized memory

read errors. The comparison now uses the strncmp() function. Thanks to Zsolt Parragi and Laurynas

Biveinis for their contributions. (Bug #28178776, Bug #90238)

• The server mishandled stored program and resource group names that differed only in accents. (Bug

#28122841)

• The optimizer skipped the second column in a composite index when executing an inner join with a LIKE

clause against the second column. (Bug #28086754)

• CREATE TABLE ... SELECT could create date columns with “zero” date default values when it should

have created them without a default value. (Bug #28022129)

• The transformation of IN subquery predicates into semijoins was not handled correctly for a very large

number of tables. (Bug #28004674)

• The bitmap used for reading fields from the storage engine was not enabled correctly when performing

the filesort which is added to the last of any temporary tables created for window functions. In the

case where there was no need for a temporary table, the server added a filesort to the output from the

select table, but the removed reference (the WHERE condition) was not added. Now in such cases, the

375

MySQL 8.0 Release Notes

reference is added to the select table when the first window function needs sorting and no temporary

table was created before processing this window function. (Bug #27975193)

• After seeing a row in the range frame, if another row was later determined to be appearing before this

range frame, the server continued to check for new rows. This led to the next frame calculation being

done incorrectly. (Bug #27973860)

• Server mishandling of SIGHUP signals could result in a server exit. (Bug #27966483, Bug #90742)

• DELETE WHERE a=constant from a table with column a and partitioned by the value of a generated

column b led to an assertion in debug builds. (Bug #27954073)

• INFORMATION_SCHEMA queries could cause a server exit when updating dynamic table statistics. (Bug

#27898108)

• A metadata locking deadlock could occur when opening a foreign key parent table. (Bug #27859086)

• Improper memory handling by account management statements could result in server misbehavior. (Bug

#27820277)

• In certain cases, window functions did not handle ORDER BY and PARTITION BY correctly. (Bug

#27816506)

• The MySQL query optimizer identifies each predicate to be pushed down to a table as a table condition;

as part of this process it checks to see whether a given predicate among the table conditions is already

known to be true in virtue of the selected access path for the table, in which case the predicate can

safely be eliminated.

For example, when executing SELECT * FROM t1 WHERE pk=1, where pk is the primary key of table

t1, the ref access method is selected. Since we know that this already returns only rows for which

pk=1, further evaluation of this condition as a filter (Using where) should be eliminated.

When optimizing a query which includes a GROUP BY or ORDER BY, a late optimizer check is performed

to discover whether sorting can be skiped by using a sorted index instead. Since this is done after

another index may have been chosen for accessing the table to be sorted, some predicates thought to

be redundant (due to the previous access path selected) could be removed prematurely. To compensate

for this, the following actions were performed:

• Reconstruction of a table condition containing predicates previously eliminated due to the access

method already being selected.

• Performing a check to see whether any sorted index existed such that sorting could be avoided,

possibly modifying the access plan.

Issues arose because the following actions also intended to remedy early predicate removal were not

performed correctly:

• Whether the access plan was modified or not, any extra predicates added back in the reconstructed

table condition mentioned previously became a permanent part of the table condition.

• When the access plan was changed to use another sorted index, no analysis was performed for the

new index in order to remove predicates made obsolete by the new index.

A further problem existed for storage engines implementing condition pushdown, such as NDBCLUSTER:

The conditions pushed down were generated from the table condition prior to analysis, such that, if the

access path was later changed, the pushed condition did not contain the predicates already removed,

making condition pushdown less efficient.

376

MySQL 8.0 Release Notes

The root cause of this issue was that part_of_refkey() analysis was performed on table predicates

before the access method for the table had been completely decided. This is fixed by removing such

early analysis. (Bug #27808758, Bug #27814026)

• A windowing function that included an ORDER BY column clause failed with Unknown field in

window order by even when the column was found in the table being queried. (Bug #27808099)

• Executing a prepared statement to do a multiple-row insert with large number of placeholders consumed

excessive memory and could execute slowly. (Bug #27703912)

• On Windows, if the Visual C++ Redistributable for Visual Studio had been removed, MySQL

uninstallation using the MSI installer failed. (Bug #27621546)

• The parser accepted invalid SET statement syntax in trigger definitions that could result in a server exit.

(Bug #27595603)

• The server failed to start if the keyring_encrypted_file plugin keyring file was invalid. (Bug

#27588064)

• Keyring migration failed with source and destination keyring plugins of keyring_okv and

keyring_encrypted_file, respectively. (Bug #27493970)

• It was possible in debug builds for a windowing function using a signed integer to mishandle a frame that

included FOLLOWING. (Bug #27452365)

• When executing a prepared statement with a procedure call with the CURSOR_TYPE_READ_ONLY flag

set, the client library hung if the procedure performed a SELECT that returned an empty result set. (Bug

#27443252, Bug #89214)

• Names of referenced columns of foreign keys were always shown in lowercase in SHOW CREATE

TABLE output and the INFORMATION_SCHEMA.KEY_COLUMN_USAGE table. (Bug #27353767, Bug

#88718)

• Loading and unloading the audit_log plugin while performing other concurrent activity could cause the

server to become unresponsive. (Bug #27325622)

• The data dictionary properties interface (dd::Properties) and implementation was revised to

provide a new method of defining valid keys for property objects. (Bug #27309072, Bug #89031, Bug

#27309082, Bug #89032)

• Installing and uninstalling the validate_password component concurrently with SET PASSWORD

could cause component failure. (Bug #27020979)

• Some typos in server source code were fixed. Thanks to Hyunwoo Park for the contribution. (Bug

#26189673, Bug #86565)

• After column privileges were granted to a table, a HANDLER READ call asserted during privilege

checking. (Bug #25987758)

• A check that ensures compatibility of referencing and referenced column types in a foreign key definition

was moved from the storage engine layer to the SQL layer. In addition, a better error message is

produced when columns are not compatible, and when a foreign key constraint references a table that

does not exist. (Bug #25722927, Bug #28371394, Bug #91712, Bug #21308781, Bug #77467, Bug

#11746132, Bug #23693)

• The parser performed some out-of-memory checks incorrectly. (Bug #25633994)

377

MySQL 8.0 Release Notes

• A race condition between user-management statements and other statements that tried to access grant

tables directly could result in deadlock and transaction rollback. (Bug #24481240)

• When the server was started with the skip_name_resolve system variable enabled, spurious

warnings could be written to the error log about ignoring accounts with a host name part of localhost.

(The accounts in fact were used and not ignored.) (Bug #23329861, Bug #81441)

• DML statements using IGNORE were not always handled correctly on tables having generated columns.

(Bug #22990029)

• MySQL now removes trivial WHERE conditions arising from constant literal expressions during

preparation, rather than at a later stage in optimization. This should result in improved plans for queries

with outer joins containing trivial conditions, such as this one:

SELECT * FROM t1 LEFT JOIN t2 ON condition_1 WHERE condition_2 OR 0 = 1

After removing the redundant OR 0 = 1 condition the optimizer can rewrite the query as an inner join,

as shown here:

SELECT * FROM t1 LEFT JOIN t2 WHERE condition_1 AND condition_2

For more information, see What Is New in MySQL 8.0, and Outer Join Optimization. (Bug #16893426,

Bug #28237111, Bug #28239008, Bug #28341790, WL #9571)

References: See also: Bug #28197977, Bug #28240054.

• Updates for BLOB columns in FEDERATED tables did not work. (Bug #11748067, Bug #34997)

• Each of the functions REGEXP_REPLACE(), REGEXP_SUBSTR(), REGEXP_LIKE(), and

REGEXP_INSTR() returned a DOUBLE instead of a value of the function's specified return type. (Bug

#90039, Bug #27682225)

• A query employing a dynamic range and an index merge could use more memory than expected. (Bug

#89953, Bug #27659490)

• Selecting from a table having a CHAR column with a NO_PAD collation yielded inconsistent results. (Bug

#89753, Bug #27578340)

Changes in MySQL 8.0.13 (2018-10-22, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Account Management Notes

• Compilation Notes

• Configuration Notes

• Data Type Notes

• Deprecation and Removal Notes

• Error Handling

• INFORMATION_SCHEMA Notes

• Logging Notes

• Optimizer Notes

378

MySQL 8.0 Release Notes

• Packaging Notes

• Performance Schema Notes

• Pluggable Authentication

• Plugin Notes

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• XA Transaction Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• It is now possible to require that attempts to change an account password be verified by specifying

the current password to be replaced. This enables DBAs to prevent users from changing a password

without proving that they know the current password. It is possible to establish password-verification

policy globally using the password_require_current system variable, as well as on a per-account

basis using the PASSWORD REQUIRE option of the CREATE USER and ALTER USER statements.

Together with existing password-management capabilities, the new capability of requiring verification

provides DBAs more complete control over password management. For more information, see Password

Management.

Important

The implementation of password-verification capability involves a change to the

structure of the mysql.user system table. If you upgrade to this MySQL release

from an earlier version, you must run mysql_upgrade (and restart the server) to

incorporate this system database change. Until this is done, password changes

are not possible.

(WL #11544)

Compilation Notes

• Solaris: MySQL now can be compiled on Solaris using gcc. (Bug #27802681)

Configuration Notes

• The new WITH_LTO CMake option controls whether to enable link-time optimization. Currently, this is

supported only by GCC 7 and 8. (Bug #28184537, Bug #28211382)

• The new WITH_RAPIDJSON CMake option controls whether to compile with the bundled or system

RapidJSON library. (Bug #28024992, Bug #90867)

• The CMAKE_BUILD_TYPE CMake option now supports a Release build type, which is like the

RelWithDebInfo build type but omits debugging information to reduce the build size. (Bug #27874068,

Bug #32287863)

379

MySQL 8.0 Release Notes

• The new sql_require_primary_key system variable makes it possible to have statements that

create new tables or alter the structure of existing tables enforce the requirement that tables have a

primary key. Enabling this variable helps avoid performance problems in row-based replication that can

occur when tables have no primary key. Suppose that a table has no primary key and an update or

delete modifies multiple rows. On the master server, this operation can be performed using a single table

scan but, when replicated using row-based replication, results in a table scan for each row to be modified

on the slave. With a primary key, these table scans do not occur. (Bug #17468242, Bug #69845, Bug

#17005592, Bug #69223, WL #11807)

• To enable the server to listen on a set of addresses, the bind_address system variable now permits a

list of comma-separated IP addresses or host names, not just a single address or name. For details, see

Server System Variables. (WL #11652)

Data Type Notes

• MySQL now supports use of expressions as default values in data type specifications. This includes

the use of expressions as default values for the BLOB, TEXT, GEOMETRY, and JSON data types, which

previously could not be assigned default values at all. For details, see Data Type Default Values. (WL

#9418)

Deprecation and Removal Notes

• Important Change: Setting user variables in statements other than SET is now deprecated due to

issues that included those listed here:

• The order of evaluation for expressions involving user variables was undefined.

• The default result type of a variable is based on its type at the beginning of the statement, which could

have unintended effects when a variable holding a value of one type at the beginning of a statement

was assigned a new value of a different type in the same statement.

• HAVING, GROUP BY, and ORDER BY clauses, when referring to a variable that was assigned a value

in the select expression list, did not work as expected because the expression was evaluated on the

client and so it was possible for stale column values from a previous row to be used.

Syntax such as SELECT @var, @var:=@var+1 is still accepted in MySQL 8.0 for backward

compatibility, but is subject to removal in a future MySQL version. (WL #12131)

• InnoDB; Partitioning: Support for placing table partitions in shared tablespaces was removed. Shared

tablespaces include the system tablespace and general tablespaces. For information about identifying

partitions in shared tablespaces and moving them to file-per-table tablespaces, see Preparing Your

Installation for Upgrade. (WL #11571, WL #9286)

• InnoDB: Support for TABLESPACE = innodb_file_per_table and TABLESPACE =

innodb_temporary clauses with CREATE TEMPORARY TABLE is deprecated and will be removed in a

future MySQL version. (WL #12179)

• The utf8mb3 character set is deprecated and will be removed in a future MySQL version. Please use

utf8mb4 instead. (WL #11109)

• Nested comments have never been supported (although they might be permitted under some

conditions), but now are considered deprecated and will be removed in a future MySQL version. (WL

#12099)

• The deprecated metadata_locks_cache_size and metadata_locks_hash_instances system

variables were removed. (WL #12212)

380

MySQL 8.0 Release Notes

• The PAD_CHAR_TO_FULL_LENGTH SQL mode has been deprecated and will be removed in a future

MySQL version. (WL #12129)

Error Handling

• The MySQL client library now returns better error messages for OpenSSL errors. Thanks to Facebook

for the patch. (Bug #27855668, Bug #90418)

• Previously, the ER_NO_REFERENCED_ROW_2 and ER_ROW_IS_REFERENCED_2 error messages for

foreign key operations were displayed and revealed information about parent tables, even when the user

had no parent table access privileges. Error handling for this situation has been revised:

• If the user does have table-level privileges for all parent tables, ER_NO_REFERENCED_ROW_2 and

ER_ROW_IS_REFERENCED_2 are displayed, the same as before.

• If the user does not have table-level privileges for all parent tables, more generic error messages are

displayed instead (ER_NO_REFERENCED_ROW and ER_ROW_IS_REFERENCED).

An exception is that, for stored programs defined to execute with DEFINER privileges, the user against

which privileges are assessed is the user in the program DEFINER clause, not the invoking user. If that

user has table-level parent table privileges, parent table information is still displayed. In this case, it is

the responsibility of the stored program creator to hide the information by including appropriate condition

handlers. (Bug #19477611, WL #8910)

INFORMATION_SCHEMA Notes

• These new INFORMATION_SCHEMA tables are available as views on data dictionary tables:

• VIEW_ROUTINE_USAGE provides information about stored functions used in view definitions.

• VIEW_TABLE_USAGE provides information about tables and views used in view definitions.

For more information, see The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table, and The

INFORMATION_SCHEMA VIEW_TABLE_USAGE Table. (WL #11864)

Logging Notes

• Incompatible Change: The system variables have been removed that previously configured error

logging to the system log (the Event Log on Windows, and syslog on Unix and Unix-like systems).

Where appropriate, the removed system variables were replaced with new system variables managed by

the log_sink_syseventlog error log component. The following table shows the old and new variable

names.

Old System Variable New System Variable

log_syslog_facility syseventlog.facility

log_syslog_include_pid syseventlog.include_pid

log_syslog_tag syseventlog.tag

log_syslog None

Important

Installations that used the old system variable names must update their

configuration to use the new variable names. For more information, see Error

Logging to the System Log.

381

MySQL 8.0 Release Notes

(WL #11828)

References: See also: Bug #27534089.

• A new system variable, log_error_suppression_list, specifies which diagnostics should not be

written to the error log when they occur with a severity of WARNING or INFORMATION. For example,

if a particular type of warning occurs frequently but is not of interest (and thus may be considered

undesirable “noise” in the error log), it now can be suppressed. (WL #11393)

• The code to handle rewriting of account-management statements was refactored to make it easier to

maintain and extend. This work resulted in a few minor user-visible effects in the audit, general, and slow

query logs:

• Plaintext passwords are replaced by <string> rather than '<string>'.

• Default clauses are not written unless specified by the user.

(WL #12007)

• Previously, messages written to the error log by several internal server methods were logged using the

ER_LOG_PRINTF_MSG error code. Each of these messages now is logged using a unique error code.

Optimizer Notes

• The optimizer now supports a Skip Scan access method that enables range access to be used in

previously inapplicable situations to improve query performance. For more information, see Skip Scan

Range Access Method. Thanks to Facebook for the patch on which this access method is based. (Bug

#26976512, Bug #88103, WL #11322)

• MySQL now supports creation of functional index key parts that index expression values rather than

column values. Functional key parts enable indexing of values that cannot be indexed otherwise, such

as JSON values. For details, see CREATE INDEX Statement. (WL #1075)

• Performance of SELECT COUNT(*) FROM tbl_name queries for InnoDB tables was improved for

single-threaded workloads and when no extra clauses such as WHERE or GROUP BY are used. (WL

#10398)

Packaging Notes

• The libevent library bundled with MySQL was upgraded to version 2.1.8. (Bug #28207237, Bug

#29041505, Bug #29055011)

• Binary packages that include curl rather than linking to the system curl library now use curl 7.60.0

rather than 7.45.0. (Bug #28043702)

• Debian packaging was updated to reflect the removal of yaSSL and that OpenSSL is the default SSL

library for all builds. (Bug #28025599)

• Test plugins have been moved from server packages to test packages. (Bug #27860172)

• MySQL Router is now included in the MySQL server source and monolithic binary packages.

Performance Schema Notes

• A new Performance Schema stage, waiting for handler commit, is available to detect threads

going through transaction commit. Thanks to Facebook for the patch. (Bug #27855592, Bug #90417)

382

MySQL 8.0 Release Notes

References: See also: Bug #28950397.

Pluggable Authentication

• Microsoft Windows: On Windows, MySQL Enterprise Edition distributions now bundle the Cyrus SASL

library files libsasl.dll and saslSCRAM.dll so that the LDAP authentication plugins can use the

SCRAM-SHA-1 authentication method. (WL #11927)

Plugin Notes

• Previously, MySQL plugins could be written in C or C++. MySQL header files used by plugins now

contain C++ code, which means that plugins must be written in C++, not C. (Bug #87725, Bug

#26781567)

Security Notes

• MySQL Enterprise Edition now provides data masking and de-identification capabilities, implemented

as a plugin library containing a plugin and a set of loadable functions. Data masking hides sensitive

information by replacing real values with substitutes. MySQL Enterprise Data Masking and De-

Identification functions enable masking existing data using several methods such as obfuscation

(removing identifying characteristics), generation of formatted random data, and data replacement or

substitution. For example:

mysql> SET @ssn = gen_rnd_ssn();

mysql> SET @masked_ssn1 = mask_ssn(@ssn);

mysql> SET @masked_ssn2 = mask_outer(mask_inner (@ssn,4,5,'A'), 3,0,'B');

mysql> SELECT @ssn, @masked_ssn1, @masked_ssn2;

+-------------+--------------+--------------+

| @ssn | @masked_ssn1 | @masked_ssn2 |

+-------------+--------------+--------------+

| 980-31-2838 | XXX-XX-2838 | BBB-AA-2838 |

+-------------+--------------+--------------+

For more information, see MySQL Enterprise Data Masking and De-Identification. (WL #7722)

Spatial Data Support

• Incompatible Change: Previously, ST_Area() supported only geometry arguments having a Cartesian

spatial reference system (SRS) and produced an error when invoked with geometry arguments that

specified a geographic SRS. ST_Area() now supports geometry arguments having a geographic SRS

and returns the geodetic area in square meters.

Note

If spatial data contains geometry values that now are interpreted differently by

ST_Area(), existing queries using this function will return different results,

compared to previous MySQL versions.

(WL #10726)

• The parser for spatial reference system (SRS) definitions in CREATE SPATIAL REFERENCE SYSTEM

statements now is stricter about rejecting invalid constructs.

The OGC 01-009 WKT grammar does not make AXIS clauses mandatory in GEOGCS spatial reference

system definitions. However, if there are no AXIS clauses, MySQL cannot determine whether a definition

has axes in latitude-longitude order or longitude-latitude order. MySQL now enforces the nonstandard

383

MySQL 8.0 Release Notes

requirement that each GEOGCS definition must include two AXIS clauses. One must be NORTH or SOUTH,

and the other EAST or WEST. The AXIS clause order determines whether the definition has axes in

latitude-longitude order or longitude-latitude order. (Bug #28186073, Bug #28147723)

• Previously, ST_Validate() supported only geometry arguments having a Cartesian spatial reference

system (SRS) and produced an error when invoked with geometry arguments that specified a

geographic SRS. ST_Validate() now supports geometry arguments having a geographic SRS.

Note

If spatial data contains geometry values that now are interpreted differently by

ST_Validate(), existing queries using this function will return different results,

compared to previous MySQL versions.

(WL #11087)

• MySQL now implements the ST_Transform() spatial function for use in converting geometry

values from one spatial reference system (SRS) to another. Currently, it supports conversion between

geographic SRSs. For details, see Spatial Operator Functions. (WL #8684)

SQL Syntax Notes

• Incompatible Change: The deprecated ASC or DESC qualifiers for GROUP BY clauses have been

removed. Queries that previously relied on GROUP BY sorting may produce results that differ from

previous MySQL versions. To produce a given sort order, provide an ORDER BY clause.

Queries and stored program definitions from MySQL 8.0.12 or lower that use ASC or DESC qualifiers for

GROUP BY clauses should be amended. Otherwise, upgrading to MySQL 8.0.13 or higher may fail, as

may replicating to MySQL 8.0.13 or higher slave servers. (WL #8693)

XA Transaction Notes

• Previously, metadata locks for XA transactions in PREPARED state could be dropped when the client

performing the transaction disconnected or the server restarted. This could lead to behavior such as one

session being able to drop tables used by an XA transaction in progress for another session. Metadata

locks for XA transactions in PREPARED state now are maintained across client disconnects and server

restarts, until an XA COMMIT or XA ROLLBACK is executed. (Bug #22710164, Bug #79940, WL #9335)

X Plugin Notes

• Important Change: X Protocol now provides a connection pooling option, which can reduce overhead

for applications that open many connections to MySQL server such as small web pages or a REST API

endpoint. Use the new mysqlx.getClient(connection, options) operation, which returns a

Client object. By using a Client object, executing an open session operation retrieves an existing

and currently unused network connection from the pool, resets it, and uses it. Closing a session marks

the underlying connection as unused and returns it to the Client object's connection pool. The

connection pool is configured using a options data dictionary, which means that a deployed application

can switch from using connection pooling or not by simply changing the connection string. (WL #11824)

• A mutex lock has been added to prevent conflict between multiple X Plugin client sessions when a large

number of sessions are being opened and closed. (Bug #28637947)

• When an X Plugin client attempted to connect to a MySQL server specifying a database that did not exist

on the server, the error message indicated that access was denied rather than that the database was not

known. The correct error message is now returned. (Bug #28110957)

384

MySQL 8.0 Release Notes

• Incorrect copying of an integer value by X Plugin caused an error relating to misaligned memory access.

The issue is now fixed. (Bug #28070946, Bug #90983)

• Now that X Plugin is loaded and enabled by default, the default verbosity setting for the error log meant

that no message was visible to indicate that X Plugin was available on the MySQL server. A message is

now issued during system startup to confirm that X Plugin has been loaded. (Bug #27287340)

• X Protocol now provides the ability to broadcast information to interested clients without the

requirement to request the information. In addition, changes related to Group Replication are

also broadcast. This work also adds the Mysqlx_notified_by_group_replication and

Mysqlx_notice_global_sent status variables. (WL #10655)

Functionality Added or Changed

• Important Change; NDB Cluster; NDB Client Programs: Removed the deprecated --ndb option for

perror. Use ndb_perror to obtain error message information from NDB error codes instead. (Bug

#81705, Bug #23523957)

References: See also: Bug #81704, Bug #23523926.

• InnoDB: The innodb_fsync_threshold system variable permits defining a threshold, in bytes, for

flushing data to disk from the operating system cache. By default, when InnoDB creates a new data file,

such as a new log file or tablespace file, the file is fully written to the operating system cache before it is

flushed to disk, which can cause a large amount of disk write activity to occur at once.

Specifying a threshold to force smaller, periodic flushes may be beneficial in cases where multiple

MySQL instances use the same storage devices. For example, creating a new MySQL instance and its

associated data files could cause large surges of disk write activity, impeding the performance of other

MySQL instances that use the same storage devices. Configuring a threshold helps avoid such surges in

write activity. (Bug #27724600)

• InnoDB: User-created temporary tables and internal temporary tables created by the optimizer are

now stored in session temporary tablespaces that are allocated to a session from a pool of temporary

tablespaces. When a session disconnects, its temporary tablespaces are truncated and released back

to the pool. In previous releases, temporary tables were created in the global temporary tablespace

(ibtmp1), which did not return disk space to the operating system after temporary tables were dropped.

The innodb_temp_tablespaces_dir variable defines the location where session temporary

tablespaces are created. The default location is the #innodb_temp directory in the data directory.

The INNODB_SESSION_TEMP_TABLESPACES table provides metadata about session temporary

tablespaces.

The global temporary tablespace (ibtmp1) now stores rollback segments for changes made to user-

created temporary tables. (WL #11613)

• InnoDB: The InnoDB data-at-rest encryption feature now supports general tablespaces. Previously,

only file-per-table tablespaces could be encrypted. To support encryption of general tablespaces,

CREATE TABLESPACE and ALTER TABLESPACE syntax was extended to include an ENCRYPTION

clause.

The INFORMATION_SCHEMA.INNODB_TABLESPACES table now includes an ENCRYPTION column that

indicates whether or not a tablespace is encrypted.

The stage/innodb/alter tablespace (encryption) Performance Schema stage instrument

was added to permit monitoring of general tablespace encryption operations. (WL #9286)

385

MySQL 8.0 Release Notes

• Replication: The group_replication_member_expel_timeout option has been added to define

the time period that the group should wait for a non-responding member before evicting the member

from the group. This enables you to configure the eviction process when the connection to members is

unreliable. (WL #11570)

• Group Replication: You can now inspect and configure the maximum number of consensus instances

at any time for a group. This maximum is referred to as the event horizon for a group, and is the

maximum number of consensus instances that the system can execute in parallel. This enables you to

fine tune the performance of your Group Replication deployment.

To inspect a group's event horizon value at runtime, issue this statement:

SELECT group_replication_get_write_concurrency()

To set the maximum number of write consensus instances, issue the statement shown here:

SELECT group_replication_set_write_concurrency(instances);

instances is the maximum number of instances used for consensus.

See Using Group Replication Group Write Consensus for more information. (Bug #27260096, WL

#11512)

• Group Replication: You can now make changes to the configuration of a group while it is running,

without having to stop all members to make changes. This functionality relies on loadable functions

which are installed with this version of the plugin, and all members of a group must have these functions

installed. To use the functions, connect to an online member and issue SELECT function_name;

Use the group_replication_set_as_primary() function to trigger the election of a specific

member as the new primary in a single-primary group, overriding the usual election process. See

Changing the Primary for more information.

In addition, you can configure the mode which a group is using while it is online, changing between

single-primary mode and multi-primary mode. To change the mode of an online group, choose one of

these options:

• Use group_replication_switch_to_single_primary_mode() to change a group running in

multi-primary mode to single-primary mode.

• Use group_replication_switch_to_multi_primary_mode() to change a group running in

single-primary mode to multi-primary mode.

See Changing the Group Mode for more information. (WL #10378)

• Solaris: On Solaris, MySQL can now be built with Developer Studio 12.6. (Bug #27055190, Bug

#88316, Bug #28165246, Bug #91214)

• Data truncation testing was rewritten to avoid undefined behavior. (Bug #28255956, Bug #91445)

• Out-of-range checking for float values was improved. (Bug #28225635)

• The upgrade check that the server runs during the startup process now verifies that partitioned InnoDB

tables do not use shared tablespaces. (Bug #28204431)

• Previously, file I/O performed in the I/O cache in the mysys library was not instrumented, affecting in

particular file I/O statistics reported by the Performance Schema about the binary log index file. Now,

this I/O is instrumented and Performance Schema statistics are accurate. Thanks to Yura Sorokin for the

contribution. (Bug #27788907, Bug #90264)

386

MySQL 8.0 Release Notes

• Performance for locating user account entries in the in-memory privilege structures has been improved.

Thanks to Eric Herman for the contribution. (Bug #27772506, Bug #90244)

• If mysqld --initialize fails to complete but creates an unusable data directory, it now displays a

message that the data directory is unusable and can safely be removed. (Bug #27675647)

• Instrumentation is now provided in the Performance Schema for transaction retries by individual applier

threads on a single-threaded or multithreaded slave. Previously, the Performance Schema table

replication_applier_status_by_worker displayed information about errors that stopped the

applier thread, but not about transient errors that occurred before a transaction was eventually applied.

With this information, you can identify transient errors that are causing replication lag on replication

slaves or Group Replication group members.

Eight new columns have been added to the Performance Schema

replication_applier_status_by_worker table:

• LAST_APPLIED_TRANSACTION_RETRIES_COUNT - The number of times the last applied transaction

was retried by the worker after the first attempt. If the transaction was applied at the first attempt, this

number is zero.

• LAST_APPLIED_TRANSACTION_LAST_TRANSIENT_ERROR_NUMBER - The error number of the last

transient error that caused the transaction to be retried.

• LAST_APPLIED_TRANSACTION_LAST_TRANSIENT_ERROR_MESSAGE - The message text for the

last transient error that caused the transaction to be retried.

• LAST_APPLIED_TRANSACTION_LAST_TRANSIENT_ERROR_TIMESTAMP - The timestamp in

'YYYY-MM-DD hh:mm:ss[.fraction]' format for the last transient error that caused the

transaction to be retried.

• APPLYING_TRANSACTION_RETRIES_COUNT - The number of times the transaction that is currently

being applied was retried until this moment. If the transaction was applied at the first attempt, this

number is zero.

• APPLYING_TRANSACTION_LAST_TRANSIENT_ERROR_NUMBER - The error number of the last

transient error that caused the current transaction to be retried.

• APPLYING_TRANSACTION_LAST_TRANSIENT_ERROR_MESSAGE - The message text for the last

transient error that caused the current transaction to be retried.

• APPLYING_TRANSACTION_LAST_TRANSIENT_ERROR_TIMESTAMP - The timestamp in 'YYYY-MM-

DD hh:mm:ss[.fraction]' format for the last transient error that caused the current transaction to

be retried.

The existing column APPLYING_TRANSACTION_START_APPLY_TIMESTAMP is no longer reset each

time a transaction is retried. It now retains the timestamp from the worker's first attempt to apply the

transaction. (WL #9131)

• Previously, CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE statements were not

supported inside transactions, procedures, functions, or triggers when using GTIDs (that is, when the

enforce_gtid_consistency system variable is set to ON). It was possible to use these statements

with GTIDs enabled, but only outside of any transaction, and only with autocommit=1.

From MySQL 8.0.13, this restriction has been removed when binlog_format is set to ROW or

MIXED. With row-based logging in use, CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE

statements can now be used inside transactions, procedures, functions, or triggers when GTIDs

387

MySQL 8.0 Release Notes

are enabled. When binlog_format is set to STATEMENT, the restriction remains. Because of this

difference in behavior, some additional restrictions now apply to changing the binlog_format setting

at runtime:

• If a session has open temporary tables, the replication format cannot be changed for the session (SET

@@SESSION.binlog_format).

• If any replication channel has open temporary tables, the replication format cannot be changed

globally (SET @@GLOBAL.binlog_format or SET @@PERSIST.binlog_format).

• If any replication channel applier thread is currently running, the replication format cannot be changed

globally (SET @@GLOBAL.binlog_format or SET @@PERSIST.binlog_format).

Trying to switch the replication format in any of these cases (or attempting to set the

current replication format) results in an error. You can, however, use PERSIST_ONLY (SET

@@PERSIST_ONLY.binlog_format) to change the replication format at any time, because this action

does not modify the runtime global system variable value, and takes effect only after a server restart.

When binlog_format is set to ROW or MIXED, CREATE TEMPORARY TABLE and DROP TEMPORARY

TABLE statements are not written to the binary log and are therefore not replicated to slaves. When they

are used in transactions, if the removal of these statements from the transaction results in an empty

transaction, the transaction is not written to the binary log. If a transaction involving these statements is

rolled back, a warning message is issued stating that the creation or dropping of the temporary tables

could not be rolled back. (WL #8872)

• The MySQL Server code for binary logging has been refactored to create new internal interfaces

for accessing events in a binary log and relay log. The new interfaces separate the write and read

processes for binary logging into input and output streams, and decouple the process of capturing and

retrieving binary log events from the process of writing them to files. A logical binary log file is used to

wrapper the storage layer operations.

The new internal interfaces make it possible for MySQL Server to use alternative storage methods for

binary log events besides a standard binary log or relay log file, including a binary log cache or memory

buffer. For example, Group Replication uses the new interfaces to serialize events directly to memory

buffers and transaction messages in order to co-ordinate transactions in the group. mysqlbinlog also

now uses them to read binary log events from standard input.

The following existing error messages are now marked as obsolete due to the new internal interfaces:

• ER_BINLOG_CANT_OPEN_LOG

• ER_BINLOG_CANT_CREATE_CACHE_FOR_LOG

• ER_BINLOG_ERROR_GETTING_NEXT_LOG_FROM_INDEX

• ER_RPL_RECOVERY_ERROR_FREEING_IO_CACHE

• ER_GRP_RPL_REINIT_OF_INTERNAL_CACHE_FOR_READ_FAILED

• ER_GRP_RPL_APPENDING_DATA_TO_INTERNAL_CACHE_FAILED

• ER_GRP_RPL_REINIT_OF_INTERNAL_CACHE_FOR_WRITE_FAILED

• ER_GRP_RPL_FAILED_TO_CREATE_COMMIT_CACHE

388

MySQL 8.0 Release Notes

• ER_GRP_RPL_REINIT_OF_COMMIT_CACHE_FOR_WRITE_FAILED

(WL #10956)

• The TempTable storage engine now supports storage of binary large object (BLOB) type columns.

This enhancement improves performance for queries that use temporary tables containing BLOB data.

Previously, temporary tables that contained BLOB data were stored in the on-disk storage engine

defined by internal_tmp_disk_storage_engine. (WL #11452)

• The MySQL Server code for deserialization of binary log events has been refactored to improve the

identification and resilient handling of corrupted and invalid event data during replication, and also during

processing with mysqlbinlog, whether or not binary log checksums are used on the server. (WL

#11567)

• Previously, executing RENAME TABLE required that there be no tables locked with LOCK TABLES. Now

it is possible to rename tables that are locked with a WRITE lock or that are the product of renaming

WRITE-locked tables from earlier steps in a multiple-table rename operation. (WL #9826)

Bugs Fixed

• InnoDB; Partitioning: Removed old InnoDB handler and partitioning code that referenced .frm files,

and thus no longer had any purpose. (Bug #27995316)

• InnoDB: An assertion was raised during a DROP TABLE operation. A thread that was accessing the

table through the memcached API released metadata locks before releasing the table. (Bug #28531148)

• InnoDB: The being_modified bit in a LOB reference was set but the bit modification was not logged,

causing an assertion failure. (Bug #28443837)

• InnoDB: Window functions returned incorrect results when the optimizer used the InnoDB storage

engine for internal temporary tables. (Bug #28430650)

• InnoDB: Adjusting the server time to an earlier time caused periodic redo flushes to be missed. (Bug

#28430358, Bug #90670)

• InnoDB: An ALTER TABLE operation that added a primary key produced a segmentation fault. (Bug

#28395278)

References: This issue is a regression of: Bug #27753193.

• InnoDB: A conditional check was removed by removing the ReadView::complete() function and

splitting its work among other functions. This change helps optimize performance on ARM 64-bit. (Bug

#28385211, Bug #91759)

• InnoDB: Leftover thread_mutex code was removed from InnoDB source code files. (Bug #28363673,

Bug #91678)

• InnoDB: Type changes were implemented to eliminate warnings that occurred when compiling InnoDB

with Microsoft Visual Studio 2017. (Bug #28338720)

• InnoDB: An invalid assertion was raised when a B-tree flag used to mark shared index locks was used

to mark a shared-exclusive index lock. (Bug #28317172)

• InnoDB: The sharp checkpoint mechanism no longer forces preflushing of dirty pages when requesting

a checkpoint for the currently available LSN.

The log checkpointer thread now takes the concurrency margin (the per thread margin for free space

in the log) into account when determining if the next checkpoint write is required and whether to wake

389

MySQL 8.0 Release Notes

up page cleaners to force a sync-flush of dirty pages. Page cleaner threads take the concurrency

margin into account when determining whether to flush dirty pages and how many pages to flush. (Bug

#28297462)

• InnoDB: A misplaced debug crash point caused a transaction timeout resulting in test failures. (Bug

#28295814)

• InnoDB: InnoDB error message format was modified to remove duplicate text. (Bug #28289789)

• InnoDB: Unnecessary cycles of freeing and allocating memory caused JSON performance degradation

on Windows. (Bug #28278737)

• InnoDB: InnoDB incorrectly permitted dropping an index used in a foreign key constraint using an in-

place ALTER TABLE statement. This operation is now blocked at the SQL layer. (Bug #28268875)

• InnoDB: To avoid checking hardware support each time a hardware-optimized checksum is computed,

asserts were converted to debug-only asserts. (Bug #28267334, Bug #91485)

• InnoDB: A patch that combined Contention-Aware Transaction Scheduling (CATS) with functionality

that releases read locks caused gap locks to be removed without granting locks to waiting transactions,

resulting in transaction timeouts. (Bug #28261530)

References: This issue is a regression of: Bug #28261530.

• InnoDB: The log_checkpointer thread failed to write new checkpoints in a timely manner when the

amount of redo was small. (Bug #28220222)

• InnoDB: The server exited during an in-place upgrade from MySQL 5.7 to MySQL 8.0 due to an

attempted eviction of a foreign-key-related table from the cache. At the end of the upgrade process,

tables with FULLTEXT indexes were marked as ready for eviction without checking for foreign key

relationships. (Bug #28212734, Bug #91325)

• InnoDB: The format of the following Performance Schema and INFORMATION_SCHEMA table columns

was modified:

• data_locks.ENGINE_LOCK_ID

• data_lock_waits.REQUESTING_ENGINE_LOCK_ID

• data_lock_waits.BLOCKING_ENGINE_LOCK_ID

• INNODB_TRX.TRX_REQUESTED_LOCK_ID

The previous format was trx_id:table_id for table locks and

trx_id:space_id:page_no:heap_no for record locks. The new format is

trx_immutable_id:table_id:lock_immutable_id for table locks and

trx_immutable_id:space_id:page_no:heap_no:lock_immutable_id for record locks.

lock_immutable_id and trx_immutable_id are 64-bit values that do not change during the

lifetime of a lock or transaction, respectively, and are unique among other instance object IDs. (Bug

#28176910)

• InnoDB: The list of permitted lock mode descriptors used by the LOCK_MODE column of the Performance

Schema data_locks table was expanded to include REC_NOT_GAP, INSERT_INTENTION,

PREDICATE, and PRDT_PAGE. REC_NOT_GAP indicates a record-only lock. INSERT_INTENTION

indicates an insert intention lock. PREDICATE and PRDT_PAGE descriptors indicate a spatial index lock.

(Bug #28176805)

390

MySQL 8.0 Release Notes

• InnoDB: Table names were not compared in lowercase on macOS with a setting of

lower_case_table_names=2, which caused instability after restarting the server. (Bug #28170699,

Bug #91204)

• InnoDB: Macros used to define constant values in InnoDB source code were changed to constant

expressions. (Bug #28152926)

• InnoDB: A flag that prevents transactions from being rolled back during commit is now set earlier to

prevent scenarios in which a high priority transaction could abort a transaction that is in the process of

being committed. (Bug #28140462)

• InnoDB: A query that scanned the primary key of a table did not return the expected result. (Bug

#28104394, Bug #91032)

• InnoDB: Unnecessary header file inclusions were removed from InnoDB source code files. (Bug

#28086759)

• InnoDB: An apparent hang due to the log writer running out of free space in the redo log caused the

server to exit. (Bug #28072385, Bug #90993)

• InnoDB: A query interruption during a lock wait caused an error. (Bug #28068293)

• InnoDB: After upgrading from MySQL 5.7 to MySQL 8.0, invalid warnings indicated that undo

tablespace IDs were not in the undo tablespace range. The warnings occurred if the MySQL 5.7

installation was configured to use separate undo tablespaces. (Bug #28060337)

• InnoDB: Error messaging was improved for startup failures on an incomplete cloned data directory. (Bug

#28032131)

• InnoDB: A segmentation fault occurred during an XA COMMIT operation. (Bug #27995891)

• InnoDB: Unused code was removed from the TempTable storage engine source code. (Bug

#27978968)

• InnoDB: An index record was not found when updating a secondary index defined on a generated

column. (Bug #27968952)

• InnoDB: A spurious negation operator in an IF condition caused the Contention-Aware Transaction

Scheduling (CATS) algorithm to be used for table locks. (Bug #27944920)

References: This issue is a regression of: Bug #27572937.

• InnoDB: The update log applied as part of an online ALTER TABLE operation did not take into account

the computed value of the generated column in the old row while updating the secondary index. (Bug

#27921932)

• InnoDB: Buffer pool memory allocation was not fully accounted for in Performance Schema memory/

innodb/buf_buf_pool statistics. (Bug #27917595, Bug #90561)

• InnoDB: An unsupported DDL operation involving a foreign key constraint raised an assertion. (Bug

#27912873)

• InnoDB: A lock-related debug assertion failure was raised when more than one lock matched a search

condition, which could lead to releasing the wrong lock. (Bug #27898384)

• InnoDB: A function that removes aborted indexes during the prepare phase of an online ALTER TABLE

operation did not record its changes. (Bug #27879325)

391

MySQL 8.0 Release Notes

• InnoDB: A general tablespace created in MySQL 5.7 with no assigned table caused a failure when

upgrading to MySQL 8.0. (Bug #27877485)

• InnoDB: Concurrent undo tablespace truncation and master key rotation operations raised an assertion.

(Bug #27872369)

• InnoDB: A boolean marker identifying whether a transaction holds a mutex was not placed in the correct

location. (Bug #27870035)

• InnoDB: An attempted foreign key check on a discarded table caused a segmentation fault. (Bug

#27804668)

• InnoDB: B-tree bulk load operations could leave a page in a partially initialized state. (Bug #27802098)

• InnoDB: Starting the server inside a Docker container on a NUMA enabled operating system raised an

“mbind: Operation not permitted” error. (Bug #27792853)

• InnoDB: A partitioned table TABLE_ID value stored in a storage-engine-private data field in the

data dictionary was not adjusted properly after an ALTER TABLE ... PARTITION operation. (Bug

#27784462)

• InnoDB: The server halted with a “log writer overwriting data after checkpoint - waited too long” error.

(Bug #27779266)

• InnoDB: With innodb_flush_log_at_trx_commit=2, the log_flusher thread could wait for

an event with a timeout period equal to the innodb_flush_log_at_timeout setting, causing an

initialization delay. (Bug #27762596)

• InnoDB: An assertion was raised during an OPTIMIZE TABLE operation. (Bug #27753193)

• InnoDB: Transaction rollback due to a deadlock caused an assertion failure in debug builds. Initiation of

an attachable transaction for accessing the data dictionary was not expected during transaction rollback.

(Bug #27729974)

• InnoDB: With innodb_flush_log_at_trx_commit=0 and binary logging enabled, redo logs were

not flushed as expected during the commit phase of DDL operations. (Bug #27691035)

• InnoDB: With REDUNDANT or COMPRESSED row format and READ COMMITTED isolation level, only the

LOB value prefix and possibly the external part of an old LOB value were returned, which could cause a

JSON document to be viewed as corrupted. If there was no LOB value prefix, an old LOB value with new

values for other fields could be returned, causing data inconsistency. (Bug #27624990)

• InnoDB: A debug option that permits pausing periodic checkpoints became obsolete after periodic

checkpoint ownership was moved from the master thread to a log checkpointer thread. The debug option

was replaced by another method of pausing periodic checkpoints. (Bug #27588328)

• InnoDB: A transaction on a table with a spatial index defined on a column with a spatial reference

identifier (SRID) was able to insert into an area selected for update by another transaction. (Bug

#27577612)

• InnoDB: A foreign key constraint name was duplicated during a rename table operation, causing a

failure during later query execution. (Bug #27545888)

• InnoDB: A serialized dictionary information (SDI) deletion failure raised an assertion. (Bug #27493634)

• InnoDB: A server exit occurred after freeing large object (LOB) index entries during a LOB purge or

rollback. (Bug #27419474)

392

MySQL 8.0 Release Notes

• InnoDB: In a function called before the execution of a statement in a stored procedure, a read and write

operation on trx->lock.start_stmt was not protected by a mutex. (Bug #27325898)

• InnoDB: The INFORMATION_SCHEMA.FILES and INFORMATION_SCHEMA.INNODB_TABLESPACES

tables did not show the actual undo tablespaces that were present in the MySQL instance. Only the two

default undo tablespaces were shown. (Bug #26820406)

• InnoDB: An error occurred during a DDL operation due to a mismatch in a REDUNDANT row format

calculation that determines the length of the online log. (Bug #26375771)

• InnoDB: Enabling innodb_undo_log_truncate negatively affected transaction processing

performance. Instead of performing two checkpoints during an undo tablespace truncate operation,

pages that belong to the tablespace file are now flushed from disk. (Bug #26322656)

• InnoDB: A helper class was introduced to improve performance associated with reading from secondary

keys when there are multiple versions of the same row.

Thanks to Domas Mituzas for the contribution. (Bug #25540277, Bug #84958)

• InnoDB: The location of the Innodb Merge Temp File that reported by the wait/io/file/innodb/

innodb_temp_file Performance Schema instrument was incorrect. (Bug #21339079, Bug #77519)

• Partitioning: When a CREATE TABLE ... PARTITION BY ... statement failed due to an invalid

partition definition, the server did not remove any partition files which might have been created prior to

encountering the invalid PARTITION clause. (Bug #27798708)

References: See also: Bug #88043, Bug #26945644.

• Partitioning: It was possible to perform FLUSH TABLES FOR EXPORT on a partitioned table created

with innodb_file_per_table=1 after discarding its tablespace. Attempting to do so now raises

ER_TABLESPACE_DISCARDED. (Bug #90545, Bug #27903881)

References: See also: Bug #80669, Bug #22899690.

• Partitioning: An extraneous row lock was imposed by an update to a partitioned InnoDB table. (Bug

#87253, Bug #26553164)

• Replication: When a replication slave is restarted by a START SLAVE statement, the columns

in the Performance Schema table replication_applier_status_by_worker beginning

APPLYING_TRANSACTION are now reset on a slave that is operating in single-threaded mode. These

columns were always reset on a multi-threaded slave, because the existing worker threads were

terminated by the statement and the information could not be retained. The behavior has now been

standardized across the slave configurations by resetting the columns for a single-threaded slave as

well. (Bug #28248026)

• Replication: If a multi-threaded replication slave was stopped, changed to a single-threaded slave

(by setting slave_parallel_workers > 0), and restarted, the Performance Schema table

replication_applier_status_by_worker showed irrelevant timestamps because the old

monitoring information had not been cleared. (Bug #28191382)

• Replication: When the binlog_group_commit_sync_delay system variable

is set to a wait time to delay synchronization of transactions to disk, and the

binlog_group_commit_sync_no_delay_count system variable is also set to a number

of transactions, the MySQL server exits the wait procedure if the specified number of

transactions is reached before the specified wait time is reached. The server manages this

process by checking on the transaction count after a delta of one tenth of the time specified by

binlog_group_commit_sync_delay has elapsed, then subtracting that interval from the remaining

wait time.

393

MySQL 8.0 Release Notes

If rounding during calculation of the delta meant that the wait time was not a multiple of the delta, the

final subtraction of the delta from the remaining wait time would cause the value to be negative, and

therefore to wrap to the maximum wait time, making the commit hang. The data type for the remaining

wait time has now been changed so that the value does not wrap in this situation, and the commit

can proceed when the original wait time has elapsed. Thanks to Yan Huang for the contribution. (Bug

#28091735, Bug #91055)

• Replication: In debug builds, an assertion failed because more than 255 collations are now available in

MySQL. (Bug #28015761)

• Replication: An assertion was raised in debug builds because the MySQL server recorded a GTID

consistency violation, but did not remove the record after the relevant statement failed to execute

successfully. The handling of this situation has now been improved to ensure that the server checks at

the end of a transaction whether a GTID consistency violation was produced by a failed statement, and if

this is the case, restores the previous GTID consistency state. (Bug #27903831, Bug #90551)

• Replication: With GTIDs in use for replication, transactions including statements that caused a parsing

error (ER_PARSE_ERROR) could not be skipped manually by the recommended method of injecting an

empty or replacement transaction with the same GTID. This action should result in the slave identifying

the GTID as already used, and therefore skipping the unwanted transaction that shared its GTID.

However, in the case of a parsing error, because the statement was parsed before the GTID was

checked to see if it needed to be skipped, the replication applier thread stopped due to the parsing error,

even though the intention was for the transaction to be skipped anyway.

With this fix, the replication applier thread now ignores parsing errors if the transaction concerned needs

to be skipped because the GTID was already used. Note that this behavior change does not apply in

the case of workloads consisting of binary log output produced by mysqlbinlog. In that situation, there

would be a risk that a transaction with a parsing error that immediately follows a skipped transaction

would also be silently skipped, when it ought to raise an error. (Bug #27638268)

• Replication: When a RESET SLAVE statement was issued on a replication slave with GTIDs in use,

the existing relay log files were purged, but the replacement new relay log file was generated before

the set of received GTIDs for the channel had been cleared. The former GTID set was therefore written

to the new relay log file as the PREVIOUS_GTIDS event, causing a fatal error in replication stating that

the slave had more GTIDs than the master, even though the gtid_executed set for both servers was

empty. Now, when RESET SLAVE is issued, the set of received GTIDs is cleared before the new relay

log file is generated, so that this situation does not occur. (Bug #27636289)

• Replication: The master's receiver thread for semisynchronous replication held a mutex while reading

acknowledgements from slaves, but the same mutex was required to add or remove a semisynchronous

slave, causing those operations to be delayed by the acknowledgement activity. The issue has now

been fixed by not acquiring the mutex to read the acknowledgements from slaves. (Bug #27610678, Bug

#89370)

• Replication: In code for replication slave reporting, a rare error situation raised an assertion in debug

builds, but in release builds, returned leaving a mutex locked. The mutex is now unlocked before

returning in this situation. Thanks to Zsolt Parragi for the patch. (Bug #27448019, Bug #89421)

• Replication: Automatic retrying of transactions on a replication slave, as specified by the

slave_transaction_retries system variable, was taking place even if the transaction had a non-

temporary error that would repeat on retrying or that indicated wider issues. Now, transactions are only

automatically retried if there is either no error, or an error that is only temporary. (Bug #27373559, Bug

#89143)

• Replication: When FLUSH statements for specific log types (such as FLUSH SLOW LOGS) resulted in

an error, the statements were still written to the binary log. This stopped replication because the error

394

MySQL 8.0 Release Notes

had occurred on the master, but did not occur on the slave. MySQL Server now checks on the outcome

of these FLUSH statements, and if an error occurred, the statement is not written to the binary log. (Bug

#24786290, Bug #83232)

• Replication: The PASSWORD() function, which produces a hash of the password, was deprecated in

MySQL 5.7 and removed in MySQL 8.0. When a SET PASSWORD statement that used this function

was replicated from a MySQL 5.6 master to a MySQL 5.7 slave, or from a MySQL 5.7 master with the

log_builtin_as_identified_by_password system variable set to ON to a MySQL 5.7 slave, the

password hash was itself also hashed before being stored on the slave. The issue has now been fixed

and the replicated password hash is stored as originally passed to the slave. (Bug #24687073)

• Replication: If an ORDER BY clause was used in retrieving records from certain Performance

Schema tables relating to replication, an empty set was returned. The issue has now been fixed. (Bug

#22958077, Bug #80777)

• Replication: When replication channels are used on a slave for multi-source replication, a START

SLAVE statement that does not specify an individual channel (so without the FOR CHANNEL clause)

should start the I/O thread and the SQL thread for all of the channels on the replication slave. However,

if a RESET SLAVE statement was used on such a slave, a subsequent START SLAVE statement did not

start the non-default channels. Now, replication channels that are deinitialized as a result of a RESET

SLAVE statement, rather than as a result of an error in the initialization process, are identified and are

restarted by a START SLAVE statement that applies to all channels. (Bug #22809607)

• Replication: Issuing RESET SLAVE on a replication slave does not change any replication connection

parameters such as master host, master port, master user, or master password, which are retained in

memory. However, these connection parameters are reset if you issue RESET SLAVE ALL. Previously,

if the slave mysqld was restarted immediately after issuing RESET SLAVE (including a server crash as

well as a deliberate restart), the connection parameters were reset as if RESET SLAVE ALL had been

used.

Now, when master_info_repository=TABLE is set on the server (which is the default from

MySQL 8.0), replication connection parameters are preserved in the crash-safe InnoDB table

mysql.slave_master_info as part of the RESET SLAVE operation. They are also retained in

memory. In the event of a server crash or deliberate restart after issuing RESET SLAVE but before

issuing START SLAVE, the replication connection parameters are retrieved from the table and reused for

the new connection.

If master_info_repository=FILE is set on the server (which is the default in MySQL 5.7),

replication connection parameters are only retained in memory, so the behavior remains the same as

previously. If the slave mysqld is restarted due to a server crash or a deliberate restart immediately

after issuing RESET SLAVE, the connection parameters are lost. In that case, you must issue a CHANGE

MASTER TO statement after the server start to respecify the connection parameters before issuing

START SLAVE.

If you want to reset the connection parameters intentionally, you need to use RESET SLAVE ALL, which

clears the connection parameters. In that case, you must issue a CHANGE MASTER TO statement after

the server start to specify the new connection parameters. (Bug #20280946)

• Replication: When a group member resumes after being suspended for some time and is not able to

process all pending messages, it enters the ERROR state. However, the remaining members see it as

UNREACHABLE, and wait until the member's suspicion expires to evict it from the group. The behavior

has now been modified and a member stopping due to some error tries to connect to a known peer to

request its removal from the group, before installing the leave view. (Bug #91433, Bug #28252687)

• Replication: Compilation warnings related to unused functions in xdr_utils have been reduced.

Thanks to Zsolt Parragi for the patch. (Bug #91071, Bug #28099963)

395

MySQL 8.0 Release Notes

• Replication: If the group_replication_recovery_retry_count variable was modified while the

member was already making a reconnection attempt, the connection attempt could enter an infinite loop.

(Bug #91057, Bug #28092714)

• Replication: The group_replication_exit_state_action variable enables you to specify

what action is taken if a member involuntarily leaves the group, but when starting a server with

group_replication_start_on_boot enabled the group_replication_exit_state_action

variable was being ignored during the following scenarios:

• valid number of group members was exceeded

• incompatible configuration of the member system variables (various)

• the joining member had more transactions than the group

• the joining member's version was not compatible with the group

(Bug #90494, Bug #27881311)

• Replication: Issuing START GROUP_REPLICATION and then forcibly stopping the mysqld process,

for example using control-C, could result in an unexpected halt of the server. (Bug #90457, Bug

#27873419)

• Group Replication: Entries in the relay log info log for the group_replication_applier and

group_replication_recovery channels were not cleared by RESET SLAVE or RESET SLAVE

ALL. (Bug #27411175)

• Group Replication: When Group Replication was started on server with an invalid

group_replication_group_name, the server stopped unexpectedly. (Bug #91347, Bug #28219136)

• Group Replication: When group_replication_group_seeds contained a DNS based entry which

resolved to its own local address, Group Replication was unable to start. (Bug #90483, Bug #27882096,

Bug #28074929)

• Microsoft Windows: An error now is written to the server log when the presence of the

NO_AUTO_CREATE_USER value for the sql_mode option in the options file prevents a MySQL 8.0 server

from starting. (Bug #28061945, Bug #90967)

• Microsoft Windows: On Windows, uninstallation of the MySQL Server MSI package through MySQL

Installer produced a spurious popup window. (Bug #27463864)

• Microsoft Windows: On Windows, DBUG_ABORT did not print the custom stack trace and other

information. (Bug #21383530)

• Microsoft Windows: Starting MySQL as a Windows service with the service-installation command that

specified a service name following the --install option ignored the directives in the named service

group of the my.ini or my.cnf options files and used default options instead. Only the default service

names (mysqld, mysql_cluster, server, mysqld-8.0) could load different parameters from an

options file. (Bug #90383, Bug #27852209)

• JSON: The server did not reject creation of a table with a generated column in which the generated

column used JSON_TABLE(), even though subqueries, parameters, variables, stored functions, and

loadable functions are not permitted in expressions for generated columns. The server now checks more

aggressively to make sure any of the disallowed constructs (including JSON_TABLE()) are rejected for

use in such expressions. (Bug #28518485)

396

MySQL 8.0 Release Notes

• JSON: SELECT ... FROM JSON_TABLE() sometimes failed with a permissions error for a user other

than MySQL root. This issue could also occur when such a query was used as the basis for a view, and

a SELECT from the view failed. (Bug #28255453, Bug #27923406)

References: See also: Bug #27189940.

• JSON: The JSON_TABLE() function subjected integer values greater than or equal to 2

wraparound. For example, the query SELECT id FROM JSON_TABLE('[{"id":"2147483648"}]',

'$[*]' COLUMNS (id BIGINT UNSIGNED PATH '$.id')) AS json returned -2147483648.

(Bug #27856835)

• JSON: In some contexts, the NULLIF() function returned its first argument as a boolean value

rather than its actual type. This was noticed when the result of this function was used as an argument

to JSON_ARRAYAGG() or JSON_OBJECTAGG(), but could have occurred in other cases in which

NULLIF() was used in a similar fashion. (Bug #90833, Bug #28007237)

• JSON: When a JSON document which contained binary data was converted to base-64 encoded

text for display, newline characters in the encoded string were not properly escaped, so that the

text representation could not be parsed as JSON, and was thus truncated, corrupted, or both. Now

MySQL makes sure that any newline characters in the encoded string are escaped. (Bug #90503, Bug

#27891359)

• filesort operations could cause a server exit. (Bug #28791531, Bug #92777)

• Debian packaging now supports Ubuntu 18.10 (Cosmic Cuttlefish). (Bug #28765706)

• On the Fedora 29 platform, OpenSSL 1.0.x is used to build packages because OpenSSL 1.1.1 support

is not ready. If you build MySQL from source, it is recommended that you build using the compat-

openssl10-devel package. (Bug #28737143)

• On the Fedora 29 platform, upgrading from MariaDB to MySQL 8.0.13 failed due to missing obsoletes.

(Bug #28727698)

• MySQL binary distributions for SLES 12 now are built using GCC 7. The lowest supported GCC version

on this platform is now 5.3 (previously 4.8.5). (Bug #28542723)

• Trying to add a functional index on a subquery should not be possible, and caused the server to hit

an assertion when trying to resolve the indexed expression. Now in such cases, the expression is

disallowed, and the servers returns an appropriate error message. (Bug #28526493)

• Added a range check when performing calculations with exponents. (Bug #28505423)

• CMAKE -DWITHOUT_SERVER=1 resulted in build errors. (Bug #28501563, Bug #92011)

• When a prefix index was specified with a length of 8 bytes, the Sub_part column in the output of SHOW

INDEXES was NULL. (Bug #28499603)

• Compilation failed for GCC 8 with MySQL configured to use some system libraries. (Bug #28471072,

Bug #91914)

• For debug builds, if the server bootstrapping phase failed, missing cleanup code caused an assertion to

be raised. (Bug #28435378, Bug #91847)

• Numeric ranges in MySQL builds could differ between the ARM and Intel x64 platforms. (Bug

#28401869)

• For mysqldump --tables output, file names now always include a .txt or .sql suffix, even for

file names that already contain a dot. Thanks to Facebook for the contribution. (Bug #28380961, Bug

#91745)

397

MySQL 8.0 Release Notes

• Concurrent INSERT and SELECT statements on a MERGE table could result in a server exit. (Bug

#28379285)

• On SLES 15, upgrading from MariaDB packages to MySQL packages failed due to incorrect obsoletes

information. (Bug #28292138)

• The data dictionary auto releaser now allocates maps for data dictionary object types dynamically.

Also, maps were added for column statistics and resource groups used in size calculations and object

removal, and an auto releaser was added for ANALYZE TABLE operations. (Bug #28245522, Bug

#91420)

• It was possible for a UNION query that mixed different character sets to fail with a spurious error. (Bug

#28237675)

References: This issue is a regression of: Bug #83895, Bug #25123839.

• CHECK TABLE ... FOR UPGRADE on temporary tables could raise an assertion. (Bug #28220374)

References: This issue is a regression of: Bug #24741307.

• A divide-by-zero error could occur in the range optimizer. (Bug #28214186)

• Due to a GCC 8 bug, recursion in foreign key checks could exhaust stack space. (Bug #28200774, Bug

#28421040, Bug #91823)

• When sql_mode was set to the empty string, queries of the form SELECT

CONCAT( FORMAT(LPAD(char,2,''), 1) ) were not handled properly; the same was also true for

similarly-formed queries using RPAD() in place of LPAD(). (Bug #28197977)

• Non-privileged users could change their own account password history and reuse properties. (Bug

#28191838)

• The OpenSSL 1.1 OPENSSL_malloc_init() call did not work well on Windows. To address this,

alternative allocation wrappers are used instead of the defaults from OpenSSL. Consequently, OpenSSL

memory instrumentation is turned off. (Bug #28179051)

• Allocation of certain object types during data dictionary lookups resulted in a stack buffer overflow. (Bug

#28176453)

• An internal server operation that attempted to perform a commit while fetching table statistics from the

INFORMATION_SCHEMA could raise an assertion. (Bug #28165060)

• Certain stored procedures could cause a server exit. (Bug #28156802)

• Output for CREATE USER statements could differ in the general query log and audit log. (Bug

#28147710)

• For UPDATE and DELETE statements that produce an error due to sql_safe_updates being enabled,

the error message was insufficiently informative. The message now includes the first diagnostic that was

produced, to provide information about the reason for failure. For example, the message may indicate

that the range_optimizer_max_mem_size value was exceeded or type conversion occurred, either

of which can preclude use of an index.

Additionally: (1) Using EXPLAIN for such statements does not produce an error, enabling users to see

from EXPLAIN plus SHOW WARNINGS output why an index is not used. (2) For multiple-table deletes and

updates, an error is produced with safe updates enabled only if any target table uses a table scan. (Bug

#28145710, Bug #91080)

398

MySQL 8.0 Release Notes

• MySQL Server and test RPM packages were missing perl-Data-Dumper as a dependency. (Bug

#28144933, Bug #72926)

• Server startup could fail if a service needed by a component was not yet initialized. (Bug #28142250)

• SHOW CREATE TABLE could omit foreign key RESTRICT options. This in turn could cause foreign key

RESTRICT options to be lost from tables dumped with mysqldump and restored from the dump file. (Bug

#28122781, Bug #91110)

• The mysql client was slow to import large multiple-line statements in batch mode. Memory allocation

is now more efficient for this situation. Thanks to Sinisa Milivojevic for the patch. (Bug #28116512, Bug

#85155)

• The SUM() and AVG() functions did not handle correctly a string argument used with a window function.

(Bug #28105241)

• Excessive nesting of geometry collections caused the server to exhaust stack space. The server now

raises an error if there is a danger of stack overrun. (Bug #28100563)

• For the mysql client, the -b short option was associated with two long options, --no-beep and --

binary-as-hex. The -b option now is associated only with --no-beep. (Bug #28093271)

• For a table with an auto-increment primary key, concurrent ALTER TABLE ... ADD ... VIRTUAL

and INSERT statements could lead to duplicate-key errors. (Bug #28089240)

• Handling of floating-point values by SUM() was improved. (Bug #28080199)

• Some expressions using ST_Simplify() could cause a server exit. (Bug #28079969)

• In builds with Undefined Behavior Sanitizer enabled, testing returned a “member call on null pointer of

type 'struct Event_db_repository'” error. (Bug #28066155)

• The WITH_GMOCK CMake option did not handle Windows path names properly. (Bug #28061409, Bug

#90964)

• INFORMATION_SCHEMA queries that attempted to cache table statistics could raise a debugging

assertion. (Bug #28035207)

• If roles were assigned to accounts, certain sql_mode settings could cause the server to be unable to

start. (Bug #28030423)

• Group lookups for LDAP authentication plugins could fail if the user had insufficient privileges. Now,

group search operations bind again using root credentials if those are available. (Bug #28016008)

• ANALYZE TABLE ... UPDATE HISTOGRAM statements produced by mysqldump contained a syntax

error. (Bug #28014376, Bug #90846)

• Generated columns having indexes and that used a string function were not always populated correctly.

(Bug #27973409)

• Fixed-length sort keys, such as those used by priority queues, that fit exactly were assumed to have

failed. (Bug #27970481, Bug #92448, Bug #28654343)

• For an empty result, REPLACE() sometimes returned a null string rather than an empty string. (Bug

#27960921)

• Dropping a table that was created with a user-defined collation no longer available could cause a server

exit. (Bug #27952999)

399

MySQL 8.0 Release Notes

• Joining the INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS and TABLE_CONSTRAINTS tables

on the CONSTRAINT_NAME failed because the column collations differed. (Bug #27945704, Bug #90690)

• Some operations on DECIMAL values could cause a server exit. (Bug #27942277)

• Very long table keys were handled incorrectly on replication slaves. (Bug #27930505)

• mysqld did not determine its installation directory correctly if that directory was the last one listed in

$PATH. (Bug #27922896)

• During server startup/shutdown, PID files could be mishandled. (Bug #27919254)

• When the server was started with --skip-grant-tables, some account-management statements

were not disabled. (Bug #27906226)

• On rare occasions, setting a savepoint could raise an assertion. (Bug #27898591)

• Runtime errors could occur for calls to copy_integer(). myfunc_int(), mysql_sys_var_int(),

or thd_killed(); for calls to MyISAM sorting functions; or for values outside the range of

representable values of type unsigned long long. (Bug #27894901, Bug #90515, Bug #27871951,

Bug #27918095, Bug #90609, Bug #27937522, Bug #90661, Bug #27978325, Bug #27962900)

• mysql_install_plugin failed to report plugin-specific errors if the server was unable to store plugin

metadata in the data dictionary. (Bug #27893406)

• ssl_fips_mode cannot be set to ON unless the OpenSSL requirements are satisfied, but a failed

attempt still resulted in the value being displayed as ON. (Bug #27891890)

• The symbol for the mysql_result_metadata() C API function was not exported by the client library

on Windows. (Bug #27868095)

• For InnoDB tables, self-referencing foreign keys could be created, causing server misbehavior. (Bug

#27864515)

• A UNION query mixing different character sets produced invalid output when performed in a prepared

statement or a stored procedure. (Bug #27849293)

• Debian packages were missing a dependency for libcurl-dev. (Bug #27844465)

• --help output for client programs did not include the current --ssl-fips-mode value. (Bug

#27838966)

• A runtime error could occur for calls to Derived_key_comp(). (Bug #27830679)

• For MEMORY tables, memory overflow errors could occur. (Bug #27799513)

• When converting from a BLOB (or TEXT) type to a smaller BLOB (or TEXT) type, no warning or error was

reported informing about the truncation or data loss. Now an appropriate error is issued in strict SQL

mode and a warning in nonstrict SQL mode. (Bug #27788685, Bug #90266)

• For debug builds, my_strnxfrm_unicode_full_bin() could raise an assertion. (Bug #27752619)

• In builds with Undefined Behavior Sanitizer enabled, signed integer overflow could occur in GIS

calculations. (Bug #27751479, Bug #27744399, Bug #27811282)

• It was possible in some cases for the internal function regexp::EvalExprToCharset() to bind a

reference to a misaligned address. (Bug #27743722)

• The severity of messages produced by the server about being unable to read key files has been

escalated from INFORMATION to WARNING. (Bug #27737195)

400

MySQL 8.0 Release Notes

• No temporary table field was created for an expression using window functions combined with a rollup,

causing queries containing these to fail. (Bug #27735167)

• The expression FIND_IN_SET( JSON_UNQUOTE( JSON_SET('{}','$','') ), 1) was not

evaluated properly. (Bug #27731699)

• Failure to create a temporary table during a MyISAM query could cause a server exit. Thanks to

Facebook for the patch. (Bug #27724519, Bug #90145)

• parser_max_mem_size was ineffective when parsing stored program definitions. (Bug #27714748)

• A BETWEEN clause comparing negative values could lead to erroneous results. (Bug #27691347)

• Some typos in server error messages were fixed. Thanks to Thomas Tsiakalakis for the contribution.

(Bug #27688294, Bug #90048)

• These scripts are no longer included in RPM packages (they are unnecessary because they

are compiled into the mysqld binary): fill_help_tables.sql, mysql_sys_schema.sql,

mysql_system_tables.sql, mysql_system_tables_data.sql, mysql_system_users.sql.

(Bug #27672991)

• Unique::io_cache was not cleaned up properly when restarting an index merge operation, leading to

an assertion in debug builds. (Bug #27599292)

• Using a binary or hexadecimal literal value in a ENUM column resulted in a string type with bytes not

permitted by the data dictionary character set. (Bug #27592803)

• It was possible for CONVERT() to fail under the following conditions:

The size of the result of the conversion was greater than max_allowed_packet

sql_mode was '' (that is, empty).

The character set of the result differed from character_set_connection (Bug #27592714)

• Use of ENUM or SET fields with JSON_TABLE() could result in unexpected behavior. (Bug #27571251)

• Host name resolution errors could cause the audit_log plugin to fail. (Bug #27567003)

• Unsuccessful connection attempts were not being written to the error log when

log_error_verbosity=3. (Bug #27539838)

• Persisted system variables with a value of NULL were written to mysqld-auto.cnf incorrectly. (Bug

#27512616)

• An earlier code cleanup caused FEDERATED storage engine failures. (Bug #27493633, Bug #89537)

References: This issue is a regression of: Bug #25943754.

• Setting max_execution_time sometimes had no effect when used with full-text search. (Bug

#27155294)

• An attempted read of an uncommitted transaction raised an assertion. (Bug #26876608)

• ALTER TABLE ... REORGANIZE PARTITION ... could result in incorrect behavior if any partition

other than the last was missing the VALUES LESS THAN part of the syntax. (Bug #26791931)

• In some cases when ER_DATA_TOO_LONG was the appropriate error,

ER_TRUNCATED_WRONG_VALUE_FOR_FIELD was reported instead. (Bug #26475237, Bug #87100)

401

MySQL 8.0 Release Notes

• A last_checked_for_upgrade column that stores the current server version number was added

to the mysql.tables data dictionary table to track successful CHECK TABLE ... FOR UPGRADE

operations. This data was previously stored in .frm files to avoid rechecking tables unnecessarily. (Bug

#24741307, Bug #83169)

• The MYSQLparse() function generated from the sql_yacc.yy file had exceeded a size limit that

caused the Microsoft Visual C++ compiler to abandon optimization. The /d2OptimizeHugeFunctions

compiler switch was enabled to restore optimization (available in Visual Studio 2017 and higher). (Bug

#24600301)

• A range check for the product of a signed and unsigned integer could be performed incorrectly. (Bug

#17081376, Bug #69715)

• Specifying the maximum possible value for a YEAR column failed when expressed as a real constant

such as 2155.0E00 or 2.15E3. (Bug #91226, Bug #28172538)

• Prevented potential member access within a null pointer of type SELECT_LEX. (Bug #90689, Bug

#27945614)

• The base used for calculation of line numbers reported in warnings generated by SELECT statements

has been changed from the number of input rows read to the actual row numbers seen by the user. For

statements using GROUP BY, this number is now based on the number of aggregate groupings. (Bug

#90667, Bug #27938507)

• Estimates contained by histograms for the number of distinct values in each bucket, which can be

employed to estimate the number of distinct values in a table, can now be used by the Optimizer's

histograms::Histogram interface. (Bug #90465, Bug #27872281)

• Selecting from the INFORMATION_SCHEMA.KEYWORDS table failed when no default database had been

selected. (Bug #90160, Bug #27729859)

• ANALYZE TABLE UPDATE HISTOGRAM failed to return an error condition to the client when

lock_wait_timeout was exceeded during statement processing. (Bug #89738, Bug #27574375)

• It was possible to create a table t having a generated column g and then to execute ALTER TABLE t

ALTER COLUMN g SET DEFAULT ...; attempting to set the default for a generated column in this

fashion now fails with Error 1221 Incorrect usage of DEFAULT and generated column. This is

the same behavior as for a similar CREATE TABLE statement. (Bug #88619, Bug #27164393)

Changes in MySQL 8.0.12 (2018-07-27, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

• Audit Log Notes

• Compilation Notes

• Configuration Notes

• Data Dictionary Notes

• Deprecation and Removal Notes

• Firewall Notes

• SQL Function and Operator Notes

402

MySQL 8.0 Release Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Plugin Notes

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Audit Log Notes

• For new MySQL installations, the USER and HOST columns in the audit_log_user table used by

MySQL Enterprise Audit now have definitions that better correspond to the definitions of the User and

Host columns in the mysql.user system table.

For upgrades to an installation for which MySQL Enterprise Audit is already installed, it is recommended

that you alter the table definitions as follows:

ALTER TABLE mysql.audit_log_user

DROP FOREIGN KEY audit_log_user_ibfk_1;

ALTER TABLE mysql.audit_log_filter

CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_as_ci;

ALTER TABLE mysql.audit_log_user

CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_as_ci;

ALTER TABLE mysql.audit_log_user

MODIFY COLUMN USER VARCHAR(32);

ALTER TABLE mysql.audit_log_user

ADD FOREIGN KEY (FILTERNAME) REFERENCES mysql.audit_log_filter(NAME);

(Bug #23706056)

Compilation Notes

• Microsoft Windows: For OpenSSL 1.1, the library names have changed for Windows. The

CMake configuration code now accounts for this. Also, it is now possible on Windows to use -

DWITHOUT_SERVER=1 to build 32-bit client binaries. (Bug #28170711, Bug #91223)

• The minimum version of the Boost library for server builds is now 1.67.0. (Bug #27866110)

Configuration Notes

• The maximum value was increased from 256 to 1024 for these Performance Schema system variables:

performance_schema_max_cond_classes

performance_schema_max_file_classes

performance_schema_max_mutex_classes

performance_schema_max_rwlock_classes

performance_schema_max_socket_classes

performance_schema_max_stage_classes

403

MySQL 8.0 Release Notes

performance_schema_max_thread_classes

The default value was increased from 250 to 300 for this Performance Schema system variable:

performance_schema_max_mutex_classes

(Bug #27647918)

• For RelWithDebInfo builds on Linux, REPRODUCIBLE_BUILD now defaults to ON. (Bug #27483447)

• The default value for the slave_pending_jobs_size_max system variable has increased from

16M to 128M. On a multi-threaded slave ( with slave_parallel_workers > 0), this value sets the

maximum amount of memory that is made available to slave worker queues holding events that have not

yet been applied. The potentially larger memory usage should be taken into account when calculating

the resources required to deploy a multi-threaded slave. Masters and single-threaded slaves are not

affected by this setting.

The new default is double the recently increased default value specified by the max_allowed_packet

system variable (now 64M). The value of slave_pending_jobs_size_max is a soft limit, so events

larger than its value (consisting of one or more packets) can be queued and processed. However,

a large transaction is held until all the slave workers have empty queues, and then processed.

All subsequent transactions are held until the large transaction has been completed. The delay

to clear the queues of all the slave workers and the wait to queue subsequent transactions can

cause lag on the replication slave and decreased concurrency of the slave workers. The value of

slave_pending_jobs_size_max should therefore be set high enough to accommodate most

expected event sizes. (WL #11348)

Data Dictionary Notes

• The following data dictionary enhancements were introduced:

• An internal method was added to protect against global read locks. The method is called before

storing, updating, or dropping data dictionary objects.

• Assertion code was added to the data dictionary API to protect against global read locks when storing,

updating, or dropping data dictionary objects.

• Protection is now implicitly acquired against backup locks and global read locks when an exclusive

metadata lock is acquired by a storage engine.

• A cost model cache validity check is now performed before releasing a cost model entry.

• A data dictionary API function was added for committing and rolling back transactions, and for

releasing transactional meta data locks.

(Bug #27937059)

Deprecation and Removal Notes

• Explicit ASC or DESC qualifiers for GROUP BY clauses are now deprecated and will be removed in a

future MySQL version. (WL #11459)

Firewall Notes

• The MySQL Enterprise Firewall firewall_whitelist table now contains a primary key column

named ID. (Bug #27164826)

404

MySQL 8.0 Release Notes

SQL Function and Operator Notes

• The BIT_AND(), BIT_OR(), and BIT_XOR() aggregate functions now can be used as window

functions, if an OVER clause is present. See Aggregate Function Descriptions. (WL #11573)

Logging Notes

• Previously, successful assignments to the dragnet.log_error_filter_rules system

variable resulted in a Note and a nonzero warning count. To avoid generating a diagnostic

for a successful operation, this Note is no longer generated. Instead, the dragnet.Status

status variable can be consulted to determine the result of the most recent assignment to

dragnet.log_error_filter_rules. (Bug #27910708, Bug #90571)

• Previously, log components listed in the log_error_services system variable had to be separated by

semicolons. Components now can be separated by commas. A given setting cannot use both semicolon

and comma separators. (Bug #27788925, Bug #90268)

Optimizer Notes

• The filesort algorithm (used by the optimizer to satisfy an ORDER BY clause when no index can

be used) is now more memory efficient. The primary change is that the optimizer allocates memory

buffers incrementally as needed, up to the size indicated by the sort_buffer_size system variable,

rather than allocating a fixed amount of sort_buffer_size bytes up front. This enables users to set

sort_buffer_size to larger values to speed up larger sorts, without concern for excessive memory

use for small sorts. (This benefit may not occur for multiple concurrent sorts on Windows, which has a

weak multithreaded malloc.)

In addition, filesort is less pessimistic with respect to worst-case scenarios. Previously, filesort

produced an error without starting if merge operations or sort-key generation might fail. Now, because

the worst case is unlikely to occur in practice, filesort produces an error only for actual rather than

prospective failures. (WL #11590)

• Previously, extended EXPLAIN output was produced only for SELECT statements. Extended output is

now produced for INSERT, REPLACE, UPDATE, and DELETE statements as well. (To display extended

output, use SHOW WARNINGS following EXPLAIN. See Extended EXPLAIN Output Format.) (WL #6033)

Packaging Notes

• For Linux, the generic binary distribution compression algorithm changed from Gzip to XZ; and the file

extension changed from .tar.gz to .tar.xz. (Bug #28450941, Bug #91889)

• Docker disables NUMA-related operations by default, so the mysqld included in Docker images now

has NUMA support disabled so that the error log does not fill with NUMA warnings. (Bug #28081363)

• RPM .spec files were updated to reflect the removal of yaSSL and that OpenSSL is the default SSL

library for all builds. (Bug #28025427)

• For generic Linux .tar.gz distributions, the mysqlxtest client has been moved from the server

package to the test package. (Bug #27744137)

• An RPM package for installing ARM 64-bit (aarch64) binaries of MySQL Server on Oracle Linux 7 is now

available in the MySQL Yum Repository and for direct download.

Known Limitation for this ARM release: You must enable the Oracle Linux 7 Software Collections

Repository (ol7_software_collections) to install this package, and must also adjust the libstdc++7 path.

See Yum's Platform Specific Notes for additional details.

405

MySQL 8.0 Release Notes

Plugin Notes

• Previously, the Rewriter query rewrite plugin permitted rewriting only for SELECT statements.

Rewritable statements now include INSERT, REPLACE, UPDATE, and DELETE as well. See The Rewriter

Query Rewrite Plugin. (WL #8776)

Security Notes

• The linked OpenSSL library for MySQL Server has been updated to version 1.0.2o. Issues fixed in

the new OpenSSL version are described at http://www.openssl.org/news/vulnerabilities.html. (Bug

#28025379)

Spatial Data Support

• Incompatible Change: The new spatial functions ST_Longitude() and ST_Latitude() return the

longitude or latitude, respectively, of their Point argument. If called with a second argument, these

functions use the argument to set the longitude or latitude, respectively, of their Point argument.

In addition, the ST_X() and ST_Y() functions now interpret their Point argument according to its

spatial reference system definition (SRS):

• ST_X() returns the coordinate value of the axis that appears first in the SRS definition, and ST_Y()

returns the coordinate value of the axis that appears second in the SRS definition.

• If ST_X() and ST_Y() are used to set the longitude or latitude of a Point argument that has a

geographic SRS, the longitude or latitude value must be in the proper range for the SRS, or an error

occurs.

Note

If spatial data contains geometry values that now are interpreted differently by

ST_X() and ST_Y(), existing queries using these functions will return different

results, compared to previous MySQL versions.

(Bug #27125600, Bug #88503, WL #11453)

• The EPSG data set containing spatial reference system data for spatial calculations has been upgraded

from version 9.2 to 9.3. (Bug #27977721)

• Spatial functions that accept geometry arguments and previously returned an

ER_LONGITUDE_OUT_OF_RANGE or ER_LATITUDE_OUT_OF_RANGE error for longitude or

latitude values out of range now return ER_GEOMETRY_PARAM_LONGITUDE_OUT_OF_RANGE or

ER_GEOMETRY_PARAM_LATITUDE_OUT_OF_RANGE instead. This does not apply to spatial functions

that parse or modify geometries: ST_xxxFromText(), ST_xxxFromWKT(), ST_xxxFromWKB(),

ST_GeomFromGeoJSON(), ST_X(), ST_Y(), ST_Longitude(), and ST_Latitude(). (Bug

#27892138)

• Previously, the parser recognized USING RTREE in index specifications, but this could not be

specified for any storage engine. Now USING RTREE is permitted for spatial index specifications. (Bug

#27836608)

• Indexes on geometry columns now must be spatial indexes. Consequently, the SPATIAL keyword is

optional but implicit for creating an index on a spatial column. A spatial index on a geometry column

is not permitted for a primary key or unique index. Also, ASC and DESC are not permitted for spatial

indexes. (Bug #21087676, WL #11808)

406

MySQL 8.0 Release Notes

SQL Syntax Notes

• Important Change: MySQL now allows a query having a WITH ROLLUP modifier to use DISTINCT.

See SELECT Statement, for more information. (Bug #87450, Bug #26640100, Bug #20671578, Bug

#76229)

• Important Change: MySQL now allows the use of ORDER BY with grouping functions in SELECT.

statements. (Bug #86312, Bug #27063525)

• Important Change: MySQL now allows ORDER BY to be used in a query having a WITH ROLLUP

modifier. For more information, see SELECT Statement. (Bug #86311, Bug #26073513)

X Plugin Notes

• Authentication errors returned from a MySQL 8.0.11 server to an X Plugin client were marked as fatal,

which caused the client to stop attempting its automatic sequence of authentication attempts using

different methods. X Plugin now ignores fatal authentication errors, and subsequent expected errors

such as write timeout errors, while the sequence of authentication attempts is in progress. If none of

the authentication methods tried are successful, X Plugin now selects and returns the most relevant

error message received from the server, which is not necessarily the last error message received. (Bug

#28135006)

• During the X Plugin automated authentication sequence, connection attempts are made using different

authentication methods in a pre-set sequence. X Plugin checks before starting the sequence whether

the connection uses SSL or not, and does not attempt connection with the PLAIN authentication method

if the connection is not encrypted. For additional verification, a check and error were added so that the

PLAIN authentication method is disallowed if attempted when the connection is not encrypted. (Bug

#27691189)

• In the event of an authentication failure, X Plugin always returned the error code ER_ACCESS_DENIED,

with a custom X Protocol error message for the error situation. The error codes that are received from

the MySQL server for authentication failures are now passed on to the client instead, with the standard

MySQL error messages that go with them. (Bug #27675699)

• During the X Plugin automated authentication sequence, where connection attempts are made using

different authentication methods in a pre-set sequence, the error returned after every failed connection

attempt was marked with the severity FATAL. Now, the errors are marked as ERROR while there are still

other authentication methods to be attempted, and only the final error that results in disconnection is

marked as FATAL. (Bug #27636947)

• The X Plugin code was being compiled twice with different preprocessor definitions. (Bug #27267054)

• A number of improvements were made to the handling of authentication issues by X Plugin:

• The X Plugin automated authentication sequence, where connection attempts are made using

different authentication methods in a pre-set sequence, is now halted if an error response indicates

that the connection has been broken or reads or writes are timing out.

• The automated authentication sequence is also now halted in the event of any fatal error.

• The last significant error is now reported for an abandoned authentication sequence, not just the last

error that occurred.

• A more specific error code and message are now reported if authentication with the

caching_sha2_password authentication plugin is attempted over an unsecure connection.

(Bug #27257774)

407

MySQL 8.0 Release Notes

• In some circumstances, a MySQL server with X Plugin loaded could experience an unexpected halt

during a shutdown process initiated by a failed start or by the RESTART command. The issue has now

been fixed. (Bug #25474793, Bug #27259783)

Functionality Added or Changed

• Important Change; Group Replication: group_replication_exit_state_action

determines how Group Replication behaves when a server instance leaves the group involuntarily,

such as when it is expelled from the group due to an unstable network connection. When

group_replication_exit_state_action is ABORT_SERVER (the default), the instance shuts itself

down; when its value is READ_ONLY, the instance switches itself to super read-only mode instead, and

goes into the Group Replication ERROR state. (WL #11568)

• InnoDB: InnoDB now supports ALGORITHM=INSTANT for the following ALTER TABLE operations:

• Adding a column. This feature is referred to as “Instant ADD COLUMN”.

• Adding or dropping a virtual column.

• Adding or dropping a column default value.

• Modifying the definition of an ENUM or SET column.

• Changing the index type.

• Renaming a table.

Operations that support ALGORITHM=INSTANT only modify metadata in the data dictionary. No

exclusive metadata locks are taken on the table during preparation and execution phases of the

operation, and table data is unaffected, making the operations instantaneous. If not specified explicitly,

ALGORITHM=INSTANT is used by default by operations that support it. If ALGORITHM=INSTANT is

specified but not supported, the operation fails immediately with an error.

For more information about operations that support ALGORITHM=INSTANT, see Online DDL Operations.

Thanks to the Tencent Games DBA team for the contribution. (Bug #28100103, Bug #91074, WL

#11250)

• InnoDB: Undo logging is now supported for small updates to large object (LOB) data, which improves

performance of LOB updates that are 100 bytes in size or less. Previously, LOB updates were a

minimum of one LOB page in size, which is less than optimal for updates that might only modify a few

bytes. This enhancement builds upon support added in MySQL 8.0.4 for partial update of LOB data. (WL

#11328)

• Replication: You can now use a shell pipe to supply an archive of compressed binary log files to

mysqlbinlog as streamed input. Previously, the files had to be extracted separately before passing

them to mysqlbinlog. Thanks to the Facebook team for this contribution.

In this example, binlog-files_1.gz contains multiple binary log files for processing. The pipeline

extracts the contents of binlog-files_1.gz, pipes the binary log files to mysqlbinlog as standard

input, and pipes the output of mysqlbinlog into the mysql client for execution:

gzip -cd binlog-files_1.gz | ./mysqlbinlog - | ./mysql -uroot -p

(Bug #27445278, Bug #89423)

References: See also: Bug #27836543.

408

MySQL 8.0 Release Notes

• Replication: The SYSTEM_VARIABLES_ADMIN and PERSIST_RO_VARIABLES_ADMIN privileges have

been added to the mysql.session reserved account. (Bug #89873, Bug #27621869)

• Replication: Information about XCom's memory usage has been added to the Performance Schema

tables. The setup_instruments table now has an entry corresponding to the XCom cache, and the

memory_summary_global_by_event_name table contains the memory usage statistics of the XCom

cache. (WL #9855)

• Microsoft Windows: On Windows, the forking used to implement RESTART was suppressible using

the --gdb option. However, this was a side effect, performed in addition to the other option actions

done to set up a debugging environment. In non-debug settings, the new --no-monitor option may

be used for the sole purpose of suppressing forking the monitor process. For a server started with either

--gdb or --no-monitor, executing RESTART causes the server to simply exit without restarting. (Bug

#27801043)

• Checking for foreign key relationships by DROP TABLE and DROP DATABASE was improved. The check

now takes place before any tables are deleted, so that in the event of a problem the statement fails

before making any changes. Parent and child tables now can be dropped in arbitrary order, as long as

they are dropped by the same DROP TABLE statement. In addition, error reporting was improved for

attempts to drop a parent table without dropping a child table. (Bug #27821060, Bug #17564464, Bug

#70531, Bug #22359539, Bug #79610)

• When support for roles was added, the ADMIN keyword became a reserved keyword. ADMIN is now

once again a nonreserved keyword. (Bug #27814204)

• When a client shuts down the server, the server now writes a message to the error log indicating which

user performed this action. (Bug #26246628, Bug #86635)

• Previously, for the --ssl-mode=VERIFY_IDENTITY option, the client checked whether the host

name that it used for connecting matched the Common Name value in the certificate but not the Subject

Alternative Name value. Now, if the client uses OpenSSL 1.0.2 or higher, the client checks whether the

host name matches either the Subject Alternative Name value or the Common Name value in the server

certificate. Thanks to Daniël van Eeden for a patch on which this change was based. (Bug #16211011,

Bug #68052, Bug #27511233, Bug #89578)

Bugs Fixed

• Important Change; JSON: The JSON_TABLE() function now automatically decodes base-64

values and prints them using the character set given by the column specification. (Bug #90157, Bug

#27729112)

References: See also: Bug #89847, Bug #27613276.

• InnoDB: New columns added to INFORMATION_SCHEMA.INNODB_TABLES and

INFORMATION_SCHEMA.INNODB_COLUMNS tables in 8.0.12 did not appear after upgrading to 8.0.12.

(Bug #28065244)

• InnoDB: Large object (LOB) version numbers stored in LOB index entries were left uninitialized at 0

instead of initialized at 1. (Bug #28046298)

• InnoDB: Adding a column to a table with a generated column raised an invalid assertion. (Bug

#28040201)

• InnoDB: An attempt to access freed memory during a checkpoint operation caused the server to exit.

(Bug #28039477)

409

MySQL 8.0 Release Notes

• InnoDB: An assertion failure occurred when starting the server with experimental system variables that

were unintentionally exposed in normal MySQL builds. (Bug #27899424, Bug #90526, Bug #27898396,

Bug #90523, Bug #27898344, Bug #90522)

• InnoDB: An invalid system variable setting raised an assertion. (Bug #27898284)

• InnoDB: Attempting to move a table from a discarded file-per-table tablespace to a shared tablespace

raised an assertion. The operation now produces an error instead. (Bug #27861972)

• InnoDB: Potential failures related to page allocation for large objects (LOBs) were not sufficiently

handled. (Bug #27852003)

• InnoDB: The ngram full-text search parser permitted comma and period characters to be tokenized as

words, which caused an inconsistency between boolean and natural language mode search results.

Comma and period characters are no longer tokenized. (Bug #27847697)

• InnoDB: Checksum mismatches and other issues were caused by concurrent modification of a

tablespace header page, and attempting to place a lock on a partially initialized page. (Bug #27823064)

• InnoDB: An I/O error returned by an fsync() operation is now treated as a hard error. (Bug

#27805553, Bug #90296)

• InnoDB: In a single thread, two minitransactions latched the first page of a large object value (LOB)

while another thread attempted to allocate the page, causing a deadlock. (Bug #27777959)

• InnoDB: After upgrading to MySQL 8.0.12, table columns including the FTS_DOC_ID column were

missing from the INFORMATION_SCHEMA.INNODB_COLUMNS table. (Bug #27774145)

• InnoDB: An invalid assertion was raised when the optimizer chose a prefix index defined on a virtual

column. (Bug #27755892)

References: This issue is a regression of: Bug #19806106.

• InnoDB: An in-memory table object for a table being truncated could be opened under improper

metadata locking protection.

A new method of preserving the AUTOINC counter value during a TRUNCATE PARTITION operation was

implemented. (Bug #27754995)

• InnoDB: An assertion was raised during a mini-transaction commit that included dirty pages but no redo

log records. The mini-transaction did not wait for space in the recently-closed buffer and subsequently

marked the page with an invalid current LSN value. After the invalid LSN value was added to the flush

list, a delayed mini-transaction added dirty pages with an earlier LSN value, breaking the flush list order.

The innodb_log_checkpoint_fuzzy_now debug option was added. Enabling this option forces

InnoDB to write a fuzzy checkpoint. Also, new internal redo log module counters were added for tracking

LSN values. The log_lsn_buf_dirty_pages_added counter tracks the LSN value up to which dirty

pages have been added, and the log_lsn_buf_pool_oldest_lwm counter tracks the low watermark

LSN for the oldest modified block in the buffer pool. (Bug #27664539)

• InnoDB: The Contention-Aware Transaction Scheduling algorithm (CATS) tracks the number of

transactions waiting for another transaction. In the case of a deadlock, the method by which the number

of waiting transactions is approximated produced inflated values. (Bug #27646322)

• InnoDB: Attempting to acquire an InnoDB ticket while holding a victim transaction lock caused a lock

order violation. (Bug #27626681)

References: This issue is a regression of: Bug #23476050.

410

MySQL 8.0 Release Notes

• InnoDB: An attempt to read a zero-length BLOB value raised an assertion failure during recovery. The

BLOB value was not yet completely inserted. (Bug #27617389)

• InnoDB: A race condition occurred when acquiring a table lock for a table that was already in memory.

(Bug #27586419, Bug #27577704)

References: This issue is a regression of: Bug #26848711.

• InnoDB: After restarting the server, attempting to create an encrypted table returned a generic error

from the storage engine. (Bug #27577339)

• InnoDB: The use of Contention-Aware Transaction Scheduling (CATS) with a spatial index caused a

transaction to wait indefinitely. (Bug #27572937)

• InnoDB: Incorrect parsing of a tablespace name that included multibyte characters caused a DROP

DATABASE operation to fail. (Bug #27566937)

• InnoDB: A check performed to identify temporary tables caused an error when the data dictionary

attempted to open a partitioned table. (Bug #27565997)

• InnoDB: A schema mismatch error reported during an import tablespace operation failed to print

mismatched table flags in a readable format. (Bug #27542720)

• InnoDB: A DDL operation failed to wait for a FULLTEXT index optimization operation to finish. (Bug

#27326796)

References: This issue is a regression of: Bug #24938374.

• InnoDB: An unnecessary check for read-only transactions was removed from the

trx_set_rw_mode() function. Thanks to Sandeep Sethia for the patch. (Bug #27211287, Bug #88739)

• InnoDB: A DDL operation that added a foreign key constraint raised an assertion when it accessed a

stale memory object that belonged to the parent table. (Bug #27208858)

• InnoDB: A failing assertion occurred after initiating a memcached get operation. (Bug #26876594)

• InnoDB: A corrupt index ID encountered during a foreign key check raised an assertion. (Bug

#26654685)

• InnoDB: A DROP TABLE operation on a table residing in a general tablespace raised an assertion when

checking index status in the post-DDL phase of the operation. (Bug #26523254)

• InnoDB: An internal deadlock during a DDL operation resulted in a long semaphore wait followed by a

server exit. (Bug #26225783)

• InnoDB: A DDL operation encountered a serious error due to an invalid lock upgrade. (Bug #26225783)

• InnoDB: On a Windows 64-bit system, invalid buffer pool configuration values caused the server to exit

on startup. (Bug #26100239, Bug #86370)

• InnoDB: A debug code block related to mutex type definitions was removed. It no longer differed from

the non-debug version of the code block. (Bug #24952279, Bug #83529)

• InnoDB: A server failure during recovery occurred due to a log parsing buffer overflow. Space is now

allocated to the log parsing buffer dynamically and incremented as necessary until it reaches the size

specified by innodb_log_buffer_size. (Bug #24734190)

• InnoDB: Table locking was optimized for concurrent updates on the same table by avoiding costly

iterations over the table locks queue.

411

MySQL 8.0 Release Notes

Thanks to Zhai Weixiang for the contribution. (Bug #18955152, Bug #72948)

• Packaging: On Windows, the mysqld.exe --help command displayed unnecessary and unexpected

details in the system output, which this fix eliminates. (Bug #27894020)

• Partitioning: Rollback of ALTER TABLE ... TRUNCATE PARTITION statements was not handled

correctly. (Bug #27603025)

References: See also: Bug #87562, Bug #26710839.

• Partitioning: For a partitioned table, partition update time could be incorrect after rebuilding the table or

restarting the server. (Bug #27073100)

• Replication: If the option --skip-log-bin was specified at server startup to disable binary logging,

no warning message was issued if both expire_logs_days and binlog_expire_logs_seconds

were set to a nonzero value. The --skip-log-bin option meant there were no binary log

files to expire, so the outcome of these binary log expiration period settings (which is that the

expire_logs_days value is ignored) had no practical effect. However, the warning message is now

issued, so that the situation can be corrected before binary logging is enabled for the server. (Bug

#27699608)

• Replication: The log messages generated when a member fails to join the group have been improved,

for example when group_replication_group_name on the member joining the group does not

match the seed's group_replication_group_name this is now described in the log message. (Bug

#27628695)

• Replication: If a MySQL server is started in crash recovery mode with an innodb_force_recovery

setting of 4 or greater, which places InnoDB into read-only mode, the semisynchronous replication

master plugin should not be initialized. Due to a change in plugin initialization order in MySQL 8.0, the

server assumed that if the plugin was registered, it had also been initialized, and incorrectly attempted

to deinitialize it. The handling of this plugin in crash recovery mode has now been corrected so that the

deinitialization function is not executed when the plugin has not been initialized. (Bug #27481872)

• Replication: The use of replication filters or binary log filters can cause issues when they are applied

to tables that are updated with XA transactions. Filtering of tables could cause an XA transaction to

be empty on a replication slave, and empty XA transactions are not supported. Also, with the settings

master_info_repository=TABLE and relay_log_info_repository=TABLE on a replication

slave, which became the defaults in MySQL 8.0, the internal state of the data engine transaction is

changed following a filtered XA transaction, and can become inconsistent with the replication transaction

context state.

Due to these issues, the use of replication filters or binary log filters in combination with XA transactions

is not supported. This fix adds the new error ER_XA_REPLICATION_FILTERS, which is logged

whenever an XA transaction is impacted by a replication filter, whether or not the transaction was empty

as a result. If the transaction is not empty, the replication slave is able to continue running, but you

should take steps to discontinue the use of replication filters with XA transactions in order to avoid

potential issues. If the transaction is empty, the replication slave stops. In that event, the replication

slave might be in an undetermined state in which the consistency of the replication process might be

compromised. In particular, the gtid_executed set on a slave of the slave might be inconsistent with

that on the master. To resolve this situation, isolate the master and stop all replication, then check GTID

consistency across the replication topology. Undo the XA transaction that generated the error message,

then restart replication. (Bug #27442477)

• Replication: When mysqlbinlog was used to read a binary log event larger than 128KB, the read

failed because 128KB was returned as the size, instead of the actual size. The issue has now been

fixed. Thanks to the Facebook team for the patch. (Bug #27417084, Bug #89326)

412

MySQL 8.0 Release Notes

• Replication: When a transaction larger than the binary log transaction cache size

(binlog_cache_size) was flushed to a temporary file during processing, and the flush failed due to

a lack of space in the temporary directory, the flush error was not handled correctly. No message was

written to the error log, and the binary log cache was not cleared after the transaction was rolled back.

Now, in this situation, the server takes an appropriate action based on the binlog_error_action

setting (shut down the server or halt logging), and writes a message to the error log. When the

transaction is rolled back, the server checks for flush errors and clears the binary log cache if any

occurred. (Bug #27399620, Bug #89272)

• Replication: When GTIDs are in use for replication, replicated transactions that are filtered out on the

slave are persisted. If binary logging is enabled on the slave, the filtered-out transaction is written to

the binary log as a Gtid_log_event followed by an empty transaction containing only BEGIN and

COMMIT statements. If binary logging is disabled, the GTID of the filtered-out transaction is written

to the mysql.gtid_executed table. This process ensures that there are no gaps in the set of

executed GTIDs, and that the filtered-out transactions are not retrieved again if the slave reconnects

to the master. Previously, this process was not done for CREATE DATABASE, ALTER DATABASE, and

DROP DATABASE statements, but it is now carried out for those statements as well as for others. (Bug

#27308751, Bug #88891)

• Replication: On a multithreaded slave, when a STOP SLAVE statement is executed on the slave,

followed by a START SLAVE statement, the error log can report a different position in the binary log for

the slave SQL thread when exiting, compared to the position reported for the slave SQL thread at the

subsequent initialization.

For a multithreaded slave, the position reported for the SQL thread on exit is a low water mark, up to

which the replication stream is consistent and has no gaps. Transactions appearing before the position

are guaranteed to have committed, but transactions after the position may have committed or not.

However, this low water mark was being reported before the process to stop the worker threads was

actually carried out, and the low water mark was subsequently updated by a checkpoint routine during

that process. The timing of the log message has now been changed so that the final low water mark is

reported as the position for the SQL thread on exit. (Bug #27300658)

• Replication: An online upgrade of a replication group that was running a version of MySQL earlier than

5.7.23 was not possible. When a member running a version earlier than either MySQL 5.7.22 or MySQL

8.0.11 tried to join a group with members running MySQL 5.7.21 or earlier, it failed to join the group

because MySQL 5.7.21 does not send the value of it lower_case_table_names system variable. This

mean that the later version compared the lower_case_table_names variable with an invalid value

and exited the group. The work around is to take the group offline, upgrade to version 5.7.23 or 8.0.12

and later. Subsequent upgrades of the group can then be carried out without taking the group offline.

See Upgrading Group Replication. (Bug #90794, Bug #27991334)

• Replication: It was possible to change the value of gtid_purged while running the Group Replication

plugin, even though this variable should never be modified in such cases. (Bug #90146, Bug #27724561)

• Replication: The PIT_TRANSACTIONS_NEGATIVE_CERTIFIED, the

PIT_TRANSACTIONS_ROWS_VALIDATING and the PIT_TRANSACTIONS_LOCAL_ROLLBACK member

messages were not being correctly decoded. (Bug #90077, Bug #27692831)

• Replication: In certain situations, such as during distributed recovery procedure, the certification info

garbage collection was purging more data than it should, resulting in conflicts not being detected. The

garbage collection procedure has been improved to take this case in consideration. (Bug #89938, Bug

#27652526)

• Replication: The ER_GRP_RPL_SQL_SERVICE_FAILED_TO_RUN_SQL_QUERY error was being logged

incorrectly. (Bug #89788, Bug #27590534)

413

MySQL 8.0 Release Notes

• Replication: Using group_replication_force_members to unblock a group, for example after

losing majority, sometimes failed with error 1231. (Bug #86957, Bug #26394418)

• Group Replication: When the group_replication_applier channel's applier thread encountered

an error, the master_log_name and end_log_pos values shown in the resulting error message were

incorrect, since the events in a transaction are replicated before they are written to the binary log of

the member where the transaction originated, with the result that the final values are unknown at the

time they are applied on the replica by the applier thread. To avoid confusion, any such error messages

encountered by a group_replication_applier channel no longer contain the binary log name or

position. (Bug #89146, Bug #27368735)

• macOS: On macOS, the server autostarted at system boot time even when set not to in the MySQL

preference pane. (Bug #27969174, Bug #90672)

• Microsoft Windows: For debug builds on Windows, CREATE SPATIAL REFERENCE SYSTEM with an

empty definition string could raise assertions. (Bug #27672683)

• In the client library, signals were incorrectly unblocked for ppoll(). Thanks to Facebook for the patch.

(Bug #28075623, Bug #90999, Bug #28096808, Bug #91067)

• Certain ALTER TABLE statements could disable table encryption. (Bug #28045585)

References: This issue is a regression of: Bug #27389878.

• Under some conditions, MyISAM code compilation failed due to a missing include file. (Bug #28039150,

Bug #90898)

• The REGEXP_REPLACE() function truncated its result when used in an UPDATE statement. (Bug

#28027093, Bug #90870)

• REGEXP_REPLACE() results from one result set row could carry forward to the next row, resulting in

accumulation of previous results in the current row. (Bug #27992118, Bug #90803)

• A heap overflow vulnerability in the MySQL client library was fixed. (Bug #27980823)

• Users who had the SUPER privilege were not permitted to modify the keyring_operations system

variable. (Bug #27976270)

• Full-text search auxiliary tables created in MySQL 5.7 and MySQL 8.0.11 with timestamps of 0 caused a

data dictionary upgrade failure when upgrading from MySQL 8.0.11 to MySQL 8.0.12. (Bug #27960500)

• A “source and destination overlap in memcpy” Valgrind error was returned when upgrading from MySQL

5.7. (Bug #27945658, Bug #90691)

• Linux binaries were unable to dump core after executing a setuid() call. (Bug #27929894, Bug

#90642, Bug #23337428, Bug #21723)

• RESET PERSIST did not flush variable values from memory. (Bug #27924206)

• For debug builds, using CREATE TABLE ... SELECT to create a table with a long numeric string and

indexing the column could lead to an assertion being raised. (Bug #27909771)

• For debug builds, RESET PERSIST for an unknown variable could cause an assertion to be raised. (Bug

#27903874, Bug #90546)

References: This issue is a regression of: Bug #27374791.

• Updates to column metadata of a view referencing a partitioned table could cause a server exit. (Bug

#27903842)

414

MySQL 8.0 Release Notes

• For debug builds, an assertion could be raised for UNION queries when computing the combined data

type of a GEOMETRY column and SELECT * FROM (SELECT NULL). (Bug #27903792, Bug #90550)

• For debug builds, starting the server with thread_stack=0 and executing ALTER TABLE could raise

an assertion. (Bug #27899274, Bug #90525)

• SHOW TABLE STATUS could cause a server exit. (Bug #27897815)

• For generated columns that used the INTERVAL() function, incorrect behavior could occur. (Bug

#27881102)

• For Fedora 28, MySQL Community RPM packages would not install if Connector ODBC native packages

were installed. (Bug #27850721)

• It was possible to drop the Performance Schema. (Bug #27830283)

• A runtime error could occur for calls to mysql_sys_var_longlong() or String::copy(). (Bug

#27822413, Bug #27808412)

• An assertion was raised by error logging code that used an inappropriate error number. (Bug

#27792903)

References: This issue is a regression of: Bug #27462408.

• The CONVERT TO CHARACTER SET charset_name clause for ALTER TABLE produced a syntax

error if charset_name was DEFAULT. (Bug #27760787, Bug #90222)

References: This issue is a regression of: Bug #27389878.

• An unencrypted connection could result from a client connection attempt specifying that an encrypted

connection was required, if the server was not configured to support SSL. (Bug #27759871)

• INSERT INTO ... SELECT did not perform as many checks as INSERT INTO ... VALUES() with

respect to requiring valid geometry values for geometry columns. (Bug #27756083)

• REGEXP_INSTR() did not return an error message when used with invalid match mode flags. (Bug

#27751277)

• Some data dictionary table definitions were modified to align more closely with their initial design.

Additionally, the data dictionary version number was incremented, and code that refers to data dictionary

table indexes now uses symbolic index names instead of numeric values. (Bug #27745526, Bug #90196)

• Executing a prepared statement to insert rows with large number of parameters was very slow. (Bug

#27699248)

• ibd2sdi could exit due to performing a divide-by-zero operation. (Bug #27692051, Bug #90071)

• The mysql-boost-8.0.4.tar.gz source distribution omitted NDB sources. (Bug #27690232)

• SHOW GRANTS could cause a server exit if executed for an unprivileged user who inherited privileges

from an anonymous user. (Bug #27678129)

• The parser incorrectly permitted the index name for CREATE INDEX to be empty. (Bug #27676427)

• Failures of server restarts initiated by systemd or mysqld_safe were not written to the error log. (Bug

#27675050, Bug #90012)

• For debug builds, if a transaction was in read-only mode, trying to create or drop a histogram could raise

an assertion. (Bug #27672693)

415

MySQL 8.0 Release Notes

• If the server was started with --skip-grant-tables, SET ROLE DEFAULT caused a server exit.

(Bug #27672154)

• Casting of VARBINARY values to TIME values was not performed correctly. (Bug #27665997)

• Error checking was not performed after creation of a condition for a const reference. (Bug #27665085)

• The dictionary information object managed by the MeCab model was used after the MeCab model was

released. (Bug #27660368)

• Attempting to abort events of the MYSQL_AUDIT_AUTHENTICATION_CLASS class caused a server exit.

These events are now not abortable. (Bug #27645636)

• These resource-group statements are now disallowed in stored functions because they cause an implicit

commit, which is not permitted in a stored function: CREATE RESOURCE GROUP, ALTER RESOURCE

GROUP, DROP RESOURCE GROUP. (Bug #27638623, Bug #89914)

• Audit log filter rules did not permit class names to be specified as an array of strings. That is now

possible. Example:

{

"filter": {

"class": [

{ "name": [ "connection", "general", "table_access" ] }

]

}

(Bug #27628325)

• On Windows, if the Visual C++ Redistributable for Visual Studio had been removed, MySQL

uninstallation using the MSI installer failed. (Bug #27621546)

• mysql_secure_installation now loads the validate_password component rather than the

deprecated validate_password plugin. (Bug #27619667)

• REGEXP_LIKE() using an expression containing a question mark (?) was not handled correctly when

included in a prepared statement. (Bug #27595368)

• REGEXP_SUBSTR() did not always handle NULL patterns correctly. (Bug #27572258)

• Some SHOW CREATE TABLE statements could raise an assertion. (Bug #27569314)

• Spurious stages could be seen in the Performance Schema events_stages_current table. (Bug

#27566220)

• Triggers for a table could execute in an order different from that specified by their PRECEDES/FOLLOWS

clauses. (Bug #27544152)

• Attempts to set some persisted variables at startup (such as keyring_operations and

mandatory_roles) produced a privilege violation error and the server did not start or did not set the

variable. (Bug #27523095)

• Under some conditions, an unused-variable warning occurred in the MeCab full-text search code.

Thanks to Laurynas Biveinis for the patch. (Bug #27519952, Bug #89598)

• Within stored procedures, it was not possible to write a condition handler to catch foreign key failures if

the table involved used the FEDERATED storage engine. (Bug #27509959)

416

MySQL 8.0 Release Notes

• It was possible to drop a primary key that served as the parent key in a foreign key relationship. In

addition, for table creation, the SQL layer now checks whether there is a parent key for the foreign key

and reports an error if it is missing. (Bug #27506922, Bug #89570, Bug #11754696, Bug #46337)

• With the NO_ENGINE_SUBSTITUTION SQL mode disabled, an error (rather than substitution)

occurred for CREATE TABLE and ALTER TABLE if the desired engine was disabled using the

disabled_storage_engines system variable. (Bug #27502530)

• Key rotation using the keyring_encrypted_file keyring plugin could cause a server exit. (Bug

#27497018)

• If MySQL Enterprise Firewall was configured with a large number of rules, server shutdown could take a

long time. (Bug #27492122)

• SET PERSIST_ONLY var_name = DEFAULT persisted the current global value, not the default value.

(Bug #27489026)

• If MySQL is configured with the LINK_RANDOMIZE CMake option enabled, the --gc-sections

compiler option is now disabled; the combination causes segmentation faults. (Bug #27484106)

• During server installation, the mysql.infoschema, mysql.session, and mysql.sys reserved

accounts were associated with the mysql_native_password authentication plugin even when the

default plugin was caching_sha2_password. (Bug #27454299)

• Some window functions used the wrong precision for their aggregated data types. (Bug #27452179)

• For a hexadecimal value H, SELECT with WHERE (-1) - H raised an assertion. (Bug #27452082)

References: See also: Bug #27041382. This issue is a regression of: Bug #21982792.

• A memory leak in the pfs-t unit test was fixed. Thanks to Yura Sorokin for the patch. (Bug #27440735,

Bug #89384)

• Multiple invocations of CHAR() within a stored program could yield different results once an invalid code

point was passed as the argument. (Bug #27410088)

• With automatic_sp_privileges enabled, the EXECUTE and ALTER ROUTINE privileges were not

correctly granted to routine creators. (Bug #27407480)

• Some queries that used ordering could access an uninitialized column during optimization and cause a

server exit. (Bug #27389294)

• For debug builds, an assertion was raised (rather than an error) for ALTER TABLE for an ARCHIVE table

with a GEOMETRY NOT NULL column containing empty strings. (Bug #27330634, Bug #89088)

• Accounts that authenticated with the auth_sock authentication plugin could not connect using older

clients. (Bug #27306178)

• If system tables could not be read or initialized, the server wrote an incomplete error message. Thanks

to Daniël van Eeden for a patch related to the fix. (Bug #27302337, Bug #89001)

• RENAME USER failed when used to rename a role that was not granted to any account or role. (Bug

#27284699)

• The keyring_okv plugin did not always fail over to the standby OKV server when the primary server

was unavailable. (Bug #27244099)

• The Performance Schema could attempt to access invalid SOURCE column values. (Bug #27231036)

• Mishandling of internal privilege structures could cause a server exit. (Bug #27230925)

417

MySQL 8.0 Release Notes

• For debug builds, use of a too-small type for calculating the determinant in GIS computations could

cause an assertion to be raised. (Bug #27135504)

• For attempts to increase the length of a VARCHAR column of an InnoDB table using ALTER TABLE with

the INPLACE algorithm, the attempt failed if the column was indexed.

If an index size exceeded the InnoDB limit of 767 bytes for COMPACT or REDUNDANT row format,

CREATE TABLE and ALTER TABLE did not report an error (in strict SQL mode) or a warning (in nonstrict

mode). (Bug #26848813)

• In MySQL 5.7.19, the mysql.gtid_executed table was excluded from dumps. This table is no longer

excluded but its data is not dumped. (Bug #26643180, Bug #87455)

References: This issue is a regression of: Bug #82848, Bug #24590891.

• The slave_rows_search_algorithms system variable controls how rows are searched for matches

when preparing batches of rows for row-based logging and replication. Specifying INDEX_SCAN as one

of the search algorithms performs an index scan if an index is present. In the situation where a different

primary key is used on the master and the slave, and a unique key is present on the slave, a bug in

the code meant that the index scan was not being performed as it should be, and a slower table scan

was being performed instead. The issue has now been corrected so that an index scan is used. (Bug

#26450129, Bug #23311892, Bug #81500, Bug #81501)

• Certain cases of subquery materialization could cause a server exit. These queries now produce an error

suggesting that materialization be disabled. (Bug #26402045)

• Spatial operations on geographic GeometryCollection values could return ER_GIS_INVALID_DATA

for valid geometries. (Bug #26174808)

• For MyISAM tables, particular sequences of INSERT and DELETE statements could cause table

corruption. (Bug #25541037)

• The SHOW CREATE USER statement requires the SELECT privilege for the mysql database, except to

see information for the current user. In addition, for the current user, the statement requires the SELECT

privilege for the mysql.user system table for display of the password hash in the IDENTIFIED AS

clause; otherwise, the hash displays as <secret>. (Bug #24911117)

• CREATE FUNCTION produced an error if there was no default database and the function body called

another function. (Bug #24357244, Bug #82350)

• For debug builds, a SELECT statement executed within a stored program could raise an assertion if

derived table resolution failed. (Bug #23221336)

• If mysqldump or mysqlpump were used to dump binary data without the --hex-blob option, reloading

the dump file could produce spurious warnings (values were inserted correctly regardless of the

warnings). Such values are now written preceded by the _binary introducer to silence the warnings.

(Bug #22601255, Bug #80150)

• String comparisons involving wildcards could reference uninitialized memory. (Bug #12635103)

• REGEXP_REPLACE() raised a Valgrind warning when invoked with an invalid capture group. (Bug

#87842, Bug #27612255)

Changes in MySQL 8.0.11 (2018-04-19, General Availability)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

418

MySQL 8.0 Release Notes

Note

Downgrade from MySQL 8.0 to MySQL 5.7 (or from a MySQL 8.0 release to a

previous MySQL 8.0 release) is not supported. The only supported alternative is to

restore a backup taken before upgrading.

• Character Set Support

• Compilation Notes

• Configuration Notes

• Deprecation and Removal Notes

• Error Handling

• INFORMATION_SCHEMA Notes

• Installation Notes

• Logging Notes

• Packaging Notes

• Performance Schema Notes

• Security Notes

• Spatial Data Support

• sys Schema Notes

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Character Set Support

• The utf8mb3 character set will be replaced by utf8mb4 in a future MySQL version. The utf8

character set is currently an alias for utf8mb3, but will at that point become a reference to utf8mb4.

To avoid ambiguity about the meaning of utf8, consider specifying utf8mb4 explicitly for character set

references instead of utf8. (WL #10778)

Compilation Notes

• MySQL source code has been converted to Google style rules using clang-format. (Bug #27414321)

• Sun RPC is being removed from glibc. CMake now detects and uses libtirpc if glibc does not

contain Sun RPC. (You might find it necessary to install libtirpc and rpcgen to take advantage of

this CMake feature.) (Bug #27368272, Bug #89168)

• The minimum version of the Boost library for server builds is now 1.66.0. (Bug #27137349, Bug #88540)

• When building from source, the provided CMake script assumed that JUnit and Ant were installed and

available at set paths. If this was not the case, building the GCS Java wrapper resulted in build errors.

419

MySQL 8.0 Release Notes

To address this a new CMake option WITH_ANT=path_name has been added to the build script, and

which works in a similar way to the existing WITH_BOOST CMake option. Set WITH_ANT to the path of a

directory where the Ant tarball, or an already unpacked archive, is saved. When WITH_ANT is not set, or

is set with the special value system, the build assumes a binary ant exists in $PATH.

Similarly, the CMake option ENABLE_DOWNLOADS already exists to download required libraries during a

build, such as the Google Test distribution. Now, when ENABLE_DOWNLOADS is set, and JUnit or Ant are

not found they are downloaded as part of the build process. (Bug #26678793)

Configuration Notes

• A new CMake option, BUNDLE_RUNTIME_LIBRARIES, enables bundling of runtime libraries with server

MSI and Zip packages for Windows. (Bug #27584796, Bug #89771)

• systemd service files now increase LimitNOFILE to 10000, to accommodate higher default settings in

MySQL 8.0. (Bug #27530282)

• The new WITH_SYSTEM_LIBS CMake option, when enabled, selects the system value for any of the

following options that are not set explicitly: WITH_EDITLINE, WITH_ICU, WITH_LIBEVENT, WITH_LZ4,

WITH_PROTOBUF, WITH_SSL, WITH_ZLIB. (Bug #27356668, Bug #89136)

• The version of the compiled-in zlib library is now available at runtime as the value of the

version_compile_zlib system variable. Thanks to Daniël van Eeden for the patch. (Bug

#27235065, Bug #88825)

Deprecation and Removal Notes

• Incompatible Change: These deprecated compatibility SQL modes have been removed: DB2, MAXDB,

MSSQL, MYSQL323, MYSQL40, ORACLE, POSTGRESQL, NO_FIELD_OPTIONS, NO_KEY_OPTIONS,

NO_TABLE_OPTIONS. They can no longer be assigned to the sql_mode system variable or used as

permitted values for the mysqldump --compatible option.

Removal of MAXDB means that the TIMESTAMP data type for CREATE TABLE or ALTER TABLE is

treated as TIMESTAMP, and is no longer treated as DATETIME.

For MySQL 5.7 applications that use SQL modes removed in MySQL 8.0, statements may fail when

replicated from a MySQL 5.7 master to a MySQL 8.0 slave, or may have different effects on master and

slave. To avoid such problems, applications that use modes removed in MySQL 8.0 should be revised to

avoid them. (WL #8383, WL #9465)

• The following features related to account management have been removed:

• Using GRANT to create users. Instead, use CREATE USER. Following this practice makes the

NO_AUTO_CREATE_USER SQL mode immaterial for GRANT statements, so it too is removed.

• Using GRANT to modify account properties other than privilege assignments. This includes

authentication, SSL, and resource-limit properties. Instead, establish such properties at account-

creation time with CREATE USER or modify them afterward with ALTER USER.

• IDENTIFIED BY PASSWORD 'hash_string' syntax for CREATE USER and GRANT. Instead, use

IDENTIFIED WITH auth_plugin AS 'hash_string' for CREATE USER and ALTER USER,

where the 'hash_string' value is in a format compatible with the named plugin.

Additionally, because IDENTIFIED BY PASSWORD syntax has been removed, the

log_builtin_as_identified_by_password system variable is superfluous and has been

removed.

420

MySQL 8.0 Release Notes

• The PASSWORD() function. Additionally, PASSWORD() removal means that SET PASSWORD ... =

PASSWORD('auth_string') syntax is no longer available.

• The old_passwords system variable.

For MySQL 5.7 applications that use features removed in MySQL 8.0, statements may fail when

replicated from a MySQL 5.7 master to a MySQL 8.0 slave, or may have different effects on master and

slave. To avoid such problems, applications that use features removed in MySQL 8.0 should be revised

to avoid them and use alternatives when possible. (Bug #27455708, WL #10774)

Error Handling

• perror is more flexible in understanding its arguments. For example, for the

ER_WRONG_VALUE_FOR_VAR error, perror understands any of these arguments: 1231, 001231,

MY-1231, or MY-001231, or ER_WRONG_VALUE_FOR_VAR. If an error number is in the range where

MySQL and operating system errors overlap, perror displays both error messages. (Bug #27462408)

INFORMATION_SCHEMA Notes

• The new INFORMATION_SCHEMA.KEYWORDS table lists the words considered keywords by MySQL

and, for each one, indicates whether it is reserved. This table provides applications a runtime source of

MySQL keyword information. See The INFORMATION_SCHEMA KEYWORDS Table.

In addition, if you build MySQL from source, the build process generates a keyword_list.h header

file containing a array of keywords and their reserved status. This file can be found in the sql directory

under the build directory. This file may be useful for applications that require a static source for the

keyword list. (WL #8989)

Installation Notes

• RPM and Debian packages now add the current MySQL series to the share directory name (for

example share/mysql-8.0). (Bug #27638192, Bug #26990531)

Logging Notes

• Messages written to the error log now indicate the subsystem in which the event occurred. Possible

subsystem values are InnoDB (the InnoDB storage engine), Repl (the replication subsystem), Server

(otherwise). (WL #11150)

Packaging Notes

• Installing or upgrading using Debian packages now presents a dialog with an option for setting

the default authentication plugin to mysql_native_password. This may be useful for backward

compatibility at some installation sites. (Bug #27454287, Bug #27667294)

• The compile_innodb script is no longer used and has been removed from MySQL distributions.

Thanks to Alexey Kopytov for the suggestion. (Bug #27448099, Bug #89437)

Performance Schema Notes

• A new Performance Schema table log_status provides information that enables an online backup tool

to copy the required log files without locking those resources for the duration of the copy process. When

the log_status table is queried, the server blocks logging and related administrative changes for just

long enough to populate the table, then releases the resources. The log_status table informs the

online backup which point it should copy up to in the master's binary log and gtid_executed record,

421

MySQL 8.0 Release Notes

and the relay log for each replication channel. It also provides relevant information for individual storage

engines, such as the last log sequence number (LSN) and the LSN of the last checkpoint taken for the

InnoDB storage engine.

The BACKUP_ADMIN privilege is required for access to the log_status table. (Bug #27599831, WL

#9452)

• Performance Schema objects now have a default character set of utf8mb4. (Bug #27407745)

Security Notes

• MySQL 8.0 builds now use OpenSSL rather than yaSSL as the default SSL library. MySQL no longer

supports building using yaSSL, and source distributions no longer include yaSSL.

The WITH_SSL CMake option no longer permits bundled (use yaSSL) as a valid value, and the default

option value has changed from bundled to system (use the version of OpenSSL installed on the host

system).

In place of yaSSL, wolfSSL may be used as a functionally equivalent alternative that has a GPLv2-

compatible license. In addition, wolfSSL (like OpenSSL) supports the TLSv1.2 protocol, which yaSSL

does not.

For instructions about building MySQL from source using wolfSSL, see the extra/README-

wolfssl.txt file in a MySQL source distribution. The WITH_SSL CMake option now permits wolfssl

as a valid value. To use -DWITH_SSL=wolfssl, you must follow the instructions in README-

wolfssl.txt. (Bug #26671671, WL #8998)

• MySQL now supports FIPS mode, if compiled using OpenSSL 1.0.2, and an OpenSSL library and FIPS

Object Module are available at runtime. FIPS mode imposes conditions on cryptographic operations

such as restrictions on acceptable encryption algorithms or requirements for longer key lengths. The

ssl_fips_mode system variable enables control of FIPS mode on the server side. The --ssl-

fips-mode client option enables control of FIPS mode on the client side for these programs: mysql,

mysqladmin, mysqlbinlog, mysqlcheck, mysqldump, mysqlimport, mysqlpump, mysqlshow,

mysqlslap, mysqltest, mysqlxtest, mysql_secure_installation, and mysql_upgrade. See

FIPS Support. (WL #8102)

Spatial Data Support

• Incompatible Change: These geometry collection changes have been implemented:

• The standard GeomCollection name for the geometry collection data type is supported as a

synonym for the GeometryCollection data type name.

• The GeomCollection() function is supported as a synonym for the GeometryCollection()

function.

• GeomCollection and GeomCollection() are the preferred data type and function names.

Incompatibility: As a consequence of the change in preferred data type name, some

INFORMATION_SCHEMA tables, statements such as SHOW CREATE TABLE, and the

ST_GeometryType() function that display data type information now display GEOMCOLLECTION rather

than GEOMETRYCOLLECTION. Applications that look for GEOMETRYCOLLECTION should be adjusted to

account for this change.

For more information, see GeometryCollection Class, and MySQL-Specific Functions That Create

Geometry Values. (WL #2388)

422

MySQL 8.0 Release Notes

sys Schema Notes

• sys Schema objects now have a default character set of utf8mb4. (Bug #27675959)

Test Suite Notes

• Reduction of compiler and platform differences in GIS handling of floating-point results enables

simplification of related test cases that no longer need rounding to avoid spurious test failures. Thanks to

Daniel Black for the patch. (Bug #26540102, Bug #87223, Bug #27462294)

X Plugin Notes

• When using MySQL as a document store, the use of SPATIAL indexes on geometry-valued columns

using the X DevAPI is now fully supported. Previously, a spatial index could be created, but the spatial

reference system identifier (SRID) was not included in the indexed column, so the index was not used by

the optimizer. The SRID attribute is now added to the indexed column. (Bug #27568243)

• Socket files used with X Plugin tests are now limited to 22-character file names. (Bug #27460677, Bug

#89464)

• The fix for Bug #26328274 resulted in an assertion in debug builds when an empty host name was used

for X Plugin connections. The issue is now fixed. (Bug #27266584, Bug #88925)

• X Plugin did not populate the password cache when a user account with no password set was used with

the PLAIN authentication method. This caused later authentication attempts to fail. The password cache

is now correctly populated with an entry if the user account's password is empty. (Bug #27257722)

• X Plugin now supports the RESTART SQL statement, which was added in MySQL 8.0.4 to enable a

MySQL server instance to be restarted from within a client session. (Bug #27245319)

• MySQL Shell connections using X Protocol can use either TCP or Unix sockets as of version 8.0.4. This

fix allows the use of encryption protocols with UNIX socket connections, so user accounts that require

encrypted connections are able to connect. (Bug #27192091)

• The fix for Bug #26647488, which corrected the handling of the DATETIME data type, now also correctly

decodes messages received from older versions of the plugin that do not have the new field available to

identify the data type. (Bug #27169735)

• X Plugin connection attempts using the X Protocol did not return an error when the default database

specified in the connection options was invalid, and the connection was allowed with a null default

database. Connection attempts using the classic MySQL protocol did return an error and disallowed the

connection. X Protocol connection attempts now also disallow the connection if an invalid schema is

specified. (Bug #26965020)

• X Plugin is now loaded by default, meaning there is no longer any need to install the plugin. (WL

#11040)

Functionality Added or Changed

• InnoDB: The ibd2sdi serialized dictionary information (SDI) extraction utility for InnoDB tablespaces

now supports a --pretty option that controls JSON pretty print formatting of SDI data. Pretty print

formatting is enabled by default. Disabling pretty print formatting using --skip-pretty reduces the

size of extracted SDI data. (Bug #27546514)

• InnoDB: To improve startup performance on systems with large buffer pools, buffer pool initialization is

now multithreaded. (Bug #22963374, Bug #80784)

423

MySQL 8.0 Release Notes

• InnoDB: The following redo logging optimizations were implemented:

• User threads can now write concurrently to the log buffer without synchronizing writes, and add dirty

pages to the flush list in a relaxed order.

• Dedicated log writer threads are now responsible for writing redo log records from the log buffer to the

system buffers and flushing the system buffers to the redo log files.

• System variables were added for configuring the use of spin delay by user threads waiting for flushed

redo:

• innodb_log_wait_for_flush_spin_hwm: Defines the maximum average log flush time beyond

which user threads no longer spin while waiting for flushed redo.

• innodb_log_spin_cpu_abs_lwm: Defines the minimum amount of CPU usage below which user

threads no longer spin while waiting for flushed redo.

• innodb_log_spin_cpu_pct_hwm: Defines the maximum amount of CPU usage above which

user threads no longer spin while waiting for flushed redo.

• The innodb_log_buffer_size configuration option is now dynamic, which permits resizing of the

log buffer while the server is running.

For more information, see Optimizing InnoDB Redo Logging. (WL #10310)

• macOS: The macOS installer now asks the user for the root password to use rather than generating a

random one. (Bug #22608157, Bug #80144)

• macOS: The MySQL preference pane included with the macOS installer now includes a setting that

specifies which my.cnf file the server should read when started by launchd. (Bug #19775549, Bug

#74214)

• Solaris: On Solaris, MySQL can now be built with Developer Studio 12.6. (Bug #27055190, Bug

#88316, Bug #28165246, Bug #91214)

• Logging during data directory initialization (for example, using mysqld --initialize) has changed:

• The startup message indicates that the server is running in initialization mode.

• A message is written indicating when initialization has completed.

• The message about the CA certificate being self-signed is suppressed.

(Bug #27557952, Bug #89693)

• The -log suffix is no longer appended to the server version string if logging is enabled. This affects, for

example, the value of the version system variable. (Bug #27532097, Bug #89626)

• Server shutdown lines written to the error log now include the server version. (Bug #27522788, Bug

#87910)

• SHOW CREATE TABLE normally does not show the ROW_FORMAT table option if the row format is the

default format. This can cause problems during table import and export operations for transportable

tablespaces. MySQL now supports a show_create_table_verbosity system variable that, when

enabled, causes SHOW CREATE TABLE to display ROW_FORMAT regardless of whether it is the default

format. (Bug #27516741)

• Performance Schema memory instrumentation overhead was reduced. (Bug #27500610)

424

MySQL 8.0 Release Notes

• During data directory initialization, the server created objects using sql_mode=''. Now the server uses

the default sql_mode value (which, among other settings, includes strict mode). (Bug #27476029, Bug

#89495)

• The collations defined in mysql-test/std_data/Index.xml are for test purposes only and should

not be used otherwise. Comments were added to the file to make this clear because some users were

using them in non-test environments. (Bug #27421838)

• RESET PERSIST no longer performs an implicit commit. (Bug #27374791)

• For a persisted variable, the SET_TIME column of the Performance Schema variables_info table

now reflects the time at which the variable was persisted, not server startup time. (Bug #25677422)

• Previously, SHOW CREATE TABLE did not show the collation for a column if the collation was the same

as the table default, even if the collation was explicitly specified at table-creation time. Now, SHOW

CREATE TABLE always shows the column collation if the collation was explicitly specified, even if the

collation is the same as the table default. (Bug #11754608, Bug #46239)

Bugs Fixed

• Important Change: When NO_ZERO_DATE SQL mode is enabled, ALTER TABLE rejects attempts to

add DATE or DATETIME columns that are declared NOT NULL to a nonempty table if no DEFAULT is

specified for that column. Since a generated column has no default value, this restriction also prevented

addition of a generated DATE NOT NULL or DATETIME NOT NULL column to a nonempty table. Since

the expression used to generate the column can be used in place of the missing default for determining

the column value, this restriction is now lifted for generated columns. (Bug #27252354)

• Important Change: For ANALYZE TABLE ... UPDATE HISTOGRAM statements, the WITH N

BUCKETS clause is now optional. If not specified, the default value for BUCKETS is 100. (Bug #89909,

Bug #27637968)

• InnoDB: The server was stopped before a fatal error message was written to the error log. (Bug

#27626478)

• InnoDB: When determining if a wait lock could be granted, locks held by victim transactions that were

being rolled back were ignored. (Bug #27607235)

• InnoDB: An error occurred in Sdi_Decompressor::decompress() when compiling a debug build

using GCC 7.2.0. (Bug #27565889)

• InnoDB: An assertion was raised when registering buffer pool chunks during parallel creation of multiple

buffer pools. A mutex is now used to protect registration of buffer pool chunks in the buffer pool chunk

map. (Bug #27565865)

• InnoDB: Enabling the standard monitor caused an error. (Bug #27534041)

• InnoDB: An internal field used to mark a column as hidden was changed from a boolean field to an

enum field to support additional levels of column visibility. (Bug #27499518, Bug #89553)

• InnoDB: An invalid zlib-related Valgrind failure reported that a conditional jump or move depends on

uninitialized value. (Bug #27482740, Bug #89509)

• InnoDB: An incorrect GROUP BY result was returned when using the TempTable storage engine and a

NO PAD collation. (Bug #27454796)

• InnoDB: An incorrect compression length value in a page compression function caused hole punching to

be skipped the first time pages are compressed. (Bug #27399897)

425

MySQL 8.0 Release Notes

• InnoDB: Starting the server with an incorrect --log-bin option value raised an assertion, and

subsequent attempts to start the server with a correct --log-bin value or without the --log-bin

option continued to produce assertion failures. (Bug #27393317)

• InnoDB: A large object (LOB) reference was not updated when a LOB was inserted during an UPDATE

operation. (Bug #27368662)

• InnoDB: After restarting the server, a TRUNCATE TABLE operation raised an assertion due to table flags

that were inconsistent with remote data directory information stored in memory. (Bug #27367639)

• InnoDB: Attempting to create a temporary table in a file-per-table tablespace using CREATE

TEMPORARY TABLE ... TABLESPACE syntax failed to report an error. Temporary tablespaces are

only permitted in the temporary tablespace. (Bug #27361662)

• InnoDB: A latch taken on the first page of a large object (LOB) was not released before another thread

attempted to allocate the page, causing a deadlock. (Bug #27360492)

• InnoDB: Converting an implicit lock to an explicit lock was optimized by the introduction of a member

variable that tracks the smallest active transaction ID.

Thanks to Zhai Weixiang for the patch. (Bug #27353468, Bug #89127)

• InnoDB: The mysql.innodb_ddl_log and mysql.innodb_dynamic_metadata tables, which are

used internally by the InnoDB storage engine, are now protected. DDL and DML operations on these

tables are no longer permitted, and the tables no longer appear in INFORMATION_SCHEMA query results.

(Bug #27353455, Bug #89129)

• InnoDB: Upgrading a MySQL 5.7 instance with an innodb_page_size setting of 4K caused

mysql_upgrade to fail with a “Specified key was too long; max key length is 768 bytes” error when

creating or modifying system tables. The error was suppressed to permit the mysql_upgrade client to

run on an instance with an innodb_page_size setting of 4K. (Bug #27338431)

• InnoDB: The recovery process could not properly determine space_id values, causing the server to exit.

(Bug #27331936)

• InnoDB: An ALTER TABLE operation that modified the nullability of an indexed column raised an

assertion. InnoDB incorrectly assumed that a new primary key must be added instead of created from

an existing unique key. (Bug #27330454, Bug #89087)

References: This issue is a regression of: Bug #24397406.

• InnoDB: After an ALTER TABLE ... IMPORT TABLESPACE operation, metadata could not be

retrieved correctly from the INFORMATION_SCHEMA.INNODB_COLUMNS table. (Bug #27322099)

• InnoDB: An INSERT operation involving a large object (LOB) value raised an assertion. After splitting a

LOB fragment, there was insufficient space for a directory entry. (Bug #27320977)

• InnoDB: On a server using the utf8mb4 character set, an INSERT or UPDATE during an ALTER TABLE

operation that changed the row format of a table that included a virtual column caused an index

corruption. (Bug #27319084)

• InnoDB: The data retrieved from INFORMATION_SCHEMA.INNODB_COLUMNS was incorrect for tables

containing a virtual column. (Bug #27316037)

• InnoDB: The server failed to start after recovery due to an invalid keyring file. The keyring file created

from backup was empty. (Bug #27307740)

426

MySQL 8.0 Release Notes

• InnoDB: A deadlock between background threads, one attempting to evict a full-text search table from

the cache, and the other attempting to synchronize a table, caused InnoDB Cluster nodes to fail. (Bug

#27304661)

• InnoDB: A typo was corrected in an InnoDB recovery message. Thanks to Daniël van Eeden for the

patch. (Bug #27287979, Bug #27010613, Bug #88185)

• InnoDB: A message stating that encryption algorithm support is missing was reported during InnoDB

recovery. (Bug #27286020)

• InnoDB: A missing or mismatched keyring file caused an assertion failure at startup. (Bug #27278324)

• InnoDB: An error was returned indicating that encryption support was missing when checking the space

ID of an encrypted tablespace file. (Bug #27278100)

• InnoDB: A debug message that prints a “too many open files” warning is now only printed if the number

of open files reaches a limit of 300. (Bug #27277844)

• InnoDB: Failure to skip predicate locks when releasing gaps locks raised debug assertions, as

did failure to remove the supremum record bit prior releasing gaps locks on the supremum. (Bug

#27272806, Bug #27294066)

• InnoDB: A tablespace ID discovery failure occurred when starting the server on a cloned data directory.

(Bug #27265874)

• InnoDB: An unprotected global variable (fil_n_file_opened) caused an assertion when shutting

down the server. (Bug #27265473)

• InnoDB: An assertion that is no longer valid was raised when checking for pending I/O on the file in use.

(Bug #27263206)

• InnoDB: An empty general tablespace caused a failure when upgrading to MySQL 8.0. The empty data

file was expected to have a specific number of pages. (Bug #27261822)

• InnoDB: A startup failure occurred because a directory specified by the --innodb-directories

option contained a keyring data file. The --innodb-directories option should only recognize

InnoDB tablespace files. (Bug #27253116)

• InnoDB: A function that calculates the increase in minimum bounding rectangle (MBR) size incorrectly

returned 0, resulting in R-tree corruption. (Bug #27237472)

• InnoDB: A REPLACE operation on a temporary table raised an assertion. (Bug #27225649, Bug

#27229072)

• InnoDB: An online ALTER TABLE operation on a table accompanied by concurrent DML on the same

table raised an assertion. An end-of-log check was not performed prior to accessing the DML log to

determine the length of a virtual column. (Bug #27158030)

• InnoDB: When the addition of a virtual index failed, the virtual index that was freed was not removed

from the lists of virtual column indexes. (Bug #27141613)

• InnoDB: Adding a virtual column and index in the same statement caused an error. (Bug #27122803)

• InnoDB: An undo tablespace truncate operation raised an assertion. The check that determines if undo

tablespace segments are inactive was invalid. (Bug #27114068)

• InnoDB: When the TempTable storage engine was unable to allocate memory using temporary files and

mmap, an invalid error was reported indicating that the defined on-disk storage engine would be used

instead. (Bug #26990375)

427

MySQL 8.0 Release Notes

• InnoDB: Latch order was incorrectly defined in debug instrumentation causing a latch order violation

during an INSERT operation. (Bug #26983412)

• InnoDB: A tablespace import operation on a server with a default row format of REDUNDANT raised an

assertion failure. (Bug #26960215)

• InnoDB: A stored field based on a generated column permitted the base column to have a NULL value.

(Bug #26958695)

• InnoDB: Evaluation of a subquery in a resolving function raised an assertion. (Bug #26909960)

• InnoDB: Locks related to data dictionary operations caused degradation in CREATE TABLE

performance. (Bug #26848711, Bug #87827)

• InnoDB: A LOCK INSTANCE FOR BACKUP operation was able to acquire a backup lock without waiting

for a concurrent DDL operation to finish. (Bug #26831155, Bug #87812)

• InnoDB: An incorrectly specified innodb_data_file_path or innodb_temp_data_file_path

value returned a syntax error that did not specify the name of the system variable that caused the

initialization failure. (Bug #26805833)

• InnoDB: An handler that was opened for a TRUNCATE TABLE operation caused the operation to assert.

The server now closes open handlers before dropping the table.

The patch for this bug also improves TRUNCATE TABLE error messages related to foreign key

constraints, and makes it possible to truncate a corrupted table. (Bug #26710839)

• InnoDB: An online DDL operation that rebuilds the table raised an assertion when the last insert log

record to be applied was split across two pages. (Bug #26696448, Bug #87532)

• InnoDB: An assertion was raised when attempting to generate a virtual column value dependent on an

off-page large object value that was not yet stored. (Bug #26625652)

• InnoDB: An R-tree search counted delete-marked records, causing it to find more records than present

in the clustered index. As result, the valid R-tree index was marked as corrupted. (Bug #26381207)

• InnoDB: A RENAME TABLE operation that renamed the schema failed to rename full-text search

common auxiliary tables that were left behind when the full-text search index was removed previously,

resulting in a assertion failure when attempting to drop the old schema. (Bug #26334149)

• InnoDB: An assertion was raised when a thread attempted to read a record containing BLOB data while

another thread was writing the same data to external pages. (Bug #26300119)

References: This issue is a regression of: Bug #23481444.

• InnoDB: Column prefixes for externally stored columns exceeded the amount of available memory in the

online log. (Bug #25928471)

• InnoDB: A problematic lock that was introduced to protect writing of dynamic metadata changes to the

redo log during a checkpoint was removed. A mutex is now used instead. The checkpoint LSN was also

adjusted to protect dynamic metadata changes. (Bug #25834374)

• InnoDB: InnoDB failed to account for a virtual column when using the column offset to search an index

for an auto-increment column. (Bug #25076416)

• InnoDB: An invalid debug condition caused a buffer pool chunk allocation failure, which resulted in an

assertion failure when a purge thread attempted to access an unallocated chunk. (Bug #23593654)

References: This issue is a regression of: Bug #21348684.

428

MySQL 8.0 Release Notes

• InnoDB: Threads were prevented from entering the InnoDB storage engine due to ticket acquisition

deadlocks. (Bug #23476050)

• Partitioning: An error returned by the storage engine while executing ALTER TABLE EXCHANGE

PARTITION was not handled correctly by the server. (Bug #27320682)

• Replication: Empty XA transactions that have been rolled back should not be recorded in the binary

log or added to the set of transactions in the gtid_executed system variable. However, if rolled-back

empty XA transactions were executed after an empty XA transaction ending with an XA COMMIT ...

ONE PHASE statement, they were being incorrectly added to the binary log as an XA ROLLBACK

statement, and also to the gtid_executed system variable. The issue is now fixed. (Bug #27435974)

• Replication: When the system variable gtid_next was set to AUTOMATIC, empty XA transactions

that were rolled back and not recorded in the binary log, were being incorrectly added to the set of

transactions in the gtid_executed system variable, causing an inconsistency. The rolled-back empty

XA transactions are no longer recorded in gtid_executed. (Bug #27407670)

• Replication: The value of LAST_CONFLICT_FREE_TRANSACTION in the

replication_group_member_stats Performance Schema table was not correctly synchronized

across group members. (Bug #27317431)

• Replication: When a member is joining a group there is a chance of the request to join being rejected.

If the rejection resulted in a retry, for example because the seed member being contacted was not in the

group, then there was a possibility of the retry cycle continuing infinitely. (Bug #27294009)

• Replication: The default binary log expiration period of 30 days is now set as the default for the

binlog_expire_logs_seconds system variable, instead of the deprecated expire_logs_days

system variable. binlog_expire_logs_seconds now defaults to a value of 2592000 (30*24*60*60

seconds), and expire_logs_days now defaults to zero.

In MySQL 8.0.3 and 8.0.4, the effects of binlog_expire_logs_seconds and expire_logs_days

were cumulative. From MySQL 8.0.11, this is no longer the case, and the new behavior is as follows:

• If you specify a non-zero value for both variables, only the value of binlog_expire_logs_seconds

is used to determine the binary log expiration period, and the value of expire_logs_days is ignored.

• If you specify a non-zero value for only one variable, that value is used to determine the binary log

expiration period, and the default for the other is not applied.

• If you specify a value for neither of the variables, the default of 30 days from

binlog_expire_logs_seconds is used as the binary log expiration period.

An error message is issued if you attempt to set one of the variables dynamically when the other is

already set, and a warning message is issued if you specify a non-zero value for both variables at

startup. A deprecation warning is also issued if you set a value for expire_logs_days.

To disable automatic purging of the binary log, specify a value of 0 explicitly for

binlog_expire_logs_seconds, and do not specify a value for expire_logs_days. For

compatibility with earlier releases, automatic purging is also disabled if you specify a value of 0 explicitly

for expire_logs_days and do not specify a value for binlog_expire_logs_seconds. In that

case, the default for binlog_expire_logs_seconds is not applied. You no longer need to set both

variables to zero to disable automatic purging. (Bug #27252658)

• Replication: The DDL statements CREATE DATABASE, ALTER DATABASE, and DROP DATABASE

are no longer allowed to execute in parallel with other statements on a multithreaded slave. These

statements require an exclusive metadata lock on the schema, causing a theoretical possibility of a

deadlock when slave_preserve_commit_order=1 is set on the replication slave. (Bug #27165446)

429

MySQL 8.0 Release Notes

• Replication: On a replication slave with binary logging disabled, an empty DDL statement (for example,

due to a replication filter) raised an assertion. With binary logging enabled, BEGIN and COMMIT

statements would be written to the binary log to produce a transaction, but these statements were not

available with binary logging disabled, causing the assertion. MySQL Server now checks for the situation

where the DDL transaction is empty and is not marked as started, and handles it without raising the

assertion. (Bug #27164661)

• Replication: A new system variable rpl_read_size is available to set the minimum amount of data in

bytes that is read from the binary log files and relay log files. The default read size is 8KB. If heavy disk I/

O activity for these files is impeding performance for the database, increasing the read size might reduce

file reads and I/O stalls if the files are not being cached by the operating system.

Note that a buffer the size of this value is allocated for each thread that reads from the binary log and

relay log files, including dump threads on masters and coordinator threads on slaves. Setting a large

value might therefore have an impact on memory consumption for servers.

Thanks to the Facebook team for the patch. (Bug #27147095)

• Replication: On a server with GTIDs enabled, if RESET MASTER was used when a transaction had

been flushed but not yet committed, the server GTIDs were left in an incorrect state. At this point, the

GTID for the transaction had been added to the set of owned GTIDs, but not yet to the set of executed

GTIDs. The GTID was removed from the binary log when the content of the uncommitted transaction

was cleared by the RESET MASTER statement, but the GTID could not be reused because it was already

owned, so the sequence of GTIDs had a gap.

With this fix, RESET MASTER acquires a global read lock to ensure that no transactions are in commit

stage during its operation, and no new transactions enter into commit stage during its operation. If

there are any ongoing commits, RESET MASTER waits until they are complete. The global read lock

is released when the reset is finished, and then storage engines are notified of the successful reset. If

FLUSH TABLES WITH READ LOCK has already been executed for the thread, RESET MASTER does

not retry the lock. (Bug #27041759)

• Replication: Attempts to set a GTID for an unsafe or empty XA transaction using a SET

@@SESSION.GTID_NEXT statement were not being handled correctly. On a server with gtid_mode

set to OFF or OFF_PERMISSIVE, and enforce_gtid_consistency set to OFF, setting a GTID

for an unsafe XA transaction (creating or dropping a temporary table) caused an inconsistency in the

server's GTID violation counter and raised an assertion. Testing also showed that setting a GTID for an

empty XA transaction caused an incorrect sequence of events to be written to the binary log. Both these

situations are now handled correctly. (Bug #27041402, Bug #88272)

• Replication: The error message issued for a server stop while rotating the binary log did not state the

correct cause for the issue. The error message has been enhanced to include the actual error causing

the server stop as part of the message. A new error ER_OOM_SAVE_GTIDS has also been added for the

situation where an out-of-memory error occurred while saving the set of GTIDs from the last binary log

into the mysql.gtid_executed table. (Bug #27040070, Bug #88262)

• Replication: The statements CREATE USER IF EXISTS (or IF NOT EXISTS) and ALTER USER IF

EXISTS (or IF NOT EXISTS) were written to the binary log even when the query resulted in an error.

MySQL Server now checks for errors that cause these queries to fail (for example, an invalid plugin

was specified), and does not log the statement in that situation. Note that if these statements succeed

but have no effect on the master because the condition is not met, the statements are written to the

binary log, as the condition might be met on a replication slave (see Bug #25813089, Bug #85733). (Bug

#26680035)

References: See also: Bug #25813089, Bug #85733.

430

MySQL 8.0 Release Notes

• Replication: Following the introduction of support for atomic DDL in MySQL 8.0, a replication slave that

supports atomic DDL can diverge from a replication master at an earlier MySQL version that does not

support atomic DDL. If the DDL statement can only be partly applied, the slave using MySQL 8.0 rolls

back the whole DDL statement, but the master using an earlier version might commit the valid parts

of the DDL statement. An error message is now logged in the event of an unsuccessful commit for an

atomic DDL statement on the master and the slave, and you should check that the states of the master

and the slave have not diverged before proceeding. (Bug #26133488)

• Replication: When GTIDs are enabled on a replication master and slave, and the slave connects to

the master with the MASTER_AUTO_POSITION=1 option set, the master must send the slave all the

transactions that the slave has not already received, committed, or both. If any of the transactions that

should be sent by the master have been already purged from the master's binary log, the master sends

the error ER_MASTER_HAS_PURGED_REQUIRED_GTIDS (1789) to the slave, and replication does not

start.

The message provided for the error ER_MASTER_HAS_PURGED_REQUIRED_GTIDS has been changed

to provide advice on the correct action in this situation, which is for the slave to replicate the missing

transactions from another source, or for the slave to be replaced by a new slave created from a more

recent backup. The message advises that the master's binary log expiration period can be revised to

avoid the situation in future. In addition, the master now identifies the GTIDs of the purged transactions

and supplies them in its error log in the warning message ER_FOUND_MISSING_GTIDS (11809), so that

you do not need to calculate the missing GTIDs manually. (Bug #26004541, Bug #29769293)

• Replication: For updates to virtual generated columns containing the BLOB data type, both the old and

the new BLOB values are required by some storage engines for replication. This fix extends the same

behavior to JSON and GEOMETRY data types, which are based on the BLOB data type and so produce

the same issue when the old value is not stored. (Bug #25873029)

• Replication: A behavior change in MySQL 8.0.0 moved the identification of generated columns from

before to after the calculation of the write set for binary logging. This caused an issue with NDB cluster

replication, because that storage engine omits the generated columns from the log event if they are

unnecessary, leading to NULL values being set for them by the applier thread on the replication slave.

The identification of generated columns has now been moved back to before the write set calculation, so

that the issue does not occur. (Bug #25827408)

• Replication: On a multithreaded replication slave (with slave_parallel_workers greater than 0),

the slave's lag behind the master was not being reported by the Seconds_Behind_Master field for

SHOW SLAVE STATUS. The value is now reported correctly. Thanks to Robert Golebiowski for the patch.

(Bug #25407335, Bug #84415)

• Replication: A plus sign (+) can be used with a GTID set in the statement SET

@@GLOBAL.GTID_PURGED to indicate that the specified GTID set does not intersect with

gtid_executed. The plus sign was also being permitted for GTID sets specified for the functions

GTID_SUBSET() and GTID_SUBTRACT(), where it was not meaningful. The plus sign can no longer

be specified with these functions. Also, error messages relating to the SET @@GLOBAL.GTID_PURGED

operation have been improved. (Bug #24675979)

• Replication: When invoked with the options --read-from-remote-server and --hexdump,

mysqlbinlog was not able to produce a hex dump of the binary log contents following an SQL

statement that generated an autoincrement value, referenced a user-defined variable, or invoked

RAND(). The event types for these events are followed by an informational row query log event, and

mysqlbinlog caches the original event for printing when the subsequent row query log event is

received. The pointer to the memory containing the original event was invalidated when the subsequent

event was received, so the original data could not be accessed to produce the hex dump. The issue has

now been fixed. (Bug #24674276)

431

MySQL 8.0 Release Notes

• Replication: A number of changes were made to the binary log decoding procedure to improve handling

of invalid or corrupted binary log entries. (Bug #24365972)

• Replication: Following the introduction of binary logging for XA transactions WL#6860, an assertion

could be raised in debug builds during replication from a master with the feature to a slave without the

feature, if MASTER_AUTO_POSITION=1 was set on the slave. The assertion has been removed, so

that debug builds now have the same behavior as non-debug builds, and can attempt replication of

unsupported event types whether or not MASTER_AUTO_POSITION=1 is set. (Bug #20677683)

• Replication: When using group_replication_ip_whitelist, it was possible to configure a group

so that it functioned even though all members could not establish the internal group communication

connection to each other, resulting in inconsistent behavior. Now, incoming connections are accepted

if the IP is in the white list or if the IP belongs to a current member of the XCom configuration. This

ensures members are always able to create the internal network required for group communication. (Bug

#87834, Bug #26846549, Bug #27406775)

• Group Replication: When MySQL was started with --plugin-load='group_replication.so'

but Group Replication was not started, starting an asynchronous slave channel resulted in an

unresponsive server. (Bug #27584141)

• Group Replication: Group Replication failed to start if certain required variables were persisted, or if

persisted variables were not set in proper timestamp order. (Bug #27545544, Bug #27522405)

• Group Replication: Group Replication files have been moved from the rapid directory to the plugin

directory. (Bug #27413789)

• Group Replication: Conflict detection uses schema and table names as part of the Primary

Key Equivalent (PKE) in order to detect and disallow conflicting transactions. The value of

lower_case_table_names changes how schema and table names are stored and externalized;

depending on the value, this could persist a table named T1 as t1. Such a difference in a group could

cause inconsistencies. Now, members must all have the same value for lower_case_table_names.

(Bug #27401817)

• Group Replication: Using an IP address or hostname in any Group Replication related configuration on

macOS was failing. (Bug #27376511, Bug #89123, Bug #27604471)

• Group Replication: Changing the Group Replication required settings incorrectly on online secondary

members could result in an unexpected halt. (Bug #27317478, Bug #27157202)

• Group Replication: After issuing START GROUP_REPLICATION the gtid_mode system variable

is locked to prevent any modification to its value until the group is online. Any attempt to modify

gtid_mode during this time is blocked. As part of the process of starting Group Replication the server

needs to set super_read_only=off, which has dependencies on locks acquired by SET GTID_MODE.

This could result in Group Replication hanging and there was no possibility to connect to the server to

resolve the situation. To prevent this situation, when it is not possible to acquire the locks needed by SET

GTID_MODE the operation aborts. (Bug #27312241)

• Group Replication: In the unlikely event of the group failing to start, for example because no seed

member could be contacted, there is a one minute period where the group retries the start process.

Attempting to modify a Group Replication plugin option during this period could result in an unexpected

halt. Now, attempting to modify a Group Replication plugin option during plugin start or stop results in

error. (Bug #27275312)

• Group Replication: Attempting to uninstall the Group Replication plugin on a server configured to start

the plugin automatically at boot could result in a deadlock. Now, the uninstall process checks to ensure

that the plugin is not in the process of starting and fails gracefully if it is. (Bug #27179336)

432

MySQL 8.0 Release Notes

• Group Replication: Group Replication uses transaction write set extraction for conflict detection on

group members. A performance regression was found in this process during detailed performance

analysis, which is handled by optimizing memory allocation has been for write set extraction and memory

copy operations. In addition, foreign key write sets are now collected only when the current table actually

has foreign keys. (Bug #27016053)

• Group Replication: In a multi-primary group, when a member was also configured with a asynchronous

replication channel, there was a possibility that the asynchronous channel could start before Group

Replication started. This could result in the asynchronous channel processing transactions before the

member became an online member of the group, causing issues when members tried to join the group.

The fix ensures that asynchronous channels on group members do not start until the member has

become online. (Bug #26648393)

• Linux: Builds on Alpine Linux now take advantage of AIO support. (Bug #27327874)

• macOS: On macOS, mysql_config --libs did not list any SSL libraries. (Bug #27232576)

• Microsoft Windows: On Windows, the RESTART statement is implemented by having mysqld fork,

with one process acting as a monitor to the other, which acts as the server. This makes determining the

server process to attach to for debugging more difficult. To alleviate this, starting the server with --gdb

now suppresses forking. A side effect is that for a server started with this option, RESTART simply exits

and does not restart. (Bug #27273229)

• JSON: The JSON_QUOTE() function could in some situations write the quoted string to the same buffer

that holds the input string, which could lead to wrong results. Now a check is made to be sure that it

does not attempt write into the same buffer that it is reading from. (Bug #27312444)

• JSON: JSON_SEARCH() no longer performs any modification of cached Json_path objects, now

making any needed updates to a String object that represents the path instead. This saves on the

number of round trips required between the path's Json_path and String representations, which

speeds up execution. In addition, the one_or_all and escape_char arguments to JSON_SEARCH()

were unnecessarily cached; these arguments are no longer cached, which should also improve this

function's execution time. (Bug #87383, Bug #26614455)

References: See also: Bug #21450084, Bug #77785, Bug #21472872.

• A check was implemented based on data dictionary version information to prevent starting the MySQL

8.0 server with a data directory created by a later MySQL release. The check was necessary to prevent

an in-place downgrade, which is currently not supported. (Bug #27708249)

• Protected data dictionary tables are no longer accessible by statements placed in a server initialization

file. (Bug #27674311, Bug #90010)

• Data dictionary and INFORMATION_SCHEMA version numbers were synchronized with the new MySQL

server version number. (Bug #27674285)

• The server did not handle correctly certain LIKE queries using a BLOB column with a prefix index. (Bug

#27660560)

• For builds configured using -DWITH_PROTOBUF=SYSTEM, building failed on systems with Protobuf 3.5

installed. (Bug #27638713, Bug #89915)

• The microseconds part of timestamps stored with persisted variables in mysqld-auto.cnf was always

000000. (Bug #27629719)

• Debian packages now handle dependencies for MeCab plugin dictionary files. Fedora packages now

handle dependencies for both MeCab packages, not just the utf-8 package. (Bug #27612730, Bug

#27613539)

433

MySQL 8.0 Release Notes

• The change in MySQL 8.0.11 for platforms that use systemd to run mysqld as a normal process

(Type=notify) and communicate using a socket file did not work on SLES before SLES 12.2. (Bug

#27604999)

• The NON_UNIQUE column in the INFORMATION_SCHEMA.STATISTICS table had type BIGINT prior

to MySQL 8.0, but became VARCHAR in MySQL 8.0 with the introduction of the data dictionary. The

NON_UNIQUE column now has an integer type again (INT because the column need not be as large as

BIGINT). (Bug #27593348, Bug #89793)

• With some inputs, ST_Crosses() could cause a server exit. (Bug #27576700)

• Some error messages were being written to the error log with an error ID of 0 rather than a legitimate

error ID. (Bug #27575608)

• mysql_upgrade did not set MYSQL_SERVER_PUBLIC_KEY correctly, leading to failure to read the key

file. (Bug #27568278)

• If autocommit was disabled, mysql_upgrade produced an error when upgrading from MySQL 5.7 to

8.0. (Bug #27549249)

• For debug builds, displaying very long stage names from the PROCESSLIST_STATE column of the

Performance Schema threads table could raise an assertion. (Bug #27545688)

• gtid_purged handling had a memory leak. (Bug #27537968, Bug #89645)

• Using SET PERSIST to persist optimizer_trace_offset resulted in an incorrect variable value after

server restart. (Bug #27536421)

• The validate_password component could leak memory. (Bug #27521770, Bug #89597)

• A typo in sql/handler.h was corrected. Thanks to Su Tristan for the patch. (Bug #27516280, Bug

#89594)

• The Performance Schema variables_info table displayed incorrect VARIABLE_SOURCE and

VARIABLE_PATH values for variables set within option files specified by !include or !includedir

directives. (Bug #27514223)

References: This issue is a regression of: Bug #25563891.

• After upgrading from MySQL 5.7 to MySQL 8.0, the first attempt to start the server on a MySQL 5.7

data directory with --default-time-zone set to a specific time value such as "+00:00" caused the

server to exit. (Bug #27512609, Bug #89584)

• Lookups of character set internal numbers was not thread safe and could cause memory leaks. (Bug

#27507950)

• Using the -DWITH_LIBEVENT=system and -DWITH_ICU=system CMake options together caused

configuration to fail. (Bug #27505535, Bug #89398)

• Some messages were being written to the server error log using client error IDs. (Bug #27503787, Bug

#89562)

• When run in key migration mode, the server could report an error for successful operations. (Bug

#27493997)

• Upgrades from MariaDB to MySQL Community Edition failed on Fedora 27. (Bug #27484835)

• ALTER TABLE could hang in a Waiting for tablespace metadata lock state. (Bug #27472087,

Bug #89487)

434

MySQL 8.0 Release Notes

• Selecting from the Performance Schema status_by_thread or variables_by_thread table was

not thread safe and could yield incorrect results. (Bug #27471510)

• INSERT ... ON DUPLICATE KEY UPDATE could be handled improperly if a source table produced

no rows. (Bug #27460607)

• SET PERSIST_ONLY ignored --skip-grant-tables and continued to perform checking against the

dynamic privileges needed to set system variables. (Bug #27455943)

• For RPM packages and Docker RPM packages, the included my.cnf file now includes

information indicating how to revert to the previous default authentication plugin (changing

caching_sha2_password to mysql_native_plugin), for compatibility with older clients. (Bug

#27454015, Bug #27675380)

• In string comparisons using >, only one operand was handled as utf32. (Bug #27452148)

• A server exit during InnoDB initialization caused AddressSanitizer (ASan) to report a memory leak. The

patch also implements proper handling of the data dictionary properties table in cases where the table

contains data that cannot be parsed. (Bug #27447981, Bug #89433)

• With -DWITH_SSL=system, if CMake could not find the system OpenSSL libraries and header files, it

produced confusing messages. Now it exits immediately with an error. (Bug #27447874)

• Configuring with the -DWITH_INNODB_EXTRA_DEBUG=ON CMake option resulted in a linker error. (Bug

#27444255, Bug #89412)

• Configuring with -DWITH_ZLIB=system resulted in a linker error. (Bug #27435371, Bug #89373)

• Metadata from result sets for UNION ALL queries could say NEWDATE rather than DATE. (Bug

#27422376)

• In builds with Undefined Behavior Sanitizer enabled, negation of -922337203685477580 could cause a

server exit. (Bug #27419181)

• With protocol compression enabled, a spurious assertion could be raised. (Bug #27418207, Bug

#89324)

References: This issue is a regression of: Bug #17922198.

• Performance related to fetching tablespace objects from the data dictionary to populate the data

dictionary cache was improved. (Bug #27402243)

• If the server was started with --skip-grant-tables, clients that authenticate with the

caching_sha2_password plugin were unable to connect. (Bug #27400095, Bug #89267)

• Linux RPM and Debian packages now include dependency information for the Perl JSON module

required to run the MySQL test suite. Linux RPM packages now include dependency information for

the Perl Digest module required to run the MySQL test suite. (Bug #27392800, Bug #89250, Bug

#27392808, Bug #89244)

• A new system variable, default_collation_for_utf8mb4, is provided for internal use by

replication. The system variable is set to the default collation for the utf8mb4 character set. The value of

the variable is replicated from a master to a slave so that the slave can correctly process data originating

from a master with a different default collation for utf8mb4.The variable is primarily intended to support

replication from a MySQL 5.7 or older master server to a MySQL 8.0 slave server, or group replication

with a MySQL 5.7 primary node and one or more MySQL 8.0 secondaries. The default collation for

utf8mb4 in MySQL 5.7 is utf8mb4_general_ci, but it is utf8mb4_0900_ai_ci in MySQL 8.0. The

variable is not present in releases earlier than MySQL 8.0, so if the slave does not receive a value for

435

MySQL 8.0 Release Notes

the variable, it assumes the master is from an earlier release, and sets the value to the previous default

collation utf8mb4_general_ci.

The default utf8mb4 collation is used in the following statements:

• SHOW COLLATION and SHOW CHARACTER SET.

• CREATE TABLE and ALTER TABLE having a CHARACTER SET utf8mb4 clause without a

COLLATION clause, either for the table character set or for a column character set.

• CREATE DATABASE and ALTER DATABASE having a CHARACTER SET utf8mb4 clause without a

COLLATION clause.

• Any statement containing a string literal of the form _utf8mb4'some text' without a COLLATE

clause.

(Bug #27389878, Bug #27081073)

• DESCRIBE with a column name option ignored the column name. (Bug #27387773, Bug #89224)

• When run in key migration mode, the server ignored invalid options. (Bug #27387331)

• SHOW GRANTS for an anonymous user could cause a server exit. (Bug #27375069)

• Path name normalization could fail for very long path names. (Bug #27368298)

• During configuration, CMake assumed that rpcgen was available rather than checking for it. (Bug

#27368078)

• The client authentication process could use memory after it had been freed. (Bug #27366143)

• -DWITH_ZLIB=system could cause other CMake feature tests to fail. (Bug #27356658, Bug #89135)

• On some systems, using mysqld --initialize to initialize the data directory was very slow. (Bug

#27349579, Bug #89122)

• Builds using RPM source packages now use a secure connection if Boost must be downloaded. (Bug

#27343289, Bug #89104)

• An internal check_datetime_range function that converted an ULONGLONG time value raised an

assertion on Windows. (Bug #27340709)

• Too much locking was being done for the caching_sha2_password authentication plugin (one

lock/unlock per connection). This is now improved to one lock/unlock per plugin install/uninstall. (Bug

#27335346)

• A CREATE TABLE ... LIKE operation that implicitly assigned 'innodb_system' as the tablespace

name for table partitions raised an assertion. (Bug #27331588)

• SET PERSIST_ONLY could store large-valued variables incorrectly. (Bug #27322254)

• The audit_log plugin could write statements to the binary log even with binary logging disabled. (Bug

#27315321)

• Certain queries using GREATEST() or LEAST() produced heap-use-after-free errors. (Bug #27312703)

• An external_language column was added to the mysql.routines data dictionary table to support

stored routines in different languages. The data stored in this column can be accessed through the

EXTERNAL_LANGUAGES column of the INFORMATION_SCHEMA.ROUTINES table. (Bug #27309116, Bug

#89038)

436

MySQL 8.0 Release Notes

• It is now prohibited to start the server with a lower_case_table_names setting that is different

from the setting used when the server was initialized. The restriction is necessary because collations

used by data dictionary table fields are determined by the setting defined when the server is initialized,

and restarting the server with a different setting would introduce inconsistencies with respect to how

identifiers are ordered and compared. (Bug #27309094, Bug #89035)

• For accounts that authenticated using the auth_sock authentication plugin, the server was unable to

accept connections from clients from older MySQL versions. (Bug #27306178)

• An audit_log plugin memory leak was corrected. (Bug #27302151)

• The INFORMATION_SCHEMA.FILES table now obtains from storage engines the information needed for

the following columns: LOGFILE_GROUP_NAME, LOGFILE_GROUP_NUMBER, ROW_FORMAT, VERSION.

(Bug #27292586)

• Dropping a loadable function did not always remove its entry from the Performance Schema

user_defined_functions table. (Bug #27270498)

• To reduce its size and storage footprint, serialized dictionary information (SDI) is now generated in a

compact JSON format. (Bug #27265584)

• Concurrent execution of RESET PERSIST and SET PERSIST from multiple sessions could cause a

server exit. (Bug #27264789)

• Tablespace statistics could be cached even if the statistics-collection process encountered an error.

(Bug #27259963)

• SET PERSIST could fail to find the proper directory into which to write the mysqld-auto.cnf file. (Bug

#27253828)

• ALTER TABLE could not create generated NOT NULL geometry columns if the table contained data.

(Bug #27252609)

• The Performance Schema variables_info table displayed incorrect VARIABLE_SOURCE values for

variables that were set in my.cnf and also persisted to mysqld-auto.cnf. (Bug #27252077)

• Improper handling of plugin loading and unloading could cause a server exit. (Bug #27247280, Bug

#27297704)

• The RESTART statement did not work for Ubuntu packages. (Bug #27245918)

• LDAP authentication plugins were not built on FreeBSD. (Bug #27238252)

• The server did not handle queries correctly when a cached value was evaluated as NULL by a

windowing function, or when its argument was part of a GROUP BY with a ROLLUP operation which could

be evaluated as NULL. (Bug #27233287)

• Windowing functions such as LAST_VALUE() did not work correctly with tables containing NOT NULL

columns in all cases. (Bug #27230463)

• Role cache invalidation could be performed incorrectly. (Bug #27225806)

• Incorrect handling of persisted variables at server startup could result in a server exit. (Bug #27224682)

• For upgrades from MySQL 5.7 to 8.0, the sql_mode value for object definitions could contain

NOT_USED. (Bug #27219709)

• JSON_TABLE() failed if no default database was selected. (Bug #27217897)

437

MySQL 8.0 Release Notes

• Adding a unique index to an InnoDB table on which multiple locks were held could raise an assertion.

(Bug #27216817)

• CREATE VIEW statements that used JSON_TABLE() in the view definition failed if no database was

selected. (Bug #27189940)

• The Doxygen documentation for CLIENT_SSL_VERIFY_SERVER_CERT was corrected. Thanks to

Bradley Grainger for the patch. (Bug #27189363, Bug #88686)

• Queries on Performance Schema replication tables could return incorrect results, particularly when the

execution plan used an index. (Bug #27184567)

• For some statements, the FILE privilege was not properly checked. (Bug #27160888)

• To better enable setting persisted variables at startup in the same order they were persisted with SET

PERSIST, settings in mysqld-auto.cnf are first sorted based on timestamp (which is now stored in

the file). (Bug #27157520)

• Setting the dragnet.log_error_filter_rules system variable to a very long value could cause a

server exit. (Bug #27120953)

• For platforms that use systemd (see Managing MySQL Server with systemd), systemd was not always

able to infer the state of a double-forked mysqld process. Consequently, systemd would attempt to

restart mysqld even when that process terminated with status 1. systemd is now configured to run

mysqld as a normal process (Type=notify rather than Type=forking). If the name of a socket file

is specified in the environment variable NOTIFY_SOCKET, mysqld attempts to open a connection for

communicating with systemd and writes its state changes there. (Bug #27109556, Bug #88463, Bug

#26538598, Bug #87210)

• ST_IsValid() returned incorrect results for some geographic polygons on non-WGS 84 ellipsoids.

(Bug #27074700)

• A multiple-insert statement on a table containing a FULLTEXT key and a FTS_DOC_ID column caused a

server error. (Bug #27041445, Bug #88267)

References: This issue is a regression of: Bug #22679185.

• In strict SQL mode, assignment of invalid values to AUTO_INCREMENT columns could be handled

incorrectly, resulting in an assertion being raised. (Bug #27041393, Bug #88273)

• Thread stack exhaustion could raise an assertion rather than returning an error. (Bug #27041350, Bug

#88277)

• SET PERSIST_ONLY did not properly consider whether the runtime validation function for persisted

variables should be invoked. (Bug #27016247)

• The audit_log plugin could mishandle aborts of event executions, causing a server exit. (Bug

#27008133)

• Some boundary cases for negation of large signed integers were corrected. (Bug #27004880, Bug

#27008075)

• An ALTER TABLE operation attempted to set the AUTO_INCREMENT value for table in a discarded

tablespace. (Bug #26935001)

• MyISAM index corruption could occur for bulk-insert and table-repair operations that involve the repair-

by-sorting algorithm and many (more than 450 million) rows. (Bug #26929724, Bug #88003, Bug

#28483283)

438

MySQL 8.0 Release Notes

• The Performance Schema could produce DIGEST_TEXT values with a trailing space. This no longer

occurs. (Bug #26908015)

• Dropping an index from a system table could cause a server exit. (Bug #26881798)

• A prepared statement using CREATE TABLE ... SELECT led to unexpected behavior when it referred

in a GROUP BY to a view having the same name. (Bug #26881703)

• With auto-commit disabled and an XA transaction in PREPARED state, attempts to execute XA COMMIT

or XA ROLLBACK failed. (Bug #26848877, Bug #87836)

• Some diagnostic messages produced by LDAP authentication plugins misleadingly suggested an error

when no error had occurred. (Bug #26844713)

• Initialization code for mysql_upgrade and mysqlpump was reorganized to avoid assertion failures.

(Bug #26802211)

• Full-text searches could raise an assertion due to improper handling of errors that occurred while

attempting to acquire metadata locks. (Bug #26799898)

• A keyring file created by the keyring_file plugin on a 32-bit server was inaccessible by the

keyring_file on a 64-bit server, and vice versa. (Bug #26793060)

• Metadata locks for column statistics were not displayed properly in the Performance Schema

metadata_locks and events_waits_xxx tables. (Bug #26772858, Bug #87708)

• The my_snprintf plugin service was removed and reimplemented using C++11 snprintf. (Bug

#26696147, Bug #87547)

• After an in-place upgrade from MySQL 5.7 to MySQL 8.0 on a server with a large number of tables,

server startup failed to complete due to excessive memory consumption during data dictionary creation.

(Bug #26486160)

• An error occurring in a statement that modifies user privileges could result in deadlock for other

transactions attempting to access the user privilege cache. (Bug #26475282)

• The thread pool plugin logged too much information for failed connections. (Bug #26368725, Bug

#86863)

• Enabling multiple components concurrently could result in a server exit. (Bug #26171471, Bug #86514)

• A malformed mysqld-auto.cnf file could cause a server exit. (Bug #26085774)

• Creating a table in a reserved tablespace did not return an error. (Bug #26073851, Bug #86309)

• For debug builds, using KILL to terminate a stored routine could raise an assertion. Thanks to Laurynas

Biveinis for the patch. (Bug #26040870, Bug #86260)

• If the init_connect system variable was set, its contents could not be executed by clients with expired

passwords, who therefore were prevented from connecting. Now, if a client has an expired password,

init_connect execution is skipped, which enables the client to connect and change password. (Bug

#25968185)

• Dates using the YYYYMMDD format were not recognized correctly in a query meeting all three of the

following conditions:

The query performed a left join.

A DATE column in the inner table of the join was part of a multi-column primary key.

439

MySQL 8.0 Release Notes

Every column in the inner table's primary key was compared with another value; this could be either a

literal or a column value. (Bug #25949639)

• An in-place ALTER TABLE operation on a table with foreign keys resulted in a table definition mismatch.

The new table definition passed to storage engine methods during the ALTER TABLE execution

contained invalid foreign key names. (Bug #25915132, Bug #85997)

• It was possible to assign nonexistent roles to an account as its default roles. (Bug #25755666, Bug

#85561)

• Using the C API, when trying to execute an INSERT prepared statement with

CURSOR_TYPE_READ_ONLY set, the client hung. (Bug #25701141, Bug #85105)

• RENAME USER failed even though the user or role to be renamed was not present in any role graph.

(Bug #25658586)

• MySQL client programs could exit unexpectedly if malformed client/server protocol packets were

received. (Bug #25471090)

• Memory statistics collected by the Performance Schema could be incorrect due to race conditions. (Bug

#25212799)

• Incorrect handling by the CONNECTION_CONTROL plugin of an internal hash led to spurious messages in

the error log and eventual server exit. (Bug #25052009)

• CURRENT_ROLE() and ROLES_GRAPHML() now return a string with the utf8 character set. Previously,

they incorrectly returned a binary string. (Bug #24843257)

• Killing INSTALL COMPONENT or UNINSTALL COMPONENT could result in multiple rows for a single

component in the mysql.component system table. (Bug #24660436)

• Performing SHOW PROCESSLIST while running a high load concurrently using the X Plugin could lead to

an unplanned server exit. (Bug #24621170)

References: See also: Bug #23057045.

• The regular expression implementation in MySQL uses a String object—intended to be initialized

as empty—to hold the current subject, and used the literal "" for this value. This could interfere with

other functions that do likewise. This is fixed by constructing the String with a nullptr instead. (Bug

#23276471)

• mysqlpump could leak memory or exit when errors occurred. (Bug #23102944)

• LDML 2.8 collation definitions could cause unexpected server behavior. (Bug #22819030)

• Log-opening operations accessed log-name system variables without holding a lock on them. Multiple

threads accessing such a variable could lead to a race condition and unexpected server behavior. (Bug

#22591899)

• When the range optimizer computed the prefix for a string of sufficient length, it was possible for it

to truncate the string in the middle of a character, which could lead to assertion and other failures in

debug builds. Now steps are taken in such cases to make sure that the string is truncated at a character

boundary. (Bug #22475473, Bug #13712655)

• Queries having subqueries or expressions in the GROUP BY clause could in some situations return

random results, due to reading of uninitialized data. (Bug #20035304)

440

MySQL 8.0 Release Notes

References: See also: Bug #21922202.

• Queries having subqueries or expressions in a GROUP BY clause sometimes returned random results

due to reading of uninitialized data. (Bug #20035304)

References: See also: Bug #21922202.

• The audit_log plugin did not log placeholder values for prepared statements. (Bug #16617026)

• ALTER TABLE ... RENAME operations could lose foreign keys defined on the table if executed using

the COPY algorithm. (Bug #11756183, Bug #48070)

• Integer columns in UNION statements could be cast to BIGINT even if a smaller integer type was more

appropriate. (Bug #11747567, Bug #33004)

• Added ER_REGEXP_INVALID_CAPTURE_GROUP_NAME (Error 13110). (Bug #89796, Bug #27597980)

• Window function row-buffer handling has been refactored to reduce the number of handler reads by

25%. (Bug #89512, Bug #27484133)

• For some frames, the functions VARIANCE(), VAR_POP(), and VAR_SAMP() produced wrong results

when evaluated with the windowing_use_high_precision system variable set to false. (Bug

#89390, Bug #27438725)

• Generated columns with a prefix index were not considered when the optimizer attempted to substitute

an expression with an equivalent generated column. This prevented use of prefix indexes to speed up

queries with predicates employing a generated column expression. (Bug #89291, Bug #27403367)

• FIRST_VALUE() did not always return NULL for an empty frame. (Bug #89116, Bug #27348276)

• Regular expression functions accepting optional arguments did not return NULL as expected when one

or more of these arguments was passed as an explicit NULL. (Bug #88872, Bug #27252630)

• Row-based replication used the wrong set of indexes on the slave. (Bug #88847, Bug #27244826)

• When executed with no default database having been chosen, EXPLAIN EXTENDED raised Error 1046

No database selected instead of the SQL syntax error expected due to the fact that the EXTENDED

keyword has been removed. (Bug #88591, Bug #27153116)

• The CMake option OPTIMIZER_TRACE=0 had no effect on builds and so is no longer used. (Bug

#88520, Bug #27130109)

• A SELECT statement using GROUP BY with no constant or aggregate column failed a check for functional

dependencies, correctly, on the first attempt but succeeded, wrongly, on the next. (Bug #88474, Bug

#27427677)

References: See also: Bug #21807579.

• A CREATE TABLE ... SELECT statement with a UNION in the SELECT failed in strict mode for a DATE

column declared as NOT NULL. (Bug #87711, Bug #27068222)

• Prepared statements using nested sub-selects were not always handled correctly. (Bug #87484, Bug

#26657904)

• The cost estimates for a query containing window functions did not take into account the cost of

PARTITION BY or ORDER BY, nor did they include the cost of using the frame buffer. (Bug #87373, Bug

#26612356)

441

MySQL 8.0 Release Notes

References: See also: Bug #26502118.

• When processing a query with a subquery, the subquery is no longer optimized if outer query is known

to produce an empty result; in such cases, EXPLAIN now shows Not optimized, outer query is

empty.

This change is made because, when the table used by the outer query is found empty at optimization,

this sets the join column to NULL even when defined as not nullable, which leads to a conflict when

optimizing the subquery.

An exception is made if the outer query has aggregates without any GROUP BY; this means that it

has a non-empty result, and that any subquery in the SELECT list must be evaluated and optimized,

which reopens the nullability issue, which is now handled correctly for such cases. (Bug #83115, Bug

#24713879)

References: See also: Bug #83216, Bug #24760317.

• When selecting from all columns making up a unique key containing nullable columns, with all columns

in the WHERE condition set to non-null values, MySQL did not take into account their uniqueness, with

the result that only_full_group_by missed detecting a functionally dependent column. (Bug #79291,

Bug #22279903)

• When using a partial index, the optimizer performed a more expensive table lookup instead of using the

index, even when the partial index covered the entire set of data needed. (Bug #74359, Bug #19806106)

Changes in MySQL 8.0.5 - 8.0.10 (Skipped version numbers)

There are no release notes for these skipped version numbers.

Changes in MySQL 8.0.4 (2018-01-23, Release Candidate)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

Beginning with MySQL 8.0.4, macOS 10.13 is a supported platform.

• Compilation Notes

• Component Notes

• Configuration Notes

• Deprecation and Removal Notes

• SQL Function and Operator Notes

442

MySQL 8.0 Release Notes

• InnoDB Notes

• Installation Notes

• Keyring Notes

• Logging Notes

• Packaging Notes

• Performance Schema Notes

• Security Notes

• Server Administration

• Spatial Data Support

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Compilation Notes

• Linux: Binary packages on Linux platforms now are built using GCC 6. The optimization level has

changed from -O3 to -O2. (WL #10343)

• macOS; Microsoft Windows: For compiling MySQL from source, the -DWITH_SSL=system CMake

option now works on Windows and macOS. (Bug #26907731, Bug #87938)

• On platforms for which the GNU gold linker is used, removal of unused functions is now enabled,

reducing the size of binaries. (Bug #26612067, Bug #87372)

• #include directives in source files were rewritten and reorganized to be unambiguous. (Bug

#26597243, Bug #87358, Bug #26897738)

• The BUILD directory containing compilation scripts is no longer maintained and has been removed from

MySQL source trees. (Bug #26576219, Bug #87323)

• The minimum version of the Boost library for server builds is now 1.65.0. (Bug #26574924, Bug #87317)

• MySQL can now be linked against OpenSSL 1.1 on Unix and Unix-like systems. (Bug #25094892, Bug

#83814)

• Work was done to clean up the source code base, including: Removing unneeded CMake checks;

removing unused macros from source files; reorganizing header files to reduce the number of

dependencies and make them more modular, removing function declarations without definitions,

replacing locally written functions with equivalent functions from industry-standard libraries.

Component Notes

• The validate_password plugin has been reimplemented to use the component infrastructure. To

install and uninstall the validate_password component, use these statements:

INSTALL COMPONENT 'file://component_validate_password';

UNINSTALL COMPONENT 'file://component_validate_password';

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MySQL 8.0 Release Notes

INSTALL PLUGIN and UNINSTALL PLUGIN still work to install and uninstall the validate_password

plugin as before, but generate warnings. The plugin form of validate_password is deprecated and

will be removed in a future MySQL version. MySQL installations that use the plugin should transition to

the component instead. See Transitioning to the Password Validation Component.

A usage difference between the component and plugin implementations of validate_password

is that, whereas the plugin exposes system and status variables with names that

begin with validate_password_, the component uses the convention of exposing

variables with names that begin with the component name and a period. For example,

the plugin exposes the validate_password_policy system variable and

validate_password_dictionary_file_words_count status variable, whereas the

corresponding variables exposed by the component are validate_password.policy and

validate_password.dictionary_file_words_count. The plugin variables, like the plugin itself,

are deprecated and will be removed in a future MySQL version. (WL #6667)

Configuration Notes

• Replication: When calculating the binary log expiration period, any value that you specify for the

deprecated expire_logs_days system variable is now ignored if binlog_expire_logs_seconds

is set, and only the value of binlog_expire_logs_seconds is used. Previously, the effects of

binlog_expire_logs_seconds and expire_logs_days were cumulative.

If you set a value for both system variables at startup, a warning message is issued stating that the value

of expire_logs_days is ignored. You cannot set or change the value of one option dynamically while

the other is set, and an error message is issued in this situation.

The default binary log expiration period of 30 days (as changed in MySQL 8.0.2) applies if neither

binlog_expire_logs_seconds nor expire_logs_days has a value set at startup. If a value for

either binlog_expire_logs_seconds or expire_logs_days is set at startup, this value overrides

the default binary log expiration period. To disable automatic purging of the binary log, you must set both

binlog_expire_logs_seconds and expire_logs_days explicitly to 0 at startup. (Bug #26274274,

Bug #86698)

• For RHEL, SLES, and Fedora RPMs, the default plugin directory for debug builds has been changed

from /usr/lib64/mysql/plugin to /usr/lib64/mysql/plugin/debug. (Bug #27072155, Bug

#88363)

• The new WITH_LZMA and WITH_RE2 CMake options control whether to compile with the bundled or

system LZMA and RE2 libraries.

• The table_open_cache system variable default variable has been increased from 2000 to 4000. This

additionally changes the default for the autosized table_definition_cache system variable from

1400 to 2000. (WL #9703)

• The optimizer_trace_max_mem_size system variable default value was changed from 16KB to

1MB to lessen the likelihood of optimizer trace truncation. (WL #11345)

• The log_error_verbosity system variable default value was changed from 3 (error, warning, and

information messages) to 2 (error and warning messages) to make mysqld error logging less verbose

by default. (WL #11143)

Deprecation and Removal Notes

• InnoDB: The innodb_undo_tablespaces configuration option is deprecated and will be removed in a

future MySQL version. (WL #10473)

444

MySQL 8.0 Release Notes

• Replication: The group_replication_primary_member status variable has been deprecated and

will be removed in a future MySQL version. (WL #10958)

• Replication: The group_replication_allow_local_disjoint_gtids_join system variable

has been removed. (WL #11139)

• When the libmysqld embedded server library was removed in MySQL 8.0.1, the following

mysql_options() options used only for libmysqld were not removed. They have now been

removed.

MYSQL_OPT_GUESS_CONNECTION

MYSQL_OPT_USE_EMBEDDED_CONNECTION

MYSQL_OPT_USE_REMOTE_CONNECTION

MYSQL_SET_CLIENT_IP

(Bug #26712418)

• mysqlpump no longer includes the SQL_NO_CACHE modifier in statements because that modifier is now

deprecated and results in deprecation warnings. (Bug #26694675)

• Generated columns no longer permit deprecated functions in the generation expression, to avoid

problems when MySQL is upgraded to a version in which the deprecated functions have been removed.

(Bug #26279884, Bug #86712)

• The Performance Schema setup_timers table has been removed, as has the TICK row in the

performance_timers table. (Bug #18296337, WL #10985, WL #10986)

SQL Function and Operator Notes

• Incompatible Change: Previously, MySQL used the Henry Spencer regular expression library

to support regular expression operators (REGEXP, RLIKE). Regular expression support has been

reimplemented using International Components for Unicode (ICU), which provides full Unicode support

and is multibyte safe. The REGEXP_LIKE() function performs regular expression matching in the

manner of the REGEXP and RLIKE operators, which now are synonyms for that function. In addition, the

REGEXP_INSTR(), REGEXP_REPLACE(), and REGEXP_SUBSTR() functions are available to find match

positions and perform substring substitution and extraction, respectively. The regexp_stack_limit

and regexp_time_limit system variables provide control over resource consumption by the match

engine.

MySQL source distributions bundle the ICU library, and the WITH_ICU CMake option controls whether

to compile with the bundled or system ICU library. The ICU_VERSION() function returns the ICU library

version.

For more information, see Regular Expressions. For information about ways in which applications

that use regular expressions may be affected by the implementation change, see Regular Expression

Compatibility Considerations. (WL #8987)

• Two new SQL functions are available to provide digest information about SQL statements. Given

an SQL statement as a string, STATEMENT_DIGEST() returns the statement digest hash value,

and STATEMENT_DIGEST_TEXT() returns the normalized statement digest. See Encryption and

Compression Functions. (WL #9637)

InnoDB Notes

• The restriction enacted in MySQL 8.0.3 against renaming of columns in a parent foreign key has been

lifted. (Bug #26659110, Bug #87490, Bug #25722221)

445

MySQL 8.0 Release Notes

References: See also: Bug #26334071.

Installation Notes

• For platforms that use systemd (see Managing MySQL Server with systemd), the data directory is

initialized if empty at server startup. This might be a problem if the data directory is a remote mount that

has temporarily disappeared: The mount point would appear to be an empty data directory, which then

would be initialized as a new data directory. It is now possible to suppress this automatic initialization

behavior. Specify the following line in the /etc/sysconfig/mysql file (create the file if it does not

exist):

NO_INIT=true

(Bug #26595288, Bug #87287)

Keyring Notes

• MySQL now supports key migration between underlying keyring keystores, permitting DBAs to switch a

MySQL installation from one keyring plugin to another. See Migrating Keys Between Keyring Keystores.

(WL #9769)

Logging Notes

• A new error log filter component, log_filter_dragnet, enables control over events

written to the error log, based on user-defined rules specified as the value of the

dragnet.log_error_filter_rules system variable. This new filtering capability is more

flexible than is achievable using the built-in log_filter_internal filter component and

log_error_verbosity system variable. For more information, see Types of Error Log Filtering. (WL

#9651)

• Messages written to the error log by the log_sink_internal log sink component now contain an

error-ID indicator. This ID has a format of [error_id]. It follows the severity indicator and precedes the

message text. For more information, see Error Log Output Format. (WL #11009)

• When the log_error_verbosity system variable for error logging is set to filter out warning and

information messages, selected important messages about non-error situations are now printed to error

logs as system messages. These messages were previously handled and labeled as errors so that they

were logged when log_error_verbosity=1 was set. The labeling function has now been decoupled

from the handling function for these messages, so that the messages can be given an appropriate label.

System messages now have the label “System” in the MySQL error log. Other log sinks that support

custom labels might also use this convention. In logs that do not support custom labels, system

messages are printed with the label used for the information level of severity. However, they are included

even if the log_error_verbosity setting normally excludes messages at this level.

If your system has additional configuration to discard messages labeled as information level, or to

redirect them to a different destination from messages labeled as errors, system messages do not

override this behavior. If the log sink involved does not use the “System” label, system messages are

now discarded or redirected along with other messages labeled as information level.

The messages that are now printed with the “System” label where supported include startup and

shutdown messages, and some significant changes to settings, as follows:

• ER_STARTING_AS

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MySQL 8.0 Release Notes

• ER_STARTUP

• ER_XA_STARTING_RECOVERY

• ER_XA_RECOVERY_DONE

• ER_NORMAL_SHUTDOWN

• ER_SHUTDOWN_COMPLETE

• ER_RPL_SLAVE_CONNECTED_TO_MASTER_REPLICATION_STARTED

• ER_RPL_SLAVE_CONNECTED_TO_MASTER_REPLICATION_RESUMED

• ER_SLAVE_CHANGE_MASTER_TO_EXECUTED

• ER_GTID_PURGED_WAS_CHANGED

• ER_GTID_EXECUTED_WAS_CHANGED

• ER_CHANGED_GTID_MODE

• ER_RPL_SLAVE_DUMP_THREAD_KILLED_BY_MASTER

(WL #10942)

Packaging Notes

• All MySQL binary distributions now are linked against OpenSSL, including Community distributions,

which previously were linked against yaSSL. In addition, OpenSSL is linked dynamically rather than

statically, which enables substitution of alternative SSL libraries for use with MySQL if desired. For some

platforms, binary distributions bundle OpenSSL libraries to ensure library availability:

• Windows: Distributions bundle libeay32.dll and ssleay32.dll, which are installed in the

same directory as MySQL binaries. Other libraries can be used by replacing those library files with

alternatives, or by using some other library-selection method supported on Windows. (See https://

msdn.microsoft.com/en-us/library/7d83bc18.aspx.)

• macOS: Distributions bundle libssl.dylib and libcrypto.dylib. MySQL binaries are linked to

expect the libraries in the same directory, and symbolic links there point to the actual library locations.

• Linux (for generic compressed tar file distributions only): Distributions bundle libssl.so and

libcrypt.so,which are installed in the same directory as the libmysqlclient.so client library.

(Bug #26272084, Bug #26134893, Bug #26927607, Bug #87996, WL #10524)

Performance Schema Notes

• The Performance Schema now uses SHA-256 hashes for statement digests rather than MD5 hashes.

To accommodate the increased storage required for SHA-256 values, DIGEST columns in Performance

Schema tables are widened from VARCHAR(32) to VARCHAR(64). (Bug #26727443)

Security Notes

• Incompatible Change: Passwords are now restricted to a maximum of 256 characters for the

caching_sha2_password and sha256_password authentication plugins, and for the PASSWORD()

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MySQL 8.0 Release Notes

function when old_passwords=2. Also, the number of password hashing rounds is capped to limit

CPU time used. (Bug #27099029, Bug #27194270)

• Incompatible Change: The caching_sha2_password and sha256_password authentication

plugins provide more secure password encryption than the mysql_native_password plugin,

and caching_sha2_password provides better performance than sha256_password. Due

to these superior security and performance characteristics of caching_sha2_password, it is

now the preferred authentication plugin, and is also the default authentication plugin rather than

mysql_native_password. This change affects both the server and the libmysqlclient client

library:

• For the server, the default value of the default_authentication_plugin system variable

changes from mysql_native_password to caching_sha2_password.

• The libmysqlclient library treats caching_sha2_password as the default authentication plugin

rather than mysql_native_password.

This change has the following implications:

• The change affects only the authentication plugin used for creating new MySQL accounts. For

accounts already existing in an upgraded installation, their authentication plugin remains unchanged.

• Clients that use an account that authenticates with caching_sha2_password must use either

a secure connection (made using TCP using TLS/SSL credentials, a Unix socket file, or shared

memory), or an unencrypted connection that supports password exchange using an RSA key

pair. This security requirement does not apply to mysql_native_passsword, so the switch to

caching_sha2_password may require additional configuration (see Caching SHA-2 Pluggable

Authentication). However, client connections in MySQL 8.0 prefer use of TLS/SSL by default, so

clients that already conform to that preference may need no additional configuration.

• Because caching_sha2_password is also now the default authentication plugin in the

libmysqlclient client library, authentication requires an extra round trip in the client/server

protocol for connections from MySQL 8.0 clients to accounts that use mysql_native_password

(the previous default authentication plugin), unless the client program is invoked with a --default-

auth=mysql_native_password option.

• Incompatibility: Clients and connectors that have not been updated to know about

caching_sha2_password cannot connect to accounts that authenticate with

caching_sha2_password because they do not recognize this plugin as valid. To work around this

issue, relink clients against libmysqlclient from MySQL 8.0.4 or higher, or obtain an updated

connector that recognizes caching_sha2_password.

• Incompatibility: Clients and connectors that have not been updated to know about

caching_sha2_password may have trouble connecting to a MySQL 8.0 server configured with

caching_sha2_password as the default authentication plugin, even to use accounts that do not

authenticate with caching_sha2_password. This issue occurs because the server specifies the

name of its default authentication plugin to clients. If a client or connector is based on a client/server

protocol implementation that does not gracefully handle an unrecognized default authentication plugin,

it may fail with an error.

For more information about the more prominent role of caching_sha2_password, including

discussion of potential compatibility issues and solutions, see caching_sha2_password as the Preferred

Authentication Plugin.

Additionally, replication slaves are now able to connect to masters using RSA key pair-based

password exchange. This RSA capability applies for accounts that authenticate with the

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MySQL 8.0 Release Notes

caching_sha2_password or sha256_password authentication plugin. (Previously, slaves could

authenticate with those plugins, but required a secure connection and could not use RSA password

exchange.) The following changes enable use of this new slave RSA capability:

• The CHANGE MASTER TO statement has clauses for specifying RSA public key information.

• For Group Replication, the group_replication_recovery_public_key_path and

group_replication_recovery_get_public_key system variables serve the same purpose.

• The SHOW SLAVE STATUS statement and the Performance Schema

replication_connection_configuration table display replication slave RSA public key

information.

More programs now support a --server-public-key-path option to enable specifying a client-side

file containing the public key for RSA key pair-based password exchange, for accounts that authenticate

with the caching_sha2_password or sha256_password authentication plugin: mysqladmin,

mysqlbinlog, mysqlcheck, mysqldump, mysqlimport, mysqlpump, mysqlshow, mysqlslap,

mysql_upgrade. Previously, only mysql and mysqltest supported --server-public-key-path.

The --server-public-key-path option is an alternative to --get-server-public-key, and may

be used when a client-side file is available that contains a copy of the RSA public key required by the

server, rather than sending a request for the public key to the server.

The new mysql_reset_server_public_key() C API function clears any cached copy of the server

RSA public key from the client library. See mysql_reset_server_public_key().

The new caching_sha2_password_auto_generate_rsa_keys system

variable enables automatic RSA private/public key-pair file generation, similar to the

sha256_password_auto_generate_rsa_keys system variable. See Automatic SSL and RSA File

Generation.

The new Caching_sha2_password_rsa_public_key status variable exposes the public key used

by the caching_sha2_password authentication plugin for RSA key pair-based password exchange.

(Bug #26751594, WL #11057)

• The linked OpenSSL library for MySQL Server has been updated to version 1.0.2n. Issues fixed in

the new OpenSSL version are described at http://www.openssl.org/news/vulnerabilities.html. (Bug

#27212666, Bug #27236394)

• Certificates automatically generated by mysqld and mysql_ssl_rsa_setup now use X509 v3 rather

than v1. (Bug #26521654)

Server Administration

• A new RESTART SQL statement is available that enables restarting a MySQL server instance from within

a client session. This feature is available for platforms on which a monitoring process is able to detect

a server shutdown performed for restart purposes: Windows (mysqld started as a Windows service or

standalone), and Unix and Unix-like systems that use systemd or mysqld_safe to manage mysqld.

See RESTART Statement. (WL #9809)

Spatial Data Support

• Incompatible Change: These spatial import functions now return an error for data in a

geographic spatial reference system for which the coordinates are outside the legal range of

values: ST_GeomCollFromText(), ST_GeomCollFromTxt(), ST_GeomCollFromWKB(),

ST_GeometryCollectionFromText(), ST_GeometryCollectionFromWKB(),

ST_GeometryFromText(), ST_GeometryFromWKB(), ST_GeomFromGeoJSON(),

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MySQL 8.0 Release Notes

ST_GeomFromText(), ST_GeomFromWKB(), ST_LineFromText(), ST_LineFromWKB(),

ST_LineStringFromText(), ST_LineStringFromWKB(), ST_MLineFromText(),

ST_MLineFromWKB(), ST_MPointFromText(), ST_MPointFromWKB(), ST_MPolyFromText(),

ST_MPolyFromWKB(), ST_MultiLineStringFromText(), ST_MultiLineStringFromWKB(),

ST_MultiPointFromText(), ST_MultiPointFromWKB(), ST_MultiPolygonFromText(),

ST_MultiPolygonFromWKB(), ST_PointFromText(), ST_PointFromWKB(),

ST_PolyFromText(), ST_PolyFromWKB(), ST_PolygonFromText(), ST_PolygonFromWKB().

(ST_LatFromGeoHash(), ST_LongFromGeoHash(), and ST_PointFromGeoHash() do not have

this behavior because they cannot represent out-of-range values.)

ST_GeomFromGeoJSON() also now returns an error if a crs member that specifies an SRID different

from the top-level object SRID is found at a lower level of the GeoJSON document.

Note

If spatial data contains SRID values that refer to a geographic spatial reference

system and the data coordinates are out of range, existing queries using these

functions will return different results, compared to previous MySQL versions.

(Bug #26941370, Bug #88031, WL #9449)

• Incompatible Change: Previously, these spatial functions ignored the spatial reference system (SRS)

for geometry arguments and computed results on a Cartesian plane. They now support computations

for geometry arguments that specify a geographic SRS: ST_Distance_Sphere(), ST_IsSimple(),

ST_IsValid(), ST_Length().

Previously, these spatial functions ignored the SRS for any geometry arguments and computed

results on a Cartesian plane. They now produce an error when invoked with geometry

arguments that specify a geographic SRS: ST_Area(), ST_Buffer(), ST_Centroid(),

ST_ConvexHull(), ST_Difference(), ST_Envelope(), ST_Intersection(), ST_IsClosed(),

ST_MakeEnvelope(), ST_Simplify(), ST_SymDifference(), ST_Union(), ST_Validate().

Previously, these spatial functions permitted geometry arguments with an undefined

SRS. They now produce an error when invoked with geometry arguments that have

an undefined SRS: ST_Dimension(), ST_Distance_Sphere(), ST_EndPoint(),

ST_ExteriorRing(), ST_GeometryN(), ST_GeometryType(), ST_InteriorRingN(),

ST_IsEmpty(), ST_IsSimple(), ST_IsValid(), ST_Length(), ST_NumGeometries(),

ST_NumInteriorRing(), ST_NumInteriorRings(), ST_NumPoints(), ST_PointN(),

ST_StartPoint(), ST_SwapXY(), ST_X(), ST_Y().

Previously, the ST_GeoHash() spatial function accepted points with any SRID. ST_GeoHash() now

accepts only points with SRID 0 or 4326.

Note

If spatial data contains geometry values that now are interpreted differently by

the functions just listed, existing queries using these functions will return different

results, compared to previous MySQL versions.

(WL #10416, WL #10926, WL #10927, WL #10999, WL #11096)

• Incompatible Change: For the following spatial functions that take an SRID argument,

they now return an error if the SRID does not exist: ST_GeomCollFromText(),

ST_GeomCollFromTxt(), ST_GeomCollFromWKB(), ST_GeometryCollectionFromText(),

ST_GeometryCollectionFromWKB(), ST_GeometryFromText(), ST_GeometryFromWKB(),

ST_GeomFromGeoJSON(), ST_GeomFromText(), ST_GeomFromWKB(), ST_LineFromText(),

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MySQL 8.0 Release Notes

ST_LineFromWKB(), ST_LineStringFromText(), ST_LineStringFromWKB(),

ST_MLineFromText(), ST_MLineFromWKB(), ST_MPointFromText(), ST_MPointFromWKB(),

ST_MPolyFromText(), ST_MPolyFromWKB(), ST_MultiLineStringFromText(),

ST_MultiLineStringFromWKB(), ST_MultiPointFromText(), ST_MultiPointFromWKB(),

ST_MultiPolygonFromText(), ST_MultiPolygonFromWKB(), ST_PointFromGeoHash(),

ST_PointFromText(), ST_PointFromWKB(), ST_PolyFromText(), ST_PolyFromWKB(),

ST_PolygonFromText(), ST_PolygonFromWKB(). (ST_SRID() already had this behavior.)

Note

If spatial data contains SRID values that refer to a nonexistent spatial reference

system, existing queries using these functions will return different results,

compared to previous MySQL versions.

(WL #9450)

• The server now prints a warning if a SPATIAL index is created that the optimizer will never use. (Bug

#27015964)

• The EPSG Dataset containing spatial reference system data for spatial calculations has been upgraded

from version 9.0 to 9.2. (Bug #26711258, Bug #87564, Bug #26990896)

• MySQL now supports CREATE SPATIAL REFERENCE SYSTEM and DROP SPATIAL REFERENCE

SYSTEM statements for creating and removing spatial reference system (SRS) definitions in the

data dictionary. See CREATE SPATIAL REFERENCE SYSTEM Statement, and DROP SPATIAL

REFERENCE SYSTEM Statement. With the implementation of these statements, direct access to the

mysql.st_spatial_reference_systems data dictionary table using statements such as SELECT,

INSERT, and UPDATE is not needed, and is no longer permitted. Read access to SRS definitions

remains available through the INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS table, as

before. (WL #9059)

Test Suite Notes

• Documentation for the MySQL Test Suite is now maintained in the MySQL source tree using Doxygen

(see the MySQL Server Doxygen documentation, available at https://dev.mysql.com/doc/index-

other.html.) The related Unix man pages that previously were produced from the old test suite manual

are no longer updated and have gone out of date. Consequently, they are no longer included in MySQL

distributions. (Bug #27021754)

• The MySQL test suite now includes CRC32() tests. Thanks to Daniel Black for the patch. (Bug

#26495791, Bug #87136)

• mysqltest now accepts an optional retry argument for these commands: copy_file

copy_files_wildcard, file_exists, move_file, remove_file, and

remove_files_wildcard. Usage is as follows:

--file_operation file_name ... [retry]

When the retry argument is specified, the command retries a failed operation the given number of

times at one-second intervals. (Bug #24671890)

X Plugin Notes

• X Plugin could incorrectly remove quotes from parameters that were passed to functions expecting

JSON strings, causing an error. (Bug #26906519)

451

MySQL 8.0 Release Notes

• After an index was created on a collection, X Plugin would list the collection as a relational table, and no

longer list it as a collection. (Bug #26906487)

• X Protocol displayed the DATE type in the same way as the DATETIME type. The two data types are now

treated differently. (Bug #26647488)

• mysqlxtest did not display fractional seconds in DATETIME values correctly. (Bug #26638422)

• X Plugin returned a column metadata field showing fractional digits for a JSON column, for which that

information was irrelevant. The field is no longer returned. (Bug #26258481)

• X Plugin handled user account lookup incorrectly if the IP address resolved to an empty host name. (Bug

#26042786)

• X Plugin can now be configured to abort any authenticated connections which are considered idle. The

following system variables have been added:

• mysqlx_interactive_timeout

• mysqlx_read_timeout

• mysqlx_wait_timeout

• mysqlx_write_timeout

(WL #9267)

• X Plugin now supports Caching SHA-2 Pluggable Authentication. To enable the support, issue:

INSTALL PLUGIN mysqlx_cache_cleaner SONAME 'mysqlx.so';

This plugin maintains the cache and removes all entries for accounts that were modified. (WL #10992)

References: See also: Bug #27213213, Bug #27042109.

Functionality Added or Changed

• InnoDB: Obsoleted InnoDB system tables that are no longer required after upgrading to MySQL 8.0.3

or later are now dropped after a successful upgrade. (Bug #26757171)

• InnoDB: Support was added to automatically upgrade data dictionary table definitions when starting the

MySQL server after upgrading MySQL binaries to a new version. At startup, the data dictionary version

of the server is compared to the version information stored in the data dictionary to determine if data

dictionary tables should be upgraded. If an upgrade is necessary and supported, the server creates

data dictionary tables with updated definitions, copies persisted metadata to the new tables, atomically

replaces the old tables with the new ones, and reinitializes the data dictionary. If an upgrade is not

necessary, startup continues without updating the data dictionary tables.

The mysqld --no-dd-upgrade option can be used to prevent automatic upgrade of data dictionary

tables at startup. (WL #9553)

• InnoDB: Moving or restoring tablespace files to a new location while the server is offline is supported by

the new --innodb-directories option, which defines directories to scan at startup for tablespace

files. For more information, see Moving Tablespace Files While the Server is Offline.

With the introduction of the --innodb-directories feature, the location of file-per-table and general

tablespace files created with an absolute path or in a location outside of the data directory should be

452

MySQL 8.0 Release Notes

added to the innodb_directories argument value. Otherwise, InnoDB is not able to locate these

files during recovery. To view tablespace file locations, query the INFORMATION_SCHEMA.FILES table:

mysql> SELECT TABLESPACE_NAME, FILE_NAME FROM INFORMATION_SCHEMA.FILES \G

The CREATE TABLESPACE ... ADD DATAFILE statement now requires that a specified directory

is known to InnoDB. Known directories include those implicitly and explicitly defined by the

innodb_directories option.

innodb_directories replaces innodb_scan_directories, which has been removed. (WL #8619)

• InnoDB: InnoDB now supports partial update of large object (LOB) data stored in external fields

outside of clustered index pages, including JSON documents updated using JSON_SET() and

JSON_REPLACE(). Previously, LOB values could only be read or modified in full, and updates of JSON

column values were done by completely removing the previous document and writing the new one in its

place.

Partial update uses an internal LOB index, or ZLOB index in the case of compressed LOB data, which is

created and stored in one or more LOB pages when a row containing LOB data is inserted or updated.

Thus, partial fetch and update of LOB data is supported for newly inserted rows, but existing rows

containing LOB data must be updated to add partial fetch and update support. The addition of LOB index

data increases the storage space required by LOB values by a small percentage.

This feature adds the following InnoDB page types for storing uncompressed and compressed LOB

data:

• FIL_PAGE_TYPE_LOB_INDEX

• FIL_PAGE_TYPE_LOB_DATA

• FIL_PAGE_TYPE_LOB_FIRST

• FIL_PAGE_TYPE_ZLOB_FIRST

• FIL_PAGE_TYPE_ZLOB_DATA

• FIL_PAGE_TYPE_ZLOB_INDEX

• FIL_PAGE_TYPE_ZLOB_FRAG

• FIL_PAGE_TYPE_ZLOB_FRAG_ENTRY

(WL #8960)

• InnoDB: The storage engine private field of the mysql.tablespaces data dictionary table and page

0 of InnoDB tablespace files now store MySQL server version and tablespace version information.

The MySQL server version is the version that created the tablespace, the version into which the

tablespace was imported, or the version of the last major MySQL upgrade. The tablespace version

tracks tablespace format changes. SERVER_VERSION and SPACE_VERSION fields were added to the

INFORMATION_SCHEMA.INNODB_TABLESPACES table to provide access to this data. (WL #5989, WL

#11063)

453

MySQL 8.0 Release Notes

• Group Replication: Host names can now be specified as part of a whitelist for group replication

connections, using the group_replication_ip_whitelist system variable. Host names support

CIDR notation. Host names that resolve to IPv6 addresses are not supported.

For host names, name resolution takes place only when a connection request is made by another

server. A host name that cannot be resolved is not considered for whitelist validation, and a warning

message is written to the error log. Forward-confirmed reverse DNS (FCrDNS) verification is carried out

for resolved host names.

Warning

Host names are inherently less secure than IP addresses in a whitelist. FCrDNS

verification provides a good level of protection, but can be compromised by

certain types of attack. Specify host names in your whitelist only when strictly

necessary, and ensure that all components used for name resolution, such as

DNS servers, are maintained under your control. You can also implement name

resolution locally using the hosts file, to avoid the use of external components.

(WL #10803, WL #11298)

• JSON: Added the JSON_TABLE() function, which accepts JSON data and returns it as a relational table

whose columns are as specified. This virtual table can be accessed using standard SQL mechanisms

This function has the syntax JSON_TABLE(expr, path COLUMNS column_list) [AS] alias),

where expr is an expression that returns JSON data, path is a JSON path applied to the source,

and column_list is a list of column definitions. Columns can be of the types FOR ORDINAL, PATH,

EXISTS PATH, and NESTED PATH or NESTED, as described in the following list:

• FOR ORDINAL: The column is a counter, similar to an AUTO_INCREMENT column.

• PATH: The column holds a scalar value using the specified JSON path. ON ERROR and ON EMPTY

options are supported for handling illegal values (such as nonscalars) and empty values, respectively.

• EXISTS PATH: The column value is 1 if a match exists for the specified JSON path, and 0 otherwise.

• NESTED PATH: Nested objects or arrays in JSON data found in the given JSON path are flattened

into a single row along with the JSON values from the parent object or array. The PATH keyword is

optional.

Two simple examples are shown here:

mysql> SELECT *

-> FROM

-> JSON_TABLE(

-> '[1, 3, 5, 7, 9]',

-> "$[*]" COLUMNS(rowid FOR ORDINALITY, col VARCHAR(50) PATH "$")

-> ) AS t1;

+-------+------+

| rowid | col |

+-------+------+

| 1 | 1 |

| 2 | 3 |

| 3 | 5 |

| 4 | 7 |

| 5 | 9 |

+-------+------+

mysql> SET @j = '[{"a": [{"x":"3"},{"y":"2"}]},

'> {"b": [{"x":"1"},{"y":"1"}]},

'> {"a": [{"x":"2"},{"y":"3"}]}]';

454

MySQL 8.0 Release Notes

mysql> SELECT *

-> FROM JSON_TABLE(

-> @j,

-> "$[*]" COLUMNS(

-> rowid FOR ORDINALITY,

-> xa INT EXISTS PATH "$.a",

-> xb INT EXISTS PATH "$.b",

-> ja JSON PATH "$.a",

-> jb JSON PATH "$.b"

-> )

-> ) AS jts;

+-------+------+------+--------------------------+--------------------------+

| rowid | xa | xb | ja | jb |

+-------+------+------+--------------------------+--------------------------+

| 1 | 1 | 0 | [{"x": "3"}, {"y": "2"}] | NULL |

| 2 | 0 | 1 | NULL | [{"x": "1"}, {"y": "1"}] |

| 3 | 1 | 0 | [{"x": "2"}, {"y": "3"}] | NULL |

+-------+------+------+--------------------------+--------------------------+

The JSON source expression can be any expression that yields a valid JSON document, including a

JSON literal, a table column, or a function call that returns JSON such as JSON_EXTRACT(t1, data,

'$.post.comments'). For complete syntax and other information about this function, see JSON Table

Functions. (WL #8867)

• The -DWITH_ASAN_SCOPE CMake option enables the AddressSanitizer -fsanitize-address-

use-after-scope Clang flag for use-after-scope detection. The default is off. To use this option, -

DWITH_ASAN must also be enabled. (Bug #27095089)

• Handling of empty JSON documents has been made more robust. (Bug #26787468, Bug #87734)

• MySQL 8.0.3 imposed a restriction against ALTER TABLE RENAME on tables in a foreign key

relationship if a LOCK TABLES was active. This restriction has been lifted. (Bug #26647340, Bug

#87467)

• If the server PID file is configured to be created in a world-writable location, the server now issues a

warning suggesting use of a more secure location. (Bug #26585560)

• For constructs using _charset character set introducers (for example, _utf8mb4 'abc'), lookup

performance was improved for mapping the introducer onto the proper character set. (Bug #25680866,

Bug #85331)

Bugs Fixed

• Important Change: The following changes are made to the PERIOD_ADD() and PERIOD_DIFF()

functions:

• A period value used with one of these functions may not be negative.

• The month part of a period value may not be equal to 0.

A period value used with one of these functions for which at least one of these conditions is true now

causes the function to fail with an error. (Bug #27004699, Bug #27004729)

• Important Change: The LEAST() and GREATEST() functions no longer attempt to infer a context for

their arguments from expressions in which they are used. For example, LEAST('11', '45', '2')

returns '11', but LEAST('11', '45', '2') + 0 treated the function arguments as integers rather

than as strings, and returned 2. Now these functions always evaluate their arguments strictly according

to type, and any data type coercion due to their inclusion in an expression is performed only on the

455

MySQL 8.0 Release Notes

result returned by the function. This means that the expression LEAST('11', '45', '2') + 0 now

evaluates to '11' + 0, and thus to the integer value 11.

This change has been made due to the following considerations:

• Rules for deriving the context were not always clear or consistent.

• The results of these functions when used in expressions were not consistent with the results of

COALESCE(), or of a UNION query.

Applications that use these functions within expressions should be checked to make sure that they do

not depend on the previous behavior, and updated if they do so. (Bug #83895, Bug #25123839)

• InnoDB: Concurrent XA transactions that ran successfully to the XA prepare stage on the master

conflicted when replayed on the slave, resulting in a lock wait timeout in the applier thread. The conflict

was due to the GAP lock range which differed when the transactions were replayed serially on the slave.

To prevent this type of conflict, GAP locks taken by XA transactions in READ COMMITTED isolation

level are now released (and no longer inherited) when XA transactions reach the prepare stage. (Bug

#27189701, Bug #25866046)

• InnoDB: An ALTER TABLE operation that added a foreign key constraint referencing a table with

generated virtual columns raised an assertion. (Bug #27189701)

• InnoDB: A DROP DATABASE operation raised an assertion due to a missing general tablespace data

file. (Bug #27151163)

• InnoDB: On Windows, an operation that altered a table partition raised an assertion. The table name

was not parsed correctly. (Bug #27075816)

• InnoDB: A TRUNCATE TABLE operation on a temporary table raised an assertion. (Bug #27073280)

• InnoDB: A call to a recovery-related function during the post-DDL phase of a DDL operation raised an

assertion. (Bug #27041487, Bug #88263)

• InnoDB: Adding a spatial index that referenced a column with an SRID attribute returned an error. (Bug

#27021029)

• InnoDB: A table with a 64-character foreign key name caused an upgrade failure. Foreign key names up

to 64 characters in length should be permitted. (Bug #27014308, Bug #88196)

• InnoDB: The InnoDB recovery process failed with a tablespace size error for a compressed table that

was upgraded from MySQL 5.7 to MySQL 8.0.

The tablespace file for a compressed table is now created using the physical page size instead of the

InnoDB page size, which makes the initial size of a tablespace file for an empty compressed table

smaller than in previous MySQL releases. (Bug #27014083, Bug #88195)

• InnoDB: Unnecessary tablespace fetch and cache update operations caused a server startup delay.

(Bug #26995951)

References: This issue is a regression of: Bug #26832347.

• InnoDB: An orphan .frm file caused an upgrade failure, and subsequent upgrade attempts were

unsuccessful due to a full-text search auxiliary table that was renamed during the first upgrade attempt.

(Bug #26995951)

• InnoDB: Workarounds introduced to address conflicting serialized dictionary information (SDI) inserts

during concurrent CREATE TABLE operations were removed. (Bug #26995534)

456

MySQL 8.0 Release Notes

References: See also: Bug #26539665.

• InnoDB: A “no space left on device” error reported an invalid error message. (Bug #26960345)

• InnoDB: During a fast shutdown, InnoDB attempted to write dynamic metadata to the data dictionary

after files were closed, resulting in an initialization failure due pending I/O on the data dictionary

tablespace. (Bug #26950659)

• InnoDB: A stack overflow error was encountered on startup after upgrading to MySQL 8.0.4 due to

repeated attempts to load an evicted InnoDB system table. (Bug #26945437, Bug #88042)

• InnoDB: Importing a compressed table raised an assertion. The operation used the clustered index

of the table instead of the serialized dictionary information (SDI) index to transform SDI pages. (Bug

#26938297)

• InnoDB: In debug builds, failed temporary table creation during a REPLACE operation raised an invalid

assertion. (Bug #26919378, Bug #26958868)

• InnoDB: DROP DATABASE failed if database tables were created in a general tablespace. General

tablespace flags were registered incorrectly causing the serialized dictionary information (SDI) operation

to fail. (Bug #26834496)

• InnoDB: With binary logging enabled, an ALTER TABLESPACE ... RENAME operation failed with a

“cannot find space” error. (Bug #26832347)

• InnoDB: An operation that failed to add an index raised an invalid adaptive hash index assertion. (Bug

#26788968)

• InnoDB: A valid table row type value read from the data dictionary raised an invalid assertion. (Bug

#26773152)

• InnoDB: Starting an upgrade with innodb_force_recovery=5 initialized InnoDB background

threads but did not exit the threads gracefully when an error was encountered. Upgrading with a nonzero

innodb_force_recovery setting is no longer permitted. (Bug #26766632)

• InnoDB: A failed CREATE TEMPORARY TABLE statement left an entry in

INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO. The in-memory table object was not freed. (Bug

#26765438)

• InnoDB: InnoDB looked up the name of a virtual column in the wrong dict_table_t array when

attempting to locate a qualifying index for a foreign key. (Bug #26764604)

• InnoDB: Attachable read-write transactions that update the table_stats and index_stats data

dictionary tables attempted to update the same row, causing a deadlock. (Bug #26762517)

• InnoDB: During recovery, the tablespace name in an in-memory tablepace object was defined using the

file name character set instead of table name character set, resulting in a “missing tablespace” error.

(Bug #26761960)

• InnoDB: Bootstrap code did not reserve the first 1024 table IDs for data dictionary tables. (Bug

#26757227)

• InnoDB: Multiple updates from different clients on a partitioned table caused an unexpected lock wait

timeout due to an incorrectly set lock type. (Bug #26731025, Bug #87619)

• InnoDB: An asynchronous rollback thread that attempted to acquire a metadata lock was interrupted,

but the resulting error was not returned to the server. This issue was addressed by removing the

metadata lock acquisition, which was not necessary for asynchronous rollback.

457

MySQL 8.0 Release Notes

Only in-memory tables were checked when opening tables for undo processing. The data dictionary is

now checked as well, in case tables are not present in memory. (Bug #26678883)

• InnoDB: An assertion was raised when attempting to open a full-text auxiliary table with a name that

was longer than expected. (Bug #26649020)

• InnoDB: Data dictionary table open functions did not properly handle table and schema name character

set conversion, resulting in an error during recovery. (Bug #26640776)

• InnoDB: A transaction end_stmt() function was not called in some ALTER TABLE ... PARTITION

scenarios, resulting in a timeout. (Bug #26629790, Bug #25886814)

• InnoDB: Acquiring a metadata lock on the serialized diction information (SDI) table during the commit

phase of a DDL operation would fail due to a lock wait timeout or halting of the query. (Bug #26628126)

• InnoDB: Redo logs for dynamic metadata updates were not considered when checking redo log

margin. Also, in read-only mode, the innodb_dynamic_metadata data dictionary table was opened

unnecessarily for writing of metadata from the redo log. (Bug #26589535)

• InnoDB: An unexpected error occurred after a failed attempt to install the memcached plugin. (Bug

#26588738)

• InnoDB: The state of a buffer pool page was altered by another thread while a buffer pool resize

operation was in progress. (Bug #26588537)

• InnoDB: Debug functions that assert for conflicting locks did not account for transaction locks that are to

be committed or rolled back. (Bug #26562371)

• InnoDB: Variance-Aware Transaction Scheduling (VATS) functionality that updates the age of waiting

record locks failed to ignore table locks, causing an assertion failure. (Bug #26538702)

• InnoDB: A DDL operation that created or modified a table partition unintentionally altered the row format

of other partitions, resulting in a row format mismatch. (Bug #26535746)

• InnoDB: An ALTER TABLE operation caused the server to halt. (Bug #26492721)

• InnoDB: The innodb_table_stats data dictionary table was not updated with new partition names

when renaming a partitioned table. (Bug #26390658, Bug #86927)

• InnoDB: Due to a regression introduced in MySQL 8.0.0, the innodb_change_buffering

configuration option could not be set dynamically. (Bug #26389442)

• InnoDB: The online log for a freed index was accessed while rolling back a concurrent UPDATE

statement during an online DDL operation. (Bug #26334475)

• InnoDB: A REPLACE operation on a table with a secondary index on the prefix of a virtual column raised

an assertion. (Bug #26330279)

• InnoDB: Setting tmpdir to the root of a drive caused “Invalid (old?) table or database name” error

messages to be printed to the error log. (Bug #26299984, Bug #86737)

• InnoDB: A race condition occurred during an INFORMATION_SCHEMA query when attempting to check

the transaction state without acquiring a transaction mutex. (Bug #26299705)

• InnoDB: A FLUSH TABLES operation failed to drop an aborted index. While removing the table from the

cache, the clustered index was dropped prior to checking for the aborted index. (Bug #26256456, Bug

#86607)

458

MySQL 8.0 Release Notes

• InnoDB: For InnoDB tables, CREATE TABLE ... LIKE did not respect the

innodb_file_per_table system variable setting, and SHOW CREATE TABLE displayed a

TABLESPACE clause even though the user specified no explicit tablespace during table creation. (Bug

#26199233, Bug #86589)

• InnoDB: An iterative approach to processing foreign cascade operations resulted in excessive memory

use. (Bug #26191879, Bug #86573)

References: This issue is a regression of: Bug #16244691.

• InnoDB: The lock acquisition sequence for a buffer pool eviction operation that evicts compressed

pages was incorrect. (Bug #25972975)

• InnoDB: Metadata locks were released while data dictionary objects were still in use. (Bug #25928984)

• InnoDB: innochecksum returned a Valgrind error when run on InnoDB files with a 1K compressed

page size. (Bug #25922124, Bug #85993)

• InnoDB: A kill thread failed to close the socket of another thread that was executing a TRUNCATE

TABLE operation, causing an assertion. (Bug #25887335, Bug #85925)

• InnoDB: An INSERT operation on a table with a spatial index raised an assertion due to a failure that

occurred during a lock conflict check. (Bug #25729649)

• InnoDB: A debug sync point intended for user tables was activated for data dictionary tables. (Bug

#25508568)

• InnoDB: A server-side check was added to prevent a foreign key constraint from being placed on the

base column of a generated stored column. (Bug #25339192)

• InnoDB: Warnings that should only appear in debug builds of MySQL were printed to the error log when

the length of the history list exceeded 2000000. (Bug #24296076, Bug #82213)

• InnoDB: Attempting to reduce the buffer pool size to less than the buffer pool chunk size did not report a

warning. (Bug #23590280)

• InnoDB: A “wrong key column” error was added to address an unsupported index creation scenario.

(Bug #22486025)

• InnoDB: Full-text search on indexed columns that use a binary collation did not return case-sensitive

matches. (Bug #21625016, Bug #78048)

• Packaging: When trying to install MySQL Server on Fedora 27 using the MySQL Yum repository,

installation failed due to a conflict with the native mariadb-connector-c-devel package. With this

fix, the appropriate “obsoletes” have been added for that and other native packages. (Bug #26963839)

• Partitioning: When creating a partitioned table using an implicit tablespace, the effect is to place each

partition in its own tablespace, with no designated tablespace for the table as a whole. Since serialized

dictionary information (SDI) was stored in all tablespaces used by a given table, the cost of storing it in a

table with many tablespaces became prohibitive. This problem is solved by including only the tablespace

for the first partition in the set of tablespaces used to store the SDI. (Bug #26762973)

References: See also: Bug #26765252.

• Partitioning: An assertion could be raised on CREATE VIEW on partitioned tables when the server tried

to prune partitions of the underlying tables. (Bug #26659699)

• Partitioning: When renaming a partitioned table, the table statistics were not updated with the new

partition names. (Bug #86074, Bug #25953183)

459

MySQL 8.0 Release Notes

• Replication; JSON: For row-based replication, partial updates to JSON documents were not applied if

the server variable binlog_row_value_options=PARTIAL_JSON (introduced in MySQL 8.0.3) was

not specified on the replication slave, as well as on the master. Now, a replication slave applies partial

updates to JSON documents whenever these are received from the master, whether or not the slave has

binlog_row_value_options=PARTIAL_JSON in its own settings. (Bug #26762675)

• Replication: The function set_unknow_error() in the Binlog_sender class has been renamed

to set_unknown_error(). Thanks to Simon Mudd for the fix (and also for the typo fix in Bug 88149).

(Bug #27149075, Bug #88559)

References: See also: Bug #26996065, Bug #88149.

• Replication: When you invoke mysqld with the --initialize or --initialize-insecure option

to initialize the data directory, a warning message is no longer issued regarding the availability of the

mysql.gtid_executed table, which should not be available at that stage. Also, the message formerly

issued as a warning regarding the generation of a new UUID is now issued as a note, because the

generation of a new UUID is normal in that situation. (Bug #27115183)

• Replication: In MySQL 8.0.3, the default base name for the binary log files and index file was

host_name-bin, using the name of the host machine. This default name was used if the --log-bin

option was not supplied, and also if the --log-bin option was supplied with no string or with an empty

string. From MySQL 8.0.4, if you do not supply the --log-bin option, MySQL now uses binlog as

the default base name for the binary log files and index file. In releases before MySQL 8.0.3, there was

no binary log with that configuration, so there is no incompatibility with existing binary logs at upgrade.

However, for compatibility with existing binary logs from releases before MySQL 8.0.3, if you supply the

--log-bin option with no string or with an empty string, the base name defaults to host_name-bin,

using the name of the host machine.

The warning messages that were previously issued at startup if you did not specify a binary log file name

using the --log-bin option (ER_LOG_BIN_BETTER_WITH_NAME) and if you did not specify a server

ID by setting the server_id system variable (ER_WARN_NO_SERVERID_SPECIFIED) are now issued

as informational messages. A warning message is still issued if replication is attempted with a nonunique

server ID. (Bug #27082922)

• Replication: In the Gtid_log_event that precedes every GTID transaction in the binary log file, the

transaction_length field used 8 bytes for transactions with 16777216 bytes or more, when it should

have used the maximum permitted 9 bytes. (Bug #26993433)

• Replication: The fix for Bug #22671846 was missing from MySQL version 8.0.3. (Bug #26985976)

• Replication: The fix for Bug #26117735 (MySQL Bug #86288) could cause a debug assertion when

running mysqlbinlog with the --read-from-remote-server option and the --rewrite-db

option, depending on the database names specified in the rewrite rule. The issue has now been

corrected. (Bug #26878022)

• Replication: With MySQL compiled using yaSSL, and semisynchronous replication in use, a deadlock

could be caused by incorrect handling of acknowledgement packets. Multiple acknowledgement packets

can be read together by yaSSL, but the receiver thread for semisynchronous replication only handled the

first acknowledgement packet seen after polling. Now, the receiver thread handles all acknowledgement

packets that are present in the buffer. (Bug #26865538)

• Replication: With semisynchronous replication in use, if RESET MASTER was issued while an active

transaction was waiting for an acknowledgement from the slave, the count of waiting sessions in the

Rpl_semi_sync_master_wait_sessions server status variable was incorrect after the wait was

completed. (Bug #26748533)

460

MySQL 8.0 Release Notes

• Replication: The --log-slave-updates and --slave-preserve-commit-order options require

binary logging. If you specify these options and also disable binary logging using the --skip-log-bin

or --disable-log-bin option, a warning or error message is issued. The --skip-log-bin and

--disable-log-bin options now disable the --log-slave-updates and --slave-preserve-

commit-order options by default, so when those options are not specified, the warning or error

message is not issued. (Bug #26666259)

• Replication: XA ROLLBACK statements that failed because an incorrect transaction ID was given,

could be recorded in the binary log with the correct transaction ID, and could therefore be actioned by

replication slaves. A check is now made for the error situation before binary logging takes place, and

failed XA ROLLBACK statements are not logged. (Bug #26618925, Bug #87393)

• Replication: For the NDB storage engine, when the slave used hashing for searches of rows (which

is included by default in the setting for the slave_rows_search_algorithms system variable from

MySQL 8.0.2), the table used to store the row hashes was not cleaned up correctly after records were

removed on the slave. The issue was caused by a variant error value returned by the NDB storage

engine, which has now been corrected to the expected value. (Bug #26434966)

• Replication: MySQL internal administration commands that update replication-specific repository tables,

for example during a replication synchronization check using the mysqlrplsync utility, can now bypass

read locks. This enables such commands to execute regardless of the settings for the read_only and

super_read_only system variables and the autocommit mode. (Bug #26414532, Bug #86224)

• Replication: The binary log function MYSQL_BIN_LOG::new_file_impl returned the error

“Can't open file” (ER_CANT_OPEN_FILE) when it should have returned “Error writing file”

(ER_ERROR_ON_WRITE). (Bug #26370868, Bug #86870)

• Replication: When write sets are used for parallelization by a replication slave (as specified by the

binlog_transaction_dependency_tracking system variable), the case and accent sensitivity

of the database are now taken into account when generating the write set information. Write set

information is generated when the transaction_write_set_extraction system variable is

enabled. Previously, duplicate keys could be incorrectly identified as different, causing transactions to

have incorrect dependencies and so potentially be executed in the wrong order. (Bug #26277771, Bug

#86078)

• Replication: The receiver thread for semisynchronous replication was not able to receive

acknowledgements from slaves that used compression of the master/slave protocol

(slave_compressed_protocol=ON). The receiver thread now handles compressed

acknowledgements correctly. (Bug #26027024, Bug #86230)

• Replication: The mysql_reset_connection() function now clears the write set session history.

(Bug #25950554, Bug #86063)

• Replication: On replication slaves, in the XA_STATE field in the Performance Schema table

events_transactions_current, the state of XA transactions was incorrectly reported as

COMMITTED instead of PREPARED after the XA PREPARE statement was applied on the slave. (Bug

#25940184)

• Replication: In a multi-source replication topology, a memory leak could occur on the slave when

binlog_rows_query_log_events was enabled on the master, and a statement already applied from

another channel was skipped on the slave. In this situation, the instance of the Rows_query log event

stored on the slave was not being deleted. The log event instance is now cleaned up and the memory is

freed. Thanks to Vlad Lesin for his contribution to the patch. (Bug #25695434, Bug #85371, Bug #85034)

• Replication: Queries to the Performance Schema replication_applier_global_filters and

replication_applier_filters tables, which show the global and channel-specific replication filters

461

MySQL 8.0 Release Notes

configured on a replication slave, have been optimized so that a view is generated only when the filters

are changed. Previously, a view was generated for every row that was created. (Bug #25694140)

• Replication: A memory leak was fixed in GTID-based replication. Memory was not being freed after the

repository tables were updated for skipped or ignored events. (Bug #25656123, Bug #85251)

• Replication: When a worker thread on a multithreaded slave failed to apply a transaction on which a

later transaction depended, the coordinator thread could begin scheduling the dependent transaction

before being notified of the issue. If a STOP SLAVE request was made during this situation, it caused an

assertion to be raised in debug builds. (Bug #25585436)

• Replication: With statement-based replication in use, if an UPDATE or DELETE statement was used

inside an XA transaction ending with XA COMMIT ONE PHASE, and the statement did not affect any

rows, a replication error occurred. An XA END statement was not written to the binary log, so slave

servers identified the XA transaction as still being active at the time of the commit request. The required

XA END statement is now written even if the transaction affected no rows. (Bug #24812958, Bug

#83295)

• Replication: Replication clients no longer enable LOCAL capability for LOAD DATA statements, because

they do not use LOAD DATA LOCAL statements. (Bug #24763131)

• Replication: The behavior of mixed-format replication (binlog_format=MIXED) has changed

with regards to temporary tables. Previously, when mixed-format binary logging was in use, if a

statement was logged by row and the session that executed the statement had any temporary tables,

all subsequent statements were treated as unsafe and logged in row-based format until all temporary

tables in use by that session were dropped. Also, on a replication slave with log_slave_updates

enabled, row-based logging was incorrectly continued across all subsequent sessions for the duration of

the connection, as reported in the bug.

Now, when mixed binary logging format is in use, statements that exclusively use temporary tables are

not logged. Statements that involve a mix of temporary and nontemporary tables are logged on the

master only for the operations on nontemporary tables, and the operations on temporary tables are

not logged. The exception is if the creation of a temporary table was recorded in the binary log using

statement-based format. In this case, a DROP TEMPORARY TABLE IF EXISTS statement is logged on

the master when the temporary table is dropped.

With this change in behavior, the remaining statements in the session that do not involve temporary

tables no longer need to be treated as unsafe. The safe statements are now logged in statement-based

format, and the unsafe statements are logged in row-based format, according to the normal behavior

for mixed format replication, regardless of the presence of temporary tables in the session. Also, the

issue reported in the bug has been fixed so that subsequent sessions using the connection now use the

appropriate logging format for the session, regardless of the format used by earlier sessions.

When binlog_format is ROW or STATEMENT, the behavior remains as before. For row-based

binary logging format, operations on temporary tables are not logged, with the exception of the DROP

TEMPORARY TABLE IF EXISTS statement as for mixed format. For statement-based binary logging

format, operations on temporary tables are logged on the master and replicated on the slave, provided

that the statements involving temporary tables can be logged safely using statement-based format.

binlog_format=STATEMENT is now the only logging mode in which temporary tables are replicated on

the slave.

You cannot now change the binlog_format setting from ROW or MIXED to STATEMENT at runtime,

because any CREATE TEMPORARY TABLE statements will have been omitted from the binary log in the

462

MySQL 8.0 Release Notes

previous mode. You can still switch from STATEMENT to ROW or MIXED format, even when temporary

tables have been created.

Thanks to George Lorch and Laurynas Biveinis from Percona for the patch. (Bug #18843730, Bug

#72475)

• Replication: During distributed recovery as part of joining the group, when the applier was signaling that

it had applied all transactions, it was also blindly searching for partial transactions. This was to avoid

future applier errors, which would happen if the applier stopped at this point. However, this search and

remove only made sense for applier stop cases. Upon execution completeness it should not be done,

otherwise it can corrupt or purge the applier relay log, which can led to data loss. To solve this issue,

when the applier is waiting for execution completeness, it no longer searches for and removes partial

transactions. (Bug #88304, Bug #27049034)

• Replication: In a group with heavy load, joining members could need to retrieve a large amount of

data to gain synchrony with the group. If the amount of data retrieved exceeded the View_change

packet size of 4Mb the members would fail to join the group and enter Error state. Now, the

packet size is taken from slave_max_allowed_packet, which defaults to 1GB. Depending on

the load your group processes, you might want to increase the packet size further by configuring

slave_max_allowed_packet. (Bug #87701, Bug #26770576)

• Replication: In a group where a joining member consistently received transactions, the joining member

could sometimes not enter the online state. This was due to the way the incoming queue of messages

was tested. (Bug #87631, Bug #26731317)

• Group Replication; Microsoft Windows: On Windows, errors generated by Group Replication now

contain a detailed error message rather than just the error number. (Bug #24918678)

• Group Replication: The thread where the Group Replication plugin was started was not being correctly

killed, making it impossible to stop or start the plugin after killing this thread. (Bug #26435775)

• Group Replication: When transaction_write_set_extraction was enabled, there was a risk

of unnecessary serialization while foreign keys were gathered if concurrent DDL took place. Group

Replication now takes advantage of the new Data Dictionary to interact with table definitions and foreign

keys, which has solved this potential serialization. (Bug #26187850)

• Group Replication: When group_replication_enforce_update_everywhere_checks is ON,

the Group Replication plugin checks whether there are any foreign key cascades and disallows updates

to tables affected by them.

SET NULL operations were not checked as part of this process, which could lead to data inconsistency.

Now, when this value is ON, operations on child tables are blocked if the table has a SET NULL option

configured. (Bug #25404162)

• Group Replication: All servers that belong to a group must have unique UUIDs set by server_uuid,

but this was not enforced by Group Replication, so that it was possible to add members with duplicate

UUIDs. (Bug #88452, Bug #27105803)

• Group Replication: When starting or stopping, the Group Replication plugin executes internal

operations on the server such as enabling or disabling read only mode using an internal session. When

this internal session was opened, if the total number of sessions exceeded the number of permitted

open sessions set by max_connections, the operation failed as expected but a thread was left behind,

which later caused issues. (Bug #88182, Bug #27008102, Bug #27016552)

• Group Replication: If Group Replication was configured to start on server boot when the server was

being initialized using --initialize or --initialize-insecure, because the replication applier

463

MySQL 8.0 Release Notes

infrastructure was not initialized, this resulted in an assertion. Now, Group Replication is not started

when the server is being initialized. (Bug #87759, Bug #26802395)

• Group Replication: Changes to Group Replication variables while starting or stopping the plugin were

not being correctly validated. Now, the variables can only be changed if the plugin is not changing state.

(Bug #86874, Bug #26372117)

• Group Replication: Regardless of the number of virtual IPs configured on a machine, Group Replication

could access only the first 12 addresses. (Bug #86772, Bug #26324852)

• Group Replication: The delayed initialization mechanism used for server starts has been improved.

Now, it blocks connections only until the server is in read mode. (Bug #86271, Bug #26037344)

References: See also: Bug #84731, Bug #25475132.

• Group Replication: When a primary member, such as the primary in a single-primary group or in a

multi-primary group which also had asynchronous replication channels feeding data into it, was stopped,

the asynchronous channels would continue applying changes. Although super_read_only was set

when STOP GROUP_REPLICATION was issued, this did not stop any running asynchronous replication

channels already running. This meant that changes could be made locally on the member, and that the

asynchronous replication channels had to be stopped manually. Now when Group Replication stops,

either due to an error or when STOP GROUP_REPLICATION is issued, all asynchronous replication

channels are stopped. (Bug #86222, Bug #26024253)

• Group Replication: Group Replication logging has been improved, and now includes includes about

when a member joins or leaves, when the view changes, and so on. (Bug #84798, Bug #25495393)

References: See also: Bug #26422857.

• Linux: On Alpine Linux, mysql would lose its connection to the server if its standard output was not

writable. Also, for mysql and mysqldump, order of result flushing for stdout and stderr is now

deterministic. (Bug #27169809)

References: See also: Bug #17583.

• Microsoft Windows: On Windows, with the myisam_use_mmap and flush system variables enabled,

MyISAM did not always flush table files properly. (Bug #26880757)

• JSON: JSON expressions used as arguments with the LAG() function were not always evaluated

correctly. (Bug #26740557)

• JSON: Repeated execution of a prepared statement that employed JSON_ARRAY() was not handled

correctly. (Bug #26704312)

References: This issue is a regression of: Bug #25867454.

• JSON: When executing the JSON_INSERT() function, the check that is performed to determine whether

or not a given insert is being made into the root element tested whether the length of the path was 1—

that is, whether the path consisted of a single leg determining which position the inserted element has

inside the root element. A problem occurred when there were auto-wrapping path legs at the beginning

of the path, in which case a path whose length is greater than 1 might also refer to an element in the

root, so that checking the path length did not reliably inform us whether the target element of the insert

was the root or some other element.

To fix this, the check of the path length for detection of the root element has been replaced with a

check as to whether the matched element has a parent; if it has none, it must be the root element. (Bug

#26649978)

464

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #86213, Bug #26022576.

• JSON: When serializing a JSON value to its binary representation, it is necessary to make sure that the

destination buffer has sufficient space to hold an integer or double value of the required size. Allocation

of this buffer previously reserved only the minimum amount of memory needed, which made it very

likely that a reallocation would be needed shortly thereafter. This could adversely affect performance,

especially when serializing arrays with many numeric values. The serialization is now performed in a

manner such that the allocation increases the size of the destination buffer size exponentially, which

reduces the amount of the time spent performing this task when processing large arrays. (Bug #88656,

Bug #27171283)

• JSON: When a JSON document was converted to string representation, floating-point values that had

no fractional part could be represented such that they became indistinguishable from integers. When

the string representation of such a JSON document was passed through the JSON parser again, the

information that the numeric value was originally specified as a floating-point value was lost.

To rectify this problem, a fractional part is now added to the string representation of a floating-point value

in a JSON document if the value has no fractional part and is not represented using scientific format.

This makes the string representation of a floating-point value distinguishable from that of an integer, so

that it continues to be treated as a floating-point number even if the string is parsed again.

This fix also makes ST_GeomFromGeoJSON() use the same JSON parser as the other JSON functions

rather than its own custom parser as had been the case since MySQL 5.7.8; this special handling was

due to the fact that ST_AsGeoJSON() dropped the fractional part of negative zero (-0 instead of -0.0),

causing the JSON parser to interpret -0 as integer 0, thus losing the distinction between positive and

negative zero. Since ST_AsGeoJSON() now uses the standard JSON parser, it represents negative

zero as correctly as -0.0, obviating any need for ST_GeomFromGeoJSON() to preserve negative zero

explicitly on its own when parsing the output from ST_AsGeoJSON(). (Bug #88230, Bug #27028889)

References: See also: Bug #19504183.

• JSON: When inserting JSON values created from the result of a GROUP BY query, the inserted values

could sometimes include the concatenation of all the values previously inserted into that column. (Bug

#87854, Bug #26867509)

• JSON: When called using strings extracted from JSON documents as arguments, the LEAD() and

LAG() functions returned the same value for every row. (Bug #87839, Bug #26848089)

• JSON: The microseconds part of the last-updated field in each histogram in the

INFORMATION_SCHEMA.COLUMN_STATISTICS table (showing when the histogram was last updated)

was dropped when serializing the histogram into JSON and so was not stored. (Bug #87833, Bug

#26846289)

• JSON: When a JSON_SET() statement updated a JSON value to the same value using a partial update

(in other words, when the partial update was essentially a NOOP), it was possible that logical diffs for this

operation were produced, even though no binary diffs were produced. Now in such cases, neither logical

update nor binary diffs are generated. (Bug #87113, Bug #26483625)

• JSON: Following the implementation of JSON partial updates, the same JSON document could have

different binary representations on the master and the slave. This could lead row-based replication—

which uses binary equality to find the matching row on the slave—to fail if this occurred. Now the string

representation of the JSON document is used for the comparison instead.

Also as a result of this fix, updates can be skipped in more cases than previously; this is true where

the binary representation has changed, but not the contents of the document. (Bug #86532, Bug

#26177130)

465

MySQL 8.0 Release Notes

• Ubuntu 14.04 and Debian 8 are no longer supported. (Bug #27422291)

• For builds on 32-bit platforms with Undefined Behavior Sanitizer enabled, a stack-overrun check could

cause a server exit. (Bug #27224961)

• The server could hang during spatial reference system (SRS) creation while another session was using

that SRS. (Bug #27220467)

• A lock for the privilege cache was acquired unnecessarily during privilege-checking operations not

involving table permissions. (Bug #27197483)

• Persisting the read-only gtid_owned or gtid_executed system variable caused an assertion failure

at server startup. These variables can no longer be persisted. (Bug #27193853)

• Improper handling of plugin loading and unloading could cause a server exit. (Bug #27151550, Bug

#88589, Bug #27116827, Bug #88483)

• Error propagation from some windowing functions was not always performed correctly. (Bug #27135084,

Bug #27136492)

• Negation of some very large values was not handled correctly by an internal function. (Bug #27134168)

• Instituted stricter checks when performing addition involving date intervals. (Bug #27134148)

• Recently introduced SRID and COLUMN_STATISTICS metadata locks were not instrumented by the

Performance Schema. (Bug #27124506)

• The name of a derived table was not saved before the table was materialized and assigned the name of

the temporary table. Later, when trying to reset the table name, this caused the server to fail due to the

missing reference to the original value of the name. (Bug #27121663)

• Performance Schema queries that used indexes on OBJECT_TYPE columns could return incorrect

results. (Bug #27121500)

• Compiling with -DWITH_ASAN=1 and -DWITH_ASAN_SCOPE=1 detected a stack-use-after-scope

memory error. (Bug #27108794, Bug #88460)

• FILE privilege checking for prepared SELECT ... INTO OUTFILE statements was incorrect. (Bug

#27094955)

• Some messages with information priority were written to the error log when log_error_verbosity

was less than 3. (Bug #27082862)

• The ha_create_table_from_engine function failed to pass a table object to the ha_create

routine. (Bug #27066335)

• Partition by and order by elements of unused window definitions were not included when estimating

memory requirements. This is resolved by assigning a parsing context (CTX_WINDOW), but only when the

current context is CTX_NONE. As part of this fix, unused window definitions are now removed after being

checked for syntax and semantic errors. (Bug #27062031)

• GROUP BY with a ROLLUP that generated NULL was not handled correctly. (Bug #27060420)

• An Event Scheduler event for which global autocommit was disabled at event expiration time caused an

assertion to be raised. (Bug #27041552, Bug #88255)

• Length calculations for string-valued user-defined variables could be incorrect if the collation was

changed. (Bug #27041543, Bug #88256)

466

MySQL 8.0 Release Notes

• CREATE TABLE ... SELECT statements that attempted to create a non-InnoDB table raised an

assertion if a pre-existing view referenced the table to be created. (Bug #27041536, Bug #88258)

• When used as an argument to the IF() function, the value of a TIMESTAMP column could be handled

differently for different collations. (Bug #27041526, Bug #88259)

• With statement-based binary logging, using CREATE TABLE ... SELECT to create a BLACKHOLE table

caused an assertion to be raised. (Bug #27041516, Bug #88260)

• For debug builds, a TIMESTAMP-related assertion could be raised with

explicit_defaults_for_timestamp enabled. (Bug #27041502, Bug #88261)

• Under LOCK TABLES, an attempt to execute a DML statement on a table with foreign keys led to

assertion failure if the statement was incompatible with the mode under which the tables in the foreign

key relationship were locked. (Bug #27041477, Bug #88264)

• With a LOCK TABLES statement active, queries that select from the INFORMATION_SCHEMA.FILES

table could raise an assertion trying to obtain a metadata lock. (Bug #27041452, Bug #88266)

• Component installation did not properly perform auto-increment handling, which could result in a server

exit. (Bug #27041374, Bug #88276)

• With big_tables=1 and character_set_connection=ucs2, SHOW TABLE STATUS could raise an

assertion. (Bug #27041323, Bug #88279)

• With a backup lock active, removal of binary log files and relay log files incorrectly was permitted. (Bug

#27030339, Bug #88238)

• When evaluating an end-range condition in a scan of a non-covering secondary index, and the end-

range condition referenced an indexed virtual column, InnoDB sometimes read the wrong column from

the index, which could lead to assertion failures or wrong results. (Bug #27010089)

• In event items in filter rules, the audit_log plugin did not properly process values specified as a JSON

array. (Bug #27010045)

• An integer overflow was sometimes possible when adding date values, with the potential to return invalid

results. (Bug #27004806)

• TRUNCATE TABLE on an InnoDB table with an active LOCK TABLES raised an assertion if more than

one table instance was locked. (Bug #26999526)

• Some windowing functions including NTH_VALUE() did not return NULL in all cases in which they should

have. (Bug #26975882)

• If one of the temporal arguments to LEAST() or GREATEST() was of type DATETIME, but the

aggregated data type was something other than VARCHAR or a temporal type, the LEAST() or

GREATEST() item had temporal properties set for it in spite of the fact that it was not of a temporal data

type. The temporal properties for the LEAST() or GREATEST() item, including its fractional precision,

were therefore not calculated correctly, leading to failure at a later point in statement execution.

To fix this issue, the data type of LEAST() or GREATEST() is now temporarily set to a temporal type if

one or more, but not all, of its arguments are of temporal types regardless of their aggregated data type.

(Bug #26975864)

• IFNULL() did not always check for errors correctly when processing multiple arguments. (Bug

#26975848, Bug #27062796, Bug #27062694)

467

MySQL 8.0 Release Notes

• With compression enabled for the client/server protocol, logical packets that are multiples of size

0xFFFFFF could cause the connection to be dropped. Thanks to Facebook Inc. for the patch. (Bug

#26974113, Bug #88092)

• Installing and uninstalling a plugin many times from multiple sessions could cause the server to become

unresponsive. (Bug #26946491)

• A virtual column definition that included a function removed in MySQL 8.0 caused startup to fail with a

“No database selected” error when starting the MySQL 8.0 server on a MySQL 5.7 data directory. (Bug

#26945125, Bug #88040)

• These errors occurred after an in-place upgrade from MySQL 5.7 to 8.0:

• Starting the server with an --explicit-defaults-for-timestamp=0 setting returned an

Invalid default value for 'cached_time' error.

• Starting the server with --initialize and --explicit-defaults-for-timestamp=0

configuration settings returned an Invalid default value for 'SET_TIME' error.

• Duplicate SET data type values caused a Duplicated value in SET error, regardless of the

sql_mode configuration setting.

(Bug #26944731, Bug #88039, Bug #26948678, Bug #88032)

• Queries with a common table expression and a derived table or view that contained a window function

produced incorrect results. (Bug #26907753, Bug #87939)

• The deprecation warnings were clarified regarding use of the --symbolic-links and --skip-

symbolic-links server options (and their equivalents). The server no longer warns about a missing

data directory when invoked with the --help option. (Bug #26898576, Bug #87913)

• VALUES() was not handled correctly in some cases. (Bug #26881946)

References: See also: Bug #19601973, Bug #17458914.

• The tablespace discovery mechanism in MySQL Cluster was disabled, which prevented serialized

dictionary information from being imported into the data dictionary in cases where the table exists in the

storage engine dictionary but not in the MySQL data dictionary. (Bug #26867488)

• For debug builds, validation checks on relevant generated columns could be missed for UPDATE

statements, leading to a server exit. (Bug #26838771)

• For window functions, an error could be produced that a window was not defined, when it was defined.

(Bug #26813454, Bug #87780)

• When a materialized derived table was determined to be superfluous, the routine that deleted the

corresponding object left it in an inconsistent state. Now in such cases, the derived table's TABLE_LIST

object left in a consistent state after its materialized object is deleted, by setting its table pointer to NULL.

(Bug #26798989)

• Incorrect results were obtained for a query with MAX() and a HAVING clause used inside a view. (Bug

#26781725)

• Metadata locking for definition changes to tables underlying a view could be inconsistent with metadata

locking for other statements on the tables. (Bug #26770836)

• In MySQL 8.0, view column names are restricted to 64 characters. A MySQL 5.7 view with longer

column names was marked as invalid during an upgrade to 8.0 was marked invalid. Now such views

468

MySQL 8.0 Release Notes

produce an error during the upgrade and must be altered to have legal column names before the

upgrade will succeed. (Bug #26743291, Bug #87650)

• Concurrent calls to GET_LOCK() could cause deadlock, even with a wait time of 0. (Bug #26739438,

Bug #87620)

• FROM_UNIXTIME() did not always work correctly with LAG(). (Bug #26739028)

• Following an INSERT statement with BLOB values in the ON DUPLICATE KEY UPDATE clause that

failed with a constraint violation, a similar statement with no reason to return an error could cause a

server exit. (Bug #26734162)

• The Performance Schema now stores rewritten rather than raw SQL statement text when available. (Bug

#26732229)

• Re-executing a prepared statement that used window functions could cause a server exit. (Bug

#26730020)

• An in-place upgrade to MySQL 8.0 caused a server exit if tables contained columns with a pre-5.0

DECIMAL data type. This data type is not supported, so upgrades now detect such columns and warn

that in-place upgrade cannot be done. Affected tables must be upgraded by dumping and restoring

them. (Bug #26727481)

• A comparison operator used to order keys in a data dictionary cache hash map incorrectly determined

that two storage-engine private IDs used by different storage engines were equal. (Bug #26723442)

• Values in the XID_GTRID column of the Performance Schema events_transactions_current

table were displayed incorrectly for XA transactions. (Bug #26710081, Bug #87559)

• Incorrect results or a server exit could result when SHA2() was passed a user-defined variable in some

character sets. (Bug #26704451)

• Incorrect NULL handling by LAG() and LEAD() could cause a server exit. (Bug #26703246, Bug

#26703156)

• If an error occurred while setting up the temporary table for duplicate weedout in a semijoin (for example,

because the disk was full), the server did not terminate gracefully with an appropriate error message.

Now in the event that the temporary table is not successfully created, the query is aborted. (Bug

#26679983)

• The server did not always clean up correctly after executing an IN subquery that used a hash semijoin.

(Bug #26679495)

• Building with the -DWITHOUT_SERVER=ON CMake option failed due to attempting to link the

authentication_ldap_sasl_client client-side plugin against the embedded server library. (Bug

#26665217)

• During data directory creation or upgrade from MySQL 5.7 to 8.0, server startup would fail due to a

Performance Schema initialization failure if the server was started in read_only mode. Additionally,

Information Schema metadata was not updated at startup, and Performance Schema and Information

Schema version information was stored without verifying that schema tables were created.

The versioning scheme used for the data dictionary and Information Schema system views is now

consistent with the Performance Schema versioning scheme. (Bug #26636238, Bug #87436)

• The CREATE_OPTIONS column in the INFORMATION_SCHEMA.TABLES table did not show correct

information. (Bug #26634507)

469

MySQL 8.0 Release Notes

• Incorrect results could be returned for queries that used an outer join and a derived table referenced a

const value from an inner table of the outer join. (Bug #26627181)

• AFTER UPDATE triggers were not invoked for INSERT ... ON DUPLICATE KEY UPDATE when the

value to be updated and the new value were the same. (Bug #26626277, Bug #87371)

• Assignment of anonymous roles to the mandatory_roles system variable was incorrectly permitted.

Additionally, assigning a value to mandatory_roles now requires the ROLE_ADMIN privilege, in

addition to the SYSTEM_VARIABLES_ADMIN or SUPER privilege normally required to set a global system

variable. (Bug #26576989)

• The server fell back to using the built-in error messages if the lc_messages_dir value was invalid at

server startup, but not if lc_messages or lc_time_names were invalid. Now the server uses the built-

in messages if any of those variables are invalid at startup. (Bug #26576922)

• SET DEFAULT ROLE ALL did not include roles named in the mandatory_roles system variable. (Bug

#26571995)

• On Windows, CMake did not automatically add x64 toolchain support for some Visual Studio versions.

(Bug #26566360)

• Problems could occur when a derived table with an ORDER BY clause was merged into an outer

query, and when the columns from the ORDER BY were not also referenced in the outer query. (Bug

#26542829)

• Parallel inserts of schema SDI into the SDI B-tree could raise an assertion when creating tables in the

same schema in parallel. (Bug #26539665, Bug #87225)

• Changing the UMASK and UMASK_DIR environment variables from their default values had no effect on

database directory and table file access. (Bug #26529942)

• For debug builds, incorrect nullability assessment of derived table column references could cause

CONCAT() to raise an assertion. (Bug #26524721)

• A server exit could result from simultaneous attempts by multiple threads to register and deregister

metadata Performance Schema objects, or to acquire and release metadata locks. (Bug #26502135)

• MSI packages for Windows failed to detect when Microsoft Visual C++ 2010 Redistributable Package

was installed. (Bug #26501092, Bug #87139)

• Queries that used window functions for tables that contained a BLOB column could cause a server exit.

(Bug #26496880)

• Persisted variables belonging to plugins were not always handled properly at server startup. (Bug

#26495619)

• A server exit could occur for queries that used DISINCT and ORDER BY ... LIMIT and were

executed using range access and a temporary table for the ORDER BY. (Bug #26483909)

• LDAP authentication plugins could fail if their associated system variables were set to invalid values.

(Bug #26474964)

• The Linux RPM spec file for RHEL6 and higher is updated with comments that recommend installing

the redhat-rpm-config package to add convenience macros that make rebuilding the RPM package

easier. Thanks to Simon Mudd for the patch. (Bug #26474153, Bug #87098)

• If the error log was misconfigured and the server could not start, no output describing the problem was

produced. (Bug #26447825, Bug #87087)

470

MySQL 8.0 Release Notes

• When a materialized semijoin operation was evaluated more than once, and one of the tables in the

materialization was a const table (that is, with join type JT_CONST), invalid data was accessed during

the second materialization when referencing the const table. (Bug #26436185)

• Password-expiration options did not work correctly for authentication plugins that use external

authentication methods. (Bug #26435766)

• Adding an ORDER BY to a query that included an outer join and a subquery caused a constant value

defined for a column in the subquery to be incorrectly promoted to a constant value in the case when the

subquery returns 0 rows. (Bug #26432173)

• For the autocommit system variable, the Performance Schema variables_info table always

reported the VARIABLE_SOURCE column as COMPILED. (Bug #26428017)

• For debug builds, INSERT IGNORE statements that tried to insert NULL into a GEOMETRY NOT NULL

column raised an assertion because there is no valid value to convert the NULL to. This is now handled

as a nonignorable ER_BAD_NULL_ERROR_NOT_IGNORED error. (Bug #26412713)

• SET PERSIST_ONLY changed the VARIABLE_SOURCE column of the Performance Schema

variables_info table when it should not have. (Bug #26395134)

• The server failed to check the maximum path length for partition names. (Bug #26390632)

• Problems occurred when a window with buffering followed an equi-join on a unique index, due to the fact

that the window modified the input record with the assumption that, the next time control passes back to

the join, a new record was read to the input record. This problem is addressed by reinstating the input

record in such cases.

Note

This fix was reverted in MySQL 8.0.27.

(Bug #26389508)

References: See also: Bug #32820802.

• Identifiers containing a mixt of backslashes and backticks could be parsed incorrectly. (Bug #26372491)

• audit_log plugin THD objects could be created with incorrect thread ID information, leading to

assertion failure. (Bug #26362452)

• The HISTOGRAM column in the column_statistics data dictionary table used a key named

charset-id to indicate collation numbers. This key has been renamed to collation-id. (Bug

#26330090, Bug #86794)

• Starting the server with the skip_name_resolve system variable enabled could cause localhost in

account entries to match non-localhost hosts. (Bug #26328274, Bug #26202411, Bug #86546)

• if a configured error log service existed but could not be initialized, log information was lost. Now if a log

service is configured at startup but cannot be initialized, diagnostics about the problem are sent to the

default log service (or if that fails, directly to the error stream), and the server exits. If a log service is

configured at runtime but cannot be initialized, diagnostics are sent to the client. (Bug #26286871, Bug

#86728)

• Installing and uninstalling Performance Schema example plugins concurrently with deletes from tables

associated with those plugins could cause a server exit. (Bug #26281359)

471

MySQL 8.0 Release Notes

• When HASH_SCAN was specified as one of the values for the slave_rows_search_algorithms

system variable, which is the default from MySQL 8.0.2, and row-based replication was in effect, updates

to a table containing virtual generated fields could raise an assertion. The issue was caused by an error

when generating string representations of the virtual generated fields in order to create hashes for use

in searches. To remove the issue, MySQL no longer creates hashes for virtual generated fields. (Bug

#26280724)

• The server permitted SHOW CREATE TABLE on nontable files created for full-text searching. (Bug

#26271244)

• For debug builds, CREATE OR REPLACE VIEW for an existing view raised an assertion for column

names greater than 64 characters. Now an appropriate error is reported. (Bug #26266789)

• SET PERSIST could be ineffective due to sorting variables written to mysqld-auto.cnf. Variables are

now written in the order persisted. (Bug #26259671)

• Attempting a partial backup with mysqlpump on a GTID-enabled server failed and produced an error

message suggesting incorrectly that this was not possible. (It is possible using the --set-gtid-

purged option.) (Bug #26199978)

• GRANT GRANT OPTION ON *.* TO user granted GRANT OPTION for static but not dynamic

privileges. REVOKE ALL ... FROM CURRENT_USER() revoked static but not dynamic privileges. (Bug

#26191109, Bug #25658967)

• Error logging could attempt to log freed messages, resulting in a server exit. (Bug #26188656, Bug

#86562)

• A HAVING condition was optimized away for an alias on an aggregate column where there was no

GROUP BY clause. (Bug #26188578)

• ST_Crosses() could return an incorrect result when at least one parameter is a geometry collection

and multiple elements of the geometry collection must be taken into account in order to determine

whether the geometries cross. (Bug #26188208, Bug #86559)

• MBROverlaps() incorrectly returned false for two crossing perpendicular lines. (Bug #26188118, Bug

#86558)

• ALTER USER user DEFAULT ROLE ALL produced an error. (Bug #26174169)

• mysqldump exited abnormally for large --where option values. (Bug #26171967, Bug #86496, Bug

#27510150)

• A query using a window function with a window which partitioned or ordered on the result of an

aggregate function where this evaluated as NULL returned incorrect results. (Bug #26164633)

• The Performance Schema could leak memory due to nondeletion of file instances created for ALTER

TABLE operations that used the table-copy algorithm. (Bug #26152751, Bug #86482)

• Failed creation of a temporary table using REPLACE could under some circumstances result in an

assertion in a later statement. (Bug #26126789, Bug #86422)

• mysqlpump did not properly parse TABLESPACE clauses in the result from SHOW CREATE TABLE

statements it executed to determine table structure. (Bug #26116415)

• The binary file for the udf_example loadable function was omitted from binary distributions. (Bug

#26115002, Bug #29178542)

• Long SET PERSIST statements could cause a server exit. (Bug #26100122)

472

MySQL 8.0 Release Notes

• An incorrect formula was used to calculate maximum length of result strings for a few string functions:

QUOTE(), AES_DECRYPT(), and WEIGHT_STRING(). This could affect, for example, the length of

character columns created for CREATE TABLE ... AS SELECT ... QUOTE(). (Bug #26049942,

Bug #86305)

• Schema creation and removal operations could fail due to checking for schema directories under the

data directory rather than checking the data dictionary. (Bug #26043994, Bug #86282)

• SHOW PLUGINS did not handle plugins that were terminating, resulting in a server exit. The statement

now displays the status for such plugins as DELETING. (Bug #26029765, Bug #86243)

• Some statements could cause a buffer overflow in the digest code. Thanks to Laurynas Biveinis and

Roel van de Paar for the patch. (Bug #26021187)

• Previously, when the Performance Schema failed to initialize, it wrote a nonspecific init failed

warning to the error log. Now it prints more specific messages about which memory allocation failed.

(Bug #25996291)

• Incorrect results could occur on a table with a unique index when the optimizer chose a Loose Index

Scan even though the unique index had no index extensions. (Bug #25989915, Bug #86165, Bug

#26532061, Bug #87207)

References: This issue is a regression of: Bug #21749123, Bug #78244.

• For XA COMMIT, precommit handling could set an error in the diagnostics area that was not reported

correctly on the calling side, causing an assertion to be raised. (Bug #25978684, Bug #86142)

• The MIN_VALUE column of the Performance Schema variables_info table displayed incorrect

values on 32-bit big-endian platforms. (Bug #25967079)

• A memory leak occurred when the optimizer excluded a subquery associated with a temporary table.

(Bug #25951134)

• An assertion could be raised for updates when a view or derived table considered read only had nested

references not seen as read only. (Bug #25832861, Bug #85796)

• Certificate and key files automatically generated by the server could have an incorrect access mode.

(Bug #25832856)

• Queries on the INFORMATION_SCHEMA TABLES and STATISTICS tables, if evaluated using Index

Condition Pushdown, could push down internal data dictionary functions, resulting in an assertion being

raised. (Bug #25820175, Bug #85765)

• ST_AsText() could read freed memory. (Bug #25818451)

• CREATE USER IF NOT EXISTS was not written to the binary log if the user existed. This could result

in inconsistent replication behavior if the user did not exist on slave servers. A similar issue occurred for

ALTER USER IF EXISTS. To avoid inconsistencies, these statements now are written to the binary log.

(Bug #25813089, Bug #85733)

• An invalid utf8 input string caused a heap buffer overflow error. (Bug #25811623, Bug #25946444)

• A race condition made it possible to cause a server exit by persisting variables from multiple sessions

simultaneously. (Bug #25768813)

• Plugins can create or drop INFORMATION_SCHEMA tables, but views that reference

INFORMATION_SCHEMA tables were not validated when plugins were unloaded or unloaded. (Bug

#25761992, Bug #85579)

473

MySQL 8.0 Release Notes

• mysql wrote some password-related statements to the .mysql_history file. (Bug #25750609)

• Incorrect handling of internal memory buffers could cause a server exit. (Bug #25737271)

• On a read-only server with GTIDs enabled, a DROP TEMPORARY TABLE IF EXISTS statement relating

to a nonexistent or filtered table could write an unnecessary transaction to the binary log and create

an unnecessary GTID. In this situation, the missing temporary table was previously assumed to be

transactional, leading to the statement being split. Now, MySQL checks that the temporary table exists

and that its DROP TEMPORARY TABLE statement is recorded in the binary log. If this is not the case, no

GTID is created. Thanks to Laurynas Biveinis for the patch. (Bug #25656992, Bug #85258)

• The MeCab full-text parser plugin failed to load on Windows. (Bug #25633175)

• The SET_TIME column of the Performance Schema variables_info table was initialized incorrectly.

(Bug #25608115)

• Executing a stored procedure containing a statement that created a table from the contents of certain

SELECT statements could result in a memory leak. (Bug #25586773)

• The Performance Schema failed to check the maximum host length for client connections. (Bug

#25510805)

• For spatial functions, some set operations produced a result with SRID 0 when given arguments in a

different SRID. (Bug #25510403)

• Large --ssl-cipher values could cause client programs to exit. (Bug #25483593)

• A missing argument-count check during preparation of a stored procedure call could result in a server

exit. (Bug #25398451, Bug #84512)

• Temporary tables used in processing a recursive common table expression with UNION DISTINCT and

a great many columns now use the MEMORY engine instead of InnoDB. (Bug #25190109)

• If the MySQL root user account was renamed, a query that accessed an INFORMATION_SCHEMA

view returned an error stating that the user specified as the definer does not exist. To avoid this

error, a new reserved account, 'mysql.infoschema'@'localhost', is now the DEFINER for

INFORMATION_SCHEMA views. (Bug #25185947, Bug #84027)

• When an UPDATE required a temporary table having a primary key larger than 1024 bytes and that table

was created using InnoDB, the server could exit. (Bug #25153670)

• SET DEFAULT ROLE was not transactional like other account-management statements. (Bug

#25122897)

• mysqlpump included the gtid_executed table in dumps of the mysql system database, causing the

gtid_executed position to be lost upon server restart after the dump was reloaded. mysqlpump no

longer dumps the gtid_executed table. (Bug #25109007)

• For geometry calculations, invalid input parameters could lead to an incorrect result buffer and cause an

assertion to be raised or a server exit. (Bug #25062396)

• IFNULL(decimal, int) could lose a digit after the decimal point when used in a query that included

GROUP BY and was executed using a temporary table. (Bug #25051195, Bug #83699)

• For some queries, such as those involving UNION, column width for GROUP_CONCAT() could be

calculated incorrectly, leading to incorrect application of group_concat_max_len. (Bug #25050090,

Bug #83667)

474

MySQL 8.0 Release Notes

• Audit logging of events for the Performance Schema global_variables table was improved so as to

not report events for rows materialized but not reported to the SQL layer. (Bug #24970428)

• ST_Buffer() could return an invalid result or raise an error for some inputs that should have produced

a valid output geometry. (Bug #24947868, Bug #26735293, Bug #25662426)

• For builds with AddressSanitizer or Undefined Behavior Sanitizer enabled, division by zero could occur

during Performance Schema timer initialization. (Bug #24785784)

• Operations that rely heavily on the metadata locking (MDL) subsystem caused a performance

degradation. Traversal of MDL ticket lists was time consuming in cases where there were large number

of MDL tickets. (Bug #24734971, Bug #83143)

• When binlog_format is ROW or MIXED, operations on temporary tables are not logged. Previously,

the exception to this rule was that when the connection was terminated at the end of the session, the

statement DROP TEMPORARY TABLE IF EXISTS was logged for any temporary tables that had been

opened in the session. For row-based replication, this behavior caused an unnecessary write to the

binary log, and added a transaction sequence number for the GTID where these were enabled.

Now, when a temporary table is created in a session, the binary logging format is tracked. The DROP

TEMPORARY TABLE IF EXISTS statement is only logged at the end of the session if statement-

based format was in effect when the temporary table was created, so the CREATE TEMPORARY TABLE

statement was logged. If row-based or mixed-format binary logging was in use when the table was

created, the DROP TEMPORARY TABLE IF EXISTS statement is not logged.

Thanks to Laurynas Biveinis for the patch. (Bug #24670909, Bug #83003, Bug #28606948)

• Concurrent INSERT, ALTER TABLE, and DROP DATABASE operations could result in deadlock. (Bug

#24510948, Bug #82704)

• Under some conditions, the audit_log plugin could recursively lock a mutex, resulting in an

unresponsive server. (Bug #24437533)

• In some cases, the optimizer chose a Loose Index Scan (QUICK_GROUP_MIN_MAX_SELECT) for a

GROUP BY query even when there was a predicate with a disjunction. This is fixed by not performing a

range scan when the condition in the WHERE clause results in more than one disjoint range tree. (Bug

#24423143)

• Incorrect results could occur when the optimizer chose an index on a generated column to fetch values.

(Bug #24345509, Bug #29451999)

• Debug symbol packages are now included for all apt platforms (previously, they were only available on

Debian 9). (Bug #24008883, Bug #27990381)

• With SQL_MODE='', UNIX_TIMESTAMP(COUNT(1)) returned NULL instead of 0 as expected. (Bug

#23529242)

• When deleting rows from a table that had an indexed virtual BLOB column with a NOT NULL constraint,

and the generated column expression evaluated to NULL in one of the rows that were being deleted,

conversion of the NULL to its NOT NULL equivalent was not performed correctly. (Bug #23321196)

References: See also: Bug #23037025, Bug #21345972.

• Setting the MYSQL_GROUP_SUFFIX environment variable had no effect. (Bug #23072792)

• A missing check for error handling during generated column evaluation could result in a server exit. (Bug

#23021693)

475

MySQL 8.0 Release Notes

• To check whether a table was empty, ALTER TABLE performed a table scan, which is inefficient. (Bug

#22688065)

• Failure to acquire tablespace metadata locks for ALTER TABLE when a LOCK TABLES was active could

cause an assertion to be raised. (Bug #22486020, Bug #79820)

• Constant propagation is no longer performed when a constant expression contains a reference to the

column it is meant to replace. (Bug #20964700)

• Queries with many left joins were slow if join buffering was used (for example, using the block nested

loop algorithm). (Bug #18898433, Bug #72854)

• REGEXP failed to find matches occurring after a \0 character in the string expression. (Bug #17541193,

Bug #70470)

• Selecting from a view that involved aggregation and WITH ROLLUP could result in a spurious Column

col_name cannot be null error. (Bug #11755860, Bug #47693)

• COALESCE() could change the value of FLOAT fields. (Bug #11751705, Bug #42666)

• In some cases, the row estimate used by the server to determine whether to use sampling could be

inaccurate. This was because the histogram process assumed that the estimate for the number of rows

in the table was current, although it was not updated by (for example) INSERT or DELETE statements.

Now the histogram process requests an updated count of rows. (Bug #88710, Bug #27197709)

• Long-running regular expression matches could not be killed. (Bug #88676, Bug #27183583)

• An optimizer SET_VAR hint (see Variable-Setting Hint Syntax) setting cte_max_recursion_depth

was ignored. (Bug #88594, Bug #27153338)

• When handling range frames, if the first row for a range frame was found, its position was not stored.

This could later cause retrieval of the row from the frame buffer to fail. (Bug #88568, Bug #27149369)

• The server did not handle triggers activated by LOAD DATA correctly when --skip-log-bin was

enabled. (Bug #88516, Bug #27128534)

References: This issue is a regression of: Bug #27041382.

• Stored procedures performing XA transactions and acting on views were not executed correctly. (Bug

#88326, Bug #27058931)

• When a table contained a column whose length was zero, the optimizer could in some cases allocate a

record buffer that was too small to hold the columns read by the query. (Bug #88283, Bug #27041288)

• A trigger containing invalid syntax, followed by an INSERT that did not specify a column list, attempted to

insert a new row regardless. (Bug #88274, Bug #27041382)

• Window functions did not always produce correct results with LAST_VALUE() and frames having

multiple ORDER BY expressions. (Bug #88186, Bug #27010574)

• A fix for a previous issue caused the aggregated data type to be set to VARCHAR whenever the result

type was string and the column size was larger than 255 characters (maximum length for CHAR). This

caused problems for data types such as JSON whose result type is a string, but which support field

values longer than 255 characters. Now in such cases the data type is set explicitly to VARCHAR when

an aggregated column is of type CHAR or BINARY (both represented internally as strings) but its size

exceeds the maximum for CHAR. (Bug #88073, Bug #26960106)

References: This issue is a regression of: Bug #83895, Bug #25123839.

476

MySQL 8.0 Release Notes

• A prepared statement containing an ORDER BY list that referred to a parameter was not always handled

correctly. (Bug #87863, Bug #26867652)

• DENSE_RANK() did not work correctly for the first row in a partition when buffering was in use, due to

premature initialization of the cache comparator for ORDER BY. (Bug #87760, Bug #26802696)

• The optimizer chose a composite index for ref access where only the first part of the key could be

used. The composite key was suitable but was seen as a higher cost. This was because, when choosing

between ref access and range access on the same index, we prefer range if certain criteria are

fulfilled, one of these being to choose to avoid ref-access if it has an overly-optimistic or unrealistically

low cost as can happen when records_per_key is very low. This was done even if the estimate of the

number of rows for range access was more reliable than the estimate for ref access. (Bug #87613,

Bug #26727773)

References: See also: Bug #23259872.

• When a stored function was used with a table column value as an argument in a WHERE predicate,

its internal not_null_tables property was falsely set to a nonempty value. If this predicate was

applied to an outer join operation and one of the arguments was from an inner table of the outer join, the

predicate was sometimes used (incorrectly) to convert the outer join to an inner join. According to the

SQL standard, only functions that have the RETURNS NULL ON NULL INPUT property should behave

in that manner. Since MySQL does not currently implement this property, stored functions are changed

such that they no longer implement the RETURNS NULL ON NULL INPUT behavior. (Bug #86922, Bug

#26389402)

• A view or derived table contained incorrect data when defined using a SELECT that performed

aggregation of a column, and whose result was filtered with HAVING. (Bug #86840, Bug #26360114)

• The server handled triggers and generated columns incorrectly. (Bug #86637, Bug #26251621)

• A query that grouped results on a subquery which returned a BLOB (or a type based on BLOB such as

JSON) sometimes failed to find the group boundaries, and so returned incorrect results. (Bug #78787,

Bug #21974696)

Changes in MySQL 8.0.3 (2017-09-21, Release Candidate)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Account Management Notes

• Atomic DDL Notes

• C API Notes

477

MySQL 8.0 Release Notes

• Character Set Support

• Compilation Notes

• Configuration Notes

• Data Dictionary Notes

• Deprecation and Removal Notes

• InnoDB Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Plugin Notes

• Security Notes

• Server Administration

• Spatial Data Support

• SQL Syntax Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• CREATE USER now permits a DEFAULT ROLE clause enabling the account default roles to be specified.

SHOW CREATE USER now displays the account default roles if the default is not NONE. (Bug #24670738,

Bug #82987)

• MySQL now maintains information about password history, which makes it possible to enable restrictions

on reuse of previous passwords. DBAs can require that new passwords not be selected from previous

passwords for some number of password changes or period of time. It is possible to establish password-

reuse policy globally using the password_history and password_reuse_interval system

variables, as well as on a per-account basis using the CREATE USER and ALTER USER statements.

Together with existing password-expiration capabilities to require that passwords be changed

periodically, the new reuse-restriction capabilities provide DBAs more complete control over password

management. For more information, see Password Management.

Important

The implementation of password-reuse restrictions involves a

change to the structure of the mysql.user system table and a new

mysql.password_history system table. If you upgrade to this MySQL release

from an earlier version, you must run mysql_upgrade (and restart the server)

to incorporate these system database changes. Until this is done, password

changes are not possible.

478

MySQL 8.0 Release Notes

(WL #6595)

Atomic DDL Notes

• MySQL now supports atomic data definition statements (atomic DDL). An atomic DDL statement

combines the data dictionary updates, storage engine operations, and binary log writes associated with a

DDL operation into a single, crash-safe, transaction that is either fully committed or rolled back.

Both table and nontable DDL statements are supported. Table-related DDL operations require storage

engine support, whereas nontable DDL operations do not. Currently, the InnoDB storage engine

supports atomic DDL.

• Supported table DDL statements include CREATE, ALTER, and DROP statements for databases,

tablespaces, tables, and indexes, and the TRUNCATE TABLE statement.

• Supported nontable DDL statements include:

• CREATE and DROP statements, and, if applicable, ALTER statements for stored programs, triggers,

views, and loadable functions. Atomic DDL support for CREATE TRIGGER and DROP TRIGGER was

added in MySQL 8.0.0.

• Account management statements: CREATE, ALTER, DROP, and, if applicable, RENAME statements

for users and roles, as well as GRANT and REVOKE statements. Atomic DDL support for account

management statements was added in MySQL 8.0.1.

For table-related DDL operations, InnoDB writes DDL logs to the mysql.innodb_ddl_log data

dictionary table. Enabling the innodb_print_ddl_logs configuration option prints DDL recovery logs

to stderr.

The atomic DDL feature changes the behavior of some statements:

• DROP VIEW fails with an error if a named view does not exist, and no changes are made. Previously,

the statement returned an error indicating which views did not exist, but also dropped the views that

did exist.

• DROP TABLE fails with an error if a named table does not exist, and no changes are made. Previously,

the statement returned an error indicating which tables did not exist, but also dropped the tables that

did exist.

• DROP TABLE is fully atomic if all named tables use an atomic DDL-supported storage engine.

• DROP DATABASE is atomic if all tables use an atomic DDL-supported storage engine. However,

removal of the database directory from the file system occurs last and is not part of the atomic

transaction. If removal of the database directory fails due to a file system error or server halt, the DROP

DATABASE transaction is not rolled back.

• Interrupted DDL operations on tables that use an atomic DDL-supported storage engine no longer

introduce discrepancies between the storage engine, data dictionary, and binary log, or leave behind

orphan files.

• Partial execution of account management statements is no longer permitted. Account management

statements either succeed for all named users or roll back and have no effect if an error occurs.

Changes to DROP TABLE, DROP VIEW, and account management statement behavior have implications

for cross-version replication configurations.

479

MySQL 8.0 Release Notes

For more information, see Atomic Data Definition Statement Support. (Bug #24620918, WL #9173, WL

#9536, WL #7896, WL #9045, WL #7743)

C API Notes

• The MySQL C API now enables clients to specify that metadata transfer for result sets is optional.

Suppression of metadata transfer can improve performance, particularly for sessions that execute many

queries that return few rows each. For more information, see Optional Result Set Metadata. (WL #8134)

Character Set Support

• MySQL now supports Russian collations for the utf8mb4 Unicode character set:

• utf8mb4_ru_0900_ai_ci is accent insensitive and case insensitive.

• utf8mb4_ru_0900_as_cs is accent sensitive and case sensitive.

(WL #10753)

Compilation Notes

• For debug builds, the SAFE_MUTEX compilation flag was disabled if the memcached plugin was included

in the build. This no longer occurs; SAFE_MUTEX is always enabled for debug builds. Some code issues

found as a result of this change were corrected. (Bug #26442367, Bug #87068)

• Binary packages on EL6 and EL7 now are compiled using Devtoolset 6 rather than Devtoolset3 and

GCC 6.2.1 rather than 4.9.2. (Bug #26436968, Bug #87061)

• MySQL now compiles for SPARC on Oracle Linux. (Bug #26306331, Bug #86745)

• MySQL compilation on macOS using Clang now requires a Clang version different from 8.0, which has

problems with certain inline constructs. (Bug #26279510, Bug #86711)

• Work was done to clean up the source code base, including: Removing unneeded CMake checks;

removing unused macros from source files; reorganizing header files to reduce the number of

dependencies and make them more modular, removing function declarations without definitions,

replacing locally written functions with equivalent functions from industry-standard libraries.

Configuration Notes

• The performance_schema_max_mutex_classes system variable default value has been increased

from 220 to 250. The performance_schema_max_thread_classes system variable default value

has been increased from 50 to 100. (Bug #26193630)

• The new cte_max_recursion_depth system variable implements a common table expression (CTE)

maximum recursion depth. The server terminates execution of any CTE that recurses more levels than

the value of this variable. For more information, see Limiting Common Table Expression Recursion. (Bug

#26136509, Bug #86444, WL #10972)

• The back_log system variable default value is now the value of max_connections, which enables the

permitted backlog to adjust to the maximum permitted number of connections. (WL #9704)

• To enable the Event Scheduler by default, the event_scheduler system variable default value was

changed from OFF to ON. (WL #9644)

480

MySQL 8.0 Release Notes

• The max_allowed_packet system variable default value has been increased from 4194304 (4M) to

67108864 (64M). (WL #8393)

• The max_error_count system variable default variable has been increased from 64 to 1024. (WL

#9686)

Data Dictionary Notes

• These INFORMATION_SCHEMA tables have been reimplemented as views on data dictionary tables:

FILES

PARTITIONS

REFERENTIAL_CONSTRAINTS

Queries on those tables are now more efficient because they obtain information from data dictionary

tables rather than by other, slower means. For example, the server no longer must create a temporary

table for each query of the INFORMATION_SCHEMA table.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes. (WL #9814, WL #11059)

Deprecation and Removal Notes

• Replication: The following obsolete mysqlbinlog options are now deprecated and will be removed in

a future MySQL version:

• --short-form, which could be used for testing to limit the output to statements alone.

• --stop-never-slave-server-id, which provided a server ID for connections using the --stop-

never option. If you require this function, use the --connection-server-id option instead.

The deprecation warnings for these options are sent to standard error, rather than to standard output, so

that they do not interfere with the operation of tools that use the output of mysqlbinlog. (WL #9632,

WL #9633)

• Replication: The deprecated global scope for the sql_log_bin system variable has been

removed. sql_log_bin now has session scope only. Applications that rely on accessing

@@GLOBAL.sql_log_bin should be adjusted. (WL #10922)

• These encryption-related deprecated items have been removed:

• The ENCODE() and DECODE() functions.

• The ENCRYPT() function.

• The DES_ENCRYPT(), and DES_DECRYPT() functions, the --des-key-file option, the

have_crypt system variable, the DES_KEY_FILE option for the FLUSH statement, and the

HAVE_CRYPT CMake option.

In place of the removed encryption functions: For ENCRYPT(), consider using SHA2() instead for one-

way hashing. For the others, consider using AES_ENCRYPT() and AES_DECRYPT() instead. (Bug

#26493987, WL #10788, WL #10789)

• The deprecated tx_isolation and tx_read_only system variables have been removed. Use

transaction_isolation and transaction_read_only instead. (WL #9636)

• The deprecated query cache has been removed. Removal includes these items:

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MySQL 8.0 Release Notes

• The FLUSH QUERY CACHE and RESET QUERY CACHE statements.

• These system variables: query_cache_limit, query_cache_min_res_unit,

query_cache_size, query_cache_type, query_cache_wlock_invalidate.

• These status variables: Qcache_free_blocks, Qcache_free_memory,

Qcache_hits, Qcache_inserts, Qcache_lowmem_prunes, Qcache_not_cached,

Qcache_queries_in_cache, Qcache_total_blocks.

• These thread states: checking privileges on cached query, checking query cache

for query, invalidating query cache entries, sending cached result to client,

storing result in query cache, Waiting for query cache lock.

• The SQL_CACHE SELECT modifier.

These deprecated query cache items remain deprecated, but have no effect, and will be removed in a

future MySQL version:

• The SQL_NO_CACHE SELECT modifier.

• The ndb_cache_check_time system variable.

The have_query_cache system variable remains deprecated, always has a value of NO, and will be

removed in a future MySQL version. (WL #10824)

• The deprecated EXTENDED and PARTITIONS keywords for the EXPLAIN statement have been

removed. These keywords are unnecessary because their effect is always enabled. (WL #9678)

• The unused date_format, datetime_format, time_format, and max_tmp_tables system

variables have been removed. (WL #9680)

• The deprecated multi_range_count system variable has been removed. (WL #10908)

• The deprecated log_warnings system variable and --log-warnings server option have been

removed. Use the log_error_verbosity system variable instead. (WL #9676)

• The deprecated secure_auth system variable and --secure-auth client option have been removed.

The MYSQL_SECURE_AUTH option for the mysql_options() C API function was removed. (WL #9674)

• The deprecated ignore_builtin_innodb system variable has been removed. (WL #9675)

• In MySQL 8.0.2, the system variables for the slave status logs, master_info_repository and

relay_log_info_repository, were set to TABLE instead of FILE by default. In MySQL 8.0.3, the

FILE setting for both these system variables is deprecated, and a warning is issued if it is used. The

FILE setting will be removed in a future MySQL version.

The TABLE setting ensures that replication repository information is stored in InnoDB tables, rather than

in files in the data directory. The use of tables makes replication resilient to unexpected halts.

The default names for the slave status logs when stored as files were master.info and relay-

log.info. The names could be changed using the --master-info-file and --relay-

log-info-file options, respectively. As InnoDB tables, the slave status logs are named

mysql.slave_master_info and mysql.slave_relay_log_info.

To modify an existing replication slave that is using a FILE repository for the slave status logs to use

TABLE repositories, convert the existing replication repositories dynamically by running the following

commands:

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MySQL 8.0 Release Notes

STOP SLAVE;

SET GLOBAL master_info_repository = 'TABLE';

SET GLOBAL relay_log_info_repository = 'TABLE';

The master info log table mysql.slave_master_info should be protected because it contains the

password for connecting to the master. When you back up the replication slave's data, ensure that you

back up the mysql.slave_master_info and mysql.slave_relay_log_info tables containing

the slave status logs, because they are needed to resume replication after you restore the data from the

slave. (WL #6959)

InnoDB Notes

• Renaming of columns in a parent foreign key is temporarily disabled due to ongoing work on foreign key

locking. This restriction will be lifted in MySQL 8.0.4. (Bug #26334071)

References: See also: Bug #26659110.

Logging Notes

• The binary log is now enabled by default at server startup. The log_bin system variable is set to ON by

default, instead of OFF, even if the --log-bin option has not been specified. Binary logging is standard

practice for production installations, so enabling it by default removes configuration and planning steps

that were usually required.

To disable binary logging, you can specify the --skip-log-bin or --disable-log-bin option at

startup.

The server_id system variable is now set to 1 by default, instead of 0. For servers in a replication

topology, you must still change this setting to specify a unique server ID for each replication server.

Previously, the server could not start with log_bin=ON if no server ID was specified. Now, the server

can start, but a warning message is issued if you did not set an explicit server ID. (From MySQL 8.0.4,

the message is only informational.)

With binary logging enabled for a server, all statements that change data are logged to the server's

binary log, which is a sequence of files with a base name and numeric extension. By default, the server

creates binary log files and an index file in the data directory. In MySQL 8.0.3, the default base name

of these files is host_name-bin, using the name of the host machine. From MySQL 8.0.4, the default

base name is binlog if you do not supply the --log-bin option, and host_name-bin if you supply

the option with no string or an empty string.

You can choose the names and locations of the binary log files and index file by specifying the --

log-bin and --log-bin-index options. You are recommended to specify a base name explicitly,

so that if the host name changes, you can easily continue to use the same binary log file names. The

log_bin_basename system variable holds the base name and any specified path for the binary log

files.

The relay log and relay log index on a replication slave, whose names are specified by the --relay-

log and --relay-log-index options, cannot be given the same names as the binary log and binary

log index. From MySQL 8.0.3, the server issues an error message and does not start if the binary log

and relay log file base names would be the same.

The server creates a new binary log file in the series each time it starts or flushes the logs. The server

also creates a new binary log file automatically after the current file's size reaches max_binlog_size,

which defaults to the maximum permitted value of 1GB. In MySQL 8.0.3, binary log files expire by default

after 30 days, and can then be automatically removed at startup or when the binary log is flushed. You

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MySQL 8.0 Release Notes

can purge binary log files manually using the PURGE BINARY LOGS statement, or specify a different

binary log expiration period using the binlog_expire_logs_seconds system variable.

Many other options are available to modify the behavior of binary logging. For more information, see The

Binary Log and Binary Logging Options and Variables. (WL #10470)

References: See also: Bug #26730000.

Optimizer Notes

• The optimizer now supports a SET_VAR hint that sets the session value of a system variable for the

duration of a single statement. Examples:

SELECT /*+ SET_VAR(sort_buffer_size = 16M) */ name FROM people ORDER BY name;

INSERT /*+ SET_VAR(foreign_key_checks=OFF) */ INTO t2 VALUES(2);

For more information, see Optimizer Hints. (Bug #22906815, WL #681)

• The optimizer now uses column-value histogram statistics stored in the column_statistics data

dictionary table to construct query execution plans. Histogram use applies to predicates involving

comparison of a column to a constant. See Optimizer Statistics. (WL #9223)

• Previously, there was no way of skipping the use of index dives to estimate index usefulness, except

by using the eq_range_index_dive_limit system variable. Now index dive skipping is possible for

single-table queries under certain query conditions (see Range Optimization). (WL #6526)

• The optimizer_switch system variable has a new flag named use_invisible_indexes to control

whether the optimizer uses invisible indexes for query execution plan construction. If the flag is off (the

default), the optimizer ignores invisible indexes (the same behavior as prior to the introduction of this

flag). If the flag is on, invisible indexes remain invisible but the optimizer takes them into account for

execution plan construction. (WL #10891)

Packaging Notes

• mysqlcheck was missing in the MySQL Server Docker image, which prevented mysql_upgrade from

running. (Bug #26400146, Bug #86968)

• For Debian, non-debug binaries were moved from the mysql-server package to the mysql-server-

core package. (Bug #26382333, Bug #86899)

• The Debian/Ubuntu mysql-community-source package is no longer produced because the MySQL

source tarball it contained is provided by other packages at dev.mysql.com. (Bug #26201482)

• The zlib library bundled with MySQL has been upgraded from version 1.2.3 to version 1.2.11. MySQL

implements compression with the help of the zlib library.

The zlib compressBound() function in zlib 1.2.11 returns a slightly higher estimate of the buffer size

required to compress a given length of bytes than it did in zlib version 1.2.3. The compressBound()

function is called by InnoDB functions that determine the maximum row size permitted when creating

compressed InnoDB tables or inserting and updating rows in compressed InnoDB tables. As a result,

CREATE TABLE ... ROW_FORMAT=COMPRESSED, INSERT, and UPDATE operations with row sizes

very close to the maximum row size that were successful in earlier releases could now fail. To avoid this

issue, test CREATE TABLE statements for compressed InnoDB tables with large rows on a MySQL 8.0

test instance prior to upgrading. (WL #10551)

484

MySQL 8.0 Release Notes

Performance Schema Notes

• As of MySQL 8.0.2, Performance Schema table definitions are maintained internally to the server. In

consequence of that change, CREATE TABLE and DROP TABLE are no longer possible for Performance

Schema tables. (Bug #26136994)

• The events_statements_summary_by_digest table now provides, for each row, a sample

statement that produces the digest value in the row. Applications can use this information

as a more efficient means of capturing statement samples than alternatives such as probing

the xxx_history_long tables. The latter approach requires enabling the corresponding

xxx_history_long consumers, which is additional overhead for applications that do not otherwise

need those tables. For more information, see Performance Schema Statement Digests and Sampling,

and Statement Summary Tables.

Additionally, the FIRST_SEEN and LAST_SEEN timestamp columns of the

events_statements_summary_by_digest table now have a fractional seconds part. (WL #9830)

• The Performance Schema setup_instruments table now has columns for instrument metadata:

Instrument properties, instrument volatility, and a documentation string describing the instrument

purpose. Also, the TIMED column now can be NULL, indicating that the instrument does not support

timing. See The setup_instruments Table.

The new Performance Schema setup_threads table exposes instrumented thread class names and

attributes. See The setup_threads Table. (WL #7801)

Plugin Notes

• The new get_sysvar_source plugin service enables plugins to retrieve the source of system variable

settings.

Note

As part of this work, the compound-part structured-variable syntax used for

referring to multiple MyISAM key caches is deprecated. See Multiple Key Caches.

(WL #9424)

Security Notes

• A new caching_sha2_password authentication plugin is available. Like the sha256_password

plugin, caching_sha2_password implements SHA-256 password hashing, but uses caching to

address latency issues at connect time. It also supports more connection protocols and does not require

linking against OpenSSL for RSA password-exchange capabilities. See Caching SHA-2 Pluggable

Authentication. (WL #9591)

• Because starting the server with --skip-grant-tables disables authentication checks, the server

also disables remote connections in that case by enabling skip_networking. (WL #4321)

Server Administration

• MySQL now supports creation and management of resource groups, and permits assigning threads

running within the server to particular groups so that threads execute according to the resources

available to the group. Group attributes enable control over its resources, to enable or restrict resource

consumption by threads in the group. DBAs can modify these attributes as appropriate for different

workloads. Currently, CPU time is a manageable resource, represented by the concept of “virtual CPU”

as a term that includes CPU cores, hyperthreads, hardware threads, and so forth. The server determines

485

MySQL 8.0 Release Notes

at startup how many virtual CPUs are available, and database administrators with appropriate privileges

can associate these CPUs with resource groups and assign threads to groups. For more information,

see Resource Groups. (WL #9467)

Spatial Data Support

• Incompatible Change: Previously, these functions that test geometry relationships supported only

Cartesian spatial reference systems (SRSs): ST_Contains(), ST_Crosses(), ST_Disjoint(),

ST_Equals(), ST_Intersects(), ST_Overlaps(), ST_Touches(), ST_Within(),

MBRContains(), MBRCoveredBy(), MBRCovers(), MBRDisjoint(), MBREquals(),

MBRIntersects(), MBROverlaps(), MBRTouches(), MBRWithin().

These functions now detect geometry arguments in a geographic SRS and return geographic results.

Calculations for projected SRSs and SRID 0 remain the same. For more information, see Spatial

Relation Functions That Use Object Shapes, and Spatial Relation Functions That Use Minimum

Bounding Rectangles.

Note

If spatial data contains SRID values that refer to a geographic spatial reference

system, existing queries using these functions will return different results,

compared to previous MySQL versions.

(WL #10827)

• InnoDB: Spatial reference identifier (SRID) support was added for InnoDB spatial indexes. (WL #10439)

• Spatial data types now permit an SRID attribute, to explicitly indicate the spatial reference system (SRS)

for values stored in the column. See Spatial Data Types.

To indicate each column's SRID attribute value, if there is one, the INFORMATION_SCHEMA.COLUMNS

table now has an SRS_ID column.

A spatial column with an explicit SRID attribute is SRID-restricted: The column takes only values with

that ID, and SPATIAL indexes on the column become subject to use by the optimizer. The optimizer

ignores SPATIAL indexes on spatial columns with no SRID attribute. See SPATIAL Index Optimization.

(WL #8592)

SQL Syntax Notes

• ALTER TABLE now supports easier column renaming using RENAME COLUMN old_name TO

new_name syntax. See ALTER TABLE Statement. For changing a column name but not its definition,

RENAME COLUMN is more convenient than CHANGE, which requires respecifying the current column

definition. With CHANGE, you must look up the definition if you do not know it, and if you do not respecify

it exactly, there is a possibility of data change or loss. (Bug #11746522, Bug #26949, Bug #11747473,

Bug #32497, Bug #11765084, Bug #58006, Bug #14031617, WL #10761)

X Plugin Notes

• The X Plugin could not be installed when the server was started with the --skip-grant-tables

option. (Bug #26516678)

• X Plugin socket connections were not working correctly. (Bug #26427112, Bug #87019)

• When compiling MySQL from source, certain infrequently used CMake arguments caused issues for the

X Plugin build. (Bug #26141933)

486

MySQL 8.0 Release Notes

• A Mysqlx.Connection.CapabilitiesGet request using X Protocol did not return the complete list

of available authentication mechanisms. (Bug #26044113)

• For mixed case or uppercase schema names, the statement list_objects could incorrectly report a

collection as a table. (Bug #25769683)

• The X Plugin was omitted from the list of plugins to include for testing data directory permissions. (Bug

#24823999)

Functionality Added or Changed

• InnoDB: The new innodb_dedicated_server configuration option, which is disabled by default,

can be used to have InnoDB automatically configure the following options according to the amount of

memory detected on the server:

• innodb_buffer_pool_size

• innodb_log_file_size

• innodb_flush_method

This option is intended for MySQL server instances that run on a dedicated server. For more information,

see Enabling Automatic Configuration for a Dedicated MySQL Server. (WL #9193)

• InnoDB: Renaming a general tablespace is now supported by ALTER TABLESPACE ... RENAME TO

syntax.

The ALTER TABLESPACE and DROP TABLESPACE ENGINE clause is deprecated and will be removed in

a future MySQL version. (WL #8972)

• InnoDB: Code related to obsoleted InnoDB system tables was removed. INFORMATION_SCHEMA

views based on InnoDB system tables were replaced by internal system views on data dictionary tables.

Affected InnoDB INFORMATION_SCHEMA views were renamed:

Table 1 Renamed InnoDB Information Schema views. The first column shows the old name. The

second column shows the new name.

Old Name New Name

INNODB_SYS_COLUMNS INNODB_COLUMNS

INNODB_SYS_DATAFILES INNODB_DATAFILES

INNODB_SYS_FIELDS INNODB_FIELDS

INNODB_SYS_FOREIGN INNODB_FOREIGN

INNODB_SYS_FOREIGN_COLS INNODB_FOREIGN_COLS

INNODB_SYS_INDEXES INNODB_INDEXES

INNODB_SYS_TABLES INNODB_TABLES

INNODB_SYS_TABLESPACES INNODB_TABLESPACES

INNODB_SYS_TABLESTATS INNODB_TABLESTATS

INNODB_SYS_VIRTUAL INNODB_VIRTUAL

After upgrading to MySQL 8.0.3 or later, update any scripts that reference previous InnoDB

INFORMATION_SCHEMA view names.

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MySQL 8.0 Release Notes

The new INFORMATION_SCHEMA.INNODB_TABLESPACES_BRIEF view provides space, name, path,

flag, and space type data for InnoDB tablespaces. (WL #9535)

• InnoDB: When InnoDB was integrated with the global data dictionary, file-per-table tablespace names

in the data dictionary were created in the form of innodb_file_per_table_x, where x is the InnoDB

tablespace ID. For ease of use, file-per-table tablespace names in the data dictionary are once again the

same as the table name.

Upgrading from MySQL 5.7 to MySQL 8.0 appends MySQL 5.7 innodb_table_stats and

innodb_index_stats tablespace names in the data dictionary with “_backup57” to differentiate them

from their MySQL 8.0 counterparts. (WL #10436)

• InnoDB: The default innodb_autoinc_lock_mode setting was changed from 1 (consecutive) to 2

(interleaved). Interleaved lock mode permits the execution of multi-row inserts in parallel, which improves

concurrency and scalability. The new innodb_autoinc_lock_mode default setting reflects the change

from statement-based replication to row based replication as the default replication type in MySQL

5.7. Statement-based replication requires the consecutive auto-increment lock mode to ensure that

auto-increment values are assigned in a predictable and repeatable order for a given sequence of SQL

statements, whereas row-based replication is not sensitive to the execution order of SQL statements.

For more information, see InnoDB AUTO_INCREMENT Lock Modes.

For systems that use statement-based replication, the new innodb_autoinc_lock_mode default

setting may break applications that depend on sequential auto-increment values. To restore the previous

default, set innodb_autoinc_lock_mode to 1. (WL #9699)

• InnoDB: Serialized dictionary information (SDI) is now present in all InnoDB tablespace files except for

temporary tablespace and undo tablespace files. SDI is serialized metadata for table and tablespace

objects. The presence of SDI data provides metadata redundancy. For example, dictionary object

metadata may be extracted from tablespace files if the data dictionary becomes unavailable. SDI

extraction is performed using the ibd2sdi tool. SDI data is stored in JSON format.

The inclusion of SDI data in tablespace files increases tablespace file size. An SDI record requires a

single index page, which is 16KB in size by default. However, SDI data is compressed when it is stored

to reduce the storage footprint. (WL #9538)

• InnoDB: The innodb_flush_neighbors default value was changed from 1 to 0, which disables

flushing of neighboring pages from the buffer pool. A setting of 0 is optimal for non-rotational storage

(SSD) devices where seek time is not a significant factor. For systems that use rotational storage (HDD),

it is recommended to change the setting back to the previous default value of 1. (WL #9631)

• InnoDB: Default values for configuration options that affect buffer pool preflushing and flushing behavior

were modified:

• The innodb_max_dirty_pages_pct_lwm default value was changed to 10. The previous default

value of 0 disables buffer pool preflushing. A value of 10 enables preflushing when the percentage of

dirty pages in the buffer pool exceeds 10%. Enabling preflushing improves performance consistency.

• The innodb_max_dirty_pages_pct default value was changed from 75 to 90. InnoDB attempts to

flush data from the buffer pool so that the percentage of dirty pages does not exceed this value. The

increased default value permits a greater percentage of dirty pages in the buffer pool.

(WL #9707, WL #9630)

• InnoDB: The minimum innodb_undo_tablespaces value changed from 0 to 2. In previous releases,

the system tablespace is used for rollback segments if innodb_undo_tablespaces is set to 0. A

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MySQL 8.0 Release Notes

minimum value of 2 ensures that rollback segments are created in undo tablespaces instead of the

system tablespace. For more information, see Undo Tablespaces. (WL #10583)

• Replication; JSON: Added the binlog_row_value_options system variable. Currently this variable

can be unset, or set to the value PARTIAL_JSON. This causes MySQL's row-based replication to use

a compact binary log format for each update modifying only a small portion of a JSON document and

using any combination of JSON_SET(), JSON_REPLACE(), and JSON_REMOVE(). The compact format

includes only the modified parts of the JSON document, not the full document, in the after-image used

for the update in the binary log. If the modification requires more space than the full document, or if it is

not possible to generate a partial update, the full document is used instead.

See the description of the variable as well as Partial Updates of JSON Values, for more information. (WL

#2955)

• Replication: The IGNORE_SERVER_IDS option of the CHANGE MASTER TO statement is now

deprecated when using GTID-based replication (gtid_mode=ON). With GTIDs, transactions that have

already been applied are automatically ignored, so this function is not needed.

Before starting GTID-based replication, check for and clear all ignored server ID lists that have

previously been set on the servers involved. The SHOW_SLAVE_STATUS statement, which can be

issued for individual channels, displays the list of ignored server IDs if there is one. If there is no list, the

Replicate_Ignore_Server_Ids field is blank.

If gtid_mode=ON is set for the server, a deprecation warning is now issued if you include the

IGNORE_SERVER_IDS option in a CHANGE MASTER TO statement. A deprecation warning is

also issued if you issue a SET GTID_MODE=ON statement when any channel has existing server

IDs set with IGNORE_SERVER_IDS. If you do receive the deprecation warning, you can still clear

a list after gtid_mode=ON is set by issuing a CHANGE MASTER TO statement containing the

IGNORE_SERVER_IDS option with an empty list. (WL #10963)

• Replication: The log_slave_updates system variable is now set to ON by default, so you do not

need to specify --log-slave-updates explicitly when you start a replication slave.

The log_slave_updates system variable is read-only. If you need to prevent a replication slave

from logging the updates performed by its SQL thread to its own binary log, specify --log-slave-

updates=OFF at slave server startup. (WL #10479)

• Group Replication: This release adds the group_replication_communication_debug_options

server system variable, making it possible to filter out debugging and tracing messages dynamically, per

Group Replication component. (WL #10200)

• Group Replication: Group Replication thread states are now shown in the MySQL Performance

Schema. (WL #10622)

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MySQL 8.0 Release Notes

• JSON: The JSON_MERGE() function is renamed to JSON_MERGE_PRESERVE().

This release also adds the JSON_MERGE_PATCH() function, an RFC 7396 compliant version of

JSON_MERGE_PRESERVE(); its behavior is the same as that of JSON_MERGE_PRESERVE(), with the

following two exceptions:

• JSON_MERGE_PATCH() removes any member in the first object with a matching key in the second

object, provided that the value associated with the key in the second object is not JSON null.

• If the second object has a member with a key matching a member in the first object,

JSON_MERGE_PATCH() replaces the value in the first object with the value in the second object,

whereas JSON_MERGE_PRESERVE() appends the second value to the first value.

This example compares the results of merging the same 3 JSON objects, each having a matching key

"a", with each of these functions:

mysql> SET @x = '{ "a": 1, "b": 2 }',

> @y = '{ "a": 3, "c": 4 }',

> @z = '{ "a": 5, "d": 6 }';

mysql> SELECT JSON_MERGE_PATCH(@x, @y, @z) AS Patch,

-> JSON_MERGE_PRESERVE(@x, @y, @z) AS Preserve\G

*************************** 1. row ***************************

Patch: {"a": 5, "b": 2, "c": 4, "d": 6}

Preserve: {"a": [1, 3, 5], "b": 2, "c": 4, "d": 6}

JSON_MERGE() is still supported as an alias of JSON_MERGE_PRESERVE(), but is now deprecated and

subject to removal in a future MySQL version.

See Functions That Modify JSON Values, for more information. (Bug #81283, Bug #23255346, WL

#9692)

• InnoDB now uses Variance-Aware Transaction Scheduling (VATS) for scheduling the release of

transaction locks when the system is highly loaded, which helps reduce lock sys wait mutex contention.

Lock scheduling uses VATS when >= 32 threads are suspended in the lock wait queue.

For more information about VATS, see Identifying the Major Sources of Variance in Transaction

Latencies: Towards More Predictable Databases.

Thanks to Jiamin Huang for the contribution. (Bug #25290971, Bug #84266, WL #10793)

• MySQL now extends metadata locks, as necessary, to tables that are related by a foreign key constraint.

Extending metadata locks prevents conflicting DML and DDL operations from executing concurrently

on related tables. This feature also enables updates to foreign key metadata when a parent table is

modified. Previously, foreign key metadata, which is owned by the child table, could not be updated

safely.

If a table is locked explicitly with LOCK TABLES, any tables related by a foreign key constraint are now

opened and locked implicitly. For foreign key checks, a shared read-only lock (LOCK TABLES READ) is

taken on related tables. For cascading updates, a shared-nothing write lock (LOCK TABLES WRITE) is

taken on related tables that are involved in the operation.

If LOCK TABLES is active for a table in a foreign key relationship, ALTER TABLE ... RENAME is

not permitted for that table. This is a temporary restriction, lifted in MySQL 8.0.4 by the patch for Bug

#26647340. (WL #6049)

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MySQL 8.0 Release Notes

• The expire_logs_days system variable, which specifies the binary log expiration period in days, is

now deprecated and will be removed in a future MySQL version. expire_logs_days does not provide

sufficient flexibility for defining the binary log expiration period.

binlog_expire_logs_seconds can be used to set the binary log expiration period in seconds.

In MySQL 8.0.3, the effects of the two variables are currently cumulative. For example, if

expire_logs_days is 1 and binlog_expire_logs_seconds is 43200, then the binary log is

purged every 1.5 days. This produces the same result as setting binlog_expire_logs_seconds to

129600 and expire_logs_days to 0. Note that the default expire_logs_days setting of 30 days

is currently added to the binary log expiration period if expire_logs_days is not specified. To use

binlog_expire_logs_seconds alone, set expire_logs_days=0 explicitly.

To disable automatic purging of the binary log, you must set both expire_logs_days and

binlog_expire_logs_seconds explicitly to 0. (WL #10924)

References: See also: Bug #26483363.

• A new type of backup lock permits DML during an online backup while preventing operations that

could result in an inconsistent snapshot. The new backup lock is supported by LOCK INSTANCE

FOR BACKUP and UNLOCK INSTANCE syntax. The BACKUP_ADMIN privilege is required to use these

statements. (WL #9451)

Bugs Fixed

• Incompatible Change; JSON: If a JSON object contained multiple members with the same key name,

MySQL kept the first member and discarded the remainder. This contradicts RFC 7159, which suggests

that duplicate key names can be handled in one of the ways listed here:

• Report an error (or otherwise fail to parse the object)

• Report all of the name-value pairs, including duplicates

• Report the last name-value pair only

When a JSON text is evaluated in JavaScript, the last name-value pair is kept if multiple pairs with the

same name are specified. MySQL now does likewise, and implements the last of the three options just

listed, as shown here:

mysql> CREATE TABLE t1 (c1 JSON);

mysql> INSERT INTO t1 VALUES ('{"x": 17, "x": "red", "x": [3, 5, 7]}');

mysql> SELECT c1 FROM t1;

+------------------+

| c1 |

+------------------+

| {"x": [3, 5, 7]} |

+------------------+

The fix for this issue also corrects a failure in the MySQL 8.0 server to handle insertion into a JSON

column of data containing JSON arrays as the values for multiple identical keys. (Bug #86620, Bug

#86866, Bug #26238736, Bug #26369555)

• Performance; JSON: Creating a representation of a JSON string now optimizes for the most common

case—that the string to be processed contains no special characters that need to be escaped—scanning

for the first special character in the string, and copying each sequence of characters which do not require

escaping in a single memcpy() call, rather than checking each character in turn to determine whether it

needed to be escaped, escaping it if so, and then copying it, one by one, as was done previously.

491

MySQL 8.0 Release Notes

This fix also corrects a failure to escape the control character \u001f, or unit separator character. (Bug

#86898, Bug #26388690, Bug #87722, Bug #26780307)

References: See also: Bug #25977595.

• InnoDB: The default value for ON UPDATE and ON DELETE foreign key clauses was changed from

RESTRICT to NO ACTION. NO ACTION is a standard SQL keyword that is equivalent to the RESTRICT

keyword in MySQL. (Bug #30186407, Bug #96466)

• InnoDB: Foreign keys records were missing from the INFORMATION_SCHEMA.INNODB_SYS_FOREIGN

table due to file name encoding of the internal parent and child table names, which caused the names to

exceed the permitted length. (Bug #27020089)

• InnoDB: A long semaphore wait occurred when executing ALTER TABLE, DROP TABLE, and DROP

DATABASE operations. (Bug #26779650)

• InnoDB: Invalid error handling code was removed from a function related to tablespace import. (Bug

#26595476)

• InnoDB: File-per-table tablespaces created prior to MySQL 5.6 caused a failure during an in-place

upgrade to MySQL 8.0.2. The tablespaces were not registered with the InnoDB SYS_TABLESPACES

system table, as required.

Tables with decimal columns created prior to MySQL 5.5 also caused a failure during an in-place

upgrade to MySQL 8.0.2, due to a precision type mismatch. (Bug #26542296, Bug #87229)

• InnoDB: During MySQL installation, an unnecessary warning was reported about creation of foreign key

constraint system tables. (Bug #26483335)

• InnoDB: A query was interrupted during concurrent ALTER TABLE operations due to a secondary index

entry count mismatch. (Bug #26381213)

• InnoDB: A segmentation fault occurred when attempting to open a table that was altered while strict

mode was disabled to include conflicting TABLESPACE and COMPRESSION attributes. (Bug #26375851)

• InnoDB: A segmentation fault occurred during a DML operation that used the TempTable storage

engine. (Bug #26363837)

• InnoDB: Implicit row format conversion during an ALTER TABLE ... REORGANIZE PARTITION

operation raised an invalid assertion. (Bug #26326611)

• InnoDB: An ALTER TABLE operation that rebuilt an encrypted table did not set the encryption attribute

properly. (Bug #26243264)

• InnoDB: A memory leak was encountered on Windows when using the TempTable storage engine for

in-memory internal temporary tables. (Bug #26237680)

• InnoDB: Misleading errors were produced when running Valgrind tests on a server build that was not

enabled for Valgrind testing. (Bug #26037206)

• InnoDB: Problematic code related to dropping orphan full-text search tables caused an invalid object ID

assertion failure on startup. (Bug #25998362)

• InnoDB: A check for discarded partitions during a DML operation only checked the first partition. Failure

to check for other discarded partitions caused an assertion failure. (Bug #25942592)

• InnoDB: Allocated memory was not initialized before it was written to a file, resulting in a Valgrind error.

(Bug #25913151, Bug #85986)

492

MySQL 8.0 Release Notes

• InnoDB: Adding a virtual column and index in the same statement caused an error. (Bug #25899959)

• InnoDB: Replication lag occurred on slave instances during large update operations on tables with many

partitions. (Bug #25687813, Bug #85352)

• InnoDB: A failure occurred during an end range comparison. (Bug #25669686)

• InnoDB: Enabling the innodb_buffer_pool_load_now setting failed in read-only mode. The event

that signals the buffer pool load thread was not initialized. (Bug #25586766)

• InnoDB: A cursor position check by a multiversion concurrency control row search function raised an

assertion. (Bug #25377592)

• InnoDB: The wrong variable was passed to the row_mysql_handle_errors routine causing an

assertion failure. (Bug #25183130)

• InnoDB: A long wait for a dictionary operation lock held by a full-text search synchronization operation

caused a server exit. (Bug #24938374, Bug #26376681, Bug #26376239)

• InnoDB: Assertion code was modified to account for the possibility of a transaction attempting to acquire

an explicit lock on a record while another transaction converts an implicit lock to an explicit lock on the

same record prior to a commit operation. (Bug #24344131)

• InnoDB: A FLUSH TABLES ... FOR EXPORT operation on an encrypted or page-compressed table

raised an assertion. (Bug #22916982)

• InnoDB: A DROP TABLE operation was not permitted with an innodb_force_recovery setting

greater than 0. (Bug #22392152)

• InnoDB: A CREATE TABLE ... SELECT operation raised an assertion failure when the newly created

table was dropped before the transaction was committed. (Bug #22154768)

• InnoDB: An in-place ALTER TABLE operation that rebuilt the table and added a foreign key without

specifying a foreign key constraint name failed due to a duplicate constraint name. InnoDB did not

account for existing foreign key constraint names. This issue was addressed in MySQL 8.0.3, when

foreign key metadata was moved to the data dictionary, and foreign key constraint name generation was

moved to the SQL layer. (Bug #18199504, Bug #71616)

• InnoDB: A misplaced function call that locks the InnoDB data dictionary during a foreign key check was

removed. (Bug #12917178, Bug #62221)

• InnoDB: The error messages reported when attempting to use an existing foreign key constraint name

were inconsistent and did not always provide sufficient information. (Bug #11925430, Bug #60633)

• Partitioning: In certain cases when fetching heap records a partition ID could be set to zero. (Bug

#86255, Bug #26034430)

• Partitioning: It was possible for a CREATE TABLE statement that failed to create a partitioned InnoDB

table not to be rolled back correctly. This was due to an extraneous commit made while performing a

check of foreign key information. Since partitioned tables do not presently support foreign keys, this

check is unnecessary, and so is no longer made in such cases. (Bug #85299, Bug #25667278)

• Partitioning: Queries involving NULL were not always handled correctly on tables that were partitioned

by LIST. (Bug #76418, Bug #20748521)

References: See also: Bug #86255, Bug #26034430.

• Replication; Group Replication: On a member which had both Group Replication and asynchronous

replication running simultaneously, asynchronous replication was not respecting restrictions imposed

493

MySQL 8.0 Release Notes

by Group Replication, such as using only the InnoDB storage engine, tables requiring primary keys,

and so on. This could also be encountered when running mysqlbinlog against the member. Now,

members running Group Replication and asynchronous replication do not allow any Group Replication

requirements to be broken. (Bug #85164, Bug #25609945)

References: See also: Bug #85781, Bug #25828806.

• Replication: On a multithreaded slave, it was possible for a deadlock state to occur due to the timing

of updates to the record of disk space used by the relay log. The timing of the update has now been

changed so that the deadlock cannot occur. (Bug #26729635)

• Replication: With slave_preserve_commit_order=1 set, a deadlock could occur between a

transaction holding a shared write lock on a table, and a transaction earlier in the commit order that also

required a shared write lock. (Bug #26666609)

• Replication: The unused variable opt_reckless_slave was removed. (Bug #26500285)

• Replication: FLUSH LOGS attempted to send an OK message after having already sent an error

response during the commit phase. Thanks to Laurynas Biveinis for the patch. (Bug #26272158, Bug

#25363745, Bug #84437)

• Replication: With GTIDs generated for incident log events, MySQL error code 1590

(ER_SLAVE_INCIDENT) could not be skipped using the --slave-skip-errors=1590 startup option

on a replication slave. (Bug #26266758)

• Replication: COUNT_TRANSACTIONS_REMOTE_IN_APPLIER_QUEUE was set to an incorrect value

when group_replication_recovery_complete_at="transactions_certified" on a

recovering member. (Bug #26180350)

• Replication: When replicating a partitioned table with an index, on a replication slave where

HASH_SCAN was specified as part of the slave_rows_search_algorithms setting, the slave I/O

thread sometimes stopped with an error HA_ERR_KEY_NOT_FOUND. (Bug #26137159)

• Replication: The system variable pseudo_slave_mode, which is for internal server use, sometimes

raised an assertion when it was changed inside a transaction. The server no longer changes this

variable inside a transaction. (Bug #26034192, Bug #86250)

• Replication: When write sets are used for parallelization by a replication slave (as specified by the

binlog_transaction_dependency_tracking system variable), empty transactions are now

ignored, and the handling of relay log rotation has been optimized. (Bug #25982097)

• Replication: The Performance Schema replication_applier_status_by_worker table

sometimes incorrectly displayed a value for APPLYING_TRANSACTION for an inactive worker, because

the table was being populated before the worker thread stopped. (Bug #25896166, Bug #85951)

• Replication: Attempting to uninstall the plugin while START GROUP_REPLICATION executed could

result in unexpected behavior. (Bug #25423650, Bug #91042, Bug #28088177)

• Replication: In case of a failure while creating multiple slave applier worker threads, some threads

would be left orphaned and their resources would not be collected. Thanks to Laurynas Biveinis for his

contribution to fixing this bug. (Bug #24679056, Bug #82980)

• Replication: The binlog_checksum option cannot be changed within a transaction. MySQL cannot

log this statement, as would be required inside a transaction, while the requested function is being

performed on the binary log. (Bug #22914463)

• Replication: group_replication_force_members could be used in situations where the group was

working properly, in other words a majority was reachable. This incorrect use could cause instability in

494

MySQL 8.0 Release Notes

the group. Therefore, its use has been restricted to the scenario for which it was created, for forming a

new membership from a subset of a previous group's membership when a majority of the members are

unreachable. (Bug #86359, Bug #26093967)

• Replication: Joining a member running a lower version to a group running a higher version resulted in

the members running the higher version becoming unreachable. (Bug #85026, Bug #25568493)

• Group Replication: Group Replication flow control variables now correctly permit you to have some

members in a group that do not affect the minimum throughput of the flow-control mechanism, effectively

ignoring those members in case they become blocked. (Bug #26537497)

• Group Replication: When the Group Replication plugin delayed initialization thread failed to start due to

unavailable resources, a locked mutex was left behind. Now we ensure that this mutex is unlocked when

the thread does not start. (Bug #26394678)

• Group Replication: In the case of delayed initialization of the Group Replication plugin deployed in

single-primary mode, secondaries were able to get writes through an asynchronous replication channel,

which is not allowed in normal initialization of the Group Replication plugin. (Bug #26314756)

• Group Replication: If the options file contained Group Replication related settings the server could stop

unexpectedly on startup. (Bug #26314472)

• Group Replication: The values for group_replication_recovery_use_ssl and

group_replication_recovery_ssl_verify_server_cert were not updated when configured

for the Group Replication recovery channel. (Bug #26142801)

• Group Replication: It was possible to set server_uuid to the same value as

group_replication_group_name, which resulted in unexpected behavior because GTIDs

are identified by UUIDs. To fix this problem, setting server_uuid to the same value as

group_replication_group_name is no longer allowed. (Bug #26035931)

• Group Replication: It was possible to start the server with invalid values for Group Replication

flow control options. Now, the --group-replication-flow-control-min-quota, --group-

replication-flow-control-max-quota, and --group-replication-flow-control-min-

recovery-quota options are validated on server startup. (Bug #87206, Bug #26531899)

• Group Replication: If hostname resolution did not work for a Group Replication member, a misleading

error returned when attempting to connect referred to credentials rather than the actual problem with

hostname resolution. (Bug #86858, Bug #26368004)

• Group Replication: The Group Replication plugin no longer sets auto_increment_increment and

auto_increment_offset when single primary mode is active. (Bug #86669, Bug #26263155)

• Group Replication: Group Replication partition threads were not visible in the Performance Schema.

(Bug #86626, Bug #26241008)

• JSON: Containers in the internal representations of JSON objects and arrays (Json_object and

Json_array) have been changed to use smart pointers rather than raw pointers to Json_dom, so that

orphaned DOM objects are now automatically destroyed. (Bug #26161264)

• JSON: ASCII character 31 (\u001f, the unit separator) in a string literal within a JSON document was

not quoted when the JSON document was formatted as a string (for example, by CAST('"\u001f"'

AS JSON)). (Bug #25977959)

• JSON: When a path_expression identified a nonarray value, the JSON_INSERT() and

JSON_ARRAY_INSERT() functions failed to evaluate path_expression[0] as equal to

path_expression. (Bug #86213, Bug #26022576)

495

MySQL 8.0 Release Notes

• JSON: Searches with JSON_EXTRACT() that used wildcards took an inordinate amount of time. (Bug

#84523, Bug #25418534)

References: See also: Bug #83959, Bug #25151440.

• Under heavy load, an infinite loop occurred in Performance Schema buffer container code. (Bug

#26666274)

• MySQL-specific typedefs such as uchar and my_bool were inadvertently reintroduced into the client

namespace if the mysql.h header file was included. (Bug #26588846, Bug #26582752, Bug #87337)

• uint8korr() and related macros were fixed so that they explicitly do unaligned accesses, even on

x86. (Bug #26568748, Bug #87298)

• The main.mysql_upgrade_grant, main.roles-upgrade, and

auth_sec.secure_file_priv_warnings, test cases mishandled the error log. The

sys_vars.innodb_redo_log_encrypt_basic test case output was unstable. Thanks to Laurynas

Biveinis for the patches. (Bug #26562401, Bug #87279, Bug #26575150, Bug #87313, Bug #26575142,

Bug #87314, Bug #26582158, Bug #87303)

• For debug builds, with sql_buffer_result enabled, recursive common table expressions caused a

server exit. (Bug #26556025)

• Incorrect resolution of a window function as a constant function could result in a server exit. (Bug

#26500442)

• For window functions, use of GROUP BY ... WITH ROLLUP could cause a server exit. (Bug

#26497353, Bug #26497247)

• For window functions, JSON columns raised an assertion. (Bug #26496733)

• For window functions, a value less than the argument for a RANGE frame caused a server exit. (Bug

#26496645)

• Compiling with -DWITHOUT_SERVER=1 resulted in my_symlink.c compilation failure due to missing

#include for my_dir.h. Thanks to Christian Hesse for the patch. (Bug #26495816, Bug #87137)

• Compiling with -DWITH_SSL=system -DWITH_ZLIB=system assumed that the system openssl

zlib command was available, which might not be the case. Now availability of that command is

checked, and if unavailable, the zlib_decompress utility is built. (Bug #26494495, Bug #87123)

• yaSSL could incorrectly perform TLS cipher negotiation. (Bug #26482173)

• Some thread_stack settings could result in a server exit. (Bug #26438067)

• For window functions, a ROW frame accepted noninteger arguments for the row count. (Bug #26411055,

Bug #86990)

• REPLACE(UUID(),...) expressions could be cached (improperly) and return the same value for each

row of a result set. (Bug #26395601)

• When building MySQL within the source tree, make install installed some CMake files into the

mysql-test directory within the tree. (Bug #26385175, Bug #86905)

• The PROCESS_ID column in the Performance Schema session_connect_attrs and

session_account_connect_attrs tables was changed from INT to BIGINT UNSIGNED to

accommodate larger process ID values. Thanks to Daniël van Eeden for the patch. (Bug #26357806,

Bug #86835)

496

MySQL 8.0 Release Notes

• The index on a generated column, whose value was generated from JSON_EXTRACT(), was sometimes

not used by the optimizer when it should have been. (Bug #26352119)

• Setting the log_error_services system variable to NULL caused a server exit. (Bug #26331795)

• For tar file packages, some test suite shared libraries were installed in the server package rather than

the test package. (Bug #26329850)

• SHOW COLUMNS for a valid view could fail. (Bug #26322203, Bug #86778)

• An operation that caused renaming or removal of histogram statistics could cause a server exit. (Bug

#26303972)

• For a VARCHAR column, sorting using an explicit collation (ORDER BY col_name COLLATE

collation_name) was much slower than with an implicit collation (no COLLATE clause), even if the

explicit collation was the same as the implicit collation. (Bug #26286790, Bug #86710)

• SET binlog_format = ROW produced a syntax error because ROW is now a reserved word. This

syntax is now recognized specially to preserve backward compatibility. (Bug #26269280)

• SET PERSIST_ONLY, should be permitted only to users who have the SYSTEM_VARIABLES_ADMIN

and PERSIST_RO_VARIABLES_ADMIN privileges, but was incorrectly also permitted to users with the

SUPER privilege. (Bug #26247864)

• The information_schema_stats configuration option, introduced in MySQL 8.0.0, was removed and

replaced by information_schema_stats_expiry.

information_schema_stats_expiry defines an expiration setting for cached

INFORMATION_SCHEMA table statistics. For more information, see Optimizing

INFORMATION_SCHEMA Queries.

The TABLES_DYNAMIC and STATISTICS_DYNAMIC internal system views were removed. (Bug

#26203731, Bug #83957)

• Source packages for Debian platforms contained prebuilt debug binaries, causing build failures on any

architectures other than the one on which those binaries were built. (Bug #26186911)

• The loadable function registration service did not work if used during server startup. (Bug #26173244)

• Disabling table instrumentation by changes to the Performance Schema setup_objects table could

cause incorrect index names in index statistics. (Bug #26162562)

• A misleading error message was returned when attempting to drop a nonexistent tablespace file. (Bug

#26133507, Bug #86438)

• When running mysqlbinlog with the --read-from-remote-server option, rewrite rules specified

using the --rewrite-db option were ignored, so data was not written to the target database. (Bug

#26117735, Bug #86288)

• Timestamp data copied from the data dictionary cache during a DDL operation was converted using a

time_zone value that was no longer valid. The resulting timestamp data was incorrect, causing an error

in release builds and an assertion failure in debug builds. (Bug #26091333, Bug #86290)

• Successful data dictionary updates but failure to write the binary log event could result in an inconsistent

state. (Bug #26037355)

• mysqlbinlog now prints the full metadata for the event type Table_map_log_event. (Bug

#26020990)

497

MySQL 8.0 Release Notes

• Some string functions in an ALTER EVENT statement could cause a server exit. (Bug #25942505)

• Uninstalling the daemon_memcached plugin caused a serious error. (Bug #25909540)

• Prepared statements that used a common table expression and many ? parameters could be slow. (Bug

#25903274, Bug #85933)

• For UPDATE or DELETE statements with an ORDER BY ... LIMIT clause, the optimizer sometimes

failed to identify a cheaper ordering method than filesort. (Bug #25899921)

• The rpl_diff.inc test case file did not find the data difference between servers. Thanks to Yura

Sorokin for the patch. (Bug #25860138, Bug #85838)

• An ngram fulltext parser search query returned incorrect results and raised an assertion. (Bug

#25851975)

• The combination of an index virtual generated column, a foreign key, and a trigger could cause an

assertion to be raised. (Bug #25817660, Bug #85757)

• Selecting from a view could yield different results with materialization enabled versus materialization

disabled. (Bug #25782811, Bug #85622)

• After using SET PERSIST to set the event_scheduler system variable, the server failed to restart if

started with the --skip-grant-tables option. (Bug #25776940)

• For debug builds, adding an index to a table that had a foreign key relationship could raise an assertion.

(Bug #25739983)

• An assertion could be raised for MIN()/MAX() access to system tables. (Bug #25738624)

• The INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS table requested foreign key information

from the InnoDB storage engine instead of the data dictionary. (Bug #25730513)

• A failed DROP VIEW could be written to the binary log. (Bug #25680097)

• SHOW CREATE VIEW sometimes added a database name prefix to table names that was not present in

the original view definition. (Bug #25634576, Bug #85176)

• The Performance Schema variables_info table displayed incorrect VARIABLE_SOURCE and

VARIABLE_PATH values for variables set within option files specified by !include or !includedir

directives. (Bug #25563891)

• Constant string propagation could fail for UCA-based collations. (Bug #25503965, Bug #84837)

• mysqlpump displayed incorrect progress information about the number of tables dumped. (Bug

#25432850)

• Calculations for UCA 9.0.0 collations were inefficient for tailoring rules containing contraction characters.

(Bug #25426632, Bug #84577, Bug #25426632, Bug #84577)

• GROUP BY DESC on DECIMAL values could incorrectly group NULL with non-NULL values. (Bug

#25407964, Bug #84537)

• Some mysqldump warnings went to the standard output rather than the standard error output and

consequently were written to the dump file. (Bug #25380000, Bug #82992)

• NULL values generated as a result of WITH ROLLUP were replaced with the previous row's value when

executing a prepared statement on a view having the GROUP BY .. WITH ROLLUP clause. (Bug

#25174118)

498

MySQL 8.0 Release Notes

• A server error occurred when a full text search result exceeded the

innodb_ft_result_cache_limit setting. The patch for this bug also backports a related patch (Bug

#21140111). (Bug #25033538)

• A parser refactoring in MySQL 8.0.1 resulted in incorrect handling of some INSERT ... ON

DUPLICATE KEY UPDATE statements. These problems have been corrected. (Bug #24716127, Bug

#25526439, Bug #25071305)

• For debug builds, a CREATE TABLE statement with a VARBINARY or BINARY column having a default

value in hexadecimal format caused a server exit. (Bug #24679166, Bug #83020)

• If a stored function was considered a constant by the optimizer, calling it from a subquery in a NOT IN

condition in the WHERE clause could cause a server exit. (Bug #23577867)

• A mysqldump memory leak was fixed. Thanks to Yura Sorokin for the patch. (Bug #23531150, Bug

#81714)

• Incorrect results or a server exit could result when a query used Batched Key Access optimization and a

virtual generated column was part of the join buffer. (Bug #23169112)

• If a session rolled back to a savepoint and then was killed, the statements up to the point of the

savepoint could be committed. (Bug #22350047, Bug #79596)

• MySQL accepted a reference to an alias of an aggregated expression defined in an outer query block

even when the reference occurred within a GROUP BY subquery where the reference was meaningless.

(Bug #21974346, Bug #78785)

• For clients that used Connector/Python and authenticated using the sha256_password plugin, the

server could handle connections incorrectly. (Bug #21421642)

• Some SELECT DISTINCT queries with GROUP BY could return incorrect results. (Bug #20692219, Bug

#76283)

Changes in MySQL 8.0.2 (2017-07-17, Development Milestone)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Account Management Notes

• Character Set Support

• Compilation Notes

• Component Notes

499

MySQL 8.0 Release Notes

• Configuration Notes

• Data Dictionary Notes

• Deprecation and Removal Notes

• SQL Function and Operator Notes

• Logging Notes

• Optimizer Notes

• Packaging Notes

• Parser Notes

• Performance Schema Notes

• Plugin Notes

• Security Notes

• Spatial Data Support

• Test Suite Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• During data directory initialization or upgrade, MySQL now creates a

'mysql.session'@'localhost' reserved account. This account is used internally by plugins to

access the server. It is locked so that it cannot be used for client connections. (Bug #25642343)

• These system variables now are available to define mandatory roles and to enable granted roles to be

automatically activated at client connection time:

• mandatory_roles takes a value listing roles the server should treat as automatically granted to all

users.

• activate_all_roles_on_login enables control over automatic activation of all granted roles

when users log in to the server.

For more information, see Using Roles. (WL #924)

Character Set Support

• For Unicode data that uses NO PAD collations, sorting of multibyte and variable-length values has been

improved:

• NO PAD collations are those based on UCA 9.0.0 and higher, such as utf8mb4_0900_ai_ci or

utf8mb4_ja_0900_as_cs.

• The performance improvement is greatest for key values with short weight strings; that is, strings

where the weight strings do not fill their entire permitted length. For a VARCHAR(10) column that uses

the utf8mb4_0900_ai_ci collation, values may take up to 160 bytes. The string 'a' uses only 2

500

MySQL 8.0 Release Notes

bytes out of a possible 160 and is more sparse than 'abcdefghij'. But even 'abcdefghij' uses

only 20 bytes of a possible 160 and is more sparse than a string of, for example, ten copies of U+337F

SQUARE CORPORATION (㍿), whose weight string requires the entire 160 bytes available.

(Bug #25750527, Bug #85546, WL #9554)

• MySQL now supports a new collation, utf8mb4_0900_as_ci, for the utf8mb4 Unicode character

set. This collation is accent sensitive and case insensitive. It is similar to the default utf8mb4 collation

(utf8mb4_0900_ai_ci) except that the default collation is accent insensitive.

MySQL also now supports a new Japanese collation, utf8mb4_ja_0900_as_cs_ks, for the utf8mb4

Unicode character set. This collation is like utf8mb4_ja_0900_as_cs in that it is accent sensitive and

case sensitive, but utf8mb4_ja_0900_as_cs_ks is also kana sensitive and distinguishes Katakana

characters from Hiragana characters. utf8mb4_ja_0900_as_cs treats Katakana and Hiragana

characters as equal for sorting. Applications that require a Japanese collation but not kana sensitivity

may use utf8mb4_ja_0900_as_cs for better sort performance. utf8mb4_ja_0900_as_cs uses

three weight levels for sorting; utf8mb4_ja_0900_as_cs_ks uses four.

utf8mb4_ja_0900_as_cs_ks is the first collation to use the _ks collation suffix. Japanese collations

without this suffix are not kana sensitive.

For more information, see Unicode Character Sets. (WL #10480, WL #10818)

• These character set changes were made to MySQL client support:

• These clients use a default character set of utf8mb4 rather than latin1: mysql, mysql_upgrade,

mysqladmin, mysqlcheck, mysqldump, mysqlimport, mysqlpump, mysqlslap, mysqlshow,

and mysqltest. (This change does not affect character set autodetection performed by mysql,

mysqladmin, mysqlcheck, mysqlimport, and mysqlshow, as described at Connection Character

Sets and Collations).

• Client connections created using the libmysqlclient library use a default character set of

utf8mb4 rather than latin1.

• The mysqltest program supports a --default-character-set option for specifying the

character set explicitly.

(WL #10353)

Compilation Notes

• Performance: The strict aliasing optimization for GCC is no longer disabled, which results in a minor

improvement for MySQL single-threaded performance. (WL #10344)

• Linux: MySQL now compiles on Alpine Linux. (Bug #25945568, Bug #80322)

• Solaris: On Solaris, server builds now use std::atomic, so they must be linked against

libstatomic. (Bug #25957991)

• MySQL now compiles using Visual Studio 2017. (Bug #25788406)

• The minimum version of the Boost library for server builds is now 1.64.0. (Bug #25772329, Bug #85593)

• These changes were made with respect to client program development:

• Client programs should only need to #include the <mysql.h> header file. In particular,

<my_config.h> should not be needed, and is no longer installed.

501

MySQL 8.0 Release Notes

• The my_init() function is no longer included in the list of symbols exported from libmysqlclient.

It need not be called explicitly by client programs because it is called implicitly by other C API

initialization functions.

(Bug #25732787)

• For the Xcode IDE, header files are added to MySQL project sources so they can be searched. (Bug

#25636986)

• Work was done to clean up the source code base, including: Removing unneeded CMake checks;

removing unused macros from source files; reorganizing header files to reduce the number of

dependencies and make them more modular, removing function declarations without definitions,

replacing locally written functions with equivalent functions from industry-standard libraries.

Component Notes

• New services are available to enable components to register and unregister system variables

(component_sys_variable_register, component_sys_variable_unregister) and to register

status variables (status_variable_registration). (WL #8020)

• Two new services are available to enable components and plugins to register

and unregister loadable functions: mysql_service_udf_registration and

mysql_service_udf_registration_aggregate provide registration services for scalar and

aggregate loadable functions, respectively. These services enable components and plugins to manage

loadable functions for themselves, without the need for CREATE FUNCTION and DROP FUNCTION

statements.

Loadable functions registered using either these services or CREATE FUNCTION are listed in the new

Performance Schema user_defined_functions table. See The user_defined_functions Table. Such

loadable functions are not listed in the mysql.func system table, so the user_defined_functions

table is preferable for checking which loadable functions are installed. (WL #8020)

• The mysql_string string-manipulation service has been converted from a plugin service to a

component service: a set of string service APIs for use by components. The password validation

component has been updated to use the revised service implementation. (WL #9503)

Configuration Notes

• Previously, LOCAL capability for LOAD DATA operations was enabled by default in some contexts: The

client library in MySQL binary distributions was compiled with client-side LOCAL capability enabled, and

the local_infile system variable was enabled on the server side. LOCAL capability is now disabled

by default in all contexts. Client programs must be configured explicitly to enable LOCAL, and the server

must be run with local_infile enabled. See Security Considerations for LOAD DATA LOCAL. (Bug

#24511108)

• mysqld startup behavior has been modified as follows. In general, these changes enable more

consistent or easier server startup when not using mysqld_safe.

• The server executable determines its own full path name at startup and uses the parent of the

directory in which it is located as the default basedir value. This in turn enables the server to use that

basedir when searching for server-related information such as the share directory containing error

messages.

• If error log output cannot be redirected to the --log-error option value, error output could be lost.

This is now less likely.

502

MySQL 8.0 Release Notes

• If the server is started using the --daemonize option and is not connected to a tty device, a default

error logging option of --log-error="" is used in the absence of an explicit logging option, to direct

error output to the default log file. Previously, an error could occur under these circumstances.

• The -D and -I options now are synonyms for --daemonize and --initialize, respectively.

(Bug #20398088, Bug #75343, WL #10441)

• MySQL now supports a SET PERSIST_ONLY variant of SET statement syntax, for making configuration

changes at runtime that also persist across server restarts. Like SET PERSIST, SET PERSIST_ONLY

writes the variable setting to an option file named mysqld-auto.cnf in the data directory. However,

unlike PERSIST, PERSIST_ONLY does not modify the runtime global system variable value. This makes

PERSIST_ONLY suitable for configuring read-only system variables that only be set can at server

startup. For more information, see Using Option Files, and SET Syntax for Variable Assignment.

Use of SET PERSIST_ONLY requires the new PERSIST_RO_VARIABLES_ADMIN privilege, in addition

to the SYSTEM_VARIABLES_ADMIN privilege necessary for persisting system variables. (WL #9787)

Data Dictionary Notes

• The column_stats system table has been removed and replaced by the column_statistics data

dictionary table. (WL #8943)

• The version data dictionary table was renamed to dd_properties.

Metadata for INFORMATION_SCHEMA tables created by dynamic plugins now is recorded in the data

dictionary and visible through the INFORMATION_SCHEMA TABLES table.

These tables are no longer visible in INFORMATION_SCHEMA: SHOW_STATISTICS,

SHOW_STATISTICS_DYNAMIC, STATISTICS_BASE, STATISTICS_DYNAMIC, TABLES_DYNAMIC. User

impact is minimal because these tables are for internal use by the server. (WL #9495)

• The InnoDB storage engine now uses the MySQL data dictionary rather than its own storage engine-

specific data dictionary. For information about the data dictionary, see MySQL Data Dictionary.

The following list briefly describes the main implications of this change:

• Upgrade and downgrade implications:

• To upgrade from MySQL 5.7 to MySQL 8.0, you must perform the upgrade procedure described at

Upgrading MySQL.

• Downgrading from MySQL 8.0 to MySQL 5.7 is only supported using the logical downgrade method

(a mysqldump downgrade). In-place downgrades are not supported.

• Metadata updates associated with exporting and importing tablespaces using the transportable

tablespace feature are now performed on global data dictionary tables instead of InnoDB data

dictionary tables.

• InnoDB in-memory metadata is now instantiated from global data dictionary objects. This metadata

was previously read from InnoDB system tables.

• Table options that signify tablespace encryption and transparent page compression are now retrieved

from the global data dictionary.

503

MySQL 8.0 Release Notes

• Data dictionary support was added for InnoDB FULLTEXT indexes. Auxiliary index table names were

changed to lowercase.

• InnoDB metadata created or modified during DDL operations is now written to the global data

dictionary.

(WL #9461, WL #9537, WL #9534, WL #9531, WL #9530, WL #9525, WL #9357)

• mysql system tables and data dictionary tables are now created in a single InnoDB tablespace file

named mysql.ibd in the MySQL data directory. Previously, these tables were created in individual

InnoDB tablespace files in the mysql database directory. Associated changes include:

• The InnoDB data dictionary buffer table, which stores fast changing InnoDB metadata, was renamed

to innodb_dynamic_metadata and moved from the InnoDB system tablespace to the data

dictionary tablespace.

• Undo tablespace metadata now resides in the data dictionary tablespace.

• Temporary tablespace metadata now resides in the data dictionary tablespace.

• Table definitions for tables created in the mysql tablespace, the InnoDB system tablespace

(innodb_system), or general tablespaces now include a TABLESPACE attribute. This change has the

following implications:

• You cannot use CREATE TEMPORY TABLE ... LIKE to create an empty table based on the

definition of a table that resides in any of the aforementioned tablespaces, as these tablespaces do

not support temporary tables.

• CREATE TABLE ... LIKE preserves the TABLESPACE attribute of the original table and creates a

new table in the defined tablespace regardless of the innodb_file_per_table setting. This is a

temporary regression.

For more information and workarounds, see CREATE TABLE ... LIKE Statement, and CREATE

TEMPORARY TABLE Statement.

(WL #9532)

Deprecation and Removal Notes

• The mysql client by default strips comments in statements sent to the server, and this behavior is

controlled using --skip-comments (strip comments), and --comments (preserve comments).

Comment stripping is now deprecated. This feature and the options to control it will be removed in a

future MySQL version. (WL #10944)

• The explicit_defaults_for_timestamp system variable is now enabled by default (previously

disabled by default), and a warning occurs if you disable it. This means that the nonstandard (and

deprecated) behaviors for default values and NULL-value handling in TIMESTAMP columns are now

disabled by default. (WL #9687)

• Support for these deprecated syntax constructs for table and column references has been removed and

their use now results in an error. Instances of these constructs should be changed to remove the leading

period.

• .col_name

504

MySQL 8.0 Release Notes

• .tbl_name

• .tbl_name.col_name

(WL #8662)

• Symbolic link support as described at Using Symbolic Links for MyISAM Tables on Unix, along with the

--symbolic-links option that controls it, is now deprecated and will be removed in a future MySQL

version. In addition, the option is now disabled by default. The related have_symlink system variable

also is deprecated and will be removed in a future MySQL version. (WL #8392)

SQL Function and Operator Notes

• MySQL now supports window functions that, for each row from a query, perform a calculation using rows

related to that row. These include functions such as RANK(), LAG(), and NTILE(). In addition, most

existing aggregate functions now can be used as window functions; for example, SUM() and AVG(). For

more information, see Window Functions.

Note

Each of the following words now is a reserved word and cannot be used as an

identifier without identifier quoting: CUME_DIST, DENSE_RANK, FIRST_VALUE,

GROUPS, LAG, LAST_VALUE, LEAD, NTH_VALUE, NTILE, OVER, PERCENT_RANK,

RANK, ROW_NUMBER, WINDOW.

(WL #9236, WL #9603, WL #9727)

Logging Notes

• Incompatible Change: These error-logging changes have been made:

• The server is more forgiving if it cannot find the configured error-message file (specified using the

lc_messages_dir and lc_messages system variables). Previously, the server wrote a message

to the error log to indicate the problem, then aborted the startup process and exited. Now the server

writes a message, but continues startup and defaults to built-in English messages. This applies to

messages the server writes to the error log and sends to clients. See Setting the Error Message

Language.

• Error logging was rewritten to use the MySQL component architecture. Traditional error logging

is implemented using built-in components, and logging using the system log is implemented as a

loadable component. In addition, a loadable JSON-format log sink is available. To control which log

components to enable, use the log_error_services system variable. For more information, see

The Error Log.

• Incompatibility: To enable logging to the system log, you must load the log_sink_syseventlog

log component and list it in the log_error_services value (see Error Logging to the System Log).

This differs from MySQL 5.7 and earlier, for which logging to the system log is enabled by default on

Windows, and on all platforms requires no component loading.

A consequence of this configuration change is that the log_syslog system variable previously used

to control logging to the system log is obsolete and changes to its value have no effect. log_syslog

is now deprecated and will be removed in a future MySQL version.

(WL #9323, WL #9342, WL #9343, WL #9344)

505

MySQL 8.0 Release Notes

Optimizer Notes

• MySQL now enables management of histogram statistics for table column values:

• The ANALYZE TABLE statement supports UPDATE HISTOGRAM and DROP HISTOGRAM clauses for

generating and removing column histogram statistics.

• The server stores histogram information in the column_statistics data dictionary table.

Histograms are viewable using the INFORMATION_SCHEMA.COLUMN_STATISTICS table.

• The histogram_generation_max_mem_size system variable controls the amount of memory

available for histogram generation.

• The Performance Schema has a memory/sql/histograms instrument for monitoring memory

allocations performed for histogram generation.

• mysqldump and mysqlpump have a --column-statistics option to add ANALYZE TABLE

statements to the output to generate histogram statistics for dumped tables when the dump file is

reloaded.

For more information, see ANALYZE TABLE Statement, Optimizer Statistics, and The

INFORMATION_SCHEMA COLUMN_STATISTICS Table. (WL #8943)

Packaging Notes

• mysqladmin was added to Docker/Minimal packages because it is needed by InnoDB Cluster. (Bug

#25998285)

• For Windows, MSI installer packages now include a check for the required Visual Studio redistributable

package, and produce a message asking the user to install it if it is missing. (Bug #25658832)

• Debian/Ubuntu packages now support multiple MySQL instances with systemd. See Managing MySQL

Server with systemd. (Bug #24559588, Bug #82785)

Parser Notes

• The parser rules for ALTER TABLE were refactored to be context independent and improve

maintainability and extensibility. A resulting effect is that some previously accepted undocumented

syntax variants are no longer accepted. For example, CREATE TABLE statements were permitted with

column names qualified by the table name, or by the current database and table name, as were certain

ALTER TABLE statements for which only column names are permitted. Such statements now produce

an error. (WL #8657)

Performance Schema Notes

• The Performance Schema threads table now contains a RESOURCE_GROUP column that indicates

resource group labels. (WL #8881)

• The Performance Schema now supports versioning, and maintains the current definitions for its

tables internally. At startup, the server compares its supported Performance Schema version with the

Performance Schema version stored in the data dictionary. If the versions differ, the server drops any

old Performance Schema tables and recreates them using the current definitions. In consequence of this

change:

• For MySQL upgrades, it is no longer necessary to run mysql_upgrade to incorporate changes to

Performance Schema tables because they are recreated automatically as necessary at server startup.

506

MySQL 8.0 Release Notes

• The mysql_system_tables.sql support script no longer includes SQL statements for Performance

Schema table creation because these table definitions are maintained internally.

To support dynamic Performance Schema table manipulation, a new component service named

pfs_table_service is now available. (WL #7900, WL #8879)

• The Performance Schema default instrumentation settings have changed:

• The transaction instrument and the events_transactions_current and

events_transactions_history consumers are now enabled by default. See Performance

Schema Transaction Tables.

• All memory/% memory instruments are now enabled by default. See Memory Summary Tables.

• The wait/lock/metadata/sql/mdl metadata lock instrument is now enabled by default. See The

metadata_locks Table.

(WL #9625, WL #9628, WL #9629)

Plugin Notes

• Incompatible Change: Plugins such as Group Replication and X Plugin now use the mysql.session

account added in this release. If you are upgrading from a previous release which did not include

the mysql.session account, you must run mysql_upgrade to ensure the account is created. If

mysql_upgrade is not run, plugins fail to start with the error message There was an error when

trying to access the server with user: mysql.session@localhost. Make sure the

user is present in the server and that mysql_upgrade was run after a server

update. User accounts previously used for this purpose, such as mysqlxsys, are no longer created.

(Bug #26042764)

References: See also: Bug #24311527, Bug #25642343, Bug #25750822, Bug #25103980, Bug #83841.

Security Notes

• The linked OpenSSL library for the MySQL Commercial Server has been updated to version

1.0.2l. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/

vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (Bug #26160962)

• Previously, any user could execute the XA RECOVER statement to discover the XID values for

outstanding prepared XA transactions, possibly leading to commit or rollback of an XA transaction by a

user other than the one who started it. Now XA RECOVER is permitted only to users who have the new

XA_RECOVER_ADMIN privilege, which is expected to be granted only to administrative users who have

need for it. This might be the case, for example, for administrators of an XA application if it has crashed

and it is necessary to find outstanding transactions started by the application so they can be rolled back.

This privilege requirement does not affect normal commit or rollback of an XA transaction because the

user who started it knows its XID.

For MySQL uprades, mysql_upgrade grants XA_RECOVER_ADMIN to users who have the SUPER

privilege, unless some account is found that already has XA_RECOVER_ADMIN. (Bug #17188129, WL

#7194)

507

MySQL 8.0 Release Notes

Spatial Data Support

• Argument suitability checking was improved for these spatial functions that test geometry relationships:

ST_Contains(), ST_Crosses(), ST_Disjoint(), ST_Equals(), ST_Intersects(),

ST_Overlaps(), ST_Touches(), ST_Within(), MBRContains(), MBRCoveredBy(),

MBRCovers(), MBRDisjoint(), MBREquals(), MBRIntersects(), MBROverlaps(),

MBRTouches(), MBRWithin(). For more information, see Spatial Relation Functions That Use Object

Shapes, and Spatial Relation Functions That Use Minimum Bounding Rectangles.

As a consequence of this work, performance of spatial relation functions was improved for cases where

both arguments contain geometries of one dimensionality; that is, where the GeometryCollection

arguments (or one GeometryCollection and another type of geometry) passed to a spatial relation

function can be reduced to a MultiPoint, MultiLineString, or MultiPolygon. In those cases,

the more complex general GeometryCollection can be avoided. (Bug #22285402, Bug #79406, WL

#8685)

Test Suite Notes

• The --do-test-list option for mysql-test-run.pl accepts an argument for a file containing tests

one per line. Lines in the file are now accepted in any of the following formats:

test_name

test_name.test

suite_name.test_name

suite_name.test_name.test

path/to/test/file

(Bug #25700362)

• mysql-test-run.pl and mysqltest are now more restrictive about permitted test case and

result file names. Names must consist only of alphanumeric characters (A-Z, a-z, 0-9), dash (-), or

underscore (_), and cannot start with dash or underscore. An error occurs for nonconforming file names.

(Bug #25487471)

• These changes were made to the --xml-report option for mysql-test-run.pl:

• A <failure> tag identifies any test failing on a retry attempt.

• Separate statistics and fields are included for skipped and disabled tests.

• The XML report is created in the build directory if no absolute path is given for out-of-source builds.

• For combination runs, a field named variation is included in the <testcase> tag.

• Results for all tests belonging to a suite are aggregated within a single <testsuite> tag.

• Information regarding failures is reported with a brief reason in an attribute named message, along

with other details within the tag.

(Bug #25349924)

• mysql-test-run.pl now supports a --report-unstable-tests option that has these effects:

• Reports any test that has passed using at least one retry attempt in a separate category called

“Unstable tests” in the summary.

• If all failures are due to unstable tests, mysql-test-run.pl produces a warning but exits

successfully.

508

MySQL 8.0 Release Notes

• Adds a new XML tag to report unstable tests, if the --xml-report option is also specified.

(Bug #24473420, Bug #25984429)

• mysqltest now supports a replace_numeric_round command that takes an argument value from

0 to 16 indicating the number of decimals to round numeric values to. This can be used to help prevent

result content mismatch errors for tests in which slightly different results are obtained across platforms

due to precision differences. Thanks to Daniel Black for the patch. (Bug #23280117, Bug #81399)

• mysql-test-run.pl now looks for a testname-client.opt file, which is analogous to the

testname-master.opt file but for specifying test-specific client options. (Bug #17084918)

X Plugin Notes

• X Plugin now handles expired SSL certificates correctly. (Bug #25835833)

• The output of clauses such as GROUP BY and HAVING has been improved by moving the

grouping_criteria expression to the derived query. (Bug #25549637, Bug #24497007)

• During install of the X Plugin a blank rule was being generated in the Firewall white list. (Bug

#24488234)

Functionality Added or Changed

• Incompatible Change; InnoDB: ADD PARTITION, DROP PARTITION, COALESCE PARTITION,

REORGANIZE PARTITION, and REBUILD PARTITION ALTER TABLE options are now supported

by native partitioning in-place APIs and may be used with ALGORITHM={COPY|INPLACE} and LOCK

clauses.

EXCHANGE PARTITION, which previously supported ALGORITHM and LOCK clauses, is performed by

a new server layer API for compatibility with the MySQL data dictionary. Partition and table exchange is

performed internally by the native partition handler.

DROP PARTITION with ALGORITHM=INPLACE deletes data stored in the partition and drops the

partition. However, DROP PARTITION with ALGORITHM=COPY or old_alter_table=ON rebuilds

the partitioned table and attempts to move data from the dropped partition to another partition with a

compatible PARTITION ... VALUES definition. Data that cannot be moved to another partition is

deleted. (WL #9559)

• InnoDB: InnoDB now uses tablespace map files during recovery to identify tablespaces that require

redo log application. This is a change from redo log tablespace discovery that was used previously.

If tablespace map files are lost or corrupted, the innodb_scan_directories startup option may be

used to specify tablespace directories when starting MySQL after a server outage.

For more information, see Tablespace Discovery During Crash Recovery. (Bug #24793413, WL #9499)

• InnoDB: In previous releases, InnoDB stores ROW_FORMAT and KEY_BLOCK_SIZE attributes specified

in CREATE TABLE or ALTER TABLE statements even if those attributes are silently ignored when

creating or altering a table. In such cases, SHOW CREATE TABLE and the Create_options column

reported by SHOW TABLE STATUS show the specified ROW_FORMAT and KEY_BLOCK_SIZE attributes

rather than the actual attributes of the table. InnoDB now stores and reports the actual ROW_FORMAT

and KEY_BLOCK_SIZE attributes of the table. (WL #9525)

• Replication: In previous versions issuing STOP GROUP_REPLICATION stopped the plugin but the

server still accepted transactions. This meant the transactions were not transmitted to the group. To

509

MySQL 8.0 Release Notes

make STOP GROUP_REPLICATION safer, now super_read_only is set to ON immediately upon

issuing STOP GROUP_REPLICATION, which ensures no transactions are accepted. (Bug #25495067,

Bug #84795, WL #10611, WL #10960)

• Replication: When there was a network partition and a member was in a

minority all queries to that member blocked. To improve this situation, the

group_replication_unreachable_majority_timeout variable has been added which enables

you to configure how long members in a minority wait to regain contact with a member in the majority

before leaving the group. (Bug #25473794)

• Replication: The group_replication_transaction_size_limit variable was added to enable

you to protect a group against large transactions causing a failure. (Bug #84785, Bug #25510757)

• Replication: Support for binary log files created by versions earlier than MySQL 5.0 has been removed,

and binary log Version 1 and Version 3 formats are no longer supported by slaves or mysqlbinlog.

(WL #9219)

• Replication: The Performance Schema replication_group_members and

replication_group_member_stats tables have been extended to provide additional

monitoring information for Group Replication. replication_group_members now includes

information about member roles and the version of MySQL running on a given member.

replication_group_member_stats now includes information about all members in the group, the

applier and local queues, and transactions which have been rolled back. (WL #10380)

• Replication: The receiver thread has been improved to no longer block other thread's activities when

waiting for disk space. This improves the monitoring of replication ensuring that it reports correctly

when the receiver thread is waiting for disk space. If you are not able to free disk space to allow the

receiver thread to continue its activity, it can be forcefully stopped without side effects in most cases.

(WL #10406)

• Replication: A new transaction length field has been added to the Gtid_log_event which stores the

transaction length in bytes. (WL #10493)

• Replication: The following variables have had their defaults changed to ensure replication is as robust

and efficient as possible by default:

• master_info_repository=TABLE and relay_log_info_repository=TABLE ensure that

replication repository information is stored in InnoDB tables, making replication resilient to unexpected

halts.

• transaction_write_set_extraction=XXHASH64 enables the optimal method for generating

write set hashes.

• slave_rows_search_algorithms='INDEX_SCAN,HASH_SCAN' enables the use of a hash

table to avoid repeated table scans when no Primary Key or Primary Key Equivalent (non-null unique

secondary index) exists for a table

• expire_logs_days=30 causes unused binary logs that are older than 30 days to be purged,

ensuring storage space is used efficiently.

(WL #10474, WL #10476, WL #10477, WL #10478)

• Replication: The Group Replication plugin now notifies other server components that relevant events

have occurred; the plugin informs listeners registered in the service registry and notifies them that an

event has occurred. These listeners, including other plugins, can then react to these events. Such events

include view changes, recovery state updates, network partitioning, and primary election. (WL #10412)

510

MySQL 8.0 Release Notes

• Group Replication: The group_replication_member_weight variable has been added which

enables you to control the election of new primaries in single-primary mode. In previous versions

primary election was based on the member's UUID, with the lowest UUID elected as the new primary

in the event of fail over. Use this variable to assign numeric weights to members to ensure that specific

members are elected, for example during scheduled maintenance of the primary or to ensure certain

hardware is prioritized. (WL #10433, WL #10959)

• Group Replication: The following system variables affecting Group Replication have been added in this

release:

• group_replication_flow_control_hold_percent

• group_replication_flow_control_max_quota

• group_replication_flow_control_member_quota_percent

• group_replication_flow_control_min_quota

• group_replication_flow_control_min_recovery_quota

• group_replication_flow_control_period

• group_replication_flow_control_release_percent

These variables enable you to fine-tune flow control of individual group members, adjusting the quota

depending on the task the member performs in the group. (WL #9838)

• JSON: Added support for ranges in the XPath expressions used with many MySQL JSON functions,

including JSON_EXTRACT() and JSON_REMOVE(). Such a range is specified using the syntax start

to end, where start and end are, respectively, the first and last indexes of a range of elements from

a JSON array (always numbered starting with 0). For example, $[1 to 3] includes the second, third,

and fourth elements, as shown here:

mysql> SELECT JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[1 to 3]');

+----------------------------------------------+

| JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[1 to 3]') |

+----------------------------------------------+

| [2, 3, 4] |

+----------------------------------------------+

1 row in set (0.00 sec)

This work also provides support in such expressions for the last keyword, which you can use to

represent the index of the last (rightmost) element in the current array, like this:

mysql> SELECT JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[last]');

+--------------------------------------------+

| JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[last]') |

+--------------------------------------------+

| 5 |

+--------------------------------------------+

1 row in set (0.00 sec)

Indexes relative to the end of the array are also supported, as shown here:

mysql> SELECT JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[last-4 to last-2]');

+--------------------------------------------------------+

| JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[last-4 to last-2]') |

+--------------------------------------------------------+

| [1, 2, 3] |

+--------------------------------------------------------+

1 row in set (0.00 sec)

511

MySQL 8.0 Release Notes

For further information and examples, see Searching and Modifying JSON Values. (Bug #79052, Bug

#22285926, WL #9831)

• JSON: The optimizer now supports partial (in-place) updates of JSON documents when using

JSON_SET(), JSON_REPLACE(), or JSON_REMOVE(). (Previously, all updates of JSON column values

were done by completely removing the previous document and writing the new one in its place.) In

general, this optimization can be performed when the replacement value is less than or equal in size to

the column's original value, and no new elements are added to the original value. It cannot be performed

for a simple replacement of the column value of the form UPDATE tbl SET json_col = json_val.

The JSON Data Type provides more information about the requirements for an update to be optimized in

this way.

This work includes the addition of two JSON utility functions, JSON_STORAGE_SIZE() and

JSON_STORAGE_FREE(), in the MySQL Server. JSON_STORAGE_SIZE() returns the number of bytes

used to store the binary representation of a JSON document, whether the document is presented as

a column value in a table, as the value of a user variable, or as a JSON literal. In the case of a JSON

column, this is the space used to store the JSON document as it was inserted into the column, prior to

any partial updates that may have been performed on it since then. JSON_STORAGE_FREE() shows the

number of bytes in the binary representation of a JSON column value that were freed by the most recent

partial update of the column. For a user variable storing a JSON document, JSON_STORAGE_FREE()

always returns 0; it also returns 0 if the argument is a JSON literal.

Each of these functions, like many other MySQL functions that act on JSON values, also accepts a string

that can be successfully parsed as a JSON document. For more information and examples, see JSON

Utility Functions. (WL #9192, WL #8963, WL #10570)

• RPM .spec files now include support for running unit tests. (Bug #25814143, Bug #85743)

• The mysql client now supports a --binary-as-hex option that causes display of binary data using

hexadecimal notation (0xvalue). Thanks to Daniël van Eeden for the patch. (Bug #25340722, Bug

#84391)

• The SHOW TABLES statement now supports an optional EXTENDED keyword that causes statement

output to list hidden tables created by failed ALTER TABLE statements. (These temporary tables have

names beginning with #sql.) For more information, see SHOW TABLES Statement. (Bug #24786075,

Bug #83241)

• Serialized dictionary information (SDI) files now have a lowercase extension (.sdi) instead of

uppercase. (WL #7069)

• The TempTable storage engine replaces the MEMORY storage engine as the default engine for in-

memory internal temporary tables. The TempTable storage engine provides efficient storage for

VARCHAR and VARBINARY columns. The internal_tmp_mem_storage_engine session variable

defines the storage engine for in-memory internal temporary tables. Permitted values are TempTable

(the default) and MEMORY. The temptable_max_ram configuration option defines the maximum amount

of memory that can be occupied by the TempTable storage engine before it starts storing data on disk.

The default value is 1073741824 bytes (1GiB).

The memory/temptable/physical_ram and memory/temptable/physical_disk Performance

Schema instruments may be used to monitor TempTable memory allocation and disk storage. (WL

#8117)

512

MySQL 8.0 Release Notes

• The MySQL 8.0.2 release introduces a number of undo related changes:

• The number of undo tablespaces can now be modified at runtime, or when the server is restarted,

using the innodb_undo_tablespaces configuration option. Previously, the number of undo

tablespaces could only be configured when initializing the MySQL instance and could not be changed

afterward. This change permits the addition of undo tablespaces and rollback segments as the

database grows.

• innodb_undo_log_truncate is enabled by default. When enabled, any undo tablespace that

exceeds the threshold value defined by innodb_max_undo_log_size is marked for truncation. See

Truncating Undo Tablespaces.

• The innodb_undo_tablespaces default value was changed from 0 to 2, which means that rollback

segments are created in two separate undo tablespaces instead of the InnoDB system tablespace by

default. A minimum of two undo tablespaces is required to permit truncation of undo logs.

Setting innodb_undo_tablespaces to 0 is deprecated and will not be supported in a future MySQL

version.

• The naming convention used for undo tablespace files is changed from undoNNN to undo_NNN, where

NNN is the undo space number.

• The innodb_rollback_segments configuration option defines the number of rollback segments

per undo tablespace. Previously, innodb_rollback_segments was a global setting that specified

the total number of rollback segments for the MySQL instance. This change increases the number

of rollback segments available for concurrent transactions. More rollback segments increases the

likelihood that concurrent transactions use separate rollback segments for undo logs, resulting in less

resource contention.

• The innodb_undo_logs configuration option is removed. The innodb_rollback_segments

configuration option performs the same function and should be used instead.

• The Innodb_available_undo_logs status variable is removed. The number of available

rollback segments per tablespace may be retrieved using SHOW VARIABLES LIKE

'innodb_rollback_segments';

(WL #9507, WL #10498, WL #10499, WL #10322)

• The SHOW COLUMNS and SHOW INDEX statements now support an optional EXTENDED keyword that

causes statement output to include information about hidden columns and indexes that MySQL uses

internally and are not accessible by users. For more information, see SHOW COLUMNS Statement, and

SHOW INDEX Statement. (WL #9570)

Bugs Fixed

• InnoDB: Queries run on INFORMATION_SCHEMA.TABLES performed more slowly with

information_schema_stats set to latest. (Bug #26197113)

• InnoDB: An ALTER TABLE ... ADD PARTITION operation that specified a DATA DIRECTORY clause

failed to ignore the TABLESPACE attribute of the table. (Bug #26113652)

• InnoDB: When foreign_key_checks is disabled, a child table with a foreign key constraint can be

created before the parent table, which can result in a foreign key constraint failure, as the parent table is

unaware of the constraint. When a table is created, there is now a call to load foreign key constraints for

the table and check for child tables. (Bug #25976199)

• InnoDB: A parsing error occurred while optimizing a table with a full-text index. (Bug #25914332)

513

MySQL 8.0 Release Notes

• InnoDB: Compiling MySQL on Windows with Microsoft Visual C++ 2015 or macOS 10.12.4 with GCC

4.2.1 or Apple LLVM version 8.0.0 (clang-800.0.38) returned warnings. (Bug #25910531)

• InnoDB: In debug builds, an assertion was raised during bootstrap when the system tablespace file

(ibdata1) ran out of space during creation of doublewrite pages. (Bug #25872368)

• InnoDB: Incorrect locking order caused a deadlock when InnoDB attempted to persist an auto-

increment counter value to disk. (Bug #25833228)

• InnoDB: Internal methods for accessing dictionary table object data did not account for virtual columns.

(Bug #25822154)

References: This issue is a regression of: Bug #23748128.

• InnoDB: The length of a virtual column field in a virtual index record was less than the expected

template column length. (Bug #25793677)

• InnoDB: In debug builds, shutting down the server with --innodb-fast-shutdown=0 raised an

assertion. (Bug #25756224)

• InnoDB: The ibd2sdi utility exited when run on an unsupported file type. (Bug #25738491)

• InnoDB: InnoDB did not set the compression algorithm when opening a partitioned table. (Bug

#25685868)

• InnoDB: An in-place ALTER TABLE operation failed to set the encryption type, causing a FLUSH

TABLES ... FOR EXPORT operation to assert. (Bug #25672779)

• InnoDB: A latch that was held while registering a file close caused a hang condition. (Bug #25658467)

• InnoDB: During recovery, prepared transactions were rolled back if the innodb_force_recovery

setting was greater than 0. (Bug #25651042)

• InnoDB: A CREATE TABLE operation that defined a unique key with an eight character prefix on a NOT

NULL TEXT field would raise an assertion if a primary key was not defined. (Bug #25647413)

• InnoDB: Updates to data dictionary tables combined with updates to InnoDB system tables for full-text

search auxiliary tables raised a lock-related assertion. (Bug #25610353)

• InnoDB: The server allocated memory unnecessarily for an operation that rebuilt the table. (Bug

#25573565, Bug #85043)

• InnoDB: Test-related code intended to simulate a random read on a nonexistent page raised an invalid

assertion. (Bug #25479538)

References: This issue is a regression of: Bug #25053705.

• InnoDB: With foreign_key_checks disabled, InnoDB incorrectly printed messages to the error log

when operations were performed on a table that referenced a nonexistent foreign key. (Bug #25365223)

• InnoDB: During a TRUNCATE TABLE operation on a file-per-table tablespace, a dictionary operation

lock was released before eviction of dirty pages from the buffer pool, causing a latch order violation.

(Bug #25357789)

• InnoDB: A DROP TABLE or TRUNCATE TABLE operation could raise an assertion following a failed

online ALTER TABLE .. ADD INDEX operation. The index root page was dropped prematurely. (Bug

#25357789)

514

MySQL 8.0 Release Notes

• InnoDB: When using an index merge optimizer switch, a SELECT COUNT(*) operation sometimes

returned 0. Partitioning code incorrectly performed a memcpy instead of a column copy of columns read

by the index, causing the wrong records to be copied. (Bug #25332330, Bug #81031)

• InnoDB: After a RENAME TABLE operation that moved a table to a different schema, InnoDB returned

an error on restart indicating that it could not locate the tablespace data file. InnoDB failed to update

INNODB_SYS_DATAFILES data dictionary table during the RENAME TABLE operation. (Bug #25189192,

Bug #84038)

• InnoDB: During an ALTER TABLE operation that rebuilt a table containing a virtual column, InnoDB

failed to apply a concurrent insert log record. (Bug #24961167)

• InnoDB: InnoDB failed to apply the concurrent delete log for an in-place ALTER TABLE operation due

to a virtual column validation issue. (Bug #24960450)

• Partitioning: Following execution of an ALTER TABLE ... OPTIMIZE PARTITION statement, names

of tablespaces used by the table were not preserved, and subsequent accesses to the table eventually

caused the server to fail. (Bug #25512556)

• Replication: When replicating a partitioned table with an index, on a replication slave where

HASH_SCAN was specified as part of the slave_rows_search_algorithms setting, the slave I/O

thread sometimes stopped with an error HA_ERR_KEY_NOT_FOUND. (Bug #26137159)

• Replication: A USE statement that followed a SET GTID_NEXT statement sometimes had no effect.

(Bug #26128931)

• Replication: A misleading warning was issued when the command FLUSH LOGS or PURGE LOGS

BEFORE was used on a binary log file with an expiry time set, and the binary log file was in use. The

warning related to the file being in use, and implied that a purge attempt had taken place, even if the

expiry time had not yet been reached. Now, MySQL checks the expiry time of the binary log file first, and

only then checks whether the file is in use. So the warning is only issued for an in-use binary log file that

is old enough to be purged. (Bug #25973525)

• Replication: Groups can now contain members running different server versions to enable you to

do online upgrades of a replication group. The rules for combining members in a group with different

versions are:

• If you have a group with 8.0 members, you cannot add a 5.7 member

• If you have a group with 5.7 members you can add a 8.0 member, but it remains in read-only mode.

Writing to this member is dangerous while the group contains multiple server versions and should be

avoided.

In a single-primary group, if the current primary leaves the group and a new primary must be elected, the

primary is first chosen from the lower version members. If no lower version member is found, the primary

is chosen from newer version members. (Bug #25876807)

• Replication: Now that XA transactions are prepared and committed in two parts, an issue with

statement-based replication has been identified. If two XA transactions committed on the master are

515

MySQL 8.0 Release Notes

being prepared on the slave in the inverse order, locking dependencies can occur that cannot be safely

resolved. The issue is not present with row-based replication.

XA transactions are therefore now considered unsafe for statement-based replication.

• When binlog_format = STATEMENT, a warning is issued for DML statements inside XA

transactions, and replication might fail with deadlock on slaves.

• When binlog_format = MIXED, DML statements inside XA transactions are logged using row-

based replication.

• When binlog_format = ROW, DML statements inside XA transactions are logged as before.

(Bug #25786490, Bug #85639)

• Replication: The following Performance Schema replication tables now continue to be populated when

the Performance Schema is disabled:

• replication_connection_configuration

• replication_connection_status

• replication_applier_configuration

• replication_applier_status

• replication_applier_status_by_coordinator

• replication_applier_status_by_worker

The exception is local timing information (start and end timestamps for transactions) in the replication

tables replication_connection_status, replication_applier_status_by_coordinator,

and replication_applier_status_by_worker. This information is not collected when the

Performance Schema is disabled. (Bug #25694813)

• Replication: When first starting the MySQL server following an installation from RPM, passwword

validation plugin is activated by default (true only for RPM installations). If binary logging was already

enabled at this time, the activation was logged, even though plugin activations should not be recorded in

the binary log. (Bug #25672750)

• Replication: The XA START, XA END, XA COMMIT, and XA ROLLBACK statements, used to perform

XA transactions, were incrementing the counter for a replicate-do-db filter that named the relevant

database. The counter is no longer incremented for these statements. (Bug #25669344)

• Replication: MySQL 8.0 servers were not able to join a replication group that contained MySQL 5.7

servers, and MySQL 5.7 servers in a replication group could not be upgraded to MySQL 8.0. (Bug

#25477979)

• Replication: When mysqlbinlog output from a MySQL 5.7 server was applied on a MySQL 8.0 server,

the MySQL 8.0 server generated its own timestamp for the original_commit_timestamp. The

fix ensures that the value of original_commit_timestamp is correctly set to 0, meaning that the

timestamp is not known. (Bug #25316086)

• Replication: If the server was started with the --log-bin option, discovery of one Performance

Schema table with invalid structure caused all subsequently checked Performance Schema tables to be

marked invalid as well. (Bug #25041396)

516

MySQL 8.0 Release Notes

• Replication: Interleaved transactions could sometimes deadlock the slave applier when the transaction

isolation level was set to REPEATABLE-READ. (Bug #25040331)

• Replication: The slave_skip_errors system variable did not permit error numbers larger than 3000.

Thanks to Tsubasa Tanaka for the patch. (Bug #24748639, Bug #83184)

• Replication: The SQL state of ER_TRANSACTION_ROLLBACK_DURING_COMMIT was HY00, which is

generic and not suitable for rollback. The SQL state has been modified to 40000. (Bug #24658431)

• Replication: mysqlbinlog, if invoked with the --raw option, does not flush the output file until

the process terminates. But if also invoked with the --stop-never option, the process never

terminates, thus nothing is ever written to the output file. Now the output is flushed after each event.

(Bug #24609402)

• Replication: A memory leak in mysqlbinlog was fixed. The leak happened when processing fake

rotate events, or when using --raw and the destination log file could not be created. The leak only

occurred when processing events from a remote server. Thanks to Laurynas Biveinis for his contribution

to fixing this bug. (Bug #24323288, Bug #82283)

• Replication: A slave server could lose events not yet applied when MASTER_AUTO_POSITION=0,

both replication threads were stopped, and the applier delay was changed using CHANGE MASTER TO

MASTER_DELAY=N. (Bug #23203678, Bug #81232)

References: See also: Bug #25340185, Bug #84375.

• Replication: Transmission of large GCS messages could take so long the sender appeared to have

died. (Bug #22671846)

• Replication: Multithreaded slaves could not be configured with small queue sizes using

slave_pending_jobs_size_max if they ever needed to process transactions larger than that

size. Any packet larger than slave_pending_jobs_size_max was rejected with the error

ER_MTS_EVENT_BIGGER_PENDING_JOBS_SIZE_MAX, even if the packet was smaller than the limit

set by slave_max_allowed_packet.

With this fix, slave_pending_jobs_size_max becomes a soft limit rather than a hard

limit. If the size of a packet exceeds slave_pending_jobs_size_max but is less than

slave_max_allowed_packet, the transaction is held until all the slave workers have empty

queues, and then processed. All subsequent transactions are held until the large transaction has been

completed. The queue size for slave workers can therefore be limited while still allowing occasional

larger transactions. (Bug #21280753, Bug #77406)

• Replication: An incident event that broke replication was not written to the binary log with a GTID, so

that it was not possible to skip the event using SET gtid_next=value. Instead, it was necessary to

set the relay log file and relay log positions directly; this meant that, when autopositioning was enabled,

it was necessary first to disable it, then to set the relay log file and position, and finally to re-enable

autopositioning.

Now in such cases MySQL writes the incident event into the statement cache, so that a GTID is

generated and written for it prior to flushing, and that the slave applier works with the change. Then

users can skip the event using the SQL statement SET gtid_next=value, followed by BEGIN and

COMMIT. (Bug #19594845)

• Replication: Setting an empty filter rule using CHANGE REPLICATION FILTER caused issues when

running tests with UBSan. (Bug #85405, Bug #25702297)

517

MySQL 8.0 Release Notes

• Replication: When the receiver thread held a lock on the relay log while queuing an event, clients

executing SHOW SLAVE STATUS or SHOW RELAYLOG EVENTS were blocked. (Bug #85084, Bug

#25584734)

• Replication: Indexes for the Performance Schema replication_applier_status_by_worker

table worked correctly only for single threaded replication. This was due to the fact that the indexing

relied exclusively on the SQL thread ID regardless of the existence of any workers. Now in such cases,

the index also considers worker thread ID when multithreading is enabled on the slave. (Bug #84646,

Bug #25444610)

• Replication: In certain cases, the master could write to the binary log a last_committed value which

was smaller than it should have been. This could cause the slave to execute in parallel transactions

which should not have been, leading to inconsistencies or other errors. (Bug #84471, Bug #25379659)

• Replication: When using group_replication_ip_whitelist=AUTOMATIC, IPs in the private

network are permitted automatically, but some class C IP addresses were not being permitted correctly.

(Bug #84329, Bug #25503458)

• Replication: The replication applier thread returns Error 3002 ER_INCONSISTENT_ERROR when there

is a difference between an expected error number and the actual error number. It is now possible to

ignore this error by using 3002 with slave_skip_errors. (Bug #83186, Bug #24753281)

• Replication: MySQL lost its GTID position following a restart when a dump from mysqldump had been

used to load data.

To keep this problem from occurring, the mysql.gtid_executed table is now excluded automatically

from dumps made by mysqldump. (Bug #82848, Bug #24590891)

References: See also: Bug #87455, Bug #26643180.

• Replication: It was possible to set binlog_format without causing an error when there were open

temporary tables. (Bug #82467, Bug #24411680)

• Replication: Corruption of relay logs for one channel in multi-source replication caused good channels

not to be initalized during a server restart. In addition, when run with --skip-slave-start=false,

the server also failed to start slave threads for those channels which were in good condition, despite the

fact that it should have started the slave threads for all good channels.

Now, regardless of any errors on other channels, the server attempts to create and initialize channels

that are in good condition, and starts slave threads for the good channels if --skip-slave-start

is disabled. As part of this fix, START SLAVE and STOP SLAVE, which are intended to operate on all

channels, are also modified such that they continue executing on all good channels even if they find bad

channels among them. (Bug #82209, Bug #24285104)

• Replication: The SQL thread was unable to GTID skip a partial transaction. (Bug #81119, Bug

#25800025)

• Replication: It was possible for FLUSH LOGS to write a Rotate_log_event into an uninitialized log

file. (Bug #80368, Bug #22732184)

References: See also: Bug #23531998, Bug #81734.

• Group Replication: When binlog_checksum was NONE following startup, when Group Replication

was started and an error occurred, the server remained in the RECOVERING state and could not be shut

down. (Bug #25793366, Bug #85667)

• Group Replication: In a Group Replication setup where circular asynchronous replication was

implemented between members of different replication groups, view change log events were repeatedly

518

MySQL 8.0 Release Notes

replicated between the groups with new generated GTIDs each time. This fix ensures that view change

log events are ignored outside the named replication group in which they occur, and never generate new

GTIDs. (Bug #25674926)

References: See also: Bug #26049695, Bug #25928854, Bug #25721175.

• Group Replication: In a setup where single-primary Group Replication was combined with

asynchronous replication, for example with servers S1 and S2 forming a group, and S2 and S3

functioning as master and slave, secondaries such as S2 accepted transactions and were then able to

enter the group. This fix prevents a secondary from creating an asynchronous replication channel when

it belongs to a single-primary group, and Group Replication from starting while asynchronous replication

is running. (Bug #25574200, Bug #85047)

References: See also: Bug #86325, Bug #26078602.

• Group Replication: Group Replication failed to start if the super_read_only system variable was

enabled. (Bug #25481287, Bug #84733)

• Group Replication: In the event that a member failed to join a group the member was not stopping

and continued to accept transactions. To avoid this set your members to use super_read_only=1

in the my.cfg file. Group Replication now checks for this setting upon successful startup, and sets

super_read_only=0. This ensures that members which do not successfully join a group cannot

accept transactions. (Bug #25474736, Bug #84728)

• Group Replication: Loading and initialization of the Group Replication plugin failed if no root account

was present. (Bug #24311527)

References: See also: Bug #25750822, Bug #25103980, Bug #83841.

• Group Replication: Issuing SHOW SLAVE STATUS FOR CHANNEL

'group_replication_recovery' following restart of a server using group replication led to an

unplanned shutdown. (Bug #85739, Bug #25813258)

• Group Replication: When an existing GTID_NEXT transaction was assigned a conflicting GTID by the

server, Group Replication generated an assert upon detecting two transactions with same GTID. This

was because Group Replication generates the GTID after conflict detection, which is later than with

asynchronous replication. When the transaction has been committed, the server issues a warning that

the GTID has already been used, and the transaction is rolled back. (Bug #84153, Bug #25232042)

• Microsoft Windows: On Windows, the Docs/INFO_SRC file was missing the build-date entry. (Bug

#25799855)

• JSON: NULLIF() failed with an assertion error in debug builds if the result from this function was used

in a JSON context. This result can now be used safely as a JSON value.

This fix includes using DBUG_ASSERT() for handling this error instead of DBUG_ABORT(), which caused

debugging problems on some platforms. (Bug #25818544)

References: See also: Bug #21383497, Bug #21383530.

• JSON: The internal Json_array now uses a std::vector instead of a Prealloced_array to store

its elements, which reduces the amount of heap space required by them. (Bug #85877, Bug #25867454)

• When the character set of one string comparison operand was a superset of the character set of the

other operand, some comparisons were disallowed that should be permitted by converting the operand

with the “smaller” character set to the “larger” character set. utf8mb4 and utf32 are considered to be a

superset of any other encoding. (Bug #27897053, Bug #25642319, Bug #85224)

519

MySQL 8.0 Release Notes

• The mysqld_pre_systemd script in RPM packages found the error log setting in option files if specified

as log-error but not as log_error, though both are permitted. (Bug #26148391, Bug #86466)

• ALTER TABLE ... ADD PARTITION statements could cause a server exit. (Bug #26132947)

• SET PERSIST did not work for X Plugin system variables. (Bug #26115672)

• REFERENCES privilege checking could use the incorrect database in some cases. (Bug #26106655)

• With the gtid_mode system variable not set in a .cnf option file or on the command-line, the server

failed to restart after using SET PERSIST or SET GLOBAL to set gtid_mode to ON_PERMISSIVE. (Bug

#26085712)

• During prepared statement execution, too many bytes of a buffer could be read. (Bug #26042934, Bug

#85937)

• Dynamic privileges were not loaded when the server was started using the --initialize option. (Bug

#26005645)

• Linux: The generic Linux build for MySQL 8.0 now supports Non-Uniform Memory Access (NUMA) on its

host system. Systems that use the build need to have libnuma installed on them. See Installing MySQL

on Unix/Linux Using Generic Binaries for more details. (Bug #26005558)

• Debian client packages were missing information about conflicts with akonadi-backend-mysql packages.

(Bug #26002288)

• mysqldump could write database names in USE statements incorrectly. (Bug #25998635)

• If the mysql_stmt_close() C API function was called, it freed memory that later could be accessed if

mysql_stmt_error(), mysql_stmt_errno(), or mysql_stmt_sqlstate() was called. To obtain

error information after a call to mysql_stmt_close(), call mysql_error(), mysql_errno(), or

mysql_sqlstate() instead. (Bug #25988681)

• Upgrading from MySQL 5.7 to MySQL 8.0 failed during data dictionary creation due to table names that

exceeded the 64 character length limit. (Bug #25973237, Bug #86120)

• Queries could be cached incorrectly, leading to incorrect query results, under these circumstances:

InnoDB table; rows are being inserted but have not yet been committed; a query uses the table as a

base table in a derived table; the optimizer chooses to materialize the derived table. (Bug #25943038,

Bug #86047)

• mysqld misbehaved if compiled with AddressSanitizer enabled and invoked with --basedir= (that is,

with an empty option value). (Bug #25914296, Bug #85994)

• The ST_LatFromGeohash(), ST_LongFromGeohash(), and ST_PointFromGeohash() functions

did not allow data that originated from a CHAR column. (Bug #25912557, Bug #85981)

• Attempting to drop a data file from a tablespace with multiple data files returned a duplicate file name

error. (Bug #25858461)

• An attribute was added to data dictionary client method declarations to generate compilation warnings

when return values are ignored. (Bug #25840927)

• The data dictionary class hierarchy was simplified. (Bug #25835968, Bug #85811)

• A restriction that prevented the data dictionary object update function

(Dictionary_client::update) from being called twice on the same object was removed. (Bug

#25833932, Bug #85800)

520

MySQL 8.0 Release Notes

• On Ubuntu platforms, the MySQL service script did not terminate correctly if the user running the script

did not have permission to access the data directory or PID file. (Bug #25825833)

• String comparison queries on the INFORMATION_SCHEMA.CHARACTER_SETS.DESCRIPTION field

were case sensitive, which is a regression from earlier releases. (Bug #25824297)

• Man pages for a few utilities were missing from Debian/Ubuntu packages. (Bug #25811814)

• An INFORMATION_SCHEMA view executed in LOCK TABLES mode, using the SERIALIZABLE isolation

level, and with autocommit disabled, failed to use non-locking reads, which could block DDL operations

or cause deadlocks. (Bug #25811413)

• Table locking failures could occur if tables were used by a trigger for which a trigger of the same name

existed in another database and the database names differed only in lettercase. (Bug #25807393)

• An in-place MySQL upgrade failed if a .TRG file was missing the created line for the trigger definition.

(This problem is unlikely to occur for upgrades to MySQL 8.0 from 5.7 because the created line is

present for MySQL 5.7.2 and higher.) (Bug #25805260, Bug #85704)

• The field-t unit test failed to run with AddressSanitizer enabled. Thanks to Laurynas Biveinis for the

patch. (Bug #25803823, Bug #85678)

• Debian client packages were missing information about conflicts with native packages. (Bug #25799475)

• The CREATE_OPTIONS column of the INFORMATION_SCHEMA.TABLES table was treated as having the

binary collation, so functions such as UPPER() and LOWER() did not have the intended result. (Bug

#25793429)

• After importing a table with DECIMAL column, accessing the table raised an assertion. (Bug #25792649)

• ALTER TABLE could fail when the default character set changed to utf8mb4 due to incorrect column

length calculations. (Bug #25779239, Bug #85614)

• If a component deinit() method failed, the component was still unloaded. (Bug #25764325)

• Stored program execution could fail for DEFINER accounts with expired passwords even if they were

locked and could not be used to connect to the server. Now DEFINER accounts are not checked for

expired passwords if they are locked. (Bug #25741966)

• DISTINCT operations on temporary tables could produce incorrect results due to allocation of too-small

comparison keys. (Bug #25740550, Bug #85518)

• In optimizer trace output, num_tmp_files did not actually indicate number of files. It has been renamed

to num_initial_chunks_spilled_to_disk and indicates the number of chunks before any

merging has occurred. (Bug #25733784, Bug #85487)

• The Perl path in #! lines at the beginning of Perl scripts has been adjusted to /usr/local/bin/perl

for FreeBSD 11. (Bug #25719975)

• With the IGNORE_SPACE SQL mode enabled, syntax error messages always reported line 1 as the line

number. (Bug #25717617)

• mysqldump failed to properly quote certain identifiers in SQL statements written to the dump output.

(Bug #25717383)

• Dropping a tablespace without that associated tablespace file failed with an error stating that the

tablespace dictionary object is invalid. (Bug #25717019)

• Client preauthorization by the server was missing a length check for a length-encoded string. (Bug

#25714674)

521

MySQL 8.0 Release Notes

• In debug builds, a CREATE TABLESPACE operation raised an invalid assertion when using the NDB

storage engine. A validation function that checked for zero-length data files did not apply to NDB

tablepaces and was removed. (Bug #25700242)

• For debug builds, EXPORT_SET() operations could raise an assertion for some arguments. (Bug

#25688192)

• For debug builds, the assertion added for Bug#59686 was too strict and could be raised when it should

not have been. (Bug #25685958)

References: See also: Bug #59686.

• A code refactoring in MySQL 8.0.1 caused several assertions to be raised in debug builds. (Bug

#25669590, Bug #25669606, Bug #25669580, Bug #25688504)

References: This issue is a regression of: Bug #25221172, Bug #84103.

• For some double-precision calculations, overflow could occur when calculating the exponent part. (Bug

#25664323, Bug #85290)

• SHOW INDEX output was inconsistent for a FULLTEXT index defined on multiple columns. (Bug

#25659276)

• During a group commit, the stack could incorrectly be reported exhausted, leading to stack overflow.

(Bug #25656875)

• An in-place (binary) upgrade could change the default character_set_client and

character_set_connection variables for stored routines, possibly resulting in different routine

behavior. (Bug #25633041)

• For debug builds, the partitioning handler could inappropriately evaluate generated column expressions

in UPDATE statements, resulting in a raised assertion. (Bug #25615803, Bug #85179)

• In strict SQL mode, an ER_TRUNCATED_WRONG_VALUE error could be converted from a warning to an

error but then ignored, leading to a raised assertion. (Bug #25586959, Bug #25586673)

• Failure occurred for ALTER TABLE on an ARCHIVE table containing a NOT NULL column having a

geometry data type. For debug builds, an assertion was raised. For non-debug builds, an error occurred.

(Bug #25582178, Bug #85059)

• For debug builds, an assertion could be raised for DROP TRIGGER of a trigger for a table used by a view.

(Bug #25581925)

• For upgrades from MySQL 5.7 to MySQL 8.0, the server wrote unnecessary parsing warnings to the

error log. These messages are now suppressed. (Bug #25518436, Bug #84889)

• The server exited abnormally attempting to access invalid memory. (Bug #25501659)

• The maximum length of the name field in the column_type_elements table in the data dictionary was

extended from 255 bytes to 1020 bytes to accommodate long ENUM and SET values that could result

from using a multibyte character set.

When using a multibyte character set, a single ENUM or SET element occupies a maximum of M x w bytes

in the column type definition in the data dictionary, where M is the element literal length and w is the

number of bytes required for the maximum-length character in the character set.

In prior releases, the maximum supported length of an individual ENUM or SET element depended on

the number of elements in the type. Thus, there could be a single element with (M x w) = 64K, or 64K

elements with (M x w) = 1.

522

MySQL 8.0 Release Notes

The maximum supported length of an individual ENUM or SET element is now M <= 255 and (M x w) <=

1020, regardless of the number of elements in the type. (Bug #25481355)

• With mysqld secured by TCP wrappers and the hosts.allow and hosts.deny files configured

to restrict access from an IP address, connection attempts from that address resulted in too many

messages to the error log. (Bug #25476479, Bug #84708)

• mysqlpump no longer includes the slave_master_info and slave_relay_log_info tables in

dumps of the mysql system database. Restoring a dump file containing these tables caused problems

by changing the replication state improperly. (Bug #25469190)

• Changes made by calling mysql_options() to set MYSQL_OPT_SSL_MODE could be affected

by later mysql_options() calls. Now setting MYSQL_OPT_SSL_MODE is unaffected by later

mysql_options() calls. (Bug #25452210)

• A race condition could occur for CREATE TABLE statements with DATA DIRECTORY or INDEX

DIRECTORY clauses. (Bug #25451091)

• With AddressSanitizer enabled, compiling the keyring_file plugin produced One-Definition Rule

violations. (Bug #25448205)

• ALTER TABLE ... MODIFY on a DATETIME NOT NULL column using an AFTER clause resulted in an

ER_INVALID_USE_OF_NULL error. (Bug #25385334)

• The range optimizer could create an incorrect query tree, resulting in a server exit. (Bug #25369742, Bug

#25586531)

• mysqld_failed to start the server if the --datadir option was specified with a relative path name.

(Bug #25364806)

• XA PREPARE, XA ROLLBACK, and XA COMMIT for a transaction from a disconnected session did not

take a global commit lock and modified the binary log and InnoDB redo log even when FLUSH TABLES

WITH READ LOCK was in effect. This could lead to inconsistent backups when backup tools assumed

that the server was in a read-only state. (Bug #25364178, Bug #84442)

• GROUP_CONCAT(DISTINCT) returned nonunique values if the data size was greater than the value of

the tmp_table_size system variable. (Bug #25331425, Bug #84320)

• The fix for Bug #78777 had different effects depending on whether the Performance Schema is enabled.

(Bug #25309017, Bug #84305)

References: This issue is a regression of: Bug #78777.

• An aggregate function in some nested queries could cause a server exit. (Bug #25303711)

• Virtual generated column expressions that used the BIN_TO_UUID(), CONV(), or HEX() functions

could cause problems if the connection character set was changed. In this context, the table character

set is now used for these functions regardless of connection character set. (Bug #25287633)

• The Rewriter plugin did not perform locking properly if the read_only system variable was enabled.

(Bug #25264253)

• With read_only enabled, creation of non-TEMPORARY tables by non-SUPER users was permitted under

certain conditions. (Bug #25250768)

• For a table having a TIMESTAMP or DATETIME column having a default of CURRENT_TIMESTAMP, the

column could be initialized to 0000-00-00 00:00:00' if the table had a BEFORE INSERT trigger.

(Bug #25209512, Bug #84077)

523

MySQL 8.0 Release Notes

• On Windows, Time values in SHOW PROCESSLIST output drifted higher over time. (Bug #25101724,

Bug #83019)

• An assertion was raised when a create function at server bootstrap attempted to evaluate non-resolved

expressions. (Bug #24961932)

• The number of data dictionary cache lookups was reduced, and ALTER TABLE handling of triggers was

improved help ensure trigger persistence in case of a server exit during ALTER TABLE processing. (Bug

#24930129, Bug #83473)

• Certain queries against InnoDB tables that used a primary key and a subquery could return incorrect

results if the index_merge_intersection flag of the optimizer_switch system variable was

enabled. (Bug #24829050, Bug #79675)

• On x86 machines, the uint3korr() macro read 4 bytes of data instead of the intended 3 bytes. (Bug

#24807826, Bug #83264)

• An assertion was raised during a fetch operation by the memcached plugin. (Bug #24605783)

• Queries that contained UNION in a subquery and GROUP BY could return incorrect results. (Bug

#24595639)

• Some syntactically incorrect CREATE INDEX statements could cause a server exit rather than a syntax

error. (Bug #24593992)

• An in-place MySQL upgrade failed if the innodb_table_stats or innodb_index_stats tables were

not present in the mysql system database. (This problem should not occur for upgrades to MySQL 8.0

from 5.7 because those tables are present in MySQL 5.7.) (Bug #24557143)

• Incorrect behavior could occur for INSERT statements executed in stored-program or prepared-

statement context, if the VALUES part of an ON DUPLICATE KEY UPDATE clause referred to a BLOB

value in the INSERT column list. (Bug #24538207, Bug #25361251, Bug #25530880, Bug #25684790)

• systemd support scripts in Debian packages contained hardcoded references to the data directory,

making it difficult to change the data directory using --datadir. (Bug #24398446, Bug #82417)

• MySQL failed to compile under macOS 10.10.5 using Clang. (Bug #24352163, Bug #82340)

• If a REPLACE statement tried to update a row in a table containing a virtual generated column of type

BLOB, subsequent DML statements could behave incorrectly. (Bug #23573575)

• Some PROXY grants were not replicated to slaves, causing incorrect replication. (Bug #23289541, Bug

#81424, Bug #23623115)

• EXPLAIN for single-table UPDATE or DELETE statements could raise an assertion attempting to optimize

away subqueries. (Bug #23209903)

• The help output from mysqlxtest has been improved. (Bug #23107137, Bug #81086)

• For builds with AddressSanitizer enabled, the ST_Simplify() function could attempt to use already

freed memory. (Bug #23023817)

• Compiler flags were adjusted to eliminate numerous warnings that occurred when compiling the

keyring_file plugin using Clang. (Bug #22834591, Bug #80524)

• If enabling the Event Scheduler caused an event defined as ON COMPLETION NOT PRESERVE to

be dropped because its execution time had passed, the drop event was not written to the binary log,

causing slaves not to replicate it and replication failure if an event of the same name was created later.

(Bug #22150112)

524

MySQL 8.0 Release Notes

• For some CREATE TABLE ... SELECT statements, adding an ORDER BY clause changed column

data types, or caused an assertion to be raised for debug builds. (Bug #16833464)

• LOAD XML performance became noticeably slower when the XML file being read contained a great

many spaces, such as those introduced by indenting or pretty-printing. Now all leading whitespace is

trimmed from each such value before reading it into memory. (Bug #16212207)

Changes in MySQL 8.0.1 (2017-04-10, Development Milestone)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

Note

This release makes several important changes in Unicode character set support. In

particular, the default character set has changed from latin1 to utf8mb4.

• Account Management Notes

• C API Notes

• Character Set Support

• Compilation Notes

• Configuration Notes

• Connection Management Notes

• Data Dictionary Notes

• Deprecation and Removal Notes

• Optimizer Notes

• Packaging Notes

• Performance Schema Notes

• Plugin Notes

• Security Notes

• Spatial Data Support

• SQL Syntax Notes

• Test Suite Notes

525

MySQL 8.0 Release Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• Incompatible Change: Components and plugins now can define privileges dynamically (at runtime),

which enables them to create privileges specifically associated with the capabilities they implement.

Implementation of dynamic privileges enables DBAs to begin migrating away from the SUPER privilege.

In the past, SUPER has been associated with a wide and growing variety of operations, not all related

to each other. Many operations covered by SUPER now are also associated with a dynamic privilege

of more limited scope, and that privilege is registered by the component or plugin that implements the

operation. Each such operation that previously required the SUPER privilege can be permitted to an

account by granting the associated dynamic privilege rather than SUPER. For example, a user who must

be able to modify global system variables can be granted SYSTEM_VARIABLES_ADMIN rather than

SUPER.

This change improves security by enabling DBAs to avoid granting SUPER and tailor user privileges more

closely to the operations permitted. SUPER is now deprecated and will be removed in a future MySQL

version.

Dynamic privileges apply only at the global level. The server stores information about current

assignments of dynamic privileges to user accounts in mysql.global_grants, a new table in the

mysql system database.

For more information, see Static Versus Dynamic Privileges. That discussion includes instructions for

migrating accounts away from SUPER to dynamic privileges.

Incompatibility: SHOW GRANTS no longer displays ALL PRIVILEGES in its global-privileges output

because the meaning of ALL PRIVILEGES at the global level varies depending on which dynamic

privileges are defined. Instead, SHOW GRANTS explicitly lists each granted global privilege. For details,

see SHOW GRANTS Statement. Applications that process SHOW GRANTS output should be adjusted

accordingly.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the mysql system database. (WL #8131)

C API Notes

• The C API implemented by libmysqlclient now includes a client interface for reading a stream of

replication events from a MySQL server binary log. For more information, see C API Binary Log Interface

(WL #7672)

Character Set Support

• Important Change: The default character set has changed from latin1 to utf8mb4. These system

variables are affected:

• The default value of the character_set_server and character_set_database system

variables has changed from latin1 to utf8mb4.

• The default value of the collation_server and collation_database system variables has

changed from latin1_swedish_ci to utf8mb4_0900_ai_ci.

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MySQL 8.0 Release Notes

As a result, the default character set and collation for new objects differ from previously unless an explicit

character set and collation are specified. This includes databases and objects within them, such as

tables, views, and stored programs. One way to preserve the previous defaults is to start the server with

these lines in the my.cnf file:

[mysqld]

character_set_server=latin1

collation_server=latin1_swedish_ci

(WL #7554)

• Performance of UCA 9.0.0-based collations (for example, utf8mb4_0900_ai_ci) was improved.

These collations are now faster than any other UCA collations.

Additionally, the max_length_for_sort_data system variable default value has been increased from

1024 to 4096. (Bug #24823885, Bug #83319)

• The default collation for the utf8mb4 character set has changed from utf8mb4_general_ci to

utf8mb4_0900_ai_ci; utf8mb4_general_ci does not handle characters outside the Basic

Multilingual Plane (BMP) correctly. (Bug #24742157)

• The pad attribute for Unicode 9.0.0 collations was changed from PAD SPACE to NO PAD. Consequently,

these collations now treat spaces at the end of strings as significant, like any other character. The

affected collations have names that contain the string _0900_.

Comparisons of nonbinary strings (CHAR, VARCHAR, and TEXT strings) that have a 9.0.0 (NO PAD)

collation differ from PAD SPACE collations with respect to trailing spaces. For example, 'a' and 'a '

compare as different strings, not the same string. Example:

mysql> SET NAMES 'latin1' COLLATE 'latin1_swedish_ci';

mysql> SELECT 'a' = 'a ';

+------------+

| 'a' = 'a ' |

+------------+

| 1 |

+------------+

mysql> SET NAMES 'utf8mb4' COLLATE 'utf8mb4_0900_ai_ci';

mysql> SELECT 'a' = 'a ';

+------------+

| 'a' = 'a ' |

+------------+

| 0 |

+------------+

See also Trailing Space Handling in Comparisons.

The INFORMATION_SCHEMA COLLATIONS table now has a PAD_ATTRIBUTE column that indicates the

pad attribute for each collation.

A problem with the latin1_de collation involving early weight string truncation has been corrected. The

only likely effect is for WEIGHT_STRING() function results. (WL #10354)

• Complementing earlier work in MySQL 8.0.0 to add case-insensitive and accent-insensitive collations

for the utf8mb4 Unicode character set, new case-sensitive and accent-sensitive collations have

been added. The general collation is named utf8mb4_0900_as_cs, and there are language-specific

collations with characteristics similar to utf8mb4_0900_as_cs except that language-specific rules take

precedence where applicable. The language-specific collations are indicated by ISO 639-1 language

codes in the collation name, as shown in the following table. In two cases the language code has an

additional item that denotes a variant (German phone book order, Traditional Spanish).

527

MySQL 8.0 Release Notes

Note

utf8mb4_ja_0900_as_cs is the first Japanese language-specific collation

available for Unicode in MySQL.

Table 2 utf8mb4 UCA 9.0.0 Language-Specific Collations

Language Collation

Croatian utf8mb4_hr_0900_as_cs

Czech utf8mb4_cs_0900_as_cs

Danish utf8mb4_da_0900_as_cs

Esperanto utf8mb4_eo_0900_as_cs

Estonian utf8mb4_et_0900_as_cs

German phone book order utf8mb4_de_pb_0900_as_cs

Hungarian utf8mb4_hu_0900_as_cs

Icelandic utf8mb4_is_0900_as_cs

Japanese utf8mb4_ja_0900_as_cs

Latvian utf8mb4_lv_0900_as_cs

Lithuanian utf8mb4_lt_0900_as_cs

Polish utf8mb4_pl_0900_as_cs

Classical Latin utf8mb4_la_0900_as_cs

Romanian utf8mb4_ro_0900_as_cs

Slovak utf8mb4_sk_0900_as_cs

Slovenian utf8mb4_sl_0900_as_cs

Modern Spanish utf8mb4_es_0900_as_cs

Traditional Spanish utf8mb4_es_trad_0900_as_cs

Swedish utf8mb4_sv_0900_as_cs

Turkish utf8mb4_tr_0900_as_cs

Vietnamese utf8mb4_vi_0900_as_cs

utf8mb4_0900_as_cs also works as an accent-sensitive, case-sensitive collation for the languages in

the following table.

Table 3 Languages for Which utf8mb4_0900_as_cs is Suitable

Language Name Language Code

German (dictionary order) de

English en

French (locale fr_FR) fr

Irish Gaelic ga

Indonesian id

Italian it

Luxembourgian lb

528

MySQL 8.0 Release Notes

Language Name Language Code

Malay ms

Dutch nl

Portuguese pt

Swahili sw

Zulu zu

utf8mb4_0900_as_cs is suitable for French French (locale fr_FR) but not for Canadian French

(locale fr_CA). For Canadian French, utf8mb4_0900_ai_ci is suitable. The reason for the difference

between ai_ci and as_cs collations is that Canadian French has a different order of accented

characters than French French.

utf8mb4_da_0900_as_cs also works as an accent-sensitive, case-sensitive collation for the

languages in the following table.

Table 4 Languages for Which utf8mb4_da_0900_as_cs is Suitable

Language Name Language Code

Norwegian no

Norwegian Bokmål nb

Norwegian Nynorsk nn

The nonlanguage-specific utf8mb4_0900_as_cs and language-specific

utf8mb4_LANG_0900_as_cs Unicode collations each have these characteristics:

• The collation is based on Unicode Collation Algorithm (UCA) 9.0.0 and Common Locale Data

Repository (CLDR) v30, is accent sensitive, and case sensitive. These characteristics are indicated by

_0900, _as, and _cs in the collation name. Exception: utf8mb4_la_0900_as_cs is not based on

CLDR because Classical Latin is not defined in CLDR.

• The collation works for all characters in the range [U+0, U+10FFFF].

• If the collation is not language specific, it sorts all characters, including supplemental characters,

in default order (described following). If the collation is language specific, it sorts characters of the

language correctly according to language-specific rules, and characters not in the language in default

order.

• By default, the collation sorts characters having a code point listed in the DUCET table (Default

Unicode Collation Element Table) according to the weight value assigned in the table. The collation

sorts characters not having a code point listed in the DUCET table using their implicit weight value,

which is constructed according to the UCA.

The collation sorts on all three DUCET weight levels, including the tertiary level. This compares with

accent-insensitive, case-insensitive collations, which sort only on the primary and secondary levels.

• For non-language-specific collations, characters in contraction sequences are treated as separate

characters. For language-specific collations, contractions might change character sorting order.

For more information, see Unicode Character Sets. (WL #9109, WL #9751)

529

MySQL 8.0 Release Notes

Compilation Notes

• Incompatible Change: The my_bool type is no longer used in MySQL source code. Any third-party

code that used this type to represent C boolean variables should use the bool or int C type instead.

Note

The change from my_bool to bool means that the mysql.h header file now

requires a C++ or C99 compiler to compile.

(Bug #25597667)

• InnoDB: A LOB page deletion function failed to delete LOB pages. (Bug #24480254)

• Windows builds now use the default runtime libraries (builds use the /MD flag). (Bug #25611609)

• CMake support was added for compiling with Developer Studio 12.6. (Bug #25384295)

• The rapidjson library included in MySQL distributions was upgraded to version 1.1.0. (Bug #24947436,

Bug #83515)

• The minimum version of the Boost library for server builds is now 1.63.0. (Bug #24579061, Bug #82834,

Bug #25126144, Bug #83905)

• For GCC versions higher than 4.4, -fno-expensive-optimizations was replaced with -ffp-

contract=off, which has the effect of enabling more optimizations. Thanks to Alexey Kopytov for the

patch. (Bug #24571672, Bug #82760)

• For building MySQL 8.0, the minimum required version of CMake is now 3.2.3 on Windows, 3.4.0 on

Solaris, and 2.8.12 otherwise. (Bug #24481181, Bug #82628)

References: See also: Bug #24687701.

• Work was done to clean up the source code base, including: Removing unneeded CMake checks;

removing unused macros from source files; reorganizing header files to reduce the number of

dependencies and make them more modular, removing function declarations without definitions,

replacing locally written functions with equivalent functions from industry-standard libraries.

Configuration Notes

• In source distributions, several utilities previously in the extra directory have been moved to the new

utilities directory. (Bug #25416084)

• Two new CMake options are available for debugging. LINK_RANDOMIZE indicates whether to randomize

the order of symbols in the mysqld binary (default OFF), and LINK_RANDOMIZE_SEED specifies a seed

value for LINK_RANDOMIZE. (Bug #25336715)

• MySQL failed to compile if -DENABLE_DEBUG_SYNC=OFF AND -DWITH_DEBUG=ON were both given.

The ENABLE_DEBUG_SYNC option has been removed and enabling WITH_DEBUG enables Debug Sync.

(Bug #18374703)

• These changes were made with respect to persisted system variables:

• A new statement, RESET PERSIST, enables removal of variable settings that were persisted with SET

PERSIST to the mysqld-auto.cnf file that stores persisted global system variable settings.

• Using SET PERSIST (or @@PERSIST.) to set a global variable to DEFAULT or to the variable literal

default value previously also added a setting for the variable to the mysqld-auto.cnf file if was is

530

MySQL 8.0 Release Notes

not present, or removed it from mysqld-auto.cnf if it was present. Now the assignment always

adds a setting for the variable to the mysqld-auto.cnf file; to remove the setting from the file, use

RESET PERSIST.

• A new Performance Schema table, persisted_variables, provides an SQL interface to the

mysqld-auto.cnf file, enabling the file contents to be inspected at runtime using SELECT

statements.

• The Performance Schema variables_info table has new columns showing when and by which

user each system variable was most recently set.

For more information, see Persisted System Variables, and RESET PERSIST Statement.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the Performance Schema. (WL #9720, WL #9763)

References: See also: Bug #24522064.

• The default value of the query_cache_size system variable has been reduced from 1M to 0.

Consequently no query cache buffer is allocated by default. (WL #9817)

Connection Management Notes

• MySQL Server now includes a plugin library that enables administrators to introduce an increasing delay

in server response to clients after a certain number of consecutive failed connection attempts. This

capability provides a deterrent that slows down brute force attacks that attempt to access MySQL user

accounts. For more information, see The Connection-Control Plugins. (WL #8885)

Data Dictionary Notes

• SQL-layer code and the storage engine API were extended to provide data dictionary support for:

• Storing information about auxiliary columns and keys that InnoDB adds to tables implicitly, storage

engine-private data and object identifiers for tables and tablespaces, and InnoDB full-text search

auxiliary tables and other similar, implicitly created objects.

• Combining data dictionary updates, storage engine changes, and binary log writes for DDL operations

into atomic transactions.

A behavior change for DROP TABLE occurs if any named tables do not exist. Previously, the statement

returned an error indicating which tables did not exist and it was unable to drop, but also dropped the

tables that did exist. Now the statement still indicates which tables did not exist, but fails with an error

and no changes are made.

For more information, see Atomic Data Definition Statement Support, and WL#7743. (WL #7743)

• These INFORMATION_SCHEMA tables have been reimplemented as views on data dictionary tables:

EVENTS

PARAMETERS

ROUTINES

TRIGGERS

Queries on those tables are now more efficient because they obtain information from data dictionary

tables rather than by other, slower means. For example, the server no longer must create a temporary

table for each query of the INFORMATION_SCHEMA table.

531

MySQL 8.0 Release Notes

Improvements for those tables also apply to SHOW statements that display information corresponding to

the INFORMATION_SCHEMA tables. For example, SHOW TRIGGERS displays the same information as the

TRIGGERS table.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes. (WL #9494)

Deprecation and Removal Notes

• Incompatible Change; InnoDB; Partitioning: The ALTER TABLE ... UPGRADE PARTITIONING

statement is no longer supported.

• The deprecated PROCEDURE ANALYSE() syntax has been removed. (WL #4745)

• The deprecated libmysqld embedded server library has been removed, along with:

• The mysql_config --libmysqld-libs, --embedded-libs, and --embedded options

• The CMake WITH_EMBEDDED_SERVER, WITH_EMBEDDED_SHARED_LIBRARY, and

INSTALL_SECURE_FILE_PRIV_EMBEDDEDDIR options

• The (undocumented) mysql --server-arg option

• The mysqltest --embedded-server, --server-arg, and --server-file options

• The mysqltest_embedded and mysql_client_test_embedded test programs

(WL #9721, WL #9722, WL #9816)

• The deprecated --temp-pool server option has been removed. (WL #8396)

• The deprecated replace utility has been removed. If you wish to continue using this utility, be sure to

retain a copy from an installed version of MySQL before upgrading to the current version. (WL #9874)

• The parser no longer considers \N as a synonym for NULL in SQL statements. Use NULL instead.

This change does not affect text file import or export operations performed with LOAD DATA or

SELECT ... INTO OUTFILE, for which NULL continues to be represented by \N. See LOAD DATA

Statement. (WL #7247)

• Support for DTrace has been removed. (WL #9581)

Optimizer Notes

• InnoDB: MySQL now supports descending indexes: DESC in an index definition is no longer ignored

but causes storage of key values in descending order. Previously, indexes could be scanned in reverse

order but at a performance penalty. A descending index can be scanned in forward order, which is more

efficient. Descending indexes also make it possible for the optimizer to use multiple-column indexes

when the most efficient scan order mixes ascending order for some columns and descending order for

others. For more information, see Descending Indexes.

Note

Previously, GROUP BY implicitly sorted by default (that is, in the absence of ASC

or DESC designators for GROUP BY columns), but relying on implicit GROUP BY

sorting was deprecated. GROUP BY no longer sorts by default, so query results

532

MySQL 8.0 Release Notes

may differ from previous MySQL versions. To produce a given sort order, use

explicit ASC or DESC designators for GROUP BY columns or provide an ORDER BY

clause.

(WL #1074, WL #7737)

• Optimizer trace output now includes more information about filesort operations, such as key and

payload size and why addon fields are not packed. (Bug #25246184, Bug #84180)

• Previously, invisible indexes were supported only for the InnoDB storage engine. Invisible indexes are

now storage engine neutral (supported for any engine). (Bug #23541244)

• A GROUPING() function has been introduced for use in GROUP BY queries that include a WITH ROLLUP

modifier. This function enables you to distinguish NULL values for super-aggregate rows in the query

result from NULL values in regular grouped rows. For more information, see Miscellaneous Functions,

and GROUP BY Modifiers. Thanks to Zhe Dong for a patch that was partially used to implement this

feature.

Note

GROUPING now is a reserved word and cannot be used as an identifier without

identifier quoting.

(Bug #11754449, Bug #46053, Bug #11745963, Bug #21728, WL #1979)

• The optimizer now supports INDEX_MERGE and NO_INDEX_MERGE hints to affect use of the Index

Merge access method. Examples:

SELECT /*+ INDEX_MERGE(t1 f1, f2, f3) */ f2 FROM t1

WHERE f1 = 'o' AND f2 = f3 AND f3 <= 4;

SELECT /*+ NO_INDEX_MERGE(t1 f2, f3) */ f1 FROM t1

WHERE (f2 = 5 OR f3 = 'c') AND (f1 = 4 OR f4 = 'f');

For more information, see Index Merge Optimization, and Optimizer Hints. (WL #9167)

• The server_cost and engine_cost optimizer cost model tables in the mysql system database now

include a default_value column that contains the default value for each cost table estimate. This

column is a read-only generated column that retains its value even if the associated cost estimate is

changed. For more information, see The Optimizer Cost Model.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the mysql system database. (WL #10128)

• In the optimizer cost model engine_cost table, the cost for memory access was decreased relative to

the cost for disk access. An implication of this change is that the execution plan may change between

two runs of the same query. For example, at server startup before data has been read into the buffer

pool, you may get a different plan than after the query has been run because then the data will be in

memory. (WL #8737)

• MySQL now supports common table expressions, both nonrecursive and recursive. Common table

expressions enable use of named temporary result sets, implemented by permitting a WITH clause

preceding SELECT statements and certain other statements. For more information, see WITH (Common

Table Expressions).

Note

RECURSIVE now is a reserved word and cannot be used as an identifier without

identifier quoting.

533

MySQL 8.0 Release Notes

(WL #883, WL #3634)

• The optimizer now supports hints that enable specifying the order in which to join tables. For more

information, see Optimizer Hints. (WL #9158)

Packaging Notes

• Microsoft Windows: Reminder: MySQL 8.0 requires the Microsoft Visual C++ 2015 Redistributable

Package to run on Windows platforms. Users should make sure the package has been installed on the

system before starting the server. The package is available at the Microsoft Download Center.

• Changes in RPM package structure require a larger set of packages to be removed to install MySQL

Server cleanly. (Bug #25603087)

• To avoid potential race conditions, Debian packages now use the GNU install utility rather than a

combination of mkdir, touch, and chown. (Bug #25258829)

• New Debian/Ubuntu packages named server-core and client-core are now available. These

packages contain binaries only, without configuration or service scripts, directory setup, man pages, and

so forth. They are installed automatically with the standard packages, but when installed by themselves

do not result in a functioning MySQL setup. They may be of interest for user which wish to customize

their own installation setup. (Bug #25146364)

• scripts/mysql_security_commands.sql and support-files/mysql.server-sys5.sh are

no longer used and have been removed from MySQL distributions. (Bug #24756400, Bug #24756442)

• RPM packages now are built with -DWITH_NUMA=ON for platforms with NUMA support: OEL higher than

EL5, Fedora, SLES, Docker. (Bug #24689078)

• The my-default.cnf.sh file (used to produce a default my-default.cnf or my-default.ini

file) is no longer included in source distributions and my-default.cnf and my-default.ini are no

longer included in or installed by distribution packages. (Bug #22525354)

• The unused and undocumented archive_reader and archive_test utilities have been removed

from MySQL source distributions. (Bug #12818207, Bug #62014)

Performance Schema Notes

• The Performance Schema maintains statement event summary tables that contain information about

minimum, maximum, and average statement latency. Those tables permit high-level assessment of

system performance. To permit assessment at a more fine-grained level, the Performance Schema now

also collects histogram data for statement latencies. These histograms provide additional insight into

latency distributions and are available in these tables:

• events_statements_histogram_by_digest: Statement histograms per schema and digest

value

• events_statements_histogram_global: Statement histogram summarized globally

For more information, see Statement Histogram Summary Tables.

In addition, the events_statements_summary_by_digest table now has columns that provide

percentile information about statement latencies. For more information, see Statement Summary Tables.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the Performance Schema. (WL #5384)

534

MySQL 8.0 Release Notes

• System and status variable information is no longer maintained in the INFORMATION_SCHEMA.

These tables have been removed: GLOBAL_VARIABLES, SESSION_VARIABLES, GLOBAL_STATUS,

SESSION_STATUS. Use the corresponding Performance Schema tables instead. See Performance

Schema System Variable Tables, and Performance Schema Status Variable Tables. In addition,

the show_compatibility_56 system variable has been removed. It was used in the transition

period during which system and status variable information in INFORMATION_SCHEMA tables was

moved to Performance Schema tables, and is no longer needed. These status variables have been

removed: Slave_heartbeat_period, Slave_last_heartbeat, Slave_received_heartbeats,

Slave_retried_transactions, Slave_running. The information they provided is available

in Performance Schema tables; see Migrating to Performance Schema System and Status Variable

Tables. (WL #8057)

• The deprecated INFORMATION_SCHEMA INNODB_LOCKS and INNODB_LOCK_WAITS tables have been

removed. To obtain InnoDB data lock information, use the Performance Schema data_locks and

data_lock_waits tables instead. Alternatively, use the sys schema innodb_lock_waits and x

$innodb_lock_waits views, which have been reimplemented to use the new Performance Schema

tables rather than the removed INFORMATION_SCHEMA tables.

The Performance Schema tables expose what data locks exist, which transaction holds each lock, and

which transaction lock requests are blocked by other locks. For InnoDB, the data_locks table reports

all data locks, in contrast to the INNODB_LOCKS table, which reported only waited-for data locks, For

more information, see The data_locks Table, and The data_lock_waits Table. For information about

mapping old table columns to new table columns, see The INFORMATION_SCHEMA INNODB_LOCKS

Table, and The INFORMATION_SCHEMA INNODB_LOCK_WAITS Table.

The tables differ in the privileges required: The INFORMATION_SCHEMA tables require the global

PROCESS privilege. The Performance Schema tables require the usual Performance Schema privilege of

SELECT on the table to be selected from.

The sys schema innodb_lock_waits and x$innodb_lock_waits views can be used without

change, with the exception that the locked_table column containing combined schema/table name

values has been removed and replaced with locked_table_schema and locked_table_name

columns that contain separate schema and table name values. In addition, these views now contain

locked_table_partition and locked_table_subpartition columns. For more information,

see The innodb_lock_waits and x$innodb_lock_waits Views,

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the Performance Schema and the sys schema.

(WL #9275, WL #6657)

Plugin Notes

• MySQL Server 8.0 includes a component-based infrastructure for improving server extensibility; see

MySQL Components. However, MySQL plugins use an interface that predates the component interface.

A new plugin service, plugin_registry_service, enables plugins to access the component registry

and its services. (WL #4989)

Security Notes

• Incompatible Change: For STANDALONE and WIN builds, the default secure_file_priv value has

changed from the empty string to NULL. This is a secure-by-default setting because it disables import

and export operations. To permit those operations, set secure_file_priv to the path name of the

directory to use for those operations. (Bug #24679907, Bug #24695274, Bug #24707666, WL #6782)

• Incompatible Change: These changes were made to mysqld_safe:

535

MySQL 8.0 Release Notes

• Unsafe use of rm and chown in mysqld_safe could result in privilege escalation. chown now can be

used only when the target directory is /var/log. An incompatible change is that if the directory for

the Unix socket file is missing, it is no longer created; instead, an error occurs. Due to these changes,

/bin/bash is required to run mysqld_safe on Solaris. /bin/sh is still used on other Unix/Linux

platforms.

• The --ledir option now is accepted only on the command line, not in option files.

• mysqld_safe ignores the current working directory.

Other related changes:

• Initialization scripts that invoke mysqld_safe pass --basedir explicitly.

• Initialization scripts create the error log file only if the base directory is /var/log or /var/lib.

• Unused systemd files for SLES were removed.

(Bug #24483092, Bug #25088048, Bug #25378439, Bug #25378565)

References: See also: Bug #24464380, Bug #24388753, Bug #24619033, Bug #82920.

• yaSSL was upgraded to version 2.4.2. This upgrade corrects issues with: Potential AES side channel

leaks; DSA padding for unusual sizes; the SSL_CTX_load_verify_locations() OpenSSL

compatibility function failing to handle long path directory names. (Bug #24512715, Bug #24740291)

• OpenSSL is ending support for version 1.0.1 in December 2016; see https://www.openssl.org/policies/

releasestrat.html. Consequently, MySQL Commercial Server builds now use version 1.0.2 rather

than version 1.0.1, and the linked OpenSSL library for the MySQL Commercial Server has been

updated from version 1.0.1 to version 1.0.2j. For a description of issues fixed in this version, see https://

www.openssl.org/news/vulnerabilities.html.

This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which

uses the yaSSL library instead. (WL #9136)

Spatial Data Support

• Incompatible Change: Previously, ST_Distance() supported only Cartesian spatial reference

systems (SRSs). ST_Distance() now detects geometry arguments in a geographic SRS and returns

the geodetic distance on the ellipsoid in meters. The only permitted geographic argument types are

Point and Point, or Point and MultiPoint (in any argument order). Calculations for projected

SRSs and SRID 0 remain the same. For more information, see Spatial Relation Functions That Use

Object Shapes.

Note

If spatial data contains SRID values that refer to a geographic spatial reference

system, existing queries using these functions will return different results,

compared to previous MySQL versions.

(WL #9347)

• Incompatible Change: These functions previously accepted either WKB strings or geometry arguments.

Geometry arguments are no longer permitted and produce an error.

• ST_GeomCollFromWKB(), ST_GeometryCollectionFromWKB()

536

MySQL 8.0 Release Notes

• ST_GeomFromWKB(), ST_GeometryFromWKB()

• ST_LineFromWKB(), ST_LinestringFromWKB()

• ST_MLineFromWKB(), ST_MultiLinestringFromWKB()

• ST_MPointFromWKB(), ST_MultiPointFromWKB()

• ST_MPolyFromWKB(), ST_MultiPolygonFromWKB()

• ST_PointFromWKB()

• ST_PolyFromWKB(), ST_PolygonFromWKB()

For information about migrating queries that refer to those functions away from using geometry

arguments to using WKB arguments, see Functions That Create Geometry Values from WKB Values.

(WL #10166)

537

MySQL 8.0 Release Notes

• Incompatible Change: These functions now interpret latitude and longitude coordinates as in the order

specified by the spatial reference system. The functions also accept an optional argument to override the

default axis order.

• ST_GeomCollFromText(), ST_GeometryCollectionFromText(), ST_GeomCollFromTxt()

• ST_GeomFromText(), ST_GeometryFromText()

• ST_LineFromText(), ST_LinestringFromText()

• ST_MLineFromText(), ST_MultiLinestringFromText()

• ST_MPointFromText(), ST_MultiPointFromText()

• ST_MPolyFromText(), ST_MultiPolygonFromText()

• ST_PointFromText()

• ST_PolyFromText(), ST_PolygonFromText()

• ST_GeomCollFromWKB(), ST_GeometryCollectionFromWKB()

• ST_GeomFromWKB(), ST_GeometryFromWKB()

• ST_LineFromWKB(), ST_LinestringFromWKB()

• ST_MLineFromWKB(), ST_MultiLinestringFromWKB()

• ST_MPointFromWKB(), ST_MultiPointFromWKB()

• ST_MPolyFromWKB(), ST_MultiPolygonFromWKB()

• ST_PointFromWKB()

• ST_PolyFromWKB(), ST_PolygonFromWKB()

For more information, see Functions That Create Geometry Values from WKT Values, and Functions

That Create Geometry Values from WKB Values.

Note

If spatial data contains SRID values that refer to a geographic spatial reference

system, existing queries using these functions will return different results,

compared to previous MySQL versions.

(WL #9434, WL #9435)

538

MySQL 8.0 Release Notes

• Incompatible Change: These functions now return latitude and longitude coordinates in the order

specified by the spatial reference system that applies to the geometry value argument. The functions

also accept an optional argument to override the default axis order.

• ST_AsBinary(), ST_AsWKB()

• ST_AsText(), ST_AsWKT()

For more information, see Geometry Format Conversion Functions.

Note

If spatial data contains SRID values that refer to a geographic spatial reference

system, existing queries using these functions will return different results,

compared to previous MySQL versions.

(WL #9432, WL #9433)

• The st_spatial_reference_systems data dictionary table that stores information about spatial

reference systems other than SRID 0 has been upgraded from EPSG Dataset 8.7 to 9.0. Also, the table

contents are now exposed through the INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS

table, which is implemented as a view on the data dictionary For more information, see The

INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table.

MySQL now has an INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS table that provides information

about table columns that store spatial data. The new table is implemented as a view on the existing

INFORMATION_SCHEMA COLUMNS table. For more information, see The INFORMATION_SCHEMA

ST_GEOMETRY_COLUMNS Table.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these INFORMATION_SCHEMA changes. (Bug #25337054, Bug #84384,

WL #9348, WL #8582)

• A new spatial function, ST_SwapXY(), accepts a geometry argument and swaps the X and Y values

of each coordinate pair within the geometry. For more information, see Geometry Format Conversion

Functions. (WL #9436)

SQL Syntax Notes

• Derived table syntax now permits a list of explicit column names following the table name, to override the

default column names taken from the select list. For example, the column names for this derived table

come from its select list:

mysql> SELECT * FROM (SELECT 1, 2, 3, 4) AS dt;

+---+---+---+---+

| 1 | 2 | 3 | 4 |

+---+---+---+---+

| 1 | 2 | 3 | 4 |

+---+---+---+---+

To provide column names, follow the derived table name with a parenthesized list of column names:

mysql> SELECT * FROM (SELECT 1, 2, 3, 4) AS dt (a, b, c, d);

+---+---+---+---+

| a | b | c | d |

+---+---+---+---+

| 1 | 2 | 3 | 4 |

+---+---+---+---+

539

MySQL 8.0 Release Notes

(WL #883)

Test Suite Notes

• mysql-test-run.pl now has a --charset-for-testdb=charset_name option for specifying

the default character set for the test database. The default value is latin1. (Bug #25494068, Bug

#84806)

• mysql-test-run.pl now has an --only-big-tests option, which causes only big tests to run.

Normal (non-big) tests are skipped. If both --big-test and --only-big-tests are given, --only-

big-tests is ignored. (Bug #25182306)

• mysql-test-run.pl has a new --discover option. When given, mysql-test-run.pl attempts to

preload discover, the Developer Studio Memory Error Discovery Tool when starting mysqld. Reports

from discover may be found in log/mysqld.%p.txt under the directory given by --vardir. This

option is supported only on SPARC-M7 systems. (Bug #25048971)

• mysqltest now supports an expr command that enables an expression to be evaluated and assigned

to a variable. For details, see the command description in the MySQL Server Doxygen documentation,

available at https://dev.mysql.com/doc/index-other.html. (Bug #24806741)

• mysqltest now supports a force-cpdir command that copies a source directory to a destination

directory recursively (that is, it copies subdirectories). (Bug #24806681)

• mysql-test-run.pl has a new --summary-report option. When given, mysql-test-run.pl

generates a plain text version of the test summary only and writes it to the file named as the option

argument. The file is suitable for sending by email. (Bug #24512357, Bug #82708)

• mysql-test-run.pl could not be run with --valgrind-option=--tool=custom_tool, for values of

custom_tool such as massif or helgrind, because it added the options for memcheck that might

not be understood by other tools. Also, the mysql-test-run.pl --callgrind option did not work

because it supplied an invalid --base option to callgrind. Thanks to Daniel Black for the patch on

which the fixes were based. (Bug #23713613, Bug #82039)

• The mysqltest connect() function now permits SOCKET and TCP values for the options argument,

to specify using the socket-file and TCP/IP connection protocols.

In addition, transport protocols now must match the current system. Previously, passing PIPE or SHM on

non-Windows systems caused the default (socket-file) transport protocol to be used. Now this causes an

error, and, similarly, passing SOCKET on Windows systems causes an error. (Bug #21046241)

• mysql-test-run.pl now supports a --bootstrap option that enables mysqld options to be

designated as bootstrap options. When mysql-test-run.pl finds --bootstrap options in a

master.opt file, it removes and reinitializes the data directory and restarts the server with the new

option settings. (Bug #18184868)

X Plugin Notes

• The MYSQLX_TCP_PORT CMake option was ignored. (Bug #25493867, Bug #84804)

• The protobuf compiler emitted “unused import” warnings for mysqlx.proto. (Bug #25444009, Bug

#84641)

• Connections were released which were not initialized when validation occurred. (Bug #25392280)

• The Mysqlx_notice_warning_sent and Mysqlx_notice_other_sent status variable values did

not increment as expected. (Bug #25289949, Bug #84258, Bug #25290001, Bug #84260)

540

MySQL 8.0 Release Notes

• The manual definition of the MYSQL_DYNAMIC_PLUGIN macro was redundant. (Bug #25162590, Bug

#83988)

• IPv6 connectivity support defined a new system variable mysqlx_bind_address with the default value

of '0.0.0.0', but the default value should have been '*' so that connections to X Plugin may be made using

an IPv6 address, an IPv4 address, or a hostname. (Bug #25047909, Bug #83688)

• The stmt field was marked as required in the message:

message Mysqlx.Crud.ModifyView {

required Collection collection = 1;

optional string definer = 2;

optional ViewAlgorithm algorithm = 3;

optional ViewSqlSecurity security = 4;

optional ViewCheckOption check = 5;

repeated string column = 6;

required Mysqlx.Crud.Find stmt = 7;

}

(Bug #24968735, Bug #83595)

• For a table created with CREATE TABLE foo (doc JSON), the statement list_objects incorrectly

reported the table as a collection. (Bug #24963952)

• Sending Expect.Open to a connected socket before authentication led to the following error messages:

... Plugin mysqlx reported: '10: Invalid message 24 received during client initialization'

... Plugin mysqlx reported: '10: ERROR reading from socket Bad file descriptor (9) 2'

(Bug #24940144, Bug #83494)

• On Linux, MySQL Shell in JavaScript and Python interactive mode hid collections if the lettercase in the

collection name was not uniform. (Bug #24848125)

• If multiple user accounts exist that match the authenticating user, the X Plugin would attempt to

authenticate all matching accounts instead of the best matching account. (Bug #24847537)

• Boost classes with corresponding functionality in C++ 11 were moved or wrapped. (Bug #24680856)

• When two X Plugin instances were started on the same port, the resulting error message was split over

two lines and contained duplicate information. (Bug #24679018, Bug #83008)

• The performance_schema.threads table did not show processlist statistics for the X Plugin.

(Bug #24638038)

• If the client sent an unknown message type to the server, the server would send back an error message

and then disconnect the client. (Bug #24611754, Bug #82868)

• When the client sent a zero length message, the X Plugin did not send a response. For a subsequent

message the client received an error E_X_BAD_MESSAGE and was disconnected, depending on the

header content. (Bug #24595459, Bug #82862)

• X Plugin displayed its version to any connected user, including those not authenticated. (Bug

#24562707, Bug #82784)

• X Plugin generated an incorrect query when a duplicate field name existed in an Update statement.

(Bug #24510083)

541

MySQL 8.0 Release Notes

• The statement list_objects returned incorrect information for some views in sys database. (Bug

#24472325)

• X Plugin was trying to send result sets to a client, even where the connection had been closed. The

plugin now stops execution of a stored procedure if the connection is reset. (Bug #24440344)

• Attempting to list objects using the list_objects statement without explicitly setting the database

name resulted in the collection being incorrectly classified as a table. (Bug #23205895, Bug #81248)

• X Plugin now supports the sha256_password plugin. (WL #9271)

Functionality Added or Changed

• Incompatible Change: Previously, for INSERT ... SELECT ... ON DUPLICATE KEY UPDATE

statements for which the UPDATE referred to SELECT columns, the results could be incorrect if the

SELECT was a UNION. Now such statements are prohibited and produce an error. To work around this

restriction, write the UNION as a derived table so that its rows can be treated as a single-table result set,

which is permitted. See INSERT ... ON DUPLICATE KEY UPDATE Statement. (WL #5094)

• InnoDB: By default, InnoDB reads uncommitted data when calculating statistics. In the case of

an uncommitted transaction that deletes rows from a table, InnoDB excludes records that are

delete-marked when calculating row estimates and index statistics, which can lead to non-optimal

execution plans for other transactions that are operating on the table concurrently using a transaction

isolation level other than READ UNCOMMITTED. To avoid this scenario, a new configuration option,

innodb_stats_include_delete_marked, can be enabled to ensure that InnoDB includes delete-

marked records when calculating persistent optimizer statistics. (Bug #23333990)

• InnoDB: Geometry parsing and bounding box computational code for R-trees was moved from InnoDB

to the server. (WL #9439)

• InnoDB: InnoDB now supports NOWAIT and SKIP LOCKED options with SELECT ... FOR SHARE

and SELECT ... FOR UPDATE locking read statements. NOWAIT causes the statement to return

immediately if a requested row is locked by another transaction. SKIP LOCKED removes locked rows

from the result set. See Locking Read Concurrency with NOWAIT and SKIP LOCKED.

SELECT ... FOR SHARE replaces SELECT ... LOCK IN SHARE MODE, but LOCK IN SHARE

MODE remains available for backward compatibility. The statements are equivalent. However, FOR

SHARE supports NOWAIT, SKIP LOCKED, and OF tbl_name options. See SELECT Statement.

OF tbl_name applies locking queries to named tables.

Note

OF now is a reserved word and cannot be used as an identifier without identifier

quoting.

SELECT ... FOR SHARE and SELECT ... FOR UPDATE statements now require the SELECT

privilege and at least one of the DELETE, LOCK TABLES, or UPDATE privileges. Previously, only the

SELECT privilege was required. (WL #8919, WL #3597)

• InnoDB: The InnoDB data-at-rest encryption feature now supports encryption of redo log and undo log

data, controlled by the innodb_redo_log_encrypt and innodb_undo_log_encrypt configuration

options. See Redo Log Encryption, and Undo Log Encryption. (WL #9290, WL #9289)

• InnoDB: InnoDB internal temporary tables that are stored on disk now support multiple cursor

positions, permitting single writer and multiple reader access within the same thread. The purpose of this

enhancement is to provide support for recursive and non-recursive common table expressions (CTEs).

542

MySQL 8.0 Release Notes

Additionally, consistent-read access to InnoDB on-disk internal temporary tables is replaced by a dirty-

read scheme, and row counts for InnoDB on-disk internal temporary tables now use row count statistics

instead of slower table scans. (WL #9248)

• InnoDB: InnoDB now compresses large objects into a sequence of smaller zlib streams for tables

that use ROW_FORMAT=COMPRESSED. Previously, large object data was compressed into a single zlib

stream. (WL #9263)

• Replication: When a negative or fractional timeout parameter was supplied to

WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS(), the server behaved in unexpected ways. With this fix:

• A fractional timeout value is read as-is, with no round-off.

• A negative timeout value is rejected with an error if the server is on a strict SQL mode; if the server is

not on a strict SQL mode, the value makes the function return NULL immediately without any waiting

and then issue a warning.

(Bug #24976304, Bug #83537)

• Replication: Work has been done to reduce contention between receiver (I/O) and applier (SQL)

replication threads. This ensures slaves keep up with a higher insert load on their master. (Bug #78246,

Bug #21753696, WL #8599)

• Replication: Added the binlog_expire_logs_seconds system variable, which sets an interval

in seconds for purging of the binary log. The effects of this variable and expire_logs_days are

cumulative, making it possible to set a period such as 1.5 days. To completely disable automatic binary

log purging, set both variables equal to 0, which is the default value for both of them. (Bug #71697, Bug

#18260088, WL #9237)

• Replication: Performance schema tables have been added to monitor replication lags and queues.

The replication_connection_status table has updated information on the last transaction

queued in the relay log, as well as the transaction currently being queued in the relay log. The

replication_applier_status_by_coordinator table has updated information on the last

transaction written to the buffer of a worker, as well as the transaction currently being processed by the

coordinator. The replication_applier_status_by_worker table has updated information on

the last transaction applied by the worker, as well as on the transaction currently being applied. The

information presented in each of these tables contains the transaction's GTID, commit timestamps,

processing stage timestamp, and the timestamp of the completion.

In the replication_applier_status_by_worker table, the LAST_SEEN_TRANSACTION column is

replaced by the APPLYING_TRANSACTION column. (WL #7374)

• Replication: The new binlog_expire_logs_seconds variable is a global server variable in addition to the

existing expire_logs_days variable. The purpose is to facilitate finer grained retention policies of binary

logs than the current day granularity. (WL #9237)

• Replication: Correct recovery of DDL statements or transactions by binary log implements support

for correct recovery of DDL transactions based on the binary log data. In the context of the new data-

dictionary it becomes possible to make metadata changes and write them to the binary log as a single

transaction by using the 2-phase commit protocol. (WL #9175)

• Replication: Multi-source replication now supports per-channel replication filters. This makes it possible

to filter out the execution of selected replicated data from a specific channel. Until now replication filters

have been global, and only applicable to all channels. (WL #7361)

543

MySQL 8.0 Release Notes

• Replication: Row-based replication now uses extended table metadata in the binary log. The extended

metadata serves two major purposes: slaves use the metadata to transfer data smoothly when its table

structure is different from master's, and external software can use the metadata to decode row events

and store the data into external databases. (WL #4618)

• Replication: An infrastructure for GTID based delayed replication and replication lag monitoring has

been added to enable you to properly monitor replication lag. Two new timestamps that are associated

with each transaction (not each event or statement) in the binary log have been introduced. The

original_commit_timestamp is in microseconds since the epoch when the transaction was committed on

the original master, and the immediate_commit_timestamp is in microseconds since the epoch when the

transaction was committed on the immediate master. (WL #7319)

• Replication: The RESET MASTER statement has been extended to allow specification of a binary log file

number. The RESET MASTER TO statement accepts an argument which specifies the index of the new

binary log file to use. The purpose is to simplify failover procedures by replacing the FLUSH BINARY

LOGS and PURGE BINARY LOGS TO statements with a single RESET MASTER statement. (WL #9110)

• Replication: The process used for how delay is defined and calculated for delayed replication have

been improved. This relies on a new timestamp in the binary log, the immediate_commit_timestamp,

which is the number of microseconds since epoch when the transaction was written to the binary log of

the immediate master. This means that the delay is no longer computed per-event, it is now applied per-

transaction. (WL #7318)

• Replication: It is now possible to specify whether information written into the binary log enables

replication slaves to parallelize based on commit timestamps, or on transaction write sets.

Using write sets has a the potential for greater parallelism than using commit timestamps since it does

not depend on the commit history. When applying binary logs in this fashion on a replication slave, it may

be able to leverage capabilities of the underlying computing hardware (such as CPU cores) and thus

speed up this process.

The interface for choosing the source of parallelization is implemented as a new server system

variable binlog_transaction_dependency_tracking which can take any one of the

values COMMIT_ORDER, WRITESET, or WRITESET_SESSION. COMMIT_ORDER (the default)

causes parallelization information to be logged using commit timestamps; WRITESET causes this

information to be logged using write sets in such a way that any transactions not updating the

same row can be parallelized; and WRITESET_SESSION acts in the same fashion as WRITESET,

except that updates originating with the same session cannot be reordered. The size of the

row hash history that is kept in memory for tracking transaction dependencies can be set using

binlog_transaction_dependency_history_size, also introduced in this release. (WL #9556,

WL #10750)

• Group Replication: View change events from a group can now be replicated to an external

multithreaded slave (MTS) of type DATABASE. (Bug #25170698, Bug #84008)

• Group Replication: Group Replication now supports SAVEPOINT SQL transactions. (WL #9837, WL

#10520)

• JSON: Added the JSON utility function JSON_PRETTY(), which prints an existing JSON value, or any

string that can successfully be parsed as a JSON document, in a format that can be easily read by

humans. Each JSON object member or array value is displayed on a separate line of the output; each

child object or array is intended 2 spaces with respect to its parent.

Examples:

mysql> SELECT JSON_PRETTY('123');

+--------------------+

544

MySQL 8.0 Release Notes

| JSON_PRETTY('123') |

+--------------------+

| 123 |

+--------------------+

mysql> SELECT JSON_PRETTY("[1,3,5]");

+------------------------+

| JSON_PRETTY("[1,3,5]") |

+------------------------+

| [

] |

+------------------------+

mysql> SELECT JSON_PRETTY('{"a":"10","b":"15","x":"25"}');

+---------------------------------------------+

| JSON_PRETTY('{"a":"10","b":"15","x":"25"}') |

+---------------------------------------------+

| {

"a": "10",

"b": "15",

"x": "25"

} |

+---------------------------------------------+

(WL #9191)

• JSON: Previously, when sorting JSON values in a query using ORDER BY, each value was represented

by a part having a fixed length in the sort key, each such part requiring 1K of memory. In many cases

this usage was excessive—for example, an integer scalar value requires only a relatively very few bytes,

so that the remainder of the 1K (90% or more) was taken up by padding.

Variable length parts for JSON sort keys have been introduced to address this issue, with each key

part now taking up only the space that is needed to store the value. This has the following benefits for

performance:

• Because sort buffer space is used more effectively, filesorts need not flush to disk as early or often,

which means that more data can be sorted in memory.

• Shorter keys can be compared more quickly than longer ones, providing a noticeable improvement in

performance for in-memory sorts as well as sorts requiring disk usage.

(WL #8741)

• The WEIGHT_STRING() debugging function no longer supports the LEVEL clause. (Bug #25469683,

Bug #84723)

• For Developer Studio 12.5, 32-bit builds are now disabled unless the FORCE_UNSUPPORTED_COMPILER

option is given. (Bug #25267157, Bug #84230)

• Several foreign key constraint checks that were storage engine agnostic were being done inside

InnoDB. These are now done at the SQL layer. (Bug #25252847)

• Some GIS out-of-bounds checking was simplified. Thanks to Daniel Black for the contribution. (Bug

#25202470, Bug #84062)

• The set of compiler flags used for Developer Studio 12.5 was improved. (Bug #25148549, Bug #83955)

• CMake now uses CMAKE_POLICY of CMP0022 NEW rather than CMP0022 OLD. (Bug #25090147, Bug

#83804)

545

MySQL 8.0 Release Notes

• If MySQL was configured to build with the -Wno-error option, mysql_config produced incorrect

output for its --cflags option.

The set of compiler options that mysql_config and pkg-config produce now is determined by

whitelisting rather than blacklisting. (Bug #25040566, Bug #22898475, Bug #80662)

• The performance of UTF-8 binary collations was improved. (Bug #24788778, Bug #83247, Bug

#25076862)

• The systemd service file for mysqld now includes a Documentation value in the [Unit] section to

provide a link to the systemd documentation in the MySQL Reference Manual. (Bug #24735762)

• Unit testing now uses Google Mock 1.8. (Bug #24572381, Bug #82823)

• The unimplemented and nonstandard WITH CUBE clause for GROUP BY is no longer supported.

Note

CUBE now is a reserved word and cannot be used as an identifier without

identifier quoting.

(Bug #24572048, Bug #82821)

• These outdated build scripts were removed from MySQL source distributions: BUILD/SETUP.sh,

BUILD/autorun.sh, BUILD/cmake_configure.sh, BUILD/compile-dist, and cmake/

configure.pl. (Bug #24512933)

• The removal of the mysql_shutdown() C API function in MySQL 8.0.0 has been reverted. It is still

to be removed in a future MySQL version, but that removal has been deferred. (Bug #24496976, Bug

#82681, WL #9014)

• Consistency and maintainability of Debian/Ubuntu packaging maintainer scripts was improved. (Bug

#23588977)

• In-place ALTER TABLE operations are now possible for column modifications of tables containing

generated columns that depend on columns with a DEFAULT value if the modified columns are not

involved in the generated column expressions. For example, changing the NULL property of a separate

column can be done in place without a table rebuild. (Bug #22987899, Bug #80832)

• For dumps of the mysql system database, mysqldump no longer generates DDL statements for the

innodb_index_stats and innodb_table_stats tables. Such statements fail at dump reload time

because those tables are not user accessible. (Bug #22655287)

• If mysqld is invoked with --daemonize, stdout and stderr are redirected to /dev/null if

connected to a terminal type device, so that mysqld can behave as a true daemon. (Bug #21627629)

• mysql_secure_installation is more strict about what it considers valid yes and no responses.

(Bug #13344753, Bug #62925)

• MySQL client and utility programs reported their own program-specific version number when invoked

with the --version option, and the version strings did not follow a consistent format. Now these

programs print the MySQL version number (same as mysqld) in a consistent format. (Bug #11763201,

Bug #55885)

• A new mysqldump option, --network-timeout, enables large tables to be dumped by setting max-

allowed-packet to its maximum value and network read and write timeouts to a large value. This

option is enabled by default. To disable it, use --skip-network-timeout. (Bug #11754493, Bug

#46103)

546

MySQL 8.0 Release Notes

• Added two JSON aggregation functions JSON_ARRAYAGG() and JSON_OBJECTAGG(). The

JSON_ARRAYAGG() function takes a column or column expression as an argument, and aggregates the

result set as a single JSON array, as shown here:

mysql> SELECT col FROM t1;

+--------------------------------------+

| col |

+--------------------------------------+

| {"key1": "value1", "key2": "value2"} |

| {"keyA": "valueA", "keyB": "valueB"} |

+--------------------------------------+

2 rows in set (0.00 sec)

mysql> SELECT JSON_ARRAYAGG(col) FROM t1;

+------------------------------------------------------------------------------+

| JSON_ARRAYAGG(col) |

+------------------------------------------------------------------------------+

| [{"key1": "value1", "key2": "value2"}, {"keyA": "valueA", "keyB": "valueB"}] |

+------------------------------------------------------------------------------+

1 row in set (0.00 sec)

The order of the array elements is unspecified.

JSON_OBJECTAGG() takes two columns or expressions which it interprets as a key and a value,

respectively; it returns the result as a single JSON object, as shown here:

mysql> SELECT id, col FROM t1;

+------+--------------------------------------+

| id | col |

+------+--------------------------------------+

| 1 | {"key1": "value1", "key2": "value2"} |

| 2 | {"keyA": "valueA", "keyB": "valueB"} |

+------+--------------------------------------+

2 rows in set (0.00 sec)

mysql> SELECT JSON_OBJECTAGG(id, col) FROM t1;

+----------------------------------------------------------------------------------------+

| JSON_OBJECTAGG(id, col) |

+----------------------------------------------------------------------------------------+

| {"1": {"key1": "value1", "key2": "value2"}, "2": {"keyA": "valueA", "keyB": "valueB"}} |

+----------------------------------------------------------------------------------------+

1 row in set (0.00 sec)

A NULL key causes an error; duplicate keys are ignored.

For more information, see Aggregate Functions. (Bug #78117, Bug #21647417, WL #7987)

• MySQL now supports an IMPORT TABLE statement that imports MyISAM tables based on information

contained in .SDI (serialized dictionary information) metadata files. This statement is useful for

exporting “raw” table files from one server and importing them into another, and provides a faster

alternative to dumping tables as a file of SQL statements using mysqldump and processing the dump

file using mysql. For more information, see IMPORT TABLE Statement. (WL #7524)

Bugs Fixed

• Incompatible Change: The stored definition of a view for which an explicit column name list was

provided could be invalid. For example, for this statement:

CREATE VIEW v1 (name2) AS SELECT 1 AS name1 UNION SELECT 2 ORDER BY name1;

The stored definition looked like this, which is invalid:

547

MySQL 8.0 Release Notes

CREATE VIEW v1 AS SELECT 1 AS name2 UNION SELECT 2 AS 2 ORDER BY name1;

Now column names within the stored definition are not replaced by the column name list:

CREATE VIEW v1 (name2) AS SELECT 1 AS name1 UNION SELECT 2 AS 2 ORDER BY name1;

An incompatibility resulting from this change is that the CREATE VIEW statement can no longer be

recreated solely from the INFORMATION_SCHEMA VIEWS table, because the VIEW_DEFINITION

value does not show the column name list. Instead, you must also consult the COLUMNS table to get the

column name list. Alternatively (and more simply), use SHOW CREATE VIEW. (Bug #23265335, Bug

#81377)

• InnoDB; Microsoft Windows: On a MySQL 64-bit build on Windows, a file I/O retry result was

misinterpreted due to a missing cast necessary for the correct operation of the retry path, resulting in a

failing assertion and operating system error. (Bug #24711351)

• InnoDB: In debug builds, a call that initialized latch debugging raised an assertion due to a race

condition. (Bug #25700405)

• InnoDB: The restriction that required the first undo tablespace to use space ID 1 was removed. The first

undo tablespace may now be assigned a space ID other than 1. Space ID values for undo tablespaces

are still assigned in a consecutive sequence. (Bug #25551311)

• InnoDB: A DROP TABLE operation raised an assertion on a server with an innodb_force_recovery

setting of 5 or 6. DROP TABLE is no longer permitted with these innodb_force_recovery settings.

(Bug #25385590)

References: This issue is a regression of: Bug #19779113.

• InnoDB: Compiling the server without the Performance Schema caused a build failure. (Bug

#25348787)

• InnoDB: During read-ahead, the wrong page size was used to calculate the tablespace size. (Bug

#25330449)

• InnoDB: Compiling on Fedora 25 using DWITH_LZ4=system resulted in a build failure due to a

deprecated LZ4_COMPRESS_LIMITEDOUTPUT function. (Bug #25297593)

• InnoDB: Disabling macros such as UNIV_PFS_MUTEX, UNIV_PFS_RWLOCK, and UNIV_PFS_THREAD

caused compilation errors. (Bug #25251082)

• InnoDB: A NULL virtual column field name in a virtual index caused a server exit during a field name

comparison that occurs while populating virtual columns affected by a foreign key constraint. (Bug

#25222337)

• InnoDB: The file handle type name for InnoDB file I/O Performance Schema instrumentation was

changed from os_pfs_file_t to pfs_os_file_t. (Bug #25220118)

• InnoDB: Transactions with subqueries on INFORMATION_SCHEMA tables could block concurrent DDL

operations. (Bug #25200952)

• InnoDB: During a range comparison, a secondary index field number was passed instead of clustered

index field number, eventually causing the retrieval of an incorrect field. (Bug #25175249)

• InnoDB: A server exit on restart was caused by missing my_thread_init() and

my_thread_exit() functions for background threads that initialize the st_my_thread_var structure.

(Bug #25167032)

548

MySQL 8.0 Release Notes

• InnoDB: A memcached read operation with a non-default read batch size configuration resulted in a

server exit. (Bug #25147515)

• InnoDB: The INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS table reported NULL for a foreign

key constraint name (UNIQUE_CONSTRAINT_NAME) after restarting the server. (Bug #25126722)

• InnoDB: A gap lock was taken unnecessarily during foreign key validation while using the READ

COMMITTED isolation level. (Bug #25082593)

• InnoDB: Loading InnoDB tables required more memory in MySQL 5.7 due primarily to the addition of

in-memory structure members introduced with temporary table optimizations. The in-memory structure

members, only used for temporary tables, are now only allocated as needed. (Bug #25080442)

• InnoDB: After a TRUNCATE TABLE operation on a table with a FULLTEXT index, space size was

incorrectly calculated resulting in an invalid read. (Bug #25053705)

• InnoDB: A prepared XA transaction was rolled back by a high priority transaction. The high priority

transaction should wait if the blocking transaction is in a prepared state. (Bug #25032066)

• InnoDB: InnoDB passed an invalid argument to syscall(SYS_futex). (Bug #24923840, Bug

#83375)

• InnoDB: After redo log recovery, the node size of an undo tablespace object could sporadically be zero,

eventually causing an error. Additionally, the undo tablespace object was incorrectly placed on the LRU

list, and the header page of the undo tablespace could be present the buffer cache when the tablespace

object is freed, causing a file-open failure on the first page read. (Bug #24916359)

• InnoDB: During a checkpoint, all MLOG_FILE_NAME redo log records were written in a single mini-

transaction (mtr), causing a log parsing buffer overflow. (Bug #24793413, Bug #83245)

• InnoDB: The GCC mach_parse_compressed function should load one to five bytes depending on the

value of the first byte. Due to a GCC bug, GCC 5 and 6 emit code to load four bytes before the first byte

value is checked (GCC Bug #77673). A workaround prevents this behavior. Thanks to Laurynas Biveinis

for the patch. (Bug #24707869, Bug #83073)

• InnoDB: Code related to tablespace type functions was improved to address issues with naming

consistency, function distribution, and function usage. (Bug #24706739, Bug #83092)

• InnoDB: A mechanism was added to debug builds to ensure that keys for InnoDB Performance Schema

instrumentation are registered with Performance Schema. The mechanism causes startup to fail on

debug builds if the number of Performance Schema keys does not match the number of registered

Performance Schema keys. (Bug #24686908)

• InnoDB: A race condition while updating table statistics could result in an estimated row count of 1 and

an incorrect query execution plan. (Bug #24666839, Bug #82968)

• InnoDB: Due to a glibc bug, short-lived detached threads could exit before the caller had returned

from pthread_create(), causing a server exit. Thanks to Laurynas Biveinis for the patch. (Bug

#24605956, Bug #82886)

• InnoDB: An error in code related to table statistics raised an assertion in the dict0stats.cc source

file. (Bug #24585978)

• InnoDB: The list of module base names representing modules in the InnoDB code base that allocate

memory using ut_malloc or ut_new was incomplete. The list is used by the Performance Schema for

reporting of InnoDB memory allocation event data. (Bug #24571816)

• InnoDB: Some InnoDB rw-lock and mutex keys were not registered for use with the Performance

Schema. (Bug #24571597)

549

MySQL 8.0 Release Notes

• InnoDB: After increasing the value of innodb_undo_logs and restarting the server, the number of

active undo tablespaces was not increased when assigning undo tablespaces to newly allocated rollback

segments. (Bug #24488141)

• InnoDB: The unused MLOG_UNDO_HDR_DISCARD redo log record type and related functions were

removed. (Bug #24482001)

• InnoDB: An assertion was raised when the purge thread started due to the server not recognizing a

tablespace ID as an undo tablespace ID. (Bug #24479773)

References: This issue is a regression of: Bug #23517560.

• InnoDB: InnoDB incorrectly reported an error about missing encryption when restoring pages from the

doublewrite buffer during recovery. (Bug #24471076)

• InnoDB: InnoDB reported an incorrect estimate for the number of pages in the buffer pool for a table.

The number of pages was not decremented correctly when pages were removed. (Bug #24464147)

References: This issue is a regression of: Bug #21747906.

• InnoDB: The following code changes related to undo tablespace management were implemented:

• An in-memory array for temporary tablespace rollback segments was added, freeing 32 slots in the

TRX_SYS page for use by redo-enabled rollback segments.

As a result of this change, you no longer need to consider temporary tablespace rollback segments

when setting the innodb_rollback_segments configuration option during configuration of separate

undo tablespaces.

• Code comments related to undo logs and rollback segments were revised.

• Fixed arrays that list rollback segments and undo tablespaces were replaced by dynamic size arrays.

• The function that initializes undo tablespaces was refactored.

• A class was added for managing just-in-time creation of undo and undo file names.

(Bug #24462978)

• InnoDB: A cached undo segment was not removed from the rollback segment history during a slow

shutdown. (Bug #24450908)

• InnoDB: An error during a table-rebuilding operation on a table with only a generated clustered index

(GEN_CLUST_INDEX) raised and assertion due to an error called with an invalid key name. (Bug

#24444831)

• InnoDB: MySQL did not build with GCC 6.1.1. (Bug #24438752)

• InnoDB: Rotating the tablespace encryption master key while the server is in read-only mode raised an

assertion instead of displaying an error message. (Bug #24404091)

• InnoDB: On a table without an explicitly defined primary key, InnoDB did not replace the implicit

clustered index (GEN_CLUST_INDEX) when a unique key was defined on a NOT NULL column. (Bug

#24397406)

• InnoDB: handler::keys_to_use_for_scanning() was removed from the handler API. The

function was no longer used. The HA_READ_ORDER index flag provides the same information for each

index. (Bug #24364448)

550

MySQL 8.0 Release Notes

• InnoDB: Page cleaner threads asserted due to a regression related to the adaptive hash index feature.

(Bug #24346574)

References: This issue is a regression of: Bug #21407023.

• InnoDB: InnoDB failed to free memory used by the full-text optimizer thread. (Bug #24331265)

• InnoDB: During recovery, InnoDB attempted to fetch LOB pages using a null reference. (Bug

#23615208)

• InnoDB: When adding a new index, the server dropped an internally defined foreign key index and

attempted to use a secondary index defined on a virtual generated column as the foreign key index,

causing a server exit. InnoDB now permits a foreign key constraint to reference a secondary index

defined on a virtual generated column. (Bug #23533396)

• InnoDB: An INFORMATION_SCHEMA.FILES query resulted in a server exit due to a race condition with

a concurrent tablespace creation operation. (Bug #23477214, Bug #81614)

• InnoDB: A concurrent DML operation during an in-place ALTER TABLE operation that rebuilt the table

did not update a virtual index, resulting in a mismatch between the virtual index and clustered index.

(Bug #23219499)

• InnoDB: A TRUNCATE TABLE operation held the dict_sys mutex while scanning for and removing

pages from the buffer pool, causing concurrent DDL operations to stall. The mutex is now released

during the scan and acquired again when the scan is completed. (Bug #23070734, Bug #80060)

• InnoDB: Inserting GIS data into an R-tree raised an assertion due to a missing page number field that

was encountered when storing the B-tree cursor. (Bug #23044098, Bug #80939)

• InnoDB: Writing to an InnoDB internal temporary table did not increment the Handler_write counter.

(Bug #23024178)

• InnoDB: Changes to the InnoDB recovery process in MySQL 5.7 could require up to three scans of the

redo log during recovery. To reduce the number of scans, the first and second scans were merged. With

this change, there is only one scan unless the redo log record hash table that is populated by the scan

reaches its memory threshold. In this case, a second scan is initiated that performs a simultaneous scan

and apply. (Bug #22963951, Bug #80788)

• InnoDB: A table-copying online ALTER TABLE operation on a ROW_FORMAT=REDUNDANT table with

indexed virtual columns raised an assertion. (Bug #22018745)

• InnoDB: After a server restart, concurrent INSERT operations a table with an auto-increment primary

key resulted in a duplicate entry error. The current auto-increment value was not changed after

auto_increment_increment and auto_increment_offset settings were modified. (Bug

#20989615, Bug #76872)

• InnoDB: Performance Schema instrumentation for InnoDB file I/O was disabled on Windows. (Bug

#14025581)

• InnoDB: An automatically generated foreign key constraint identifier that exceeded the 64 character limit

appeared truncated in the INFORMATION_SCHEMA.TABLE_CONSTRAINTS CONSTRAINT_NAME column.

Automatically generated foreign key constraint identifiers can no longer exceed the 64 character limit.

(Bug #11745347, Bug #13942)

• InnoDB: The row_search_mvcc() function unnecessarily traversed the entire table for a range query,

which occurred when the record was not in the transaction read view. (Bug #84202, Bug #23481444,

Bug #25251375)

551

MySQL 8.0 Release Notes

• Packaging: The my_create_minidump function in the mysys library called the Windows API function

MiniDumpWriteDump with an incorrect value (NULL) for the ExceptionParam parameter. This resulted

in exception information being omitted from the minidump file. (Bug #24505650, Bug #82695)

• Partitioning: For a partitioned table, dropping a partition dropped triggers for the table as well. (Bug

#24449174)

• Partitioning: Updating a row of a table that had partitioning on a generated column could raise an

assertion failure for debug builds, and return incorrect results in nondebug builds. (Bug #22574695, Bug

#80080)

• Replication: MySQL 8.0.1 adds the original commit timestamp related statements, but mysqlbinlog

was wrongly reporting that these statements have been present since MySQL 8.0.0 because they were

written to the log with the incorrect version number 80000. The fix changes the version to 80001 in

mysqlbinlog dumps. (Bug #25710507)

• Replication: Lock contention impeded binary relay performance during processing of the relay log file

on the slave. (Bug #25321231, Bug #77778)

• Replication: A failed node that was removed from the cluster could be expelled upon rejoining the

cluster. (Bug #25311008)

• Replication: When using a multithreaded slave, applier errors displayed worker ID data that was

inconsistent with data externalized in Performance Schema replication tables. (Bug #25231367)

• Replication: Compiling MySQL 5.7.17 failed with a variable length array error. (Bug #25163241, Bug

#83994)

• Replication: In row-based replication, a message that incorrectly displayed field lengths was returned

when replicating from a table with a utf8mb3 column to a table of the same definition where the column

was defined with a utf8mb4 character set. (Bug #25135304, Bug #83918)

• Replication: If the binary log on a master server was rotated and a full disk condition occurred on the

partition where the binary log file was being stored, the server could stop unexpectedly. The fix adds

a check for the existence of the binary log when the dump thread switches to next binary log file. If the

binary log is disabled, all binary logs up to the current active log are transmitted to slave and an error is

returned to the receiver thread. (Bug #25076007)

• Replication: The GTID transaction skipping mechanism that silently skips a GTID transaction that was

previously executed did not work properly for XA transactions. (Bug #25041920)

• Replication: If a relay log index file named relay log files that did not exist, RESET SLAVE ALL

sometimes did not fully clean up properly. (Bug #24901077)

• Replication: When the MTS slave applier stopped because of an (injected) error, it reported no useful

information for troubleshooting. (Bug #24822686)

• Replication: FLUSH BINARY LOGS could become slow with data replicated from many servers. (Bug

#24806259, Bug #83270)

• Replication: When using XA transactions, if a lock wait timeout or deadlock occurred for the applier

(SQL) thread on a replication slave, the automatic retry did not work. The cause was that while the

SQL thread would do a rollback, it would not roll the XA transaction back. This meant that when the

transaction was retried, the first event was XA START which was invalid as the XA transaction was

already in progress, leading to an XAER_RMFAIL error. (Bug #24764800)

References: See also: Bug #83588, Bug #24923091, Bug #24966941.

552

MySQL 8.0 Release Notes

• Replication: A partially failed CREATE USER, RENAME USER, or ALTER USER statement was not

correctly consuming an auto-generated or specified GTID when binary logging was disabled. (Bug

#24693798)

• Replication: Binlog_sender, which writes events from the binary log to a packet buffer and then

sends the packet to the slave, did not reduce the size of the send buffer as expected. (Bug #24643036)

• Replication: The group commit update of GTIDs has been refactored to improve performance on

workloads with many small transactions. (Bug #24398760)

• Replication: If the relay_log option was not specified in a configuration file, the

relay_log_basename variable was being internally constructed on the fly using hostname but the

relay_log_basename variable was not set. When a slave tried to access this uninitialized variable it

resulted in an unexpected halt of the server. (Bug #24352667)

• Replication: When using a multithreaded slave (slave_parallel_workers greater than 0) the value

of Seconds_Behind_Master was incorrect when rotating a relay log. (Bug #23532304)

• Replication: An XA PREPARE statement that failed during the intermediate steps could lead to an

inconsistent XA transaction state, where ID = -1 but the binlogged flag was set to true. This caused

asserts while executing XA COMMIT and XA ROLLBACK queries. (Bug #22915670)

• Replication: The server prevented several replication-related administrative statements from working if

the read_only system variable was enabled. (Bug #22857926, Bug #25363745, Bug #25326058, Bug

#84350, Bug #84437)

• Replication: CHANGE MASTER TO for a channel that did not exist could raise an assertion. (Bug

#22255698)

• Replication: The delay specified by the binlog_group_commit_sync_delay system variable was

applied to too many binary log commit groups. (Bug #21420180)

• Replication: The number of generated unwanted fseeks into the binary log file being replicated to a

slave has been reduced. (Bug #83226, Bug #24763579)

• Replication: The fix for Bug #81657 was not correctly merged into MySQL 8.0. Thanks to Laurynas

Biveinis for alerting us. (Bug #83124, Bug #24715790)

• Replication: The rpl.rpl_binlog_errors test was failing sporadically on Windows. (Bug #82302,

Bug #24330138)

• Replication: When binlog_group_commit_sync_delay was set to a value

between 1 and 9, if binlog_group_commit_sync_no_delay_count was set

to a value greater than 1, and the number of transaction commits was less than

binlog_group_commit_sync_no_delay_count, these commits hung forever if no more commits

were received; and if binlog_group_commit_sync_no_delay_count was set to 0, all transaction

commits hung forever. (Bug #80652, Bug #22891628)

• Replication: Concurrent CREATE TRIGGER and DROP TRIGGER statements were not being binary

logged in the correct order, causing slaves to fail. (Bug #77095, Bug #21114768)

• Group Replication; Microsoft Windows: Removed unnecessary warnings raised when the Group

Replication plugin was compiled on Windows platforms. (Bug #25119288)

• Group Replication; Microsoft Windows: Building Group Replication support on Windows now requires

CMake version 2.8.12 or later. (Bug #24964522)

553

MySQL 8.0 Release Notes

• Group Replication: The MEMBER_STATE of a group replication member did not change from ERROR

to OFFLINE when the STOP GROUP_REPLICATION command was executed when the error was

ER_GROUP_REPLICATION_CONFIGURATION. (Bug #25674926)

• Group Replication: With flow control enabled, reaching a minimum flow control quota of 1 caused

Group Replication not to stop throttling when the reason for throttling was no longer in effect. (Bug

#25461354)

• Group Replication: Using an unresolvable host name in group_replication_group_seeds

caused START GROUP_REPLICATION to fail. This fix ensures that host names in

group_replication_group_seeds are validated when starting Group Replication and that the list

contains at least one valid address. Invalid addresses are ignored. (Bug #25460324, Bug #84674)

• Group Replication: The _gr_user account created by Group Replication plugin installation was not

reliably removed when the plugin was uninstalled. (Bug #25298987)

• Group Replication: When starting Group Replication on an offline node, it was possible for the node to

be configured for replication, but but be unable to recover. (Bug #25256910)

• Group Replication: Group Replication GCS did not discard messages from an inactive member of the

group. (Bug #25134074)

• Group Replication: An attempt by the Group Replication plugin to contact the server that was no longer

possible led to an assertion. (Bug #25071492)

• Group Replication: After executing restarts on the group replication applier SQL thread, the plugin

could no longer detect failure of the thread. (Bug #24969065)

• Group Replication: Enabling the group replication plugin caused the

performance_schema_max_mutex_classes default value of 200 to be exceeded.

As a result, some group replication mutex instruments did not appear in the

performance_schema.setup_instruments table. (Bug #24746530)

• Group Replication: For servers built with yaSSL, using group replication with encrypted connections

could result in timeout failures waiting for view delivery. (Bug #23592214)

• Microsoft Windows: On Windows, SHOW TABLES FROM db_name hung if db_name was given in

uppercase. (Bug #24800048, Bug #83262)

• Microsoft Windows: 32-bit builds are no longer supported on Windows, but CMake failed to detect

when a 32-built build would be attempted, resulting in compilation errors later. Now CMake detects 32-bit

build attempts and produces an appropriate error message. (Bug #24487483, Bug #82645)

• Solaris: When the WITH_INNODB_MEMCACHED CMake option is enabled, memcached now can be built

on Solaris 11 and 12 using the Developer Studio 12.5 compiler. (Bug #24504155, Bug #82692)

• Solaris: Library search path handling on Solaris was incorrect. (Bug #24487934, Bug #82646)

• Solaris: The minimum required version of Solaris is now Solaris 11 update 3, due to a dependency on

system runtime libraries.

• Solaris: On Solaris, MySQL is now built with Developer Studio 12.5 instead of gcc. The binaries require

the Developer Studio C/C++ runtime libraries to be installed. See here for how to install only the libraries:

https://docs.oracle.com/cd/E60778_01/html/E60743/gozsu.html

• JSON: When a JSON value consisted of a large sub-document wrapped in many levels of JSON arrays,

objects, or both, serialization of the JSON value sometimes required an excessive amount time to

complete. (Bug #23031146)

554

MySQL 8.0 Release Notes

• JSON: When a NULL value existed in a JSON column, the result from a query using GROUP_CONCAT()

together with the ORDER BY clause was not always correct. (Bug #22992666)

• JSON: The internal rapid_json_handler used its own data structures to represent a partially-built

DOM; these had to be converted into a Json_dom graph before returning the result. Now this handler

builds the graph directly, which reduces the amount of work required to build it, and thus to parse a

JSON document. (Bug #22900110)

• JSON: The internal function Item_func_case::val_json() did not always set the null value flag

as expected when a CASE expression evaluated to NULL, leading to an assertion in debug builds of the

server. (Bug #22887227)

• JSON: The SUM() function truncated decimal values extracted from JSON documents, producing an

integer result. (Bug #84935, Bug #25530204)

• JSON: A JSON document that contained a double value slightly greater than the maximum value that

can be represented by a double silently replaced it with zero instead of rejecting the value and raising an

error. Such values are now handled correctly in MySQL JSON documents.

The underlying issue was traced to a problem with RapidJSON, which has been reported to that library's

developers as Issue #849. (Bug #84891, Bug #25518504)

• JSON: The JSON_SEARCH() and JSON_CONTAINS_PATH() functions did not work when the

one_or_all argument was specified using UTF-16 encoding. For both of these functions, this

argument is now converted to utfmb4 if need be before its value is checked. (Bug #84880, Bug

#22516960)

• JSON: The JSON_UNQUOTE() function did not work with strings that used UTF-16 encoding. Now these

strings are converted to utfmb4 internally before being processed. (Bug #84878, Bug #25516881)

• JSON: Updating the same JSON column in a single statement could cause incorrect values to be written

into the table. This occurred when the second update overwrote the column value with a subset of itself.

An example of such a statement is shown here:

UPDATE t SET col = JSON_ARRAY(value), col = col->'$[0]';

(Bug #84694, Bug #25461627)

• JSON: The functions JSON_QUOTE() and JSON_UNQUOTE() did not work correctly with multibyte

character sets such as utf8mb4. (Bug #84680, Bug #25455065)

References: See also: Bug #77234, Bug #21193273.

• JSON: The error message for Error 3152 ER_JSON_USED_AS_KEY has been changed from JSON

column '%s' cannot be used in key specification to the less confusing and more accurate

JSON column '%s' supports indexing only via generated columns on a specified

JSON path. (Bug #81364, Bug #23274244)

• JSON: Internal tests for MySQL JSON functionality ran out of stack space on some platforms when run

against a debug-enabled server. Because timely checks were not made for stack usage, the server did

not detect this situation, leading to a server exit.

The fix for this issue is twofold:

• Stack overrun checks are now made before attempting to serialize a nested array or object, so that the

operation fails gracefully when processing deeply nested JSON documents, rather than causing an

exit.

555

MySQL 8.0 Release Notes

• Serialization of JSON documents has been reorganized so that it requires less use of the stack when

compiled without optimization.

(Bug #81083, Bug #23106330, Bug #26399306)

• BIN() could produce incorrect truncation with multibyte character sets when used within UNION. (Bug

#27511490, Bug #89581)

• MySQL did not compile with GCC 7. (Bug #25643811, Bug #26825211)

• The (undocumented) WINDOWS_RUNTIME_MD CMake option has been removed. (Bug #25611359)

• If --skip-innodb or one of its variants was used, a spurious warning about

avoid_temporal_upgrade was generated. (Bug #25573578)

• mysqld_safe failed to restart the server if a PID_FILE.shutdown file was present. (Bug #25572504)

References: This issue is a regression of: Bug #11751149.

• For Debian/Ubuntu packages, user-defined collation files could be overwritten during MySQL upgrades.

Charset files are now marked as conffiles so that user customizations generate a prompt during

upgrades whether to overwrite them. (Bug #25525628, Bug #84761)

• For CREATE TABLE statements that specified the table name with a database qualifier and included a

DATA DIRECTORY or INDEX DIRECTORY option, an error occurred if there was no default database.

(Bug #25514146, Bug #84861)

• referenced_table_schema and referenced_table_name field values in the

mysql.foreign_keys data dictionary table were not stored in lowercase when

lower_case_table_names was enabled. (Bug #25495714)

• Starting the server with performance_schema_digests_size=1 caused an abnormal exit. (Bug

#25492129, Bug #84786)

• For clients linked against yaSSL, connections became invalid when a read timeout occurred, rather than

retrying the read. (Bug #25444075)

• MySQL compilation in different directories produced different builds to leakage of absolute paths into

debug information and __FILE__. (Bug #25436469, Bug #84608, Bug #25859274, Bug #85855)

• Calculations for UCA 9.0.0 collations were inefficient for tailoring rules containing contraction characters.

(Bug #25426632, Bug #84577, Bug #25426632, Bug #84577)

• A negative internal connection timeout value caused the connection to go idle and abort. A negative

value now causes the connection to block indefinitely in the absence of I/O. (Bug #25408557)

• A mutex Performance Schema name was too long and produced a warning at server startup. (Bug

#25406915)

• MySQL failed to compile on some platforms with -DWITH_LIBWRAP=ON. CMake support now checks

whether tcpd.h has proper function prototypes. (Bug #25395543, Bug #84495)

• An index defined on a data dictionary table column exceeded the maximum index key length when the

instance was initiated with innodb_page_size=4k. (Bug #25384527)

• mysqld_safe did not check whether the directory named by the --basedir option existed. (Bug

#25365194)

556

MySQL 8.0 Release Notes

• Configuring CMake with -G ninja resulted in build output that was inappropriate for build platforms

other than Xcode or Visual Studio. (Bug #25358460)

• mysqld_safe failed if the error log file named by the --log-error option was a FIFO. (Bug

#25356221, Bug #84427)

• For prepared statements, an alias within a subquery or derived table might cause incorrect behavior

during statement execution if another alias depended on it. (Bug #25343335, Bug #84398, Bug

#25171608)

• mysqld_safe could fail if the --datadir option value ended with a / character. (Bug #25319457)

• A recent change to mysqld_safe caused the mysql.server script to be unable to start it if the base

directory was specified as an absolute path that differed from the compiled-in default absolute path. (Bug

#25319392, Bug #84263)

• The CONNECTION_CONTROL plugin failed to compile if the Performance Schema was disabled. (Bug

#25308357, Bug #84304)

• Passwords did not expire correctly for accounts created using MySQL Workbench. (Bug #25299309)

• For System V init scripts for RPMs, the [mysqld] option-file section was being ignored for some

options, such as pid-file. (Bug #25287707, Bug #84172)

• Init scripts failed to launch mysqld_safe if a non-default base directory was used. (Bug #25261472,

Bug #84219)

• CMake now detects whether a GCC 5.3.0 loop optimization bug occurs and attempts a workaround if so.

(Bug #25253540)

• mysqld_safe --no-defaults did not work (inadvertent consequence of an earlier bug fix). (Bug

#25244898, Bug #84173)

• Semicolon (;) characters within or between statements could cause distinct digests to be generated from

identical statements. (Bug #25244533, Bug #83253)

• Components could not register services without referring to their private implementation. A

SERVICE_IMPLEMENTATION(component,service) macro now enables this to be avoided. (Bug

#25238906)

• Certain stored functions, if used in a query WHERE clause, could be handled using Index Condition

Pushdown (which should not happen), resulting in a server exit. (Bug #25196653, Bug #25174454)

• For ai_ci collations based on Unicode Collation Algorithm 9.0.0, accented characters that compare

equal were treated as different by LIKE comparisons. (Bug #25167284, Bug #83999)

• For a client linked against libmysqlclient, invalid memory access could occur during use of

prepared statements. (Bug #25164932)

• Some Linux startup scripts did not process the datadir setting correctly. (Bug #25159791)

• If a character set is specified for a column of a partitioned table, a segmentation fault could occur while

upgrading. (Bug #25153261)

• LOAD DATA failed to accept multibyte characters that followed an escape sequence. (Bug #25147988,

Bug #83950, Bug #25865525)

• The fix for Bug #25088048 caused the command used by mysqld_safe to start the MySQL server to

no longer include the mysqld path. (Bug #25144379)

557

MySQL 8.0 Release Notes

References: This issue is a regression of: Bug #25088048.

• For UCA collations, LIKE comparisons against a pattern that ended with the escape character returned

incorrect results. (Bug #25140629, Bug #83930)

• The default character set and collation were used instead of the character set and collation defined in

db.opt file when upgrading the schema from MySQL 5.7 to MySQL 8.0. (Bug #25139901)

• Instead of updating the data dictionary cache at the end of DDL statements using separate function calls,

the data dictionary cache is now updated as part of transaction commit. (Bug #25095798, Bug #83818)

• CREATE TABLE now requires the FILE privilege if DATA DIRECTORY or INDEX DIRECTORY is

specified explicitly as a table or partition option. ALTER TABLE requires the FILE privilege if either

option is specified explicitly as a partition option (it ignores them if specified as table options). (Bug

#25092566)

• There were some differences between ICU order and MySQL Unicode collations for Hungarian

contractions and ligatures. MySQL now follows ICU order. (Bug #25090543)

• The data dictionary failed to initialize and start when using a binary collation. The query string generated

to create the data dictionary schema did not add quotes to the binary collation name. (Bug #25054104,

Bug #83706)

• Executing a stored procedure containing a query that accessed a view could allocate memory that was

not freed until the session ended. (Bug #25053286)

• Compilation on FreeBSD 11 failed attempting to check MAP_NORESERVE, which is no longer defined.

(Bug #25048128, Bug #83689)

• mysql-test-run.pl now checks whether the TSAN_OPTIONS environment variable is set. If so, the

value is taken as the path name of a file containing ThreadSanitizer suppressions (errors to be ignored

during test runs). Additionally, the --sanitize option now causes mysql-test-run.pl to scan the

server error logs for ThreadSanizer messages. (Bug #24970905, Bug #83601)

• After starting the server with a nonzero --lower-case-table-names setting, an assertion was raised

when USE INFORMATION_SCHEMA; was the first instruction from the first client. (Bug #24963580)

• For case-insensitive Unicode collations, the various space characters did not hash to the same value,

resulting in incorrect comparisons between them. (Bug #24956750, Bug #83549)

• Dictionary clients now track uncommitted dictionary objects that are being modified by DDL statements,

making uncommitted changes by the same session visible to a dictionary client without affecting the

dictionary object cache prior to commit time. (Bug #24956365, Bug #83548)

• Simultaneous dictionary object cache misses were not handled correctly. An object retrieved by one

thread could be evicted from the cache before a waiting thread attempted to access it. (Bug #24949179)

• CMake now avoids configuring the -fexpensive-optimizations option for GCC versions for which

the option triggers faulty shift-or optimizations. (Bug #24947597, Bug #83517)

• CMake support was added for compiling using the -std=c++03 option under Developer Studio 12.5.

This is now used rather than stlport by default. (Bug #24947136, Bug #83512, Bug #25229424)

• NCHAR and NATIONAL CHAR are synonyms, but CAST(expr AS NCHAR) succeeded, whereas

CAST(expr AS NATIONAL CHAR) did not. Now both work. (Bug #24934161)

• OEL RPM packages now better detect which platforms have multilib support (for which 32-bit and 64-bit

libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24925181, Bug #83457)

558

MySQL 8.0 Release Notes

• OEL RPM packages now better detect which platforms do not have multilib support (for which 32-bit and

64-bit libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24916428, Bug #83428)

• The LOCATE() function returned NULL if the substr or str argument was NULL, but not if the pos

argument was NULL. Now it returns NULL if any argument is NULL. (Bug #24911350, Bug #83427)

• Bit operations could cause a server exit to occur if argument nullability was mishandled. (Bug

#24910958, Bug #24930038, Bug #24930829)

• The Block Nested Loop algorithm could allocate too much memory during query execution. (Bug

#24909223)

• Information about building MySQL 5.6 compatibility libraries in the MySQL 5.7 and higher .spec file is

needed only for building libmysqlclient and libmysqld. Information about building the InnoDB

memcached plugin was removed. (Bug #24908345, Bug #83409)

• Incorrect updating of view metadata could raise an assertion. (Bug #24834622)

• Initialization of the keyring_okv plugin failed if the STANDBY_SERVER setting was missing from the

okvclient.ora configuration file, effectively making this a mandatory setting. STANDBY_SERVER is

now optional. (Bug #24816271)

• Data dictionary objects acquired by Dictionary_client::acquire_uncached() are now owned

by the current auto-releaser instead of the caller. Also, acquisition of TABLE_SHARE view objects is

performed by acquire() and clone() instead of acquire_uncached(). (Bug #24813358, Bug

#83296)

• Privilege checking could be incorrect for a derived table used within a multiple-table UPDATE invoked

within a stored procedure or view object, for the second or subsequent execution of the object, if the

derived table was merged into the outer query. (Bug #24810564)

• The Created_tmp_tables status variable was incremented in some cases when no temporary table

was created. (Bug #24808970, Bug #83287)

• An in-place upgrade from MySQL 5.7 to MySQL 8.0 failed if parsing of a stored routine body failed while

migrating the routine. Now a warning is reported and the routine is created without parsing its body.

Also, warnings are now reported when dependency resolution fails for a view during view migration. (Bug

#24805140, Bug #83275)

• For compilation, mysql_upgrade is dependent on the dynamically generated

sql_commands_system_tables_data_fix.h file, but a missing dependency could cause that file

not to be generated. (Bug #24802377, Bug #83272)

• A race condition between transactions accessing the access-control list (ACL) cache and use of the ACL

cache to populate INFORMATION_SCHEMA tables could cause a server exit. (Bug #24786029)

• For debug builds, EXPLAIN or DESCRIBE for a table with a database or table name longer than

the maximum permitted length raised an assertion rather than displaying an appropriate error. (Bug

#24751177, Bug #83114)

• The implementation of several INFORMATION_SCHEMA tables as views on data dictionary tables

introduced a number of native SQL functions intended only for internal use by the server, but they could

be invoked by users. Those functions now produce an error if invoked by users. (Bug #24749248, Bug

#83189)

• CASE, COALESCE(), IF() and IFNULL() could merge a mix of signed and unsigned arguments

incorrectly and produce an incorrect result type. (Bug #24733658, Bug #83148)

559

MySQL 8.0 Release Notes

• Connections from a client to a server with SSL enabled succeeded even if --ssl-mode had a value of

VERIFY_CA or VERIFY_IDENTITY and the client did not provide a CA certificate. (Bug #24732452, Bug

#23189252, Bug #25397416, Bug #84508)

• Manual creation of a directory in the data directory resulted in USE dir_name succeeding even though

the directory was not registered as a database in the data dictionary. (Bug #24732194, Bug #83140)

• If InnoDB statistics were incorrect, FOUND_ROWS() could return 1 even when the previous SELECT

returned no rows. (Bug #24714857, Bug #83110)

• ALTER TABLE on a temporary table could raise an assertion if a nontemporary table with the same

name existed. (Bug #24713918, Bug #83117)

• CMake now sets -DWITH_NUMA=ON for Debian platforms where possible. (Bug #24689101)

• To better provide atomic file creation, Debian packaging scripts now use the coreutils install

command rather than touch, chmod, and chown. (Bug #24688682)

• Enabling the DISABLE_SHARED CMake option caused compilation failure. (Bug #24687701, Bug

#83039)

References: This issue is a regression of: Bug #24481181.

• The BIN(), OCT(), and HEX() functions could mishandle values of the BIT data type. (Bug

#24686658, Bug #83031)

• For debug builds, an invalid utf8 character in the comment of a CREATE EVENT or ALTER EVENT

statement raised an assertion. This now produces an ER_INVALID_CHARACTER_STRING error. (Bug

#24679962)

• The encoding for the utf8 character set permitted characters between U+D800 and U+DFFF as valid,

though they are reserved for surrogate pairs and do not directly represent characters. They are now

considered invalid. (Bug #24672415)

• A query could produce incorrect results if the WHERE clause contained a dependent subquery, the table

had a secondary index on the columns in the select list followed by the columns in the subquery, and

GROUP BY or DISTINCT permitted the query to use a Loose Index Scan. (Bug #24671968, Bug #83005)

• After a RENAME TABLE operation on a table with a foreign key, the generated constraint name was not

updated in TABLE_CONSTRAINTS. (Bug #24666169)

• On macOS, CMake AddressSanitizer support did not work. (Bug #24661626, Bug #82976)

References: This issue is a regression of: Bug #23759968.

• Compilation failed on macOS 10.11 with Xcode 8.0. (Bug #24661523, Bug #82975)

• Index hints applied to invisible indexes produced no error. (Bug #24660093, Bug #82960)

• In some cases, INFORMATION_SCHEMA.KEY_COLUMN_USAGE did not report data for all foreign key

constraints. (Bug #24655803, Bug #82961)

• REPLACE() on large strings could be slow and unkillable. (Bug #24652792)

• The DebugPrintTest and DebugPrintDeathTest unit tests did not handle divide-by-zero testing

properly on the Aarch64 platform. Thanks to Alexey Kopytov for the patch. (Bug #24624555, Bug

#82889)

• Compilation on FreeBSD using GCC 6 did not work. (Bug #24619561, Bug #82922)

560

MySQL 8.0 Release Notes

• Changes made to mysqld_safe in recent MySQL releases require the --ledir, --mysqld, --

mysqld-version options to be specified on the command line; they can no longer be specified in

option files. This could cause failure of init scripts that invoke mysqld_safe. Such scripts now pass the

value of the MYSQLD_OPTS environment variable as the first command-line argument to mysqld_safe,

with the value set to such command line-only mysqld_safe option values as may be required. On

platforms that use systemd, the MYSQLD_OPTS value can be set in /etc/sysconfig/mysqld with a

line such as this:

MYSQLD_OPTS=" --ledir=/mysqld_ledir --mysqld=my_wrapper "

The value of MYSQLD_OPTS can also include mysqld options for mysqld_safe to pass to mysqld.

(Bug #24619033, Bug #82920)

References: This issue is a regression of: Bug #24464380, Bug #24483092, Bug #25088048, Bug

#25378439, Bug #25378565.

• SET PERSIST innodb_buffer_pool_size = value stored the original value of

innodb_buffer_pool_size to mysqld-auto.cnf, not the new value. (Bug #24613005, Bug

#82905)

• For SLES packages, a typo in the installation script postamble prevented some cleanup from occurring.

(Bug #24605300, Bug #82389)

• Some messages written by the server to the error log while upgrading the data directory were missing

the standard timestamp and process ID information. (Bug #24600054, Bug #82874)

• It was possible for the session values of the Last_query_cost and Last_query_partial_plans

status variables to be accessed before they had been initialized. (Bug #24596263)

• Warnings occurring during CREATE TABLE ... SELECT could cause a server exit. (Bug #24595992)

• For LOAD DATA used to insert data into an updateable view, the check to verify whether a column is

actually updatable was missing. (Bug #24595937)

• The server could dereference a null pointer when a deterministic function returning LONGTEXT was used

in a subquery. (Bug #24595581)

• A view altered with ALTER VIEW might be dropped if the statement failed with an error. (Bug

#24594140)

• Conversion of JSON documents to string could be slow if the document was large and contained many

signed integers. (Bug #24586888)

• The data dictionary can contain entries for temporary tables (names beginning with #sql). These

tables were exposed to INFORMATION_SCHEMA queries and through SHOW statements. This could

cause mysqldump and mysqlpump to fail when they attempted to dump such tables. Temporary

tables are now hidden to INFORMATION_SCHEMA queries and SHOW statements. (Bug #24580599, Bug

#24571427)

• When a view was defined, the character set of the definition was not considered. If this differed from

the default character set, table names used in the view might not be recognized, causing the view to be

marked invalid.

For debug builds, an assertion could be raised if an error occurred while parsing an ALTER VIEW

statement and the diagnostics area was empty. (Bug #24580586)

• For LOAD DATA statements, input data with too many column values produced only a warning, rather

than an error as in MySQL 5.6. An error now occurs. (Bug #24577194, Bug #82830)

561

MySQL 8.0 Release Notes

• Using SET PERSIST with the global_log system variable was ineffective. (Bug #24569624, Bug

#82807)

• In the Performance Schema variables_info table, the VARIABLE_SOURCE column was not set

properly for some boolean options specified in option files without a variable. (Bug #24567960)

• The .mylogin.cnf option file is intended for use by client programs, but the server was reading it as

well. The server no longer reads it. (Bug #24557925)

• Use of boost::chrono was replaced with std::chrono because the former was causing link errors.

(Bug #24556808, Bug #82781)

• The X Plugin was built with compilation options different from other plugins. (Bug #24555770, Bug

#82777)

• When populating the variables_by_thread table, the Performance Schema could attempt to access

session variables of other threads that were being deinitialized. (Bug #24555658)

• Users without proper privileges could load and unload server components. (Bug #24528148)

• Concurrent execution of INSTALL COMPONENT and UNINSTALL COMPONENT statements could cause a

server exit. (Bug #24527148)

• On Debian/Ubuntu platforms, the systemd startup script for MySQL ignored datadir settings in /etc/

mysql/my.cnf. (Bug #24517024, Bug #82709)

• With a LOCK TABLES statement in effect, DML statements on a table that had triggers could cause a

server exit. (Bug #24506766)

• Parallel slave threads running account-management statements could fail due to a race condition in

handling privilege cache locks. (Bug #24503606)

• Executing ALTER TABLE on a table that has triggers concurrently with other DDL operations could result

in a corrupted data dictionary. (Bug #24497803)

• If mysqladmin shutdown encountered an error determining the server process ID file, it displayed

an error message that did not clearly indicate the error was nonfatal. It now indicates that execution

continues. (Bug #24496214)

• For the null_audit plugin, setting the null_audit_event_record system variable improperly

could cause a server exit. This variable should be set only from within the null_audit plugin, so it is

now read only. (Bug #24493829, Bug #82670)

• In certain contexts, an expression such as IF(col_name > 5000, (1 / col_name), 5000) could

get a type of DECIMAL(6,4), which would truncate results. (Bug #24492965, Bug #82668)

• The data structure used for ZEROFILL columns could experience memory corruption, leading eventually

to a server exit. (Bug #24489302)

• Operation of the mysql-multi.server.sh script was based on my.cnf in the data directory. That

option file is no longer used, so mysql-multi.server.sh has been removed. (Bug #24487870)

• A query could produce incorrect results if MIN() or MAX() in a subquery referred to an indexed column.

(Bug #24484060, Bug #82638, Bug #24657798, Bug #82965)

• SHOW TRIGGERS output order could differ on Linux and Windows. (Bug #24482919, Bug #82637)

• mysqld_safe attempted to read my.cnf in the data directory, although that is no longer a standard

option file location. (Bug #24482156)

562

MySQL 8.0 Release Notes

• After running mysql_upgrade, executing an INSTALL COMPONENT statement could cause a server

exit. (Bug #24453571)

• A regular expression pattern match into a large string could result in a server exit due to memory

allocation failure or integer overflow. (Bug #24449076, Bug #24449090)

• Starting the server with a MySQL 5.7 data directory resulted in failure due to absence of the

default_roles and role_edges system tables. (Bug #24447771)

• An incorrect error was reported for CREATE TABLE statements with a large value for the CONNECTION

table option. The value is now limited to 1024 bytes. (Bug #24437124)

• An assertion could be raised if an ER_LOCK_WAIT_TIMEOUT error occurred during execution of SHOW

CREATE TRIGGER. (Bug #24420809, Bug #82483)

• Constant folding could produce incorrect results for large unsigned integers. (Bug #24401273, Bug

#82425)

• Use of very long subpartition names could result in a server exit. Now partition or subpartition names

larger than 64 characters produce an ER_TOO_LONG_IDENT error. (Bug #24400628, Bug #82429)

• The Gis_wkb_vector<Gis_point> copy constructor was not explicitly instantiated, causing build

problems for the Intel compiler. (Bug #24397833, Bug #82358)

• Privilege escalation was possible by exploiting the way REPAIR TABLE used temporary files. (Bug

#24388746)

• A race condition between UNINSTALL PLUGIN and SHOW PLUGINS could result in a server exit. (Bug

#24344026)

• With ROW mode binary logging, component installation raised an assertion. (Bug #24343582)

• A potential memory leak related to roles was fixed. (Bug #24337928)

• Subqueries that were converted to semijoins and programmatically generated an

INFORMATION_SCHEMA table could incorrectly treat the INFORMATION_SCHEMA table as empty.

A workaround for this problem prior to the bug fix: SET optimizer_switch='semijoin=off'; (Bug

#24287772, Bug #82214)

• mysqldumpslow failed to parse timestamps in the slow query log; it had not been updated to track a

change in log timestamp format. (Bug #24007040)

• The AppArmor profile installed by Ubuntu packages was missing an entry permitting libnuma to read a

/sys hierarchy path, resulting in server startup failure. (Bug #23854929)

• The optimizer could incorrectly treat RAND() as a constant for queries subjected to semijoin

transformation. (Bug #23854015)

• For debug builds, unequal-length binary operands for bit operators could raise an assertion. (Bug

#23853628)

• If a transaction rollback request rolled back only a statement and not the whole transaction, any attempt

at attaching another operation to the transaction raised an assertion. (Bug #23753319, Bug #82143)

• STRCMP() for arguments with the utf8mb4_unicode_ci collation could return results different from

ORDER BY. STRCMP() has been corrected. (Bug #23752284, Bug #82132)

• Complete logical backups made with mysqlpump could not be restored if GTIDs were enabled.

563

MySQL 8.0 Release Notes

To enable control over GTID information written to the dump file, mysqlpump now has a --set-gtid-

purged option that indicates whether to add a SET @@GLOBAL.gtid_purged statement to the output.

(Bug #23748432)

• Infinite recursion could occur if the audit_log plugin signalled an error while handling an error. (Bug

#23717558, Bug #82052)

• Messages written by the audit_log plugin to the error log regarding MYSQL_AUDIT_CONNECT event

failures now print the underlying error cause as well to aid debugging. (Bug #23710632)

• MySQL now uses readdir() rather than readdir_r(). The latter has been deprecated since glibc

2.24 and caused debug builds of MySQL and builds using GCC 6.1 to fail.

Additionally, several problems resulting in GCC 6.1 compiler warnings were corrected. (Bug #23708395,

Bug #24437737, Bug #82515, Bug #24459890, Bug #82583, Bug #25103242)

• FORCE INDEX was ineffective for SELECT COUNT(*) queries. (Bug #23596760, Bug #81854)

• During startup, the server creates a lock file for the Unix socket file (for example, mysql.sock.lock as

a lock file for mysql.sock). If the server failed to write the process ID to the lock file, it failed to remove

that file, which could cause subsequent server startups to fail until the file was removed manually. (Bug

#23582603, Bug #81838)

• For debug builds, queries executed using Item_func_spatial_collection::val_str() could

raise an assertion. (Bug #23573720)

• For audit log events in the connection class, the connection_type value was available only for

connect events. The value is now available in connect, disconnect, and change-user events. (Bug

#23541550)

• The audit_log plugin audit_log_filter_remove_filter() function caused a server exit if given

a NULL argument. (Bug #23522793)

• Attempts to configure MySQL without the FEDERATED storage engine failed (the CMake -

DWITH_FEDERATED_STORAGE_ENGINE=0 option did not work). (Bug #23508203, Bug #81665)

• On Solaris, gettimeofday() could return an invalid value and cause a server shutdown. (Bug

#23499695)

• The keyring_file plugin could attempt to write keys to its storage file when the file did not exist. To

ensure that keys are flushed only when the correct storage file exists, keyring_file now stores a

SHA-256 checksum of the keyring in the file. Before updating the file, the plugin verifies that it contains

the expected checksum. (Bug #23498254)

• A union query resulting in tuples larger than max_join_size could result in a server exit. (Bug

#23303485)

• Grant tables with incorrect structure may cause problems in user management operations. As a

consequence of the fix for this, for any operation that modifies a grant table, the server now checks

whether the table has the expected structure and produces an error if not. mysql_upgrade must be run

to update the tables to the expected structure. (Bug #23295423, Bug #25095876, Bug #25448037)

• ST_ExteriorRing() could cause a server exit due to being passed an invalid WKB string believed to

be valid. (Bug #23280574)

• For debug builds, failure to prepare a branch of an XA transaction could lead to a server exit. (Bug

#23264552, Bug #81375)

564

MySQL 8.0 Release Notes

• The optimizer could choose ref access on a secondary index rather than range access on the primary

key, even when the cost was higher. (Bug #23259872, Bug #81341)

• An instance of the disk-full error message contained the wrong error code. (Bug #23247332, Bug

#81346)

• For a query with ORDER BY and LIMIT, an optimizer trace did not record the optimizer's switch to a

different index. (Bug #23227428, Bug #81250)

• Improper handling of a lock used by the version_tokens plugin and functions could result in a server

exit if one of the functions was called while version_tokens was being uninstalled. (Bug #23210850)

• Certain errors in DML statements executed within stored programs could be mishandled and result in a

server exit. (Bug #23209989)

• The QUOTE() function could allocate excessive memory. A limit of max_allowed_packet bytes is now

imposed and returns NULL with a warning for attempts to allocate more. (Bug #23195404)

• For some deeply nested expressions, the optimizer failed to detect stack overflow, resulting in a server

exit. (Bug #23135667)

• For sessions created through the X Plugin, incorrect thread attachment/detachment could cause a server

exit. (Bug #23057045)

• When attempting to locate the data directory, mysqld_safe incorrectly considered

$MY_BASEDIR_VERSION/var as one of the possible locations. (Bug #23013510, Bug #80866)

• For some generated columns, character set conversion of the column definition for table rebuilds could

change column values. (Bug #22991924)

• The OS X DMG installer did not properly set up keyring plugin installation. (Bug #22991650)

• If a query performed a GROUP BY on a column of a derived table and the select list contained

an expression mixing an aggregate function and the group column, an error was raised if the

ONLY_FULL_GROUP_BY SQL mode was enabled. (Bug #22924183, Bug #80726)

• A binary (in-place) upgrade from MySQL 5.6 to 5.7 followed by a data export performed using

mysqlpump resulted in an Invalid default value for date_column error for attempts to reload

the dump file. (Bug #22919028, Bug #80706)

• A failed cast of a long float to integer could cause a server exit. (Bug #22907691)

• On Unix and Unix-like systems, the error log file resulting from specifying --log-error without an

option value was incorrectly created in the directory of the PID file if the --pid-file option was also

given. (Bug #22900354)

• The main.log_tables-big test case could be unstable on highly loaded hosts. Thanks to Laurynas

Biveinis for the patch. (Bug #22874167, Bug #80607)

• SQL statements executed through the X Plugin were not instrumented in the Performance Schema. (Bug

#22859462)

• The rpl.rpl_key_rotation test case did not synchronize properly with the master server. Thanks to

Laurynas Biveinis for the patch. (Bug #22838596, Bug #80531)

• DROP INDEX operations could fail due to inconsistent handling of index prefix lengths for TEXT-type

columns (TINYTEXT and so forth).

A consequence of this fix is more restrictive behavior for CREATE TABLE and CREATE INDEX

statements for which a specified index prefix exceeds the maximum column data type size:

565

MySQL 8.0 Release Notes

• For a nonunique index, either an error occurs (if strict SQL mode is enabled), or the index length is

reduced to lie within the maximum column data type size and a warning is produced (if strict mode is

not enabled).

• For a unique index, an error occurs regardless of SQL mode because reducing the index length might

enable insertion of nonunique entries that do not meet the specified uniqueness requirement.

(Bug #22740093, Bug #80392)

• Metadata locking on stored routine names was performed on a case-sensitive basis, but routine names

are not case sensitive. (Bug #22700385)

• Queries that used an aggregate function with DISTINCT could produce incorrect results. (Bug

#22686994, Bug #80310)

• The innodb_numa_interleave system variable was erroneously available on some systems that

were not NUMA-enabled. Thanks to Tomislav Plavcic for the patch.

CMake now sets the default WITH_NUMA value based on whether the current platform has NUMA support.

For platforms without NUMA support, CMake behaves as follows:

• With no NUMA option (the normal case), CMake continues normally, producing only this warning:

NUMA library missing or required version not available

• With -DWITH_NUMA=ON, CMake aborts with this error: NUMA library missing or required version not

available

(Bug #22678436, Bug #80288)

• Certain SQL queries involving complex WHERE conditions could cause warnings, memory corruption, or a

server exit. (Bug #22671573)

• When taking the server offline, a race condition within the Performance Schema could lead to a server

exit. (Bug #22551677)

• On macOS, if a table with an associated trigger was renamed to a new name containing both lowercase

and uppercase characters, DROP TRIGGER for the trigger resulted in an ER_NO_SUCH_TABLE error for

the table. (Bug #22512899, Bug #79873)

• In the MYSQL_FIELD C API structure, the org_table value for derived tables was *, which could

cause failure for queries that depend on this value. The org_table value for views and derived tables

now is set as follows: If the column is selected from a view, org_table names the view. If the column

is selected from a derived table, org_table names the base table. If a derived table wraps a view,

org_table still names the base table. If the column is an expression, org_table is the empty string.

(Bug #22364401, Bug #79641)

• For RPM packages, the default error-log location in the deployed /etc/my.cnf file differed from the

location in the installed logrotate script, causing logrotate to fail. (Bug #22322685)

• The Performance Schema events_statements_summary_by_digest table could contain multiple

rows for the same statement digest and schema combination, rather than the expected single (unique)

row. (Bug #22320066, Bug #79533)

• For Performance Schema system and status variable tables, variable values expressed in a character

set different from utf8 could be truncated or incorrect. (Bug #22313205)

566

MySQL 8.0 Release Notes

• For debug builds, altering a table partitioning expression using an expression attribute with an invalid

UTF-8 name caused an assertion to be raised. (Bug #22152229)

• After performing inserts in a table containing an AUTO_INCREMENT column and then performing

a SELECT operation, the LAST_INSERT_ID() returns the correct value, but the value of the

mysql_insert_id() C API function was being reset to 0. (Bug #22028117, Bug #78778)

• On Ubuntu, error messages were displayed during upgrades from Community to Commercial packages

that made it appear as though mysqld and my_print_defaults had not been installed. Those

messages were spurious and have been silenced. (Bug #21807248)

• With the use_index_extensions flag of the optimizer_switch system variable disabled, some

SELECT DISTINCT queries could return incorrect results. (Bug #21749123, Bug #78244)

• An invalid string value in the WHERE clause of an UPDATE statement, caused an index scan rather

than a range scan to be used. For values not present in the index, this could be much slower. Now the

optimizer determines this to be an “impossible WHERE” condition. (Bug #21032418, Bug #76933)

• Debian packages were missing an AppArmor-related include file and incorrectly were marked dependent

on AppArmor (making it impossible to disable AppArmor by uninstalling it). (Bug #20768958)

• When the automatic_sp_privileges system variable was enabled, it did not have the expected

effect for anonymous users. (Bug #20266641)

• In a replication environment, SET PASSWORD or ALTER USER could fail to execute on the slave due to

failure to parse the hash string correctly. (Bug #20228478)

• The optimizer resolve_const_item() function called Item_decimal() with the last two arguments

in the wrong order. (Bug #19062566)

• An in-place ALTER TABLE operation failed to report an error when adding a DATE or DATETIME column

under these conditions: a) the column was NOT NULL and no default value was supplied; b) strict and

NO_ZERO_DATE SQL modes were enabled; c) the table was not empty.

An ALTER TABLE operation failed with an error rather than a warning when adding a DATE or

DATETIME column under these conditions: a) the column was NOT NULL and no default value was

supplied; b) strict SQL mode was enabled and NO_ZERO_DATE SQL mode was not enabled; c) the table

was not empty. (Bug #16888677)

• Inserting a TIME, DATE, or TIMESTAMP value with a fractional seconds part into a column

having the same type but fewer fractional digits resulted in rounding. This differs from MySQL

5.5, which used truncation rather than rounding. To enable control over this behavior, a new

TIME_TRUNCATE_FRACTIONAL SQL mode is available. The default is to use rounding. If this mode is

enabled, truncation occurs instead. (Bug #16583910, Bug #68760)

• NOT IN subqueries could produce incorrect results when an index prefix of an inner table was used.

(Bug #13915291)

• On non-Linux Unix systems, the mysql.server startup script used the Linux command pidof rather

than pgrep. (Bug #13788154, Bug #64342)

• Starting multiple instances of mysqld_safe after an abnormal server exit could result in one

mysqld_safe instance killing another. As a consequence of the bug fix, the mysqld_safe.pid file is

no longer used. (Bug #11751149, Bug #41908)

• The --help message for mysqld_safe was corrected to mention that the --no-defaults, --

defaults-file, and --defaults-extra-file options, if given, must be the first argument. (Bug

#11745176, Bug #11192)

567

MySQL 8.0 Release Notes

• The bounds check for the XML parser position stack for each level (which has a fixed depth) used the

size of the array as the upper limit, and so was off by one. This is fixed by decreasing the allowable

depth by one, which actually matches the maximum number of elements in the position stack. (Bug

#83871, Bug #25111907)

References: See also: Bug #14040071, Bug #15948580.

Changes in MySQL 8.0.0 (2016-09-12, Development Milestone)

For general information about upgrades, downgrades, platform support, etc., please visit https://

dev.mysql.com/doc/relnotes/mysql/8.0/en/.

Note

This is a milestone release, for use at your own risk. Upgrades between milestone

releases (or from a milestone release to a GA release) are not supported.

Significant development changes take place in milestone releases and you may

encounter compatibility issues, such as data format changes that require attention

in addition to the usual procedure of running mysql_upgrade. For example, you

may find it necessary to dump your data with mysqldump before the upgrade and

reload it afterward. (Making a backup before the upgrade is a prudent precaution in

any case.)

• Account Management Notes

• C API Notes

• Character Set Support

• Compilation Notes

• Component Notes

• Configuration Notes

• Data Dictionary Notes

• Data Type Notes

• Deprecation and Removal Notes

• Doxygen Notes

• Optimizer Notes

• Packaging Notes

• Parser Notes

• Performance Schema Notes

• Security Notes

• Spatial Data Support

• Test Suite Notes

568

MySQL 8.0 Release Notes

• X Plugin Notes

• Functionality Added or Changed

• Bugs Fixed

Account Management Notes

• Incompatible Change: The grant tables in the mysql system database are now InnoDB (transactional)

tables. Previously, these were MyISAM (nontransactional) tables. This change applies to these tables:

user, db, tables_priv, columns_priv, procs_priv, proxies_priv.

The change of grant table storage engine underlies an accompanying change to the behavior of

account-management statements. Previously, an account-management statement that named multiple

users could succeed for some users and fail for others. Now, each statement is transactional and either

succeeds for all named users or rolls back and has no effect if any error occurs. The statement is written

to the binary log if it succeeds, but not if it fails; in that case, rollback occurs and no changes are made.

The preceding behavior applies to these statements: ALTER USER, CREATE ROLE, CREATE USER,

DROP ROLE, DROP USER, GRANT, RENAME USER, REVOKE. (SET PASSWORD is not listed because

it applies to at most one user and is effectively transactional already.) A side effect of this change in

behavior is that partially completed account management statements on a MySQL 5.7 master fail when

replicated on a MySQL 8.0 slave. For more information, see Atomic Data Definition Statement Support.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the mysql system database.

Note

If MySQL is upgraded from an older version but the grant tables have not been

upgraded from MyISAM to InnoDB, the server considers them read only and

account-management statements produce an error.

Due to the change of storage engine from MyISAM to InnoDB, SELECT without ORDER BY on grant

tables can produce different row orders than previously. If a query result must have specific row ordering

characteristics, include an ORDER BY clause. (WL #7158, WL #9045)

• MySQL now supports roles, which are named collections of privileges. Roles enable assignment of sets

of privileges to accounts and provide a convenient alternative to granting individual privileges, both for

conceptualizing desired privilege assignments and implementing them:

• Roles can be created and dropped.

• Roles can have privileges granted to and revoked from them.

• Roles can be granted to and revoked from user accounts.

• The active roles for an account can be selected from among those granted to the account, and can be

changed during sessions for that account.

For more information, see Using Roles.

Note

ROLE now is a reserved word and cannot be used as an identifier without

identifier quoting.

(WL #988)

569

MySQL 8.0 Release Notes

C API Notes

• The libmysqlclient shared library major version number is increased from 20 (used in MySQL 5.7)

to 21 for MySQL 8.0. (Bug #77600, Bug #21363863)

Character Set Support

• The utf8mb4 Unicode character set has a new general collation named utf8mb4_0900_ai_ci.

utf8mb4 also has several new language-specific collations with characteristics similar to

utf8mb4_0900_ai_ci except that language-specific rules take precedence where applicable. The

language-specific collations are indicated by ISO 639-1 language codes in the collation name, as shown

in the following table. In two cases the language code has an additional item that denotes a variant

(German phone book order, Traditional Spanish).

Table 5 utf8mb4 UCA 9.0.0 language-specific collations

Language Collation

Croatian utf8mb4_hr_0900_ai_ci

Czech utf8mb4_cs_0900_ai_ci

Danish utf8mb4_da_0900_ai_ci

Esperanto utf8mb4_eo_0900_ai_ci

Estonian utf8mb4_et_0900_ai_ci

German phone book order utf8mb4_de_pb_0900_ai_ci

Hungarian utf8mb4_hu_0900_ai_ci

Icelandic utf8mb4_is_0900_ai_ci

Latvian utf8mb4_lv_0900_ai_ci

Lithuanian utf8mb4_lt_0900_ai_ci

Polish utf8mb4_pl_0900_ai_ci

Classical Latin utf8mb4_la_0900_ai_ci

Romanian utf8mb4_ro_0900_ai_ci

Slovak utf8mb4_sk_0900_ai_ci

Slovenian utf8mb4_sl_0900_ai_ci

Modern Spanish utf8mb4_es_0900_ai_ci

Traditional Spanish utf8mb4_es_trad_0900_ai_ci

Swedish utf8mb4_sv_0900_ai_ci

Turkish utf8mb4_tr_0900_ai_ci

Vietnamese utf8mb4_vi_0900_ai_ci

utf8mb4_0900_ai_ci also works as an accent- insensitive, case-insensitive collation for the

languages in the following table.

Table 6 Languages for which utf8mb4_0900_ai_ci is suitable

Language Name Language Code

German (dictionary order) de

English en

570

MySQL 8.0 Release Notes

Language Name Language Code

Canadian French (locale fr_CA) fr

Irish Gaelic ga

Indonesian id

Italian it

Luxembourgian lb

Malay ms

Dutch nl

Portuguese pt

Swahili sw

Zulu zu

utf8mb4_da_0900_ai_ci also works as an accent-insensitive, case-insensitive collation for the

languages in the following table.

Table 7 Languages for Which utf8mb4_da_0900_ai_ci is Suitable

Language Name Language Code

Norwegian no

Norwegian Bokmål nb

Norwegian Nynorsk nn

The nonlanguage-specific utf8mb4_0900_ai_ci and language-specific

utf8mb4_LANG_0900_ai_ci Unicode collations each have these characteristics:

• The collation is based on Unicode Collation Algorithm (UCA) 9.0.0 and Common Locale Data

Repository (CLDR) v30, is accent insensitive, and case insensitive. These characteristics are indicated

by _0900, _ai, and _ci in the collation name. Exception: utf8mb4_la_0900_ai_ci is not based

on CLDR because Classical Latin is not defined in CLDR.

• The collation works for all characters in the range [U+0, U+10FFFF].

• If the collation is not language specific, it sorts all characters, including supplemental characters,

in default order (described following). If the collation is language specific, it sorts characters of the

language correctly according to language-specific rules, and characters not in the language in default

order.

• By default, the collation sorts characters having a code point listed in the DUCET table (Default

Unicode Collation Element Table) according to the weight value assigned in the table. The collation

sorts characters not having a code point listed in the DUCET table using their implicit weight value,

which is constructed according to the UCA.

• For non-language-specific collations, characters in contraction sequences are treated as separate

characters. For language-specific collations, contractions might change character sorting order.

For more information, see Unicode Character Sets. (WL #9125, WL #9108, WL #9479)

571

MySQL 8.0 Release Notes

Compilation Notes

• Microsoft Windows: For building MySQL on Windows, the toolchain now prefers 64-bit tools when

possible (previously 32-bit). This speeds up linking and avoids issues related to limited address space

with the 32-bit linker. (Bug #80675, Bug #22900585)

• CMake now causes the build process to link with the GNU gold linker if it is available and not

explicitly disabled. To disable use of this linker, specify the -DUSE_LD_GOLD=OFF CMake option. (Bug

#23759968, Bug #82163)

• The WITH_EXTRA_CHARSETS CMake option has been removed. MySQL builds are configured

with all character sets by default now. Users who want fewer character sets can edit cmake/

character_sets.cmake directly and recompile the server. (Bug #80005, Bug #22552125)

• The minimum version of the Boost library for server builds is now 1.60.0. (Bug #79380, Bug #22253921)

• Work was done to clean up the source code base, including: Removing unneeded CMake checks;

removing unused macros from source files; reorganizing header files to reduce the number of

dependencies and make them more modular, removing function declarations without definitions,

replacing locally written functions with equivalent functions from industry-standard libraries.

• MySQL source code now permits and uses C++11 features. To enable a good level of C++11 support

across all supported platforms, the following minimum compiler versions now apply:

• GCC: 4.8 or higher

• Clang: 3.4 or higher (Xcode 7 on OS X)

• Solaris Studio: 12.4 or higher (Solaris client build only)

• Visual Studio: 2015

• CMake: On Windows, the required Visual Studio version results in a required CMake version of 3.2.3

or higher

On Solaris, the stlport library is no longer used. This makes the SUNPRO_CXX_LIBRARY CMake

option obsolete, so it has been removed. (WL #8896)

Component Notes

• MySQL Server now includes a component-based infrastructure for improving server extensibility:

• A component provides services that are available to the server and other components. (With respect

to service use, the server is a component, equal to other components.) Components interact with each

other only through the services they provide.

• The INSTALL COMPONENT and UNINSTALL COMPONENT statements provide an SQL interface for

component manipulation at runtime.

• A loader service registers installed components in the mysql.component system table, and installs

registered components during the startup sequence for subsequent server restarts.

For general information about the component infrastructure and its SQL-level interface, see MySQL

Components. For information about the internal implementation of components, see the MySQL Server

Doxygen documentation, available at https://dev.mysql.com/doc/index-other.html. (WL #4102)

572

MySQL 8.0 Release Notes

Configuration Notes

• Incompatible Change; InnoDB: Previously, enabling the innodb_read_only system variable

prevented creating and dropping tables only for the InnoDB storage. As of MySQL 8.0. enabling

innodb_read_only prevents these operations for all storage engines. Table creation and drop

operations modify data dictionary tables in the mysql system database, but those tables use the

InnoDB storage engine and cannot be modified when innodb_read_only is enabled. The same

principle applies to other table operations that require modifying data dictionary tables, and to operations

that modify other tables in the mysql database that use the InnoDB storage engine, such as the grant

tables and the func and plugin tables. (Bug #21611899)

• The hardcoded memory page size of 8KB for the memory-mapped transaction coordinator was too

small for platforms such as ARM64 and PowerPC where the page size is much larger. The server now

invokes a system call to get the page size of the current platform rather than using a hardcoded value.

A consequence for the --log-tc-size option is that the minimum and default values are now 6 times

the page size. Also, the value must be a multiple of the page size. Thanks to Alexey Kopytov for the

patch. (Bug #23014086, Bug #80818, Bug #26931470, Bug #87995)

• MySQL now supports a SET PERSIST variant of SET statement syntax, for making configuration

changes at runtime that also persist across server restarts. Like SET GLOBAL, SET PERSIST is

permitted for any global system variable that is dynamic (settable at runtime). The statement changes

the runtime variable value, but also writes the variable setting to an option file named mysqld-

auto.cnf in the data directory. At startup, the server processes this file after all other option files. For

more information, see Persisted System Variables.

To provide information showing how each system variable was most recently set, the Performance

Schema now has a variables_info table that lists each system variable and the source from which it

got its value. See Performance Schema variables_info Table.

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate this change into the Performance Schema. (WL #8688)

Data Dictionary Notes

• Incompatible Change: MySQL Server now incorporates a global data dictionary containing information

about database objects in transactional tables. In previous MySQL releases, dictionary data was stored

in metadata files and nontransactional system tables.

Important

A data dictionary-enabled server entails some general operational differences

compared to a server that does not have a data dictionary; see Data Dictionary

Usage Differences. Also, for upgrades to MySQL 8.0, the upgrade procedure

differs somewhat from previous MySQL releases and requires that you verify

the upgrade readiness of your installation by checking specific prerequisites. For

more information, see Upgrading MySQL, particularly Preparing Your Installation

for Upgrade.

InnoDB continues to use its own data dictionary in the MySQL 8.0.0 release.

The following list briefly describes the main implications of this change:

• The .frm metadata files previously associated with base tables and views no longer exist. Metadata

previously stored in .frm files is now stored in data dictionary tables.

573

MySQL 8.0 Release Notes

Similarly, trigger metadata previously stored in .TRG and .TRN files is stored in a data dictionary table

and those files no longer exist.

• With the removal of .frm files, the 64KB table definition size limit imposed by the .frm file structure is

removed.

• With the removal of .frm files, the INFORMATION_SCHEMA.TABLES VERSION field now reports a

hardcoded value of 10, which is the last .frm file version used in MySQL 5.7.

• With the removal of .frm files, the sync_frm system variable is removed.

• A new dictionary object cache that serves the MySQL data dictionary stores previously accessed data

dictionary objects in memory to enable object reuse and minimize disk I/O. An LRU-based eviction

strategy is used to evict least recently used objects from memory. The cache comprises several

partitions that store different object types. For more information, see Dictionary Object Cache.

• New internal data dictionary APIs enable the server, internal storage engines, and plugins to access

and store data in the MySQL data dictionary. Internal data dictionary APIs are introduced for handling

of schemas, tablespaces, tablespace files, tables, partitioned tables, table partition data, triggers,

stored routines, events, table objects, views, character sets, and collations.

With this change, data dictionary updates and binary log writes for CREATE TRIGGER and DROP

TRIGGER operations are combined into a single, atomic transaction.

• Data dictionary tables are invisible, but in most cases there are corresponding

INFORMATION_SCHEMA tables that can be queried instead. This enables the underlying data

dictionary tables to be changed as server development proceeds, while maintaining a stable

INFORMATION_SCHEMA interface for application use.

Some INFORMATION_SCHEMA tables have been reimplemented entirely as views on data dictionary

tables:

CHARACTER_SETS

COLLATIONS

COLLATION_CHARACTER_SET_APPLICABILITY

COLUMNS

KEY_COLUMN_USAGE

SCHEMATA

STATISTICS

TABLES

TABLE_CONSTRAINTS

VIEWS

Queries on those tables are now more efficient because they obtain information from data dictionary

tables rather than by other, slower means. In particular, for each INFORMATION_SCHEMA table that is

a view on data dictionary tables:

• The server no longer must create a temporary table for each query of the INFORMATION_SCHEMA

table.

• When the underlying data dictionary tables store values previously obtained by directory

scans (for example, to enumerate database names or table names within databases) or file-

opening operations (for example, to read information from .frm files), INFORMATION_SCHEMA

queries for those values now use table lookups instead. (Additionally, even for a non-view

INFORMATION_SCHEMA table, values such as database and table names are retrieved by lookups

from the data dictionary and do not require directory or file scans.)

574

MySQL 8.0 Release Notes

• Indexes on the underlying data dictionary tables permit the optimizer to construct efficient

query execution plans, something not true for the previous implementation that processed the

INFORMATION_SCHEMA table using a temporary table per query.

The preceding improvements also apply to SHOW statements that display information corresponding

to the INFORMATION_SCHEMA tables that are views on data dictionary tables. For example, SHOW

DATABASES displays the same information as the SCHEMATA table.

For INFORMATION_SCHEMA queries that retrieve table statistics, the server now can use statistics

cached in INFORMATION_SCHEMA tables, or obtain the latest statistics directly from storage engines.

The information_schema_stats system variable controls which statistics source the server uses.

• When information_schema_stats is CACHED (the default), the server uses cached statistics

stored in the STATISTICS and TABLES tables.

• When information_schema_stats is LATEST, the server obtains statistics directly from storage

engines. In this case, the server treats queries on STATISTICS and TABLES as queries for the

latest statistics stored in the STATISTICS_DYNAMIC and TABLES_DYNAMIC tables.

Affected INFORMATION_SCHEMA table statistic columns include:

STATISTICS.CARDINALITY

TABLES.AUTO_INCREMENT

TABLES.AVG_ROW_LENGTH

TABLES.CHECKSUM

TABLES.CHECK_TIME

TABLES.CREATE_TIME

TABLES.DATA_FREE

TABLES.DATA_LENGTH

TABLES.INDEX_LENGTH

TABLES.MAX_DATA_LENGTH

TABLES.TABLE_ROWS

TABLES.UPDATE_TIME

For more information, see Optimizing INFORMATION_SCHEMA Queries.

• The foreign_keys and foreign_key_column_usage tables now store foreign key information.

The standard SQL way to obtain foreign key information is by using the INFORMATION_SCHEMA

REFERENTIAL_CONSTRAINTS and KEY_COLUMN_USAGE tables; these tables are now implemented

as views on the foreign_keys, foreign_key_column_usage, and other data dictionary tables.

For some foreign key errors, the server now produces more appropriate and more informative error

messages.

Note

Incompatibility: Previously, MySQL supported foreign key names longer

than 64 characters. Foreign key names as stored in the foreign_keys and

foreign_key_column_usage tables are a maximum of 64 characters, per

the SQL standard, so longer foreign key names are no longer permitted.

• Because the data dictionary provides information about database objects, the server no longer checks

directory names in the data directory to find databases. Consequently, the --ignore-db-dir option

and ignore_db_dirs system variable are extraneous and have been removed. Update system

configurations and application programs accordingly.

575

MySQL 8.0 Release Notes

• Previously, this was possible to use CREATE TEMPORARY TABLE to create a table in a nonexistent

database by qualifying the table name with the name of a nonexistent database. This is no longer

permitted.

• System table changes:

• Many system tables have been converted from MyISAM (nontransactional) tables to InnoDB

(transactional) tables. For example, as discussed elsewhere in these release notes, the grant tables

are now InnoDB tables. Other examples follow.

• The func table that stores loadable function information in the mysql system database now is an

InnoDB (transactional) table. Previously, it was a MyISAM (nontransactional) table.

In consequence of this change, CREATE FUNCTION and DROP FUNCTION statements cause an

implicit commit, even when used for loadable functions (see Statements That Cause an Implicit

Commit). Previously, they caused an implicit commit when used for stored functions, but not for

loadable functions.

• Previously, information about stored routines and events was stored in the proc and event tables

of the mysql system database. Those tables are no longer used. Instead, information about stored

routines and events is stored in the routines, events, and parameters data dictionary tables

in the mysql system database. The old tables used the MyISAM (nontransactional) storage engine.

The new tables use the InnoDB (transactional) engine.

Previously, creating a stored routine that contained illegal characters produced a warning. This is

now an error.

• To permit access to system tables (for example, time zone or log tables) to be distinguished from

access to nonsystem tables, the server uses the Locking system tables and Opening

system tables thread states rather than the System lock and Opening tables thread

states. See General Thread States.

• InnoDB changes:

• Persistent InnoDB tablespaces now include transactional storage for Serialized Dictionary

Information (SDI), which is dictionary object data in serialized form. Along with the disappearance

of .frm and trigger metadata files, mentioned previously, you might notice the appearance of .SDI

files. These are serialized dictionary information files. SDI transactional storage is reserved for an in-

progress feature not yet fully implemented.

• A new command-line utility, ibd2sdi, is used to extract serialized dictionary information (SDI) from

persistent InnoDB tablespaces. SDI data is not present in persistent InnoDB tablespaces in this

release. The ibd2sdi utility is reserved for future use.

• InnoDB startup code was refactored to support MySQL initialization changes related to the MySQL

data dictionary feature.

576

MySQL 8.0 Release Notes

• Upgrade and downgrade implications:

• To upgrade to MySQL 8.0 from MySQL 5.7, you must perform the upgrade procedure described at

Upgrading MySQL.

• Downgrading from MySQL 8.0 to MySQL 5.7 is only supported using the logical downgrade method

(a mysqldump downgrade). In-place downgrades are not supported.

(Bug #80481, Bug #22811659, WL #6378, WL #6383, WL #7896, WL #6384, WL #7897, WL #6388, WL

#7898, WL #7284, WL #7630, WL #7836, WL #6390, WL #6382, WL #6389, WL #6387, WL #6385, WL

#7053, WL #7158, WL #8980, WL #8150, WL #7488, WL #7066, WL #6929, WL #6391, WL #6392, WL

#6599)

Data Type Notes

• Bit functions and operators comprise BIT_COUNT(), BIT_AND(), BIT_OR(), BIT_XOR(), &, |, ^, ~,

<<, and >>. Prior to MySQL 8.0, bit functions and operators required BIGINT (64-bit integer) arguments

and returned BIGINT values, so they had a maximum range of 64 bits. Non-BIGINT arguments were

converted to BIGINT prior to performing the operation and truncation could occur. Now bit functions and

operators permit binary string type arguments (BINARY, VARBINARY, and the BLOB types) and return a

value of like type, which enables them to take arguments and produce return values larger than 64 bits.

Nonbinary string arguments are converted to BIGINT and processed as such, as before.

Permitting binary string arguments for bit functions and operators makes it easier not only to manipulate

larger values, but to perform bit operations not easily done previously on certain types of data, such as

UUID and IPv6 values. For examples, see Bit Functions and Operators.

An implication of this change in behavior is that bit operations on binary string arguments might produce

a different result in MySQL 8.0 than in 5.7. For information about how to prepare in MySQL 5.7 for

potential incompatibilities between MySQL 5.7 and 8.0, see Bit Functions and Operators, in MySQL 5.7

Reference Manual. (WL #8699)

Deprecation and Removal Notes

• Important Change; InnoDB: The following InnoDB file format configuration options were deprecated in

MySQL 5.7.7 and are now removed:

• innodb_file_format

• innodb_file_format_check

• innodb_file_format_max

• innodb_large_prefix

File format configuration options were necessary for creating tables compatible with earlier versions of

InnoDB in MySQL 5.1. Now that MySQL 5.1 has reached the end of its product lifecycle, these options

are no longer required.

The FILE_FORMAT column was removed from the INNODB_SYS_TABLES and

INNODB_SYS_TABLESPACES Information Schema tables. (WL #7704)

• InnoDB: The innodb_stats_sample_pages system variable was removed.

innodb_stats_sample_pages was deprecated in MySQL 5.6.3 and replaced by

innodb_stats_transient_sample_pages. (WL #8903)

577

MySQL 8.0 Release Notes

• InnoDB: The innodb_locks_unsafe_for_binlog system variable was removed.

innodb_locks_unsafe_for_binlog was deprecated in MySQL 5.6.3. The READ COMMITTED

isolation level provides similar functionality. (WL #8894)

• InnoDB: The innodb_support_xa system variable, which enables support for two-phase commit

in XA transactions, was removed. As of MySQL 5.7.10, InnoDB support for two-phase commit in XA

transactions is always enabled. (WL #8843)

• The deprecated mysql_install_db program has been removed from MySQL distributions. Data

directory initialization should be performed by invoking mysqld with the --initialize or --

initialize-insecure option instead. In addition, the deprecated --bootstrap option for mysqld

that was used by mysql_install_db has been removed, and the INSTALL_SCRIPTDIR CMake

option that controlled the installation location for mysql_install_db has been removed.

Version 1 test suite code previously was located in the mysql-test/lib/v1 directory of

MySQL source distributions. This code used mysql_install_db and has been removed. The

MYSQL_INSTALL_DB environment variable and a value of 1 for the MTR_VERSION environment variable

are no longer supported. (WL #9071)

• The mysql_plugin utility has been removed. Alternatives include loading plugins at server startup

using the --plugin-load or --plugin-load-add option, or at runtime using the INSTALL PLUGIN

statement. (WL #8927)

• The deprecated mysql_shutdown() C API function and corresponding COM_SHUTDOWN client/

server protocol command have been removed. Instead, use mysql_query() to execute a SHUTDOWN

statement. (WL #9014)

Doxygen Notes

• The MySQL source code has been updated to use Doxygen for the internal documentation. This is a

work in progress. As new MySQL versions are distributed, the Doxygen documentation will be updated,

with the latest version always available at https://dev.mysql.com/doc/index-other.html.

It is also possible to generate the Doxygen content locally from a MySQL source distribution using the

instructions at Generating MySQL Doxygen Documentation Content. (WL #8493)

Optimizer Notes

• InnoDB: The storage engine interface now enables the optimizer to provide information about the size of

the record buffer to be used for scans that the optimizer estimates will read multiple rows. The buffer size

can vary based on the size of the estimate. InnoDB uses this variable-size buffering capability to take

advantage of row prefetching, and to reduce the overhead of latching and B-tree navigation. Previously,

InnoDB used a small, fixed-size buffer. (WL #7093)

• The optimizer now supports table-level MERGE and NO_MERGE hints for specifying whether derived tables

or views should be merged into the outer query block or materialized using an internal temporary table.

Examples:

SELECT /*+ MERGE(dt) */ * FROM (SELECT * FROM t1) AS dt;

SELECT /*+ NO_MERGE(dt) */ * FROM (SELECT * FROM t1) AS dt;

For more information, see Optimizer Hints. (Bug #79554, Bug #22328100, WL #9307)

• MySQL now supports invisible indexes. An invisible index is not used by the optimizer at all, but is

otherwise maintained normally. Indexes are visible by default. Invisible indexes make it possible to test

the effect of removing an index on query performance, without making a destructive change that must be

578

MySQL 8.0 Release Notes

undone should the index turn out to be required. This feature applies to InnoDB tables, for indexes other

than primary keys.

To control whether an index is invisible explicitly for a new index, use a VISIBLE or INVISIBLE

keyword as part of the index definition for CREATE TABLE, CREATE INDEX, or ALTER TABLE. To alter

the invisibility of an existing index, use a VISIBLE or INVISIBLE keyword with the ALTER TABLE ...

ALTER INDEX operation. For more information, see Invisible Indexes. (WL #8697)

• The mysql system database now contains a column_stats table designed to store statistics about

column values. For more information, see Optimizer Statistics. (WL #8706)

Packaging Notes

• Development milestone releases in previous MySQL series were numbered using a suffix of -mN,

to indicate development milestone N. In MySQL 8.0, development releases use the suffix -dmr. For

example, this release of MySQL is numbered 8.0.0-dmr. (Bug #80408, Bug #22748154)

• As a consequence of the use of C++11 features described elsewhere in these release notes, the

following packaging changes have been made:

• Support for Red Hat Enterprise Linux 5 and Oracle Linux 5 RPMs has been dropped

• Generic binary tarball builds have been moved to Red Hat Enterprise Linux 6

(WL #8896)

Parser Notes

• Incompatible Change: The parser rules for SELECT and UNION were refactored to be more consistent

(the same SELECT syntax applies uniformly in each such context) and reduce duplication. Several user-

visible effects resulted from this work, which may require rewriting of certain statements:

• NATURAL JOIN permits an optional INNER keyword (NATURAL INNER JOIN), in compliance with

standard SQL.

• Right-deep joins without parentheses are permitted (for example, ... JOIN ... JOIN ...

ON ... ON), in compliance with standard SQL.

• STRAIGHT_JOIN now permits a USING clause, similar to other inner joins.

• The parser accepts parentheses around query expressions. For example, (SELECT ... UNION

SELECT ...) is permitted.

• The parser better conforms to the documented permitted placement of the SQL_CACHE and

SQL_NO_CACHE query modifiers.

• Left-hand nesting of unions, previously permitted only in subqueries, is now permitted in top-level

statements. For example, this statement is now accepted as valid:

(SELECT 1 UNION SELECT 1) UNION SELECT 1;

• Locking clauses (FOR UPDATE, LOCK IN SHARE MODE) are allowed only in non-UNION queries.

This means that parentheses must be used for SELECT statements containing locking clauses. This

statement is no longer accepted as valid:

SELECT 1 FOR UPDATE UNION SELECT 1 FOR UPDATE;

579

MySQL 8.0 Release Notes

Instead, write the statement like this:

(SELECT 1 FOR UPDATE) UNION (SELECT 1 FOR UPDATE);

(Bug #11746363, Bug #25734, WL #8083, WL #8907)

• The parser rules for CREATE TABLE were refactored to be context independent and improve

maintainability and extensibility. Several user-visible effects resulted from this work:

• For generated columns, including NOT NULL NULL resulted in a column that included the NOT NULL

attribute, which differed from nongenerated columns. Such definitions now use the final attribute NULL,

resulting in a nullable column (consistent with nongenerated columns).

• CREATE TEMPORARY TABLE no longer permits multiple instances of TEMPORARY.

• Previously, PARSE_GCOL_EXPR was a keyword and could not be used as a label in stored programs.

It is no longer a keyword and can be used as a label.

• Messages for some syntax errors are more precise with respect to the location of the error within the

statement.

(WL #7840, WL #8067, WL #8433, WL #8434, WL #8345)

Performance Schema Notes

• Incompatible Change: The Performance Schema now instruments server errors (and warnings), and

exposes statistical information about them through a set of summary tables:

• The error instrument controls whether error information is collected (enabled by default).

• Several tables contain error information, summarized in various ways:

events_errors_summary_global_by_error,

events_errors_summary_by_account_by_error,

events_errors_summary_by_host_by_error,

events_errors_summary_by_thread_by_error,

events_errors_summary_by_user_by_error.

• The performance_schema_error_size system variable controls the number of instrumented

errors.

For more information, see Error Summary Tables

If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and

restart the server) to incorporate these changes into the performance_schema database.

In consequence of the preceding changes, two server error symbols were renamed:

ER_CANT_SET_ENFORCE_GTID_CONSISTENCY_ON_WITH_ONGOING_GTID_VIOLATING_TRANSACTIONS

is now ER_CANT_ENFORCE_GTID_CONSISTENCY_WITH_ONGOING_GTID_VIOLATING_TX and

ER_SET_ENFORCE_GTID_CONSISTENCY_WARN_WITH_ONGOING_GTID_VIOLATING_TRANSACTIONS

is now ER_ENFORCE_GTID_CONSISTENCY_WARN_WITH_ONGOING_GTID_VIOLATING_TX.

Also, several server error codes were found to be no longer used in the server and have been removed

as obsolete. Applications that test specifically for any of these errors should be updated:

ER_BINLOG_READ_EVENT_CHECKSUM_FAILURE

ER_BINLOG_ROW_RBR_TO_SBR

ER_BINLOG_ROW_WRONG_TABLE_DEF

580

MySQL 8.0 Release Notes

ER_CANT_ACTIVATE_LOG

ER_CANT_CHANGE_GTID_NEXT_IN_TRANSACTION

ER_CANT_CREATE_FEDERATED_TABLE

ER_CANT_CREATE_SROUTINE

ER_CANT_DELETE_FILE

ER_CANT_GET_WD

ER_CANT_SET_GTID_PURGED_WHEN_GTID_MODE_IS_OFF

ER_CANT_SET_WD

ER_CANT_WRITE_LOCK_LOG_TABLE

ER_CREATE_DB_WITH_READ_LOCK

ER_CYCLIC_REFERENCE

ER_DB_DROP_DELETE

ER_DELAYED_NOT_SUPPORTED

ER_DIFF_GROUPS_PROC

ER_DISK_FULL

ER_DROP_DB_WITH_READ_LOCK

ER_DROP_USER

ER_DUMP_NOT_IMPLEMENTED

ER_ERROR_DURING_CHECKPOINT

ER_ERROR_ON_CLOSE

ER_EVENTS_DB_ERROR

ER_EVENT_CANNOT_DELETE

ER_EVENT_CANT_ALTER

ER_EVENT_COMPILE_ERROR

ER_EVENT_DATA_TOO_LONG

ER_EVENT_DROP_FAILED

ER_EVENT_MODIFY_QUEUE_ERROR

ER_EVENT_NEITHER_M_EXPR_NOR_M_AT

ER_EVENT_OPEN_TABLE_FAILED

ER_EVENT_STORE_FAILED

ER_EXEC_STMT_WITH_OPEN_CURSOR

ER_FAILED_ROUTINE_BREAK_BINLOG

ER_FLUSH_MASTER_BINLOG_CLOSED

ER_FORM_NOT_FOUND

ER_FOUND_GTID_EVENT_WHEN_GTID_MODE_IS_OFF__UNUSED

ER_FRM_UNKNOWN_TYPE

ER_GOT_SIGNAL

ER_GRANT_PLUGIN_USER_EXISTS

ER_GTID_MODE_REQUIRES_BINLOG

ER_GTID_NEXT_IS_NOT_IN_GTID_NEXT_LIST

ER_HASHCHK

ER_INDEX_REBUILD

ER_INNODB_NO_FT_USES_PARSER

ER_LIST_OF_FIELDS_ONLY_IN_HASH_ERROR

ER_LOAD_DATA_INVALID_COLUMN_UNUSED

ER_LOGGING_PROHIBIT_CHANGING_OF

ER_MALFORMED_DEFINER

ER_MASTER_KEY_ROTATION_ERROR_BY_SE

ER_NDB_CANT_SWITCH_BINLOG_FORMAT

ER_NEVER_USED

ER_NISAMCHK

ER_NO_CONST_EXPR_IN_RANGE_OR_LIST_ERROR

ER_NO_FILE_MAPPING

ER_NO_GROUP_FOR_PROC

ER_NO_RAID_COMPILED

ER_NO_SUCH_KEY_VALUE

ER_NO_SUCH_PARTITION__UNUSED

ER_OBSOLETE_CANNOT_LOAD_FROM_TABLE

ER_OBSOLETE_COL_COUNT_DOESNT_MATCH_CORRUPTED

ER_ORDER_WITH_PROC

ER_PARTITION_SUBPARTITION_ERROR

ER_PARTITION_SUBPART_MIX_ERROR

ER_PART_STATE_ERROR

ER_PASSWD_LENGTH

ER_QUERY_ON_MASTER

ER_RBR_NOT_AVAILABLE

ER_SKIPPING_LOGGED_TRANSACTION

581

MySQL 8.0 Release Notes

ER_SLAVE_CHANNEL_DELETE

ER_SLAVE_MULTIPLE_CHANNELS_HOST_PORT

ER_SLAVE_MUST_STOP

ER_SLAVE_WAS_NOT_RUNNING

ER_SLAVE_WAS_RUNNING

ER_SP_GOTO_IN_HNDLR

ER_SP_PROC_TABLE_CORRUPT

ER_SQL_MODE_NO_EFFECT

ER_SR_INVALID_CREATION_CTX

ER_TABLE_NEEDS_UPG_PART

ER_TOO_MUCH_AUTO_TIMESTAMP_COLS

ER_UNEXPECTED_EOF

ER_UNION_TABLES_IN_DIFFERENT_DIR

ER_UNSUPPORTED_BY_REPLICATION_THREAD

ER_UNUSED1

ER_UNUSED2

ER_UNUSED3

ER_UNUSED4

ER_UNUSED5

ER_UNUSED6

ER_VIEW_SELECT_DERIVED_UNUSED

ER_WRONG_MAGIC

ER_WSAS_FAILED

(WL #8058)

• Previously, the DIGEST and DIGEST_TEXT columns in the Performance Schema

events_statements_current table were populated only after statement execution ended. Now,

the columns are populated just after parsing and before statement execution begins. This enables

monitoring applications to access statement digest information during statement execution. (Bug

#23336542)

• Previously, Performance Schema optimizations focused on reducing the overhead involved in collecting

monitoring data. Complementing that earlier work, overhead now is also reduced for Performance

Schema queries that retrieve that data. This is achieved by the addition of indexes to most Performance

Schema tables, which gives the optimizer access to execution plans other than full table scans. These

indexes also improve performance for related objects, such as sys schema views that use those tables.

For more information, see Optimizing Performance Schema Queries. (WL #6616)

• The size of the ROLE column of the setup_actors Performance Schema table was increased from 16

to 32 characters. (WL #9262)

Security Notes

• The validate_password_check_user_name system variable is now enabled by default rather than

disabled. This means that when the validate_password plugin is enabled, by default it now rejects

passwords that match the current session user name. (WL #9480)

• The client-side --ssl and --ssl-verify-server-cert options have been removed. Use --ssl-

mode=REQUIRED instead of --ssl=1 or --enable-ssl. Use --ssl-mode=DISABLED instead of --

ssl=0, --skip-ssl, or --disable-ssl. Use --ssl-mode=VERIFY_IDENTITY instead of --ssl-

verify-server-cert options. (The server-side --ssl option remains unchanged.)

For the C API, MYSQL_OPT_SSL_ENFORCE and MYSQL_OPT_SSL_VERIFY_SERVER_CERT options for

mysql_options() correspond to the client-side --ssl and --ssl-verify-server-cert options

and have been removed. Use MYSQL_OPT_SSL_MODE with an option value of SSL_MODE_REQUIRED or

SSL_MODE_VERIFY_IDENTITY instead. (WL #9091)

582

MySQL 8.0 Release Notes

Spatial Data Support

• Spatial functions for import and export of Well-Known Text (WKT) values used MySQL

'GEOMETRYCOLLECTION()' nonstandard syntax rather than OpenGIS 'GEOMETRYCOLLECTION

EMPTY' standard syntax. Now both syntaxes are understood for import and the standard syntax is

used for export. See Functions That Create Geometry Values from WKT Values. (Bug #23632147, Bug

#81964)

• The ST_X() and ST_Y() spatial functions now permit an optional second argument that specifies an

X or Y coordinate value, respectively. With two arguments, the function result is the point value from

the first argument with the appropriate coordinate modified. In addition, ST_X() and ST_Y() with a

single argument now are stricter and produce an ER_UNEXPECTED_GEOMETRY_TYPE error rather than

returning NULL if the argument is a valid geometry but not a point. For more information, see Point

Property Functions. (WL #8606)

• The ST_SRID() spatial function now permits an optional second argument that specifies a SRID value.

With two arguments, the function result is the geometry value from the first argument with its SRID

modified according to the second argument. For more information, see General Geometry Property

Functions. (WL #8543)

• MySQL now stores information about spatial reference systems other than SRID 0, for use with spatial

data. This information is stored in the st_spatial_reference_systems data dictionary table and

is based on EPSG Dataset 8.7. For information about spatial reference systems, see Spatial Reference

System Support.

Previously, the ST_IsValid(), ST_MakeEnvelope(), and ST_Validate() functions required

geometry arguments with SRID 0. They now accept geometry arguments with an SRID for a projected

spatial reference system. (WL #8579)

• In MySQL 5.7, several spatial functions available under multiple names were deprecated to move in the

direction of making the spatial function namespace more consistent, the goal being that each spatial

function name begin with ST_ if it performs an exact operation, or with MBR if it performs an operation

based on minimum bounding rectangles. The deprecated functions have now been removed to leave

only the corresponding ST_ and MBR functions:

• These functions are removed in favor of the MBR names: Contains(), Disjoint(), Equals(),

Intersects(), Overlaps(), Within().

• These functions are removed in favor of the ST_ names: Area(), AsBinary(), AsText(),

AsWKB(), AsWKT(), Buffer(), Centroid(), ConvexHull(), Crosses(), Dimension(),

Distance(), EndPoint(), Envelope(), ExteriorRing(), GeomCollFromText(),

GeomCollFromWKB(), GeomFromText(), GeomFromWKB(), GeometryCollectionFromText(),

GeometryCollectionFromWKB(), GeometryFromText(), GeometryFromWKB(),

GeometryN(), GeometryType(), InteriorRingN(), IsClosed(), IsEmpty(),

IsSimple(), LineFromText(), LineFromWKB(), LineStringFromText(),

LineStringFromWKB(), MLineFromText(), MLineFromWKB(), MPointFromText(),

MPointFromWKB(), MPolyFromText(), MPolyFromWKB(), MultiLineStringFromText(),

MultiLineStringFromWKB(), MultiPointFromText(), MultiPointFromWKB(),

MultiPolygonFromText(), MultiPolygonFromWKB(), NumGeometries(),

NumInteriorRings(), NumPoints(), PointFromText(), PointFromWKB(), PointN(),

PolyFromText(), PolyFromWKB(), PolygonFromText(), PolygonFromWKB(), SRID(),

StartPoint(), Touches(), X(), Y().

• GLength() is removed in favor of ST_Length().

(WL #8157)

583

MySQL 8.0 Release Notes

Test Suite Notes

• mysql-test-run.pl now supports a --do-suite option, which is similar to --do-test but permits

specifying entire suites of tests to run. (Bug #24350345)

• The mysqltest rmdir command fails if the directory to be removed contains any files or directories.

To enable recursive removal of a directory as well as its contents, if any, mysqltest now supports a

force-rmdir command. (Bug #24316799)

• Two new test suite options make it easier to debug test cases:

• mysql-test-run.pl supports a --mysqltest=options option that enables options to be passed

to mysqltest.

• mysqltest supports a --trace-exec option that causes it to immediately print output from

executed programs to stdout.

mysql-test-run.pl now recognizes the MTR_CTEST_TIMEOUT environment variable. If set, the

value is a timeout in seconds to pass to ctest unit test commands. (Bug #21821049, Bug #21278845)

• For test cases in the MySQL test suite, it was previously possible to use symbolic error names for the --

error command only for server errors. This is now also possible for client errors. For example:

--error CR_SERVER_GONE_ERROR

(Bug #21048973, Bug #76972)

• The mysqltest program now has a copy_files_wildcard command that copies all files that

match a pattern from a source directory to a destination directory. See the MySQL Server Doxygen

documentation, available at https://dev.mysql.com/doc/index-other.html. (Bug #82111, Bug #23743035)

X Plugin Notes

• The Protobuf decoder class limited the number of nested objects to 50 (the default value). (Bug

#23707238, Bug #82025)

• The statement list_objects incorrectly reported a table as a collection. (Bug #23631240)

• The create_collection statement created a collection table with a unique key index on the '_id'

column instead of on the primary key. (Bug #23284569)

Functionality Added or Changed

• Incompatible Change; Partitioning: The generic partitioning handler has been removed

from the MySQL server. As part of this change, mysqld no longer supports the --

partition and --skip-partition options, and the server can no longer be built using -

DWITH_PARTITION_STORAGE_ENGINE. partition is also no longer displayed in the output of SHOW

PLUGINS, or shown in the INFORMATION_SCHEMA.PLUGINS table.

In order to support partitioning of a given table, the storage engine used for the table must now provide

its own (“native”) partitioning handler. InnoDB is the only storage engine supported in MySQL 8.0 which

includes a native partitioning handler. An attempt to create partitioned tables in MySQL 8.0 using any

other storage engine fails. (The NDB storage engine used by MySQL NDB Cluster also provides its own

partitioning handler, but is currently not supported by MySQL 8.0.)

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MySQL 8.0 Release Notes

Effects on upgrades. The direct upgrade of a partitioned table using a storage engine other than

InnoDB (such as MyISAM) from MySQL 5.7 (or earlier) to MySQL 8.0 is not supported. There are two

options for upgrading such a table to be compatible with MySQL 8.0, listed here:

• Remove the table's partitioning; you can do this without any data loss by executing an ALTER

TABLE ... REMOVE PARTITIONING statement.

• Change the storage engine used for the table to InnoDB, using ALTER TABLE ...

ENGINE=INNODB; this leaves the table's partitioning in place. At least one of these operations must

be performed for any partitioned non-InnoDB table, prior to upgrading the server to MySQL 8.0.

Otherwise, such a table cannot be used following the upgrade.

For information about converting MyISAM tables to InnoDB, see Converting Tables from MyISAM to

InnoDB.

An analogous situation is met when importing databases from a dump file that was created in MySQL

5.7 or earlier using mysqldump into a MySQL 8.0 server, due to the fact that table creation statements

that would result in a partitioned table using a storage engine without such support fail with an error in

MySQL 8.0. For this reason you must ensure that any statements in the dump file creating partitioned

tables do not also specify an unsupported storage engine. You can do this either by removing any

references to partitioning from CREATE TABLE statements that use a value for the STORAGE ENGINE

option other than InnoDB, or by specifying the storage engine as InnoDB (or allowing InnoDB to be

used by default).

For more information, see Partitioning Limitations Relating to Storage Engines. (WL #8971, WL #9457)

• InnoDB: The innodb_buffer_pool_debug option permits multiple buffer pool instances when the

buffer pool is less than 1GB in size, ignoring the 1GB minimum buffer pool size constraint imposed on

innodb_buffer_pool_instances. (Bug #24287290)

• InnoDB: A new dynamic configuration option, innodb_deadlock_detect, may be used to disable

deadlock detection. On high concurrency systems, deadlock detection can cause a slowdown when

numerous threads wait for the same lock. At times, it may be more efficient to disable deadlock detection

and rely on the innodb_lock_wait_timeout setting for transaction rollback when a deadlock occurs.

(Bug #23477773, WL #9383)

• InnoDB: The libinnodb_zipdecompress.a library allows external tools to use the

page_zip_decompress_low() function to decompress InnoDB pages. (Bug #21405300, Bug

#77664)

• InnoDB: To address contention that could occur under some workloads, the buffer pool mutex was

removed and replaced by several list and hash protecting mutexes. Also, several buffer pool related

variables no longer require buffer pool mutex protection. Thanks to Yasufumi Kinoshita and Laurynas

Biveinis for the patch. (Bug #20381905, Bug #75534, WL #8423)

• InnoDB: InnoDB now avoids intermediate commits that would occur every 10000 rows during

ALTER TABLE ALGORITHM=COPY operations. The purpose of intermediate commits was to speed up

recovery in the case of an aborted ALTER TABLE ALGORITHM=COPY operation. If an ALTER TABLE

ALGORITHM=COPY operation is aborted, the new, uncommitted table is now dropped during DDL log

recovery before the undo log is rolled back, thereby avoiding time-consuming data rollback for the

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MySQL 8.0 Release Notes

uncommitted table. Undo logging is now suppressed for ALTER TABLE ALGORITHM=COPY operations

unless there is an IGNORE clause or something else that requires rollback capability.

If there is full-text index on the table being altered, full-text data is inserted into full-text auxiliary tables

as the ALTER TABLE ALGORITHM=COPY operation inserts rows into the new, uncommitted table.

Previously, full-text data was only processed on transaction commit. (Bug #17479594)

• InnoDB: To reduce read-write lock contention that can result from multiple purge threads purging rows

from the same table, undo records are now grouped and assigned to different purge threads by table ID.

(WL #9387)

• InnoDB: InnoDB code now uses the C++ std::thread library for thread management. (WL #9359)

• InnoDB: BLOB code was refactored to provide an internal C++ interface for operations on compressed

and uncompressed BLOB data. (WL #8985, WL #9141)

• InnoDB: The InnoDB memcached plugin now supports multiple get operations (fetching multiple key/

value pairs in a single memcached query) and range queries. See InnoDB memcached Multiple get and

Range Query Support. (WL #6650)

• InnoDB: When encountering index tree corruption, InnoDB writes a corruption flag to the redo log,

which makes the corruption flag crash safe. InnoDB also writes in-memory corruption flag data to an

engine-private system table on each checkpoint. During recovery, InnoDB reads corruption flags from

both locations and merges results before marking in-memory table and index objects as corrupt. (WL

#7816)

• InnoDB: InnoDB no longer creates .isl files (InnoDB Symbolic Link files) when creating tablespace

data files outside of the MySQL data directory.

With this change, moving a remote tablespace while the server is offline by manually modifying an .isl

file is not supported. (WL #6416)

• InnoDB: InnoDB no longer supports compressed temporary tables. When innodb_strict_mode

is enabled (the default), CREATE TEMPORARY TABLE returns an error if ROW_FORMAT=COMPRESSED

or KEY_BLOCK_SIZE is specified. If innodb_strict_mode is disabled, warnings are issued and the

temporary table is created using a non-compressed row format.

With this change, all temporary tables are created in the shared temporary tablespace, ibtmp1.

The PER_TABLE_TABLESPACE and IS_COMPRESSED columns were removed from the

INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO. (WL #7899)

• InnoDB: The new INFORMATION_SCHEMA.INNODB_CACHED_INDEXES table reports the number of

index pages cached in the InnoDB buffer pool for each index. (WL #7170)

• InnoDB: The innodb_checksums system variable was removed. innodb_checksums was replaced

by innodb_checksum_algorithm in MySQL 5.6.3. (WL #8893)

• InnoDB: InnoDB startup code was refactored. (WL #7488)

• InnoDB: The innodb_flush_method default value is no longer NULL. On Unix-like systems, the

default value is fsync. On Windows systems, the default value is unbuffered.

On Windows, the innodb_flush_method setting no longer affects the innodb_use_native_aio

setting. There are now two possible settings for innodb_flush_method on Windows, unbuffered

(unbuffered I/O) and normal (buffered I/O). With this change, you can enable asynchronous

I/O with buffered I/O, which is a new combination (innodb_use_native_aio=ON and

innodb_flush_method=normal). The async_unbuffered setting was removed.

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MySQL 8.0 Release Notes

You can now set innodb_flush_method and innodb_change_buffering configuration options

using numeric values. (WL #7488)

• InnoDB: InnoDB no longer creates an .isl file (InnoDB Symbolic Link files) when creating a file-per-

table tablespace data file outside of the MySQL data directory. InnoDB now uses the redo log to locate

remote tablespace data files.

Offline relocation of a file-per-table tablespace data file created outside of the MySQL data directory by

modifying the .isl file is no longer supported. (WL #6416)

• InnoDB: The current maximum auto-increment counter value is now written to the redo log each time

the value changes, and saved to an engine-private system table on each checkpoint. These changes

make the current maximum auto-increment counter value persistent across server restarts. Additionally:

• A server restart no longer cancels the effect of the AUTO_INCREMENT = N table option. If you

initialize the auto-increment counter to a specific value, or if you alter the auto-increment counter value

to a larger value, the new value is persisted across server restarts.

• A server restart immediately following a ROLLBACK operation no longer results in the reuse of auto-

increment values that were allocated to the rolled-back transaction.

• If you modify an AUTO_INCREMENT column value to a value larger than the current maximum auto-

increment value (in an UPDATE operation, for example), the new value is persisted, and subsequent

INSERT operations allocate auto-increment values starting from the new, larger value.

For more information, see AUTO_INCREMENT Handling in InnoDB, and InnoDB AUTO_INCREMENT

Counter Initialization. (Bug #199, Bug #13726455, WL #6204)

• Replication: There are two improvements to how a CHANGE MASTER TO statement is written into the

error log (mysqld.log):

• Before, no commas were put between the option specifications (for example MASTER_USER = and

MASTER_PASSWORD = ), so users who wanted to use the statement by copy and paste had to insert

the commas manually. Commas are now inserted when the statement is written to the error log.

• When the literal “<secret>” is inserted as a placeholder for the MASTER_PASSWORD value, no quotes

are used now, so users who forget to replace the literal with the real password before a copy and

paste gets a syntax error immediately, instead of running into other issues.

(Bug #18194384)

• Replication: It is now possible to restore a backup of a GTID-based replication server because you can

add GTIDs to gtid_purged, regardless of whether gtid_executed is empty or not. This enables

you to restore backups from GTID-based replication servers without losing existing GTID information

and binary logs. The GTIDs to add are those which existed in gtid_executed at the time of taking

the backup. The syntax for SET GTID_PURGED has been extended so that SET GTID_PURGED

="+gtid_set" adds gtid_set to the existing gtid_purged GTID set. (WL #6591)

• Replication: New Performance Schema stages have been added to show the progress of row-

based replication. You can use these stages to check the progress of slow operations in row-based

replication. Additionally you can find out which database the changes are being applied to. This assists

in troubleshooting row-based replication issues and provides more information for performance tuning.

For more information see Monitoring Row-based Replication (WL #7364)

• JSON: This release adds an unquoting extraction operator ->>, sometimes also referred to as an inline

path operator, for use with JSON documents stored in MySQL. The new operator is similar to the ->

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MySQL 8.0 Release Notes

operator, but performs JSON unquoting of the value as well. For a JSON column mycol and JSON path

expression mypath, the following three expressions are equivalent:

• JSON_UNQUOTE( JSON_EXTRACT(mycol, "$.mypath") )

• JSON_UNQUOTE(mycol->"$.mypath")

• mycol->>"$.mypath"

The ->> operator can be used in SQL statements wherever JSON_UNQUOTE(JSON_EXTRACT()) would

be allowed. This includes (but is not limited to) SELECT lists, WHERE and HAVING clauses, and ORDER

BY and GROUP BY clauses.

For more information, see Functions That Search JSON Values, and JSON Path Syntax. (Bug #78736,

Bug #21980346, WL #9124)

• To produce more accurate estimates, the MEMORY storage engine now calculates index statistics

(records per key estimates) using floating-point rather than integer arithmetic. (Bug #23024059)

• A new CMake option, INSTALL_STATIC_LIBRARIES, enables control over whether to install static

libraries. The default is ON. If set to OFF, these libraries are not installed: libmysqlclient.a,

libmysqld.a, libmysqlservices.a. (Bug #22891432)

• The internal mysql_prepare_create_table() server function has been refactored for improved

code maintainability and clarity. This code revision results in the following minor changes of behavior for

CREATE TABLE and ALTER TABLE:

• Attempts to create a second primary key based on a NULL column now produce an

ER_MULTIPLE_PRI_KEY error rather than ER_PRIMARY_CANT_HAVE_NULL.

• Attempts to create a second primary key based on a generated column now produce an

ER_MULTIPLE_PRI_KEY error rather than ER_UNSUPPORTED_ACTION_ON_GENERATED_COLUMN.

• Attempts to create a full-text key on a JSON column now produce an ER_JSON_USED_AS_KEY error

rather than ER_BAD_FT_COLUMN.

• Attempts to create a key in a storage engine that does not support keys (for example, EXAMPLE) now

produce an ER_TOO_MANY_KEYS error rather than ER_TOO_MANY_KEY_PARTS.

(Bug #22884886)

• Previously, the Performance Schema was not built for libmysqld, the embedded

server. This prevented use of the SHOW STATUS and SHOW VARIABLES statements with

show_compatibility_56=OFF because, with that setting, those statements take their results

from Performance Schema tables. Now for libmysqld, the required Performance Schema tables

are built (with no instrumentation collected), so that those SHOW statements can be supported with

show_compatibility_56=OFF. (Bug #22809694)

• Several internal functions used by JSON_CONTAINS(), JSON_SEARCH(), and other MySQL JSON

functions created excessive numbers of local copies of keys, values, or both, when performing

inspections of JSON objects. Such copying has been eliminated or reduced in many cases. In addition,

the lifetimes of temporary objects used by some of these functions have been reduced. These changes

should make these and related JSON functions perform more efficiently than previously, and with fewer

resources required. (Bug #22602142)

• If the system lz4 and openssl zlib commands are available, the lz4_decompress and

zlib_decompress utilities are unneeded. Two changes enable those utilities not to be built: If the new

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MySQL 8.0 Release Notes

WITH_LZ4 CMake option is set to system, lz4_decompress is not built or installed. If the WITH_ZLIB

CMake option is set to system, zlib_decompress is not built or installed. (Bug #22329851)

• Source files for the MySQL strings library have been converted from C (.c suffix) to C++ (.cc suffix).

This enables stricter compilation checks and use of C++ features in the library code. (Bug #22124719)

• Source code for the mysys library now uses C++ rather than C to take advantage of stricter compilation

checks and permit use of C++ features. (Bug #21881278)

• For improved performance and better compatibility with other platforms, my_sync() on OS X now uses

fsync() rather than fcntl() with the F_FULLSYNC flag. (Bug #20742269)

• A new CMake option, WITH_TSAN, permits enabling ThreadSanitizer for compilers that support it. (Bug

#80409, Bug #23171902)

• The global list of connections, previously protected by a single mutex, has been partitioned into eight

parts, each protected by its own instance of the mutex. The result is a reduction of overhead and

improved performance for connection processing. An implication of this change for monitoring purposes

is that the Performance Schema now exposes eight different instances each of the LOCK_thd_list

mutex, LOCK_thd_remove mutex, and COND_thd_list condition variable. (WL #9250)

• MySQL now provides functions to manipulate UUID values and make them easier to work with:

• UUID_TO_BIN() and BIN_TO_UUID() convert between UUID values in string and binary formats

(represented as hexadecimal characters and VARBINARY(16), respectively). This permits conversion

of string UUID values to binary values that take less storage space. UUID values converted to binary

can be represented in a way that permits improved indexing efficiency.

• IS_UUID() returns 1 or 0 to indicate whether its argument is a valid string-format UUID value.

For more information about these functions, see Miscellaneous Functions (WL #8920)

• The server now relies on storage engines to clean up temporary tables left from previous server runs.

InnoDB does this by discarding the temporary tablespace on restart. MyISAM and other similar storage

engines still rely on scanning the temporary directory to detect leftover tables, by looking for files

belonging to these engines with a certain name pattern. (WL #7784)

• The server no longer performs conversion of pre-MySQL 5.1 database names containing special

characters to 5.1 format with the addition of a #mysql50# prefix. Because these conversions are

no longer performed, the --fix-db-names and --fix-table-names options for mysqlcheck,

the UPGRADE DATA DIRECTORY NAME clause for the ALTER DATABASE statement, and the

Com_alter_db_upgrade status variable have been removed.

Upgrades are supported only from one major version to another (for example, 5.0 to 5.1, or 5.1 to 5.5),

so there should be little remaining need for conversion of older 5.0 database names to current versions

of MySQL. As a workaround, upgrade a MySQL 5.0 installation to MySQL 5.1 before upgrading to a

more recent release. (WL #8186)

Bugs Fixed

• Incompatible Change: Concatenation of spatial values makes little sense, so the CONCAT() and

CONCAT_WS() functions now produce an error for spatial arguments. (Bug #22893669)

• Important Change; JSON: The empty string value is now accepted as a key when used with JSON

functions such as JSON_EXTRACT(). In such cases, it must be quoted. (Bug #79643, Bug #22366102)

• NDB Cluster: Previously, the mysql.ndb_binlog_index table was created even if the server was

built without NDB. Now the table is created only if the server is built with NDB. (Bug #22874872)

589

MySQL 8.0 Release Notes

• InnoDB; Microsoft Windows: An unspecified block size resulted in an empty

INFORMATION_SCHEMA.TABLESPACES table on Windows NTFS with a cluster page size greater than

or equal to 8K. (Bug #23598872)

• InnoDB; Microsoft Windows: Compilation of InnoDB with Visual Studio 2015 Update 2 returned

warnings. (Bug #23056963)

• InnoDB: An ALTER TABLE ... ALGORITHM=COPY operation that added a foreign key constraint

failed after due to an intermediate commit that occurred after 10000 rows were copied. The intermediate

commit reset the foreign key checks flag, causing the operation to fail. The intermediate commit no

longer occurs. (Bug #28662255, Bug #92471)

References: See also: Bug #17479594.

• InnoDB: Unnecessary checks were removed from the ut_cpuid() function which is used to fetch

information about the CPU. (Bug #24405292)

• InnoDB: An asynchronous read operation on a deleted tablespace raised an error. (Bug #24388498)

• InnoDB: dict_col_t accessors were added to the InnoDB code. (Bug #24363566)

• InnoDB: dict_col functions in the InnoDB code were replaced by accessors. (Bug #24361098)

• InnoDB: dict_index_t functions in the InnoDB code were replaced by accessors. (Bug #24361023)

• InnoDB: Unnecessary code that checked for and released reserved adaptive hash index search latches

was removed. (Bug #24300175)

• InnoDB: A system tablespace data file size greater than 4G on a 32-bit operating system could result in

an overflow condition. (Bug #23753625)

• InnoDB: Internal methods for accessing table object data were added to dict_table_t. (Bug

#23748128)

• InnoDB: The restriction that required the first undo tablespace to use space_id 1 was removed to

avoid space_id conflicts with existing tablespaces during upgrade. The first undo tablespace can now

use a space_id other than 1. space_id values for undo tablespaces are still assigned in a consecutive

sequence. (Bug #23517560)

• InnoDB: Internal accessor functions for iterating the indexes of a table were replaced with accessor

methods. Dead code was removed. (Bug #23336108)

• InnoDB: The mysql.innodb_index_stats and mysql.innodb_table_stats table

definitions, which were previously created by an SQL script, are now hard-coded. As a result, the

dict_table_schema_check function is longer required and was removed. (Bug #23336079)

• InnoDB: The ut_snprint function was replaced by the C++11 snprintf function. (Bug #23329353)

• InnoDB: For consistency, instances of ulint in InnoDB code were replaced with space_id_t and

page_no_t data types. (Bug #23297169)

• InnoDB: Use of boost::atomic in InnoDB code was replaced with std::atomic. (Bug #23280649)

• InnoDB: MySQL binaries were not built with the NUMA feature. (Bug #23259754)

• InnoDB: References to UNIV_NONINL and UNIV_MUST_NOT_INLINE were removed. The

fut0fut.cc and ut0byte.cc files, which were only necessary when UNIV_NONINL was defined,

were also removed. (Bug #23150562)

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MySQL 8.0 Release Notes

• InnoDB: The mutex_own() mapping caused warnings when compiling with Clang or newer GCC

compilers. (Bug #23090278)

• InnoDB: Querying the Performance Schema for InnoDB memory allocation event data incorrectly

reported values of 0. (Bug #23020280)

• InnoDB: DBUG_OFF compile-time flags were replaced by UNIV_DEBUG flags. To improve error log

output, ut_dbg_assertion_failed() now uses sql_print_error() to display the file name, line

number, and message in a single line. The thread ID is displayed in a subsequent line. (Bug #22996442,

Bug #23028144)

• InnoDB: SHOW ENGINE INNODB STATUS output displayed negative spin rounds per wait values.

Thanks to Laurynas Biveinis for the patch. (Bug #22844987, Bug #79703)

• InnoDB: The innodb_disable_resize_buffer_pool_debug option was removed. The patch

for this change also removed a code variable and simplified the buf_pool_resize() function. (Bug

#22755053)

• InnoDB: A global counter (ut_rnd_ulint_counter) was changed to a thread-local counter to make it

scalable on multi-core systems. (Bug #22733635, Bug #80354)

• InnoDB: After a successful ALTER TABLE ... ALGORITHM=COPY operation, an assertion was raised

while building a previous version of a clustered index record. (Bug #22707367)

• InnoDB: A DML operation that updated a counter in a table with a virtual index raised on assertion in

row_parse_int(). (Bug #22650195)

• InnoDB: The InnoDB memcached plugin would not load when compiled with libevent 2.0. (Bug

#22646919)

• InnoDB: Unused calculations for integer-based rec_per_key values were removed from InnoDB.

Integer-based rec_per_key information was replaced by floating point index statistics in an earlier

release. (Bug #22625348)

• InnoDB: On slow shutdown, purge thread shutdown was initiated before the background rollback thread

exited, resulting in an assertion failure. (Bug #22561332)

• InnoDB: Blocks were lost in row_vers_old_has_index_entry() due to unfreed heaps. (Bug

#22543834, Bug #79973)

• InnoDB: A transportable tablespace debug test raised an assertion that was due to a race condition.

(Bug #22453668)

• InnoDB: The server failed to start due to missing undo tablespaces. (Bug #22452992)

• InnoDB: InnoDB recovery asserted while attempting to close an undo tablespace due to buffered undo

tablespace changes introduced by the recovery process. (Bug #22361764)

• InnoDB: Reallocation of memcached-referenced memory raised an assertion. (Bug #22304250, Bug

#79500)

• InnoDB: Building InnoDB with C++11 returned “register” deprecation warnings. Handling of “register”

deprecation warnings remained in the code after the deprecated “register” keyword was removed. Also,

an unused declaration of yyset_extra() was removed. (Bug #22292704)

• InnoDB: SHOW CREATE TABLE output for partitioned tables did not accurately display tablespace

assignment information for table partitions. (Bug #22245554)

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MySQL 8.0 Release Notes

• InnoDB: An ALTER TABLE...TRUNCATE PARTITION operation ignored the table's

KEY_BLOCK_SIZE attribute and used the default value instead, which is half of the

innodb_page_size value. (Bug #22186558, Bug #79223)

• InnoDB: Memory leaks in innochecksum were corrected. (Bug #22179518)

• InnoDB: A SPACE_ID column was added to the INNODB_CACHED_INDEXES table. The INDEX_ID

value is no longer a global unique identifier. (Bug #22172026)

• InnoDB: A purge thread open table callback for virtual columns raised an assertion due to an

unexpected data dictionary table latch. As a temporary workaround, purge is temporarily disabled for

virtual generated columns. This temporary workaround may cause b-tree expansion due to unpurged

delete-marked records for indexes on virtual columns. (Bug #22153217)

• InnoDB: Creating a table with a full-text index and a foreign key constraint failed when

foreign_key_checks was disabled. (Bug #22094601, Bug #78955)

References: This issue is a regression of: Bug #16845421.

• InnoDB: The ha_innobase::m_primary_key field was removed. It was redundant. A boolean

predicate, TABLE_SHARE::is_missing_primary_key(), was added. (Bug #21928734, Bug

#78662)

• InnoDB: A buffer pool load operation that attempted to load an uninitialized page caused a Valgrind

failure. (Bug #21747906)

• InnoDB: Unused functions introduced by the InnoDB memcached plugin were removed. (Bug

#21625760)

• InnoDB: An internal global variable used by the innodb_buffer_pool_size configuration option was

removed. (Bug #21512749)

• InnoDB: An InnoDB page cleaner thread asserted during a buffer pool resize operation. (Bug

#21473497)

• InnoDB: Log buffer contention was reduced with the addition of a second buffer, allowing for concurrent

log buffer writing and flushing. A new mutex was added to protect log buffer flushing. Thanks to Zhai

Weixiang for the patch. (Bug #21352937, Bug #77094)

• InnoDB: Unused InnoDB and libsql functions and variables were removed, and global symbols were

converted to static keywords, where possible. (Bug #21153166, Bug #21141390, Bug #77146, Bug

#21178589)

• InnoDB: A number of unused predefined functions were removed from an internal SQL parser that is

used for implementing full-text indexes, updating the data dictionary, and updating persistent statistics.

(Bug #21126390, Bug #77111)

• InnoDB: The SysTablespace::parse_units() function now returns the number of pages in a

file instead of the number of megabytes. The SysTablespace::normalize_size() function was

removed. Error messages in SysTablespace::parse_params() were revised. (Bug #21040199,

Bug #76949)

• InnoDB: For persistent tables, the internal unique identifier for InnoDB indexes (index_id) now

includes a tablespace identifier (space_id,index_id). This change makes index identifiers unique

at the tablespace level as well as the InnoDB instance level, and supports future work related to index

identifier allocation. (Bug #20737524, Bug #76392)

• InnoDB: In mtr0mtr.cc, a redundant function was removed, and the ReleaseBlocks function was

renamed to AddDirtyBlocksToFlushList. (Bug #20735882, Bug #76343)

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MySQL 8.0 Release Notes

• InnoDB: Code related to innochecksum was cleaned up and reorganized. Checksum functionality is

now located in buf0checksum.cc. (Bug #20518099)

• InnoDB: __attribute__((nonnull)) was removed from InnoDB code. The attribute is no longer

permitted by InnoDB coding guidelines. (Bug #20468234)

• InnoDB: A new struct was added to provide a logical interface for handling and manipulating external

BLOB field references. (Bug #18195972)

• InnoDB: TRUNCATE TABLE is now mapped to DROP TABLE and CREATE TABLE. This change has the

following implications:

• On systems with a large buffer pool and innodb_adaptive_hash_index enabled, TRUNCATE

TABLE operations previously caused a temporary drop in system performance due to an LRU scan

that occurred when removing the table's adaptive hash index entries. The remapping of TRUNCATE

TABLE to DROP TABLE and CREATE TABLE avoids the problematic LRU scan.

• TRUNCATE TABLE is temporarily non-atomic. A server exit during a TRUNCATE TABLE operation

can result in a dropped table and orphaned foreign key constraints in the InnoDB SYS_FOREIGN and

SYS_FOREIGN_COLS system tables.

• The InnoDB memcached plugin flush_all command invokes DELETE instead of TRUNCATE

TABLE. DELETE has a higher overhead cost than FLUSH TABLES since it involves undo-logging,

delete-marking, and eventually purging each deleted row.

• A log checkpoint that occurred for internal truncate table operations on file-per-table tablespaces was

replaced by a log flush.

(Bug #16834993, Bug #68184, Bug #16207919, WL #6795)

• InnoDB: InnoDB wasted most pages in extents used for fragment pages. (Bug #16204823, Bug

#67963)

• Partitioning: In some cases, an issue with partition pruning being attempted a second time during

optimization after all partitions had already been pruned at parsing time led to an assert. (Bug

#23194259)

• Partitioning: A partitioned table whose table name and any partition name had a combined length in

excess of 61 characters could not be imported from a backup created using mysqldump. When the table

also employed subpartitioning, then the combined length of the table name, any partition name, and the

name of any subpartition of this partition could not exceed 57 characters without triggering the same

issue.

This was due to the fact that the internal mysql.innodb_table_stats table allowed a maximum of

64 characters for the column used to store the table name, even though InnoDB stores, for a partitioned

or subpartitioned table, a row in innodb_table_stats for each partition or subpartition wherein the

value actually used to represent the table name follows the pattern table_name#P#partition_name

or table_name#P#partition_name#SP#subpartition_name, respectively. This issue is fixed by

changing the definition of the innodb_table_stats to accommodate the maximum combined length

of these attributes plus #P# and #SP# (199 characters). (Bug #72061, Bug #18416479)

• Replication: In Slave_worker::write_info(), DBUG_ENTER() had

“Master_info::write_info” as its argument instead of “Slave_worker::write_info”. This fix

corrects the argument. Thanks to Stewart Smith for the patch. (Bug #21658067, Bug #78133)

• Replication: When using START SLAVE UNTIL position statements with a multithreaded slave

the only UNTIL clause available was SQL_BEFORE_GTIDS. Now multithreaded slaves are compatible

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MySQL 8.0 Release Notes

with the START SLAVE UNTIL MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS =

log_position and START SLAVE UNTIL RELAY_LOG_FILE = 'log_name', RELAY_LOG_POS

= log_position statements. (Bug #75843, Bug #20513547)

• Microsoft Windows: On Windows, setting the global log_syslog system variable in multiple threads

could cause a server exit. (Bug #22180046)

• Solaris: The client library failed to build on Solaris using the Cstd library. (Bug #24353920, Bug

#82347)

• JSON: CHECKSUM TABLE calculated the checksums for JSON values using the memory addresses of

the values rather than the values themselves, which made the checksum vary. Now in such cases the

calculation is based on the actual JSON value, and not on that value's address. (Bug #23535703)

• JSON: Passing NULL to a stored procedure expecting a JSON parameter led to an assertion failure in

debug builds. (Bug #23209914)

• JSON: Parsing of JSON path arguments failed to distinguish between a NULL path and one that was

syntactically invalid.

This has been changed so that parsing of these paths now clearly distinguishes between valid non-NULL

paths, NULL paths, and invalid paths. (Bug #22816576)

• JSON: For debug builds, an assertion could be raised when the server created a temporary table to hold

JSON objects. (Bug #22782948)

• JSON: Queries that executed a JSON function that raised an error could cause a server exit. (Bug

#22253965)

• Renaming a table to be part of a nonexistent database failed (correctly), but with an Unknown error

message. A proper error message is now produced; this was corrected as part of the data dictionary

implementation. (Bug #25167507, Bug #84000)

• For segmentation faults on FreeBSD, the server did not generate a stack trace. (Bug #24566529, Bug

#23575445, Bug #81827)

• On macOS, stack trace demangling now occurs for builds compiled using Clang, just as for GCC. (Bug

#23606094, Bug #81908)

• libevent was built on macOS even when not needed. (Bug #23228287, Bug #81311)

• A function that returns a JSON value could cause a server exit if called as part of a CASE statement in a

stored procedure. (Bug #23212765)

• Previously, different values were reported by SHOW ENGINE PERFORMANCE_SCHEMA STATUS

and SELECT * FROM performance_schema.memory_summary_global_by_event_name

for total memory used in the Performance Schema. The memory for scalable buffer pages,

instrumented as memory/performance_schema/scalable_buffer, was missing from the

SHOW ENGINE STATUS output. That statement now includes the missing memory, displayed as

(pfs_buffer_scalable_container).memory. (Bug #23104498)

• The -fexpensive-optimizations option to GCC caused ARM64 and PowerPC builds to compute

floating-point operations slightly differently from other platforms. This option was enabled by -O2 and

higher optimization levels. The option now is disabled on platforms negatively affected by it. (Bug

#23046775)

• After a failed administrative operation such as ALTER TABLE ... OPTIMIZE PARTITION, selecting

from the Performance Schema in lock-tables mode could hang. (Bug #23044286)

594

MySQL 8.0 Release Notes

• In builds with AddressSanitizer enabled, CAST(... AS BINARY) could cause a server exit. (Bug

#22900560)

• Some spatial functions were reported using a different spatial function name in error messages. (Bug

#22883056, Bug #80627)

• Fixed Valgrind warnings with Clang in optimized mode for the my_strtod_int() function. (Bug

#22839888)

• Precision math operations on values with 64 decimals could produce a 0 result. (Bug #22828692)

• ST_GeomFromGeoJSON() could return an error with valid arguments. (Bug #22804853)

• For debug builds with STRICT_TRANS_TABLES SQL mode enabled, an assertion could be raised

by INSERT or REPLACE statements that had made changes that could not be rolled back and that

subsequently generated an ER_NO_DEFAULT_FOR_FIELD error. (Bug #22635253)

• The optimizer contained a memcpy() call that did not check for overlapping source and destination. (Bug

#22537196)

• For debug builds, a missing error check on the result of a subquery that accessed a JSON value could

raise an assertion. (Bug #22522073)

• Preparing a CREATE TABLE ... SELECT statement, then flushing tables (thus closing the table) and

executing the prepared statement could cause a server exit. (Bug #22393309)

• A prepared statement that used a parameter in the select list of a derived table that was part of a join

could cause a server exit. (Bug #22392374, Bug #24380263)

• Some grant tables did not account for the increase in maximum user name length from 16 to 32

characters in MySQL 5.7.8. (Bug #22379607, Bug #79680)

• Re-evaluation of a generated column expression could cause access to previously freed memory and a

server exit. (Bug #22346120)

• HANDLER read statements that searched an index when the target index value was not stored into the

row buffer successfully could cause a server exit. (Bug #22321965)

• Improper handling of numeric-to-ZEROFILL conversion for NULL values could lead to a server exit. (Bug

#22281205)

• Using a subquery containing a row constructor to set a variable in a SET statement could cause a server

exit. (Bug #22276843)

• If the SQL mode did not include ALLOW_INVALID_DATES, a query that contained invalid_date IN

(subquery) and was handled by subquery materialization could cause a server exit. (Bug #22262843)

• For the embedded server, the code following the check for invalid arguments was invoked with missing

or incorrect arguments, which could lead to an improper exit. (Bug #22262706)

• On OS X, vio_io_wait() used select(), limiting the number of file descriptors to 1024. Now

kqueue event notification is used instead to avoid this limit. FreeBSD was changed to use kqueue as

well. (Bug #22244911)

• Memory leaks could result if stored routine loading involved temporarily changing the default database

and errors occurred restoring the original default database. (Bug #22179795)

• CMake configuration was adjusted to check for -Wxxx compiler options instead of -Wno-xxx because

the latter produce false positives for GCC. (Bug #21881753)

595

MySQL 8.0 Release Notes

• There could be discrepancies between the values of

INFORMATION_SCHEMA.EVENTS.LAST_EXECUTED and mysql.event.last_executed. This no

longer occurs. Event information is stored in the mysql.events data dictionary table, which is invisible,

so that INFORMATION_SCHEMA.EVENTS is the sole interface to event metadata. (Bug #21374010)

• Views could evaluate user-defined or SQL functions before evaluating restrictions from the view

definition. (Bug #20933307)

• With -DENABLE_DTRACE=ON, CMake did not check whether a working DTrace installation was present.

Now it checks and aborts if DTrace cannot be found. (Bug #20671056)

• SHOW CREATE USER returned unexpected results. (Bug #20625566)

• If given a relative path name for the --log-error option, mysqld could sent stdout and stderr to

the wrong location. (Bug #20609063)

• Evaluation of LEAST() and GREATEST() could use too small a sort buffer for datetime and string

literals, causing an assertion to be raised. (Bug #20565160)

• The range of error numbers for errors that are new in MySQL 8.0 has been designated to begin with

3500. (Bug #20538173)

• Debian packaging was updated not to set the sql_mode system variable in my.cnf. (Bug #20535729)

• Event loading from the mysql.event system table could fail if the PAD_CHAR_TO_FULL_LENGTH SQL

mode was enabled. (Bug #20073523, Bug #74947)

• Statements such as INSERT and LOAD DATA that use the REPLACE or IGNORE keyword to handle

duplicate records could affect subsequent operations. (Bug #20017428)

• CREATE TABLE ... SELECT where non-BIT data was selected from the source table into a BIT

column in the destination table could cause a server exit. (Bug #19930894)

• Compilation failed on OS X when MySQL was configured with -DMYSQL_MAINTAINER_MODE=1 and

compiled with clang/Xcode 6.0. (Bug #19694515, Bug #74100)

• For CHANGE MASTER TO statements rewritten to filter the password before being written to the general

query log, any MASTER_AUTO_POSITION clause was lost. (Bug #19622609)

• Use of the VALUES() function in a SELECT clause could result in a server exit. (Bug #19601973)

• A potential null-pointer dereference and memory leak in table-rename code were corrected. (Bug

#18194270)

• Using MATCH ... AGAINST to compare a character column and an aggregate function could cause a

server exit. (Bug #17865492)

• Slightly different values for the number of connections could be reported in various information sources,

such as the Connections status variable, Performance Schema threads and global_status

tables, and SHOW PROCESSLIST statement. (Bug #17666696)

• A query with a subquery containing a set operation with an outer reference might cause a server exit.

(Bug #17270896)

• Using GRANT to change a password for an invalid user produced an error, but also updated the

mysql.user system table. (Bug #17180985)

• The parser for spatial WKT data accepted numbers such as 0.23 but not .23, the equivalent value

without the leading zero. Now both formats are accepted. (Bug #17167633)

596

MySQL 8.0 Release Notes

• Previously, if a client attempted to send connection attribute key/value pairs that in aggregate had a

size larger than the value of the performance_schema_session_connect_attrs_size system

variable, the Performance Schema truncated the attribute data. In addition, the Performance Schema

wrote this message to the error log if the log_warnings system variable was greater than zero:

[Warning] Connection attributes of length N were truncated

This message was not helpful to a DBA attempting to determine the problematic client, so several

changes have been made to connection attribute handling:

• Truncation of connection attributes still occurs for excessive data, but the log message is more

informative. It includes the number of bytes lost, the connection identifier, and information about the

client user. The additional information should enable DBAs to more easily identify clients for which

attribute truncation occurred.

• When truncation occurs, a _truncated attribute is added to the session attributes with a value

indicating how many bytes were lost, if the attribute buffer has sufficient space. This enables the

Performance Schema to expose per-connection truncation information in the connection attribute

tables.

• A new status variable, Performance_schema_session_connect_attrs_longest_seen,

indicates the longest connection attribute buffer smaller than 64KB seen by the server. If this value

is larger than performance_schema_session_connect_attrs_size, attribute truncation has

occurred, and DBAs may wish to increase the latter value, or, alternatively, investigate which clients

are sending large amounts of attribute data.

For more information, see Performance Schema Connection Attribute Tables. (Bug #16576959)

• Introduction of the data dictionary enables several INFORMATION_SCHEMA problems to be addressed:

• Queries on INFORMATION_SCHEMA.STATISTICS could return different results depending on the

order of columns in the select list.

• Some INFORMATION_SCHEMA tables had suboptimal column types and sizes. Such tables that are

now views on data dictionary tables in the mysql system database have more appropriate column

definitions.

• Queries on INFORMATION_SCHEMA tables that resulted in directory scans to determine database or

file names no longer do so, but instead read database and table names from the data dictionary.

• Queries on INFORMATION_SCHEMA tables that opened .frm files to obtain table metadata no longer

do so, but instead read this information from the data dictionary.

• For comparisons of database or table names in INFORMATION_SCHEMA queries, using COLLATE to

force a given collation worked only if applied to the INFORMATION_SCHEMA table column, but not if

applied to the comparison value.

For additional information about performing such comparisons, see Using Collation in

INFORMATION_SCHEMA Searches.

(Bug #14017351, Bug #65121, Bug #17559183, Bug #70462, Bug #23259470, Bug #81347, Bug

#20372562, Bug #75532, Bug #13878164, Bug #11756519, Bug #48445)

• For abnormal server exit on Windows, the server previously created a minidump file named

module_name.dmp, where module_name is the name of the server executable file. To prevent earlier

minidump files from being overwritten, minidump file names now include the process ID and have the

form module_name..piddmp; for example, mysqld.exe.7296.dmp. (Bug #12779463)

597

MySQL 8.0 Release Notes

• For queries on INFORMATION_SCHEMA tables, comparisons of schema and table names could be

case sensitive or insensitive, depending on the characteristics of the underlying file system and the

lower_case_table_names system variable value. Furthermore, it was ineffective to provide a

COLLATE clause to change the comparison properties because that clause was ignored. This has been

changed so that COLLATE is no longer ignored and can be used to obtain the desired comparison

properties. (Bug #11748044, Bug #34921)

• FLOOR(CEIL()) truncated large BIGINT UNSIGNED arguments. (Bug #80873, Bug #23013359)

• Manipulation of a value returned by the JSON_MERGE() function using JSON_SET() sometimes

produced an invalid result. (Bug #80787, Bug #22961128)

• ST_AsGeoJSON() failed when geometry arguments were supplied using user-defined variables. (Bug

#80697, Bug #22912800)

• CAST(expr AS BINARY(N) ) unexpectedly returned NULL for some valid values of N. (Bug #80630,

Bug #22885819)

• Geometry import functions that took an SRID parameter cast it to an unsigned 32-bit integer without

warning or error, so negative values or values larger than unsigned 32-bit integer range were silently

converted to a number within the range. Now, all geometry functions that take the SRID as a parameter

check that it is within unsigned 32-bit integer range and produce an ER_DATA_OUT_OF_RANGE error if

not. This also applies to GeoJSON and GeoHash functions that previously checked that the parameter

was within range but returned a different error code. (Bug #80499, Bug #22819614)

• If rounding occurred while storing a predicate value, the range optimizer might not return correct results

for the < and <= operators. (Bug #80244, Bug #22661012)

• For the mf_iocache unit test, add a missing va_end(), fix a memory leak by calling my_end(), and

add a target for the test. Thanks to Daniel Black for the patch on which these changes were based. (Bug

#80085, Bug #22578670)

• SELECT DISTINCT SUBSTR() could incorrectly discard values as duplicates for large position or

length arguments. The same issue also affected LEFT() and RIGHT(). (Bug #80047, Bug #22565155)

• SUBSTRING_INDEX(str, delim, count) did not properly handle count values larger than 32 bits.

(Bug #79978, Bug #22545429)

• For calls to CONVERT(), literal string arguments could be modified during execution, producing incorrect

results. (Bug #79924, Bug #22531111)

• REPLACE('a', BINARY 'b', NULL) returned 'a' rather than NULL. (Bug #79912, Bug #22523836)

• Transaction state tracking now avoids a function that is not 8-bit safe, for enhanced compatibility with

nonstandard character sets. (Bug #79905, Bug #22523383)

• GREATEST() and LEAST() treated all integer input as signed. (Bug #79902, Bug #22523685)

• Lines in the general query log were missing a tab between the timestamp and the thread ID. Thanks to

Tsubasa Tanaka for the patch. (Bug #79868, Bug #22508563)

• Some comparisons between unsigned values and negative upper limits could return incorrect results (for

example, CAST(100 AS UNSIGNED) BETWEEN 1 AND -1). (Bug #79857, Bug #22501606)

• The REPEAT() function did not properly handle output from the SUBSTR() function. (Bug #79695, Bug

#22391186)

• The JSON_TYPE() function now shows the type of BIT literals cast to JSON as BLOB, rather than BIT.

(Bug #79308, Bug #22297987)

598

MySQL 8.0 Release Notes

• Configuring MySQL with the -DWITH_UBSAN=ON CMake option produced a server that was not fully

functional. (Bug #79238, Bug #22194071)

• sql_common.h, a header file included in MySQL distributions, included and was therefore dependent

on hash.h, a header file not included in MySQL distributions. This resulted in compilation failures. To

eliminate this dependency, sql_common.h was modified to no longer include hash.h. (Bug #79237,

Bug #22187997, Bug #70672, Bug #17633467)

• Timers used for checking maximum statement execution time were initialized even when the server

was started with the --help option. If --help is given, this is no longer done. (Bug #79182, Bug

#22172389)

• The optimizer failed when trying to optimize away expressions of the form IF(true, '2015-01-01',

'2015-01-01') IS NOT NULL. (Bug #79114, Bug #22148586)

• Subtraction of an unsigned decimal could return a negative value, but with metadata type information

of UNSIGNED BINARY. Subtraction for unsigned decimal subtraction now is handled the same way as

for unsigned integer: Produce an ER_DATA_OUT_OF_RANGE error if the result is negative, unless the

NO_UNSIGNED_SUBTRACTION SQL mode is enabled. (Bug #78914, Bug #22083757)

• Handling by the HEX() function of numbers larger than 2

was improved. (Bug #78828, Bug

#22297983)

References: This issue is a regression of: Bug #9854.

• The client-side plugin deinitialization function signature was changed from int (*deinit)() to int

(*deinit)(void) to avoid warnings when compiling with -Wstrict-prototypes. (Bug #78177,

Bug #21680094, Bug #81419, Bug #23282498)

• CREATE TABLE reported an incorrect error if a very long or incorrect path name was specified for the

DATA DIRECTORY or INDEX DIRECTORY table option. Now ER_PATH_LENGTH or ER_WRONG_VALUE

are reported for those cases. (Bug #76635, Bug #20857556)

• The server now tries to provide more informative messages for these error codes:

ER_CANT_CREATE_DB, ER_CANT_CREATE_TABLE, ER_DB_DROP_RMDIR,

ER_ERROR_DURING_COMMIT, ER_ERROR_DURING_ROLLBACK, ER_GET_ERRNO. (Bug #76298, Bug

#20694494)

• For some instances of failure to prepare an XA transaction, incomplete transaction cleanup could raise

an assertion. (Bug #75809, Bug #20488921)

• mysqld could attempt to close an invalid socket file descriptor. Thanks to Zhai Weixiang for the patch.

(Bug #75778, Bug #20504513)

• A statement of the following form converted the table data to latin1, but also changed the table default

character set to latin1 and ignored the utf8 clause:

ALTER TABLE tbl_name CHARACTER SET utf8, CONVERT TO CHARACTER SET latin1;

Thanks to Daniel Black for the patch. (Bug #75320, Bug #20279241)

• In mysqld.cc, the abort_loop variable was quantified with volatile, which on some platforms

could result in changes not being seen immediately in threads running on different cores. Thanks to

Stewart Smith for the patch. (Bug #74846, Bug #20134637)

• Calling a procedure which created a view from a trigger, or creating a function that called a procedure

that executed RENAME TABLE could, under certain circumstances, raise an assertion. (Bug #74740, Bug

#19988193, Bug #21198646)

599

MySQL 8.0 Release Notes

• Timestamps for server-side prepared statements could be written to the binary log up to a second behind

timestamps for the corresponding nonprepared statements, leading to time value differences between

master and slave servers. (Bug #74550, Bug #19894382, Bug #25187670)

• For dynamic storage engine plugins, DROP TABLE, TRUNCATE TABLE, and RENAME TABLE did not

work due to incorrectly determining the engine from the .frm file. (Bug #74277, Bug #19902868)

• Executed prepared statements are logged with ? parameter markers replaced by data values.

Construction of the logged string was inefficient and has been improved. (Bug #73056, Bug #20955496)

• Assignment by a plugin to its thread variables of string type could leak memory. (Bug #71759, Bug

#19917521)

• Grouping with a view could produce an ER_INVALID_GROUP_FUNC_USE error (“Invalid use of group

function”) when selecting from the base table did not. (Bug #70220, Bug #17406425)

• Queries with multiple LIMIT clauses were not always interpreted in accordance with the SQL standard.

For example, each of the following queries now returns two rows, as expected:

SELECT * FROM t LIMIT 2;

(SELECT * FROM t LIMIT 2) LIMIT 4;

((SELECT * FROM t LIMIT 2) LIMIT 4) LIMIT 3;

This also fixes an issue with UNION subselects using FROM DUAL; for example, the following query

raised an error:

SELECT 'A' AS `x` FROM DUAL

UNION

SELECT 'B' FROM DUAL

UNION

SELECT 'C' FROM DUAL

ORDER BY `x` ASC;

(Bug #50510, Bug #74251, Bug #11758322, Bug #19774083)

• Test cases that were intended to be storage engine-agnostic but were actually using a specific engine

were corrected. (WL #7264)

Index

Symbols

!, 304

!include, 419, 477

!includedir, 419, 477

#define, 86

$, 42

%, 17

&>, 304

* (asterisk), 218

--abort-slave-event-count, 86

--admin-ssl option, 143

--basedir, 499

--binary-as-hex, 260, 378, 499

--binary-as-hex option, 182

--character-set-client-handshake, 17

600

MySQL 8.0 Release Notes

--column-statistics, 499

--comments, 499

--compress, 42, 304

--compression-algorithms, 42

--daemonize, 499

--default-time-zone, 122

--des-key-file, 477

--disabled-storage-engines, 218

--disconnect-slave-event-count, 86

--early-plugin-load, 304

--gdb, 402, 419

--get-server-public-key, 442

--help mysqld option, 143

--hex-blob, 402

--initialize, 499

--keyring-migration-to-component option, 166

--log-raw, 260

--log-warnings, 477

--loose, 8

--malloc-lib, 218

--mtr-port-exclude, 218

--network-namespace, 199

--network-timeout, 525

--new, 17

--no-beep, 378

--no-dd-upgrade, 330

--no-monitor, 402

--old, 17

--secure-auth, 477

--server-public-key-path, 442

--set-gtid-purged, 42

--single-transaction, 42

--skip-comments, 499

--skip-grant-tables, 378, 402, 477

--skip-grant-tables mysqld option, 218

--skip-host-cache, 70

--skip-log-bin, 442

--skip-symbolic-links, 442

--ssl, 568

--ssl option, 143

--ssl-cipher, 442

--ssl-fips-mode, 330, 378

--ssl-mode, 568

--ssl-mode=VERIFY_IDENTITY, 402

--ssl-verify-server-cert, 402, 568

--symbolic-links, 442, 499

--temp-pool, 525

--transaction-isolation, 477

--transaction-read_only, 477

--upgrade, 330

--verbose mysqld option, 143

-1, 218

-DDISABLE_PSI_MEMORY, 143

.mysql_secret, 330

601

MySQL 8.0 Release Notes

1F, 477

32-bit, 568

=, 260

>ut_allocator(), 143

\u001f, 477

_, 17

` (backtick), 218

||, 304

, 103, 182

Aborted_connects, 330

account categories, 330

account management, 260, 330, 378, 419, 499, 568

ACL, 4

adaptive hash index, 13, 42, 70, 143, 182, 442, 525, 568

ADD COLUMN, 55, 70, 143, 240, 304, 356, 402

ADD INDEX, 240, 284

ADD PARTITION, 55

Address Sanitizer, 166, 182, 218

AddressSanitizer, 419

ADD_GDB_INDEX, 284

add_not_null_conds(), 330

ADMIN, 402

ADMINISTRABLE_ROLE_AUTHORIZATIONS, 260

admin_address, 199, 356

admin_port, 356

admin_tls_version, 103

AES_DECRYPT(), 442

aggregate functions, 166, 166, 182, 260

AggregateIterator, 143

aggregates, 122

aggregation, 86, 103, 122, 166, 182, 304, 442, 525

aggregation functions, 86

AIO, 182

ALGORITHM, 330

ALGORITHM-INSTANT, 70

ALGORITHM=COPY, 568

ALGORITHM=INSTANT, 8, 42, 55, 70, 86, 103, 402

algrind, 86

alias, 260, 330

aliases, 86, 260

ALLOW_INVALID_DATES, 330

Alpine Linux, 419, 442, 499

ALTER COLUMN, 378

ALTER EVENT, 34

ALTER INSTANCE, 218

ALTER INSTANCE RELOAD KEYRING statement, 55, 166

ALTER INSTANCE RELOAD TLS, 34, 218

ALTER RESOURCE GROUP, 402

ALTER SCHEMA, 260

ALTER TABLE, 34, 42, 86, 166, 182, 199, 218, 260, 284, 304, 330, 356, 378, 402,

419, 442, 477, 499, 525, 568

602

MySQL 8.0 Release Notes

ALTER TABLE ... ALGORITHM=COPY, 8

ALTER TABLE ... IMPORT TABLESPACE, 199

ALTER TABLE statement, 182

ALTER TABLESPACE, 284, 356, 442

ALTER USER, 34, 240, 304, 356, 419

AlternativeIterator, 260

ANALYZE, 13

ANALYZE TABLE, 55, 122, 199, 260, 419, 499

ANALYZE TABLE statement, 166

ANALYZE TABLE UPDATE HISTOGRAM, 378

AND, 260

antijoin, 304

antijoins, 34

ANY, 199

API, 70

APPLICABLE_ROLES, 260

ARCHIVE, 304, 356

arguments checking, 17

Arg_comparator, 122

ARM, 4

ARM 64-bit, 304, 378

ARRAY, 260, 304

arrays, 442

ASAN, 166, 182, 218

ASC, 378, 402

ASCII, 55, 103

ASCII 31, 477

assert, 13

assertion, 42, 143

ASSERT_COLUMN_MARKED_FOR_READ, 356

asymmetric_encrypt(), 34

async client, 23

asynchronous I/O, 330

AT TIME ZONE, 199

atomic DDL, 218, 419, 477, 525, 568

atomic operations, 568

atomics, 182

ATTRIBUTE, 218

audit log, 34

audit log plugin, 17, 23

audit plugins, 330

AUDIT_ADMIN, 304

audit_api_message_emit, 356

audit_api_message_emit_udf(), 356

audit_log plugin, 17, 23, 34, 42, 55, 70, 103, 122, 143, 166, 199, 218, 260, 284,

304, 330, 356, 378, 402, 419, 442, 525

audit_log_connection_policy, 23

audit_log_disable, 103

audit_log_exclude_accounts, 23

audit_log_filter_id, 218

audit_log_flush, 55

audit_log_format_unix_timestamp system variable, 143

audit_log_include_accounts, 23

audit_log_max_size system variable, 143

603

MySQL 8.0 Release Notes

audit_log_password_history_keep_days, 304

audit_log_policy, 23

audit_log_prune_seconds system variable, 143

audit_log_read() function, 199

audit_log_rotate, 42

audit_log_rotate(), 55

audit_log_rotate_on_size system variable, 143

audit_log_statement_policy, 23

audit_null plugin, 304

authentication, 23, 42, 55, 86

authentication plugins, 17, 23, 42, 70, 122, 143, 166, 182, 199, 218, 240, 260, 284,

330, 356, 378, 419, 442, 477

authentication_fido_client plugin, 17, 34

authentication_kerberos, 4

authentication_kerberos authentication plugin, 143

authentication_kerberos_client authentication plugin, 143

authentication_ldap_sasl, 218

authentication_ldap_sasl_log_status, 284

authentication_ldap_sasl_referral system variable, 240

Authentication_ldap_sasl_supported_methods, 218

authentication_ldap_simple_log_status, 284

authentication_ldap_simple_referral system variable, 240

authentication_oci, 23

authentication_oci_client, 34

AUTHENTICATION_PAM_LOG, 13

authenticator data, 86

auth_sock plugin, 419

auth_socket, 42

auto-increment, 284, 477, 499, 568

autocommit, 442

AUTOEXTEND_SIZE, 166, 182

AutomaticThreadConfig, 34

automatic_sp_privileges, 402

autopositioning, 499

autoscale, 477

autowrapping, 477

AUTO_INCREMENT, 34, 86, 218, 304

auto_increment_increment, 304, 356

auto_increment_offset, 356

averages, 4

AVG(), 34, 304, 356, 378

B-tree, 86, 378

backup, 477

back_log, 477

Barracuda, 568

base-64, 402

basedir, 499

batch mode, 304

batched key access, 143

BETWEEN, 86, 378

BETWEEN operator, 182

604

MySQL 8.0 Release Notes

BIGINT, 260

big_tables, 442

BIN(), 525

BINARY, 122, 304

binary, 378

binary log, 23, 34, 166, 477, 499, 525, 568

binary log compression, 17, 23

binary log events, 23

binary log sender thread, 55

binary logging, 55

bind_address, 199, 378

binlog, 42

binlog_direct_non_transactional_updates, 356

binlog_encryption, 218

binlog_expire_logs_auto_purge, 86

binlog_expire_logs_seconds, 55, 402, 442, 525

binlog_format, 23, 356, 499

binlog_order_commits, 34

binlog_rows_query_log_events, 356

binlog_row_image, 356

binlog_row_value_options, 356, 442, 477

binlog_transaction_dependency_history_size, 525

binlog_transaction_dependency_tracking, 17, 442, 525

BIN_TO_UUID(), 568

Bison, 86

BIT, 55, 103, 568

bit functions, 122

bit operations, 568

bitwise operators, 284

BIT_AND(), 166, 402

BIT_OR(), 166, 304, 402

BIT_XOR(), 166, 402

BKA, 143

BLACKHOLE, 442

BLACKHOLE storage engine, 122

BLOB, 122, 182, 330, 419, 442, 568

bool, 525

boolean, 304

Boost, 86, 122, 199, 218, 284, 304, 330, 356, 402, 419, 442, 499, 525, 568

bootstrap, 442, 499

Bounded_queue, 23

BUCKETS, 419

buffer pool, 55, 122, 143, 166, 199, 240, 378, 402, 419, 442, 477, 525, 568

buffer pool mutex, 568

buffer pool scan, 568

buffers, 23

buf_validate(), 103

build_id, 55

bulk_insert_buffer_size, 356

BUNDLE_RUNTIME_LIBRARIES, 419

c api, 23

605

MySQL 8.0 Release Notes

C API, 70, 103, 122, 182, 199, 218, 240, 304, 330, 442, 477, 499, 525, 568

C++11, 568

C++14, 330

C++17, 122

C++23, 17

CACHE INDEX, 304

caching_sha2_password, 330, 419, 442, 477

caching_sha2_password plugin, 166

caching_sha2_password_auto_generate_rsa_keys, 442

caching_sha2_password_digest_rounds system variable, 166

capture groups, 402

CAP_SYS_NICE, 356

CASE, 122, 166, 304, 525

CASE function, 34

case sensitivity, 240

CAST, 55, 166, 402

cast injection, 218, 284

CAST(), 55, 122, 166, 199, 260, 284, 304, 568

CAST() function, 166

CATS, 378

CDATA, 218

CEIL(), 568

CEILING(), 260

change buffer, 218, 284, 568

change buffering, 442

CHANGE MASTER TO, 42, 199, 442

CHANGE MASTER TO statement, 166

CHANGE REPLICATION FILTER, 499

channel initialization, 499

CHAR, 356

CHAR(), 402

character escapes, 477

CHARACTER SET, 122

character sets, 34, 55, 166, 182, 240, 260, 284, 304, 330, 356, 378, 419, 442, 477,

499, 525, 568

character_set_client, 304

character_set_connection, 442

character_set_database, 356, 525

character_set_filesystem, 356

character_set_server, 8, 525

charsets, 23, 34, 122, 143, 166, 378

CHECK constraints, 143, 240, 260, 330

CHECK TABLE, 330, 356, 378

checkpoint, 378

checksum, 378, 568

checksum algorithm, 122

checksum mismatch, 402

CHECKSUM TABLE, 568

CHECK_CONSTRAINTS, 330

check_stack_overrun(), 525

Chinese, 330

clang, 23, 70

Clang, 42, 103, 122, 199, 240, 499, 568

client metadata, 8

606

MySQL 8.0 Release Notes

client/server protocol, 143

CLIENT_NO_SCHEMA, 42

CLIENT_SSL_VERIFY_SERVER_CERT, 419

clock_gettime(), 260

clone, 86

clone plugin, 8, 86, 122, 143, 166, 199, 240, 260, 284, 304

clone_delay_after_data_drop, 86

clone_os_copy_file_to_buf(), 42

Clone_Snapshot, 17

clone_status table, 23

CMake, 13, 17, 55, 70, 260, 304, 330, 356, 378, 419

cmake, 34, 55, 70

CMAKE_BUILD_TYPE, 356, 378

COALESCE, 330

COALESCE(), 442

coercibility, 218

COLLATE, 34, 122, 477

collation-server, 34

collations, 23, 55, 70, 122, 166, 182, 199, 218, 240, 260, 284, 304, 330, 378, 419,

477, 499, 525, 568

collation_database, 356, 525

collation_server, 525

column prefixes, 17

column references, 23

COLUMNS table, 182

columns_priv table, 568

COLUMN_FORMAT, 304

column_statistics table, 70, 477, 499

COLUMN_STATISTICS table, 499

column_stats table, 499

COMMENT, 218

comments, 4, 240, 260, 378, 499

common table expressions, 70, 86, 122, 218, 240, 260, 284, 356, 442, 477, 525

compare_pair_for_nulls(), 23

comparisons, 143, 218

COMPILATION_COMMENT, 356

COMPILATION_COMMENT_SERVER, 330, 356

compile_cluster, 304

COMPILE_DEFINITIONS, 330

COMPILE_FLAGS, 330

compiling, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166, 166, 182,

199, 218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

component service, 55, 143

components, 42, 55, 218, 304, 356, 419, 442, 499, 525, 568

component_enterprise_encryption, 34

component_keyring_encrypted_file component, 23, 166

component_keyring_file component, 23, 166

component_keyring_oci, 42, 55

component_keyring_oci component, 55

component_masking component, 34

component_masking_functions component, 34

component_sys_variable_register service, 499

component_sys_variable_unregister service, 499

composite indexes, 356

607

MySQL 8.0 Release Notes

Compression, 42

compression, 218, 260, 284, 477, 525, 568

COMPRESS_DEBUG_SECTIONS, 199

comp_err, 166, 218, 240, 304

COM_SHUTDOWN, 568

CONCAT(), 218, 330, 442

CONCAT_WS(), 218

concurrent DDL, 55

condition count, 199

condition pushdown, 8, 34, 42, 55, 70, 86, 103, 122, 284, 330

COND_FILTER_STALE, 304

configuration, 199, 218, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

connection, 42

connection attributes, 260, 304

connection handling, 166, 568

connection management, 199, 218

connections, 4, 42

CONNECTION_CONTROL, 419

CONNECTION_CONTROL plugin, 240, 525

CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS plugin, 525

CONNECTION_ID(), 70

connection_memory_chunk_size, 23

Connectors, 103

const, 199, 260, 304, 330, 402

constant expressions, 284

constant folding, 122, 284, 330

constant propagation, 122, 442

constraints, 260, 284, 304

Contention-Aware Transaction Scheduling (CATS), 240, 284, 304, 330, 378, 402, 419

contribution, 260

contributions, 86

CONV(), 260

conversions, 356

CONVERT TO CHARACTER SET, 304

CONVERT(), 34, 103, 199, 304, 378, 568

CONVERT_TZ(), 103

copy functions, 143

core file, 356

correlated subqueries, 166

corruption, 568

cost model, 525

cost tables, 525

COUNT(), 166, 304, 330, 356, 442, 499

COUNT(*), 378

COUNT_SECONDARY, 86

crc32, 568

CREATE DATABASE, 122

CREATE EVENT, 34

CREATE FUNCTION, 86, 499

CREATE INDEX, 103, 402, 525

CREATE MASTER, 568

CREATE PROCEDURE, 86

CREATE RESOURCE GROUP, 402

CREATE ROLE, 17

608

MySQL 8.0 Release Notes

CREATE SPATIAL REFERENCE SYSTEM, 402, 442

CREATE TABLE, 86, 166, 284, 304, 330, 356, 402, 419, 442, 477, 499, 525, 568

CREATE TABLE ... SELECT, 218, 419

CREATE TABLE ... SELECT statement, 122

CREATE TABLE LIKE, 419, 442

CREATE TABLE SELECT, 419

CREATE TABLE statement, 182

CREATE TABLESPACE, 166, 218, 260, 304, 356, 499

CREATE TEMPORARY TABLE, 442, 568

CREATE TRIGGER, 86

CREATE USER, 8, 34, 55, 122, 199, 284, 304, 330, 356, 419, 477

CREATE VIEW, 122, 199, 284, 419, 442

create_admin_listener_thread, 199, 240, 356

CREATE_OPTIONS, 442

crypto policy, 34

CSV, 143

CTE, 42, 86, 143

CTEs, 13, 17, 23, 34, 70

cte_max_recursion_depth, 442, 477

CTX_NONE, 442

CTX_WINDOW, 442

curl, 17, 23, 34, 42, 55, 70, 103, 143, 166, 166, 240, 260, 284, 330, 378

CURRENT_ROLE(), 419

CURRENT_USER, 330

CURRENT_USER(), 23

CURSOR_TYPE_READ_ONLY, 419

daemon_keyring_proxy_plugin plugin, 166

data dictionary, 34, 42, 103, 182, 218, 240, 284, 304, 330, 356, 356, 378, 402, 419,

442, 477, 499, 525, 568

data dictionary cache, 499

DATA DIRECTORY, 218, 356

data encryption, 86, 143, 260

data file, 568

data masking, 34, 86, 122, 378

data types, 42, 260, 284, 378, 477, 568

data_locks table, 4, 8, 356, 378

data_locks_waits table, 4

data_lockwaits table, 378

data_masking, 42, 70

data_masking plugin, 34

DATE, 86, 166, 284, 304, 330, 419

date arithmetic, 442

DATETIME, 86, 166, 330, 419

datetime, 260

datetime_format, 477

DATE_ADD(), 103

date_format, 477

DATE_SUB(), 103

db table, 568

DBL_MAX, 260

DBSPJ, 240

609

MySQL 8.0 Release Notes

DBUG package, 284

DBUG_ABORT(), 378, 499

DDL, 23, 86, 103, 122, 199, 330, 378, 402, 419, 442, 477, 525

DDL log, 218

ddl_rewriter, 330

dd_properties table, 499

de-identification, 34

deadlock, 8, 122, 143, 218, 240, 260, 284, 356, 402, 419, 568

deadlock checks, 240

deadlock detection, 356

debug, 4, 8, 356, 378, 402, 419, 442, 568

Debug Sync, 525

debugging, 284, 304

debug_sync, 356

dec, 103

DECIMAL, 23, 86, 260, 284, 304

decimal precision, 122

decimals, 166

DECODE(), 477

deduplication, 240, 304

DEFAULT, 23, 240, 304, 378

DEFAULT ROLE, 284

default values, 218, 378

DEFAULT(), 86, 122

DEFAULT() function, 34

default_authentication_plugin, 122, 442

default_collation_for_utf8mb4, 356, 419

default_roles, 218

default_table_encryption, 330

definer, 8

degenerate hash joins, 218

deinitialization, 8

delay, 4

DELETE, 42, 103, 122, 218, 330, 356, 402, 442

DELETE IGNORE, 218

DENSE_RANK(), 34, 442

DENSE_RANK() OVER, 442

deprecation, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166, 182, 199, 218, 240, 260,

284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

deprecations, 23

derived condition pushdown, 199

derived tables, 34, 55, 70, 166, 284, 304, 330, 356, 442, 525

DESC, 166, 378, 402

descending indexes, 525

DESCRIBE, 17, 419

DES_DECRYPT(), 477

DES_ENCRYPT(), 477

detached transactions, 86

dictionary object cache, 568

dict_sys, 143

disabled_storage_engines, 402

DISABLE_PSI_MEMORY, 182

DISABLE_SHARED, 284

DISCARD OLD PASSWORD, 356

610

MySQL 8.0 Release Notes

DISCARD TABLESPACE, 55, 103, 260, 284, 402

disk is full, 442

disk space, 442

display width, 304

display widths, 260

DISTINCT, 13, 86, 122, 143, 182, 218, 240, 260, 284, 304, 330, 402, 499

DIV operator, 166

division, 122

DML, 86, 103, 122, 166, 199, 568

Docker, 122, 166, 330, 356, 477

Docker image, 218

dollar sign, 42

DOM, 525

DOUBLE, 86, 166, 304

double, 525

doublewrite, 260

doublewrite buffer, 34, 70, 143, 218, 240

downgrade, 419

downgrades, 17

Doxygen, 34, 86, 182

doxygen, 419, 568

dragnet.log_error_filter_rules, 402, 442

dragnet.Status, 402

DROP COLUMN, 42, 55, 70, 86, 240

DROP DATABASE, 143, 218, 402, 442, 477, 525

DROP DATAFILE, 499

DROP FUNCTION, 499

DROP INDEX, 525

DROP PARTITION, 199

DROP privilege, 182

DROP RESOURCE GROUP, 402

DROP ROLE, 17, 330

drop role, 330

DROP SPATIAL REFERENCE SYSTEM, 442

DROP TABLE, 55, 70, 182, 218, 402, 477, 499, 525

DROP TABLESPACE, 103, 284, 499

DROP USER, 199

DROP VIEW, 477

DST, 304

DTrace, 525

dual passwords, 356

DUMP 103003, 284

DUMP 103004, 284

DUMP 103005, 284

duplicate key error, 260, 304

duplicate keys, 304, 477

duplicate weedout, 240

dynamic metadata, 419

DYNAMIC_STRING, 199

EL7, 23

embedded server, 525

611

MySQL 8.0 Release Notes

empty string, 568

ENABLED_ROLES, 260

ENABLE_DOWNLOADS CMake option, 143

ENCODE(), 477

ENCRYPT(), 477

encryption, 70, 86, 103, 122, 143, 166, 182, 199, 218, 240, 260, 284, 304, 330, 356,

402, 419, 442, 477, 499, 525

end-range condition, 442

ENUM, 122, 356, 499

EOF, 23

epoch, 240

EPSG, 402, 442

equi-join, 284

equi-joins, 442

equijoins, 55

eq_ref, 55, 86, 304, 330

error handling, 55, 86, 122, 166, 182

error log, 143, 419

error logging, 70, 240, 442, 499

error messages, 34, 284

errors, 4, 8, 34, 42, 55, 103, 122, 143, 166, 182, 199, 218, 240, 260, 284, 304,

330, 356, 378, 402, 419, 442, 477, 499, 525, 568

error_log, 199

ER_DUP_ENTRY, 304

ER_FILESORT_TERMINATED, 260

ER_FILSORT_ABORT, 260

ER_GEOMETRY_PARAM_LATITUDE_OUT_OF_RANGE, 402

ER_GEOMETRY_PARAM_LONGITUDE_OUT_OF_RANGE, 402

ER_IB_MSG_720, 356

ER_INCONSISTENT_ERROR, 499

ER_INVALID_CHARACTER_STRING error, 143

ER_JSON_SCHEMA_VALIDATION_ERROR_WITH_DETAILED_REPORT, 260

ER_LATITUDE_OUT_OF_RANGE, 402

ER_LONGITUDE_OUT_OF_RANGE, 402

ER_NEED_REPREPARE, 356

ER_REGEXP_ILLEGAL_ARGUMENT, 330

ER_REGEXP_INVALID_CAPTURE_GROUP_NAME, 419

ER_REGEX_NUMBER_TOO_BIG, 199

ER_WRONG_FIELD_WITH_GROUP, 330

ER_WRONG_VALUE_FOR_VAR, 356

ESCAPE, 166

Event Scheduler, 55, 103, 143, 199, 499

EventMutex, 199

events, 260

events table, 568

events_statements_current, 356

events_statements_history, 356

events_statements_history_long, 356

events_statements_summary_by_digest, 477

event_scheduler, 477

EXCEPT, 55

exception handling, 122

EXCHANGE, 304, 419

EXCHANGE PARTITION, 182, 260, 330, 356

612

MySQL 8.0 Release Notes

EXECUTION_ENGINE, 86

EXISTS, 23, 34, 122, 166, 218, 330

expired passwords, 122

expire_logs_days, 402, 442

EXPLAIN, 4, 42, 70, 86, 103, 122, 199, 218, 240, 284, 304, 330, 378, 402

EXPLAIN ANALYZE, 34, 55, 70, 143, 218, 240, 260, 284

EXPLAIN EXTENDED, 419, 477

EXPLAIN FOR CONNECTION, 356

EXPLAIN FORMAT=JSON, 284

EXPLAIN FORMAT=TREE, 34, 240

EXPLAIN PARTITIONS, 477

EXPLAIN statement, 143

explicit_defaults_for_timestamp, 199, 356, 442, 499

exponents, 378

expression default values, 378

expressions, 330

EXTENDED, 499

extent, 568

FAILED_LOGIN_ATTEMPTS, 260

failover, 34

false, 330

FALSE AND ..., 199

fastcov, 284

FEDERATED, 356, 378, 402, 525

FEDERATED storage, 70

FEDERATED storage engine, 143

FIDO pluggable authentication, 17, 34, 86, 122

fido2, 70

Field_json::cmp_binary(), 442

field_phy_pos, 70

Field_tiny::pack(), 284

file operation error, 86

file space allocation, 304

file writes, 240

FILES, 218, 419, 442

filesort, 23, 86, 199, 218, 240, 356, 402

fil_shard mutex, 8, 122

fil_space_acquire(), 122, 143

fil_space_acquire_silent(), 122

fil_tablespace_redo_extend(), 143

find_in_group_list(), 122

FIND_IN_SET(), 86, 378

FIPS, 284, 419

firewall, 86, 122, 143, 166, 182, 240, 356, 402

FIREWALL_EXEMPT, 70

firstmatch, 304

FIRST_VALUE(), 419

FLOAT, 42, 70, 103, 166, 284, 304, 378

floating-point, 42, 166, 182

floating-point numbers, 442

FLOOR(), 260, 568

613

MySQL 8.0 Release Notes

flush, 442

FLUSH DES_KEY_FILE, 477

FLUSH HOSTS statement, 182

FLUSH LOGS, 499

flush method, 568

FLUSH OPTIMIZER_COSTS statement, 182

FLUSH QUERY CACHE, 477

FLUSH STATUS, 330

FLUSH STATUS statement, 182

FLUSH TABLES, 442, 477, 499

FLUSH TABLES FOR EXPORT, 378

FLUSH TABLES statement, 182

FLUSH TABLES WITH READ LOCK, 218

FLUSH TABLES WITH READ LOCK statement, 182

FLUSH USER_RESOURCES statement, 182

FLUSH_OPTIMIZER_COSTS privilege, 182

FLUSH_STATUS privilege, 182

FLUSH_TABLES privilege, 182

FLUSH_USER_RESOURCES privilege, 182

FOLLOWING, 356

FOR SHARE, 199

FORCE INDEX, 477

FORCE_INSOURCE_BUILD, 356

foreign key check, 378

foreign key constraint, 330, 378, 477, 525

foreign keys, 143, 218, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

foreign_key_checks, 86

FORMAT=TREE, 122, 284

formatting, 499

FORMAT_BYTES(), 260, 330

FORMAT_PICO_TIME(), 260, 330

FOUND_ROWS(), 304

FPROFILE_GENERATE, 260

FPROFILE_USE, 260

fragment page, 568

frame buffer partition offset, 182

FreeBSD, 240, 525

frm files, 304, 378

FROM_DAYS(), 218

FROM_UNIXTIME(), 103, 199, 330, 442

fsync, 378

FULL, 42

full-text index, 86, 103, 122, 143

full-text search, 103, 143, 166, 182, 199, 260, 304, 356, 402, 419, 442, 477, 499, 525,

568

FULLTEXT, 55, 143

fulltext, 182

fulltext index, 122

FULLTEXT index, 182, 199, 240, 304, 378, 402, 499, 525

func table, 568

functional dependencies, 419

functional indexes, 4, 70, 166, 182, 199, 218, 260, 284, 304, 356, 378

functional key parts, 378

functions, 13, 34, 103, 260, 330, 525

614

MySQL 8.0 Release Notes

futex, 525

gap lock, 525

gap locks, 419

garbage collection, 4

gcc, 34

GCC, 70, 86, 143, 166, 240

general tablespace, 477

generated column, 70

generated columns, 34, 103, 122, 143, 218, 260, 304, 330, 356, 378, 402, 419, 442, 499,

525, 568

generated expressions, 199

generated invisible primary keys, 70

GenError, 4

gen_blacklist() function, 182

gen_blocklist() function, 182

gen_dictionary() function, 122

gen_range(), 4, 218

gen_range() function, 122

gen_rnd_pan() function, 122

GeomCollection, 419

GeomCollection(), 419

GEOMETRY, 240, 260

geometry, 240, 525

GeometryCollection, 419

GeometryCollection(), 419

GET_LOCK(), 356, 442

get_mysql_time_from_str_no_warn(), 330

GIPK mode, 70

GIS, 42, 70, 122, 143, 166, 182, 199, 218, 240, 284, 304, 330, 356, 378, 402, 419,

442, 477, 499, 525, 568

glibc, 23, 525

GLOBAL_STATUS, 525

global_variables, 442

GLOBAL_VARIABLES, 525

Google Test, 143

googlemock, 4

googletest, 218, 284

GPG key, 13, 103

GRANT, 23, 330, 419, 442

GRANT OPTION, 304

grants, 17

GREATEST(), 55, 260, 284, 304, 419, 442, 568

group, 55, 86, 122, 143, 182, 218, 240, 260, 284, 330, 356, 378, 402, 419, 442, 477,

499, 525

Group, 477

GROUP BY, 8, 42, 143, 182, 218, 240, 260, 304, 330, 378, 402, 419, 442

group commit, 525, 568

group recovery, 8

Group Replication, 4, 4, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143,

166, 182, 199, 218, 240, 260, 284, 304, 330, 356, 356, 378, 402, 419, 442, 477, 499,

525

615

MySQL 8.0 Release Notes

grouping, 122, 402, 442

GROUPING(), 143, 525

GROUP_CONCAT(), 17, 103, 166, 442, 499, 525

GROUP_CONCAT() function, 143

group_concat_max_len, 103, 442

group_concat_max_len system variable, 143

group_replication_components_stop_timeout, 122

group_replication_exit_state_action, 8

group_replication_recovery_get_public_key, 442

group_replication_recovery_public_key_path, 442

group_replication_set_as_primary(), 8

GSSAPI, 42, 240

GTID, 182, 240, 499, 525, 568

GTID sets, 8

GTID skip, 499

GTIDs, 55

gtid_executed, 284, 402, 442

gtid_executed_compression_period, 182

gtid_mode, 477, 499

gtid_next, 356

GTID_SUBSET(), 70

HANDLER, 304

HANDLER READ, 182

handler::position(), 284

Handler::rnd_pos(), 419

Handler_read_key, 284

Handler_read_next, 284

hash functions, 70

hash indexes, 240

hash join, 240, 260, 284

hash joins, 86, 103, 122, 143, 182, 199, 240, 260

hash outer joins, 34

hash scans, 34

hash semijoin, 442

hashes, 182

hashing, 13

hash_join, 260

have_crypt, 477

have_openssl system variable, 143

have_query_cache, 477

have_ssl system variable, 143

have_symlink, 499

HAVING, 13, 23, 34, 103, 143, 199, 304, 442

heap size, 499

heap-use-after-free, 419

Henry Spencer Library, 330

HEX(), 568

hexadecimal, 402

HISTOGRAM, 13, 442

histogram, 442

histogram sampling, 199, 218, 240

616

MySQL 8.0 Release Notes

histogram smapling, 55

histogram statistics, 143, 260, 477, 499

histograms, 55, 70, 86, 103, 330, 378

histogram_generation_max_mem_size, 356, 499

history list, 442

hole punch, 103

host cache, 182

host name maximum length, 304

host_application_signal component service, 356

host_cache table, 182

host_cache_size, 284

hotfix, 143

hp8, 103

ib::fatal(), 122

ibd2sdi, 402, 419, 477, 499, 568

ibtmp1, 568

ICU, 23, 103, 218, 442

ICU_VERSION(), 442

identifiers, 42

IF, 122, 166, 304

IF EXISTS, 70

IF NOT EXISTS, 86

IF(), 166, 442

IFNULL(), 284, 442

IGNORE, 356

IGNORE UNKNOWN USER, 70

ignore_builtin_innodb, 477

IGNORE_SPACE, 499

implicit commits, 103

implicit tablespace, 442

import, 442, 568

IMPORT TABLE, 525

IMPORT TABLESPACE, 55, 218, 260

Important Change, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 199, 218, 240,

260, 356, 378, 402, 419, 442, 525, 568

Important Note, 86, 166

impossible ON, 34, 304

impossible WHERE, 240

IN, 8, 34, 55, 166, 199, 240, 356, 442

IN subqueries, 330

IN subquery, 304

IN(), 122, 143

in-place update, 499

Incident event, 499

Incompatible Change, 17, 55, 103, 122, 143, 166, 218, 240, 284, 330, 378, 402, 419,

442, 477, 499, 525, 568

incomplete predicates, 304

incremental backup, 86

index, 525

index condition pushdown, 166, 442

index dives, 477

617

MySQL 8.0 Release Notes

index extensions, 143

Index Merge, 23

index merge, 122

index merge scan, 86

index prefixes, 218

index range scans, 103

index scan, 143

index scans, 70, 284

index skip scans, 23

index statistics, 86, 182, 568

index tree, 166

Index.xml, 419

indexes, 260, 378, 402, 419

IndexRangeScanIterator, 103

index_id, 568

INDEX_MERGE, 34, 525

Information Schema, 86, 166, 442

INFORMATION_SCHEMA, 122, 182, 199, 218, 240, 260, 284, 330, 356, 378, 402, 419, 442,

477, 499, 525, 568

INFORMATION_SCHEMA.COLUMNS, 477

INFORMATION_SCHEMA.COLUMN_STATISTICS, 442

INFORMATION_SCHEMA.FILES, 70, 86, 122, 525

INFORMATION_SCHEMA.INNODB_BUFFER_PAGE, 166

INFORMATION_SCHEMA.INNODB_COLUMNS, 284, 402

INFORMATION_SCHEMA.INNODB_SYS_FOREIGN, 477

INFORMATION_SCHEMA.INNODB_TABLESPACES, 182

INFORMATION_SCHEMA.KEYWORDS, 378

INFORMATION_SCHEMA.KEY_COLUMN_USAGE, 86

INFORMATION_SCHEMA.PROCESS_LIST, 103, 122

INFORMATION_SCHEMA.STATISTICS, 419

INFORMATION_SCHEMA.TABLES, 86, 330, 442

initialization, 55, 166, 304

initialize, 378

init_connect, 419

init_file, 240, 284

init_file system variable, 182

inner hash joins, 70

innochecksum, 330, 442, 568

InnoDB, 4, 4, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166,

182, 199, 218, 240, 260, 284, 304, 330, 356, 356, 378, 402, 419, 442, 477, 499, 525,

568

InnoDB memcached plugin, 143, 199

InnoDB system tablespace, 70

innodb_buffer_pool_evict, 240

innodb_buffer_pool_instances, 260

Innodb_buffer_pool_resize_status_code, 55

Innodb_buffer_pool_resize_status_progress, 55

INNODB_CACHED_INDEXES, 568

INNODB_COLUMNS, 218

Innodb_data_pending_fsyncs, 34

innodb_ddl_log table, 419

innodb_dedicated_server, 143, 356

innodb_directories, 143, 304

innodb_doublewrite, 34, 70

618

MySQL 8.0 Release Notes

innodb_dynamic_metadata table, 419

innodb_extend_and_initialize, 166

innodb_fast_shutdown, 199

innodb_file_format, 568

innodb_file_format_check, 568

innodb_file_format_max, 568

innodb_file_per_table, 378, 442

innodb_flush_log_at_trx_commit, 17, 378

innodb_flush_method, 330, 356

innodb_force_recovery, 260

INNODB_FOREIGN, 330

innodb_fsync_threshold, 378

innodb_idle_flush_pct, 284

innodb_interpreter, 103

innodb_large_prefix, 568

innodb_limit_optimistic_insert_debug, 284

innodb_log_buffer_size, 70

innodb_log_checkpoint_fuzzy_now, 402

innodb_log_files_in_group, 70

innodb_log_file_size, 70

innodb_log_writer_threads, 143, 166

INNODB_METRICS, 330

INNODB_METRICS table, 218, 284, 304

innodb_numa_interleave, 525

innodb_open_files, 103, 122, 166

innodb_redo_log_capacity, 70

innodb_redo_log_consumer_advance(), 55

innodb_redo_log_encrypt, 143

innodb_segment_reserve_factor, 143

innodb_spin_wait_delay, 356

innodb_spin_wait_pause_multiplier, 330

innodb_status_output, 86

innodb_strict_mode system variable, 143

innodb_tmpdir, 304

INNODB_TRX, 182

INNODB_TRX table, 378

innodb_validate_tablespace_paths, 166

INPLACE, 304

INSERT, 17, 42, 103, 199, 304, 402, 442, 525

INSERT ... ON DUPLICATE KEY UPDATE, 240, 330, 419

INSERT IGNORE, 442

INSERT SELECT, 103, 143

INSERT(), 143, 182

INSTALL COMPONENT, 34, 419, 442, 568

INSTALL PLUGIN, 304

installing, 13, 103, 143, 199, 218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442,

499, 525

INSTALL_STATIC_LIBRARIES, 568

integer, 86

internal SQL parser, 568

internal temporary table, 199, 525

internal_tmp_disk_storage_engine, 330

internal_tmp_mem_storage_engine, 86, 122, 182

INTERSECT, 17, 42, 55

619

MySQL 8.0 Release Notes

introducers, 218, 442

inversion, 240

invisible columns, 166, 182

invisible indexes, 166, 199

IPv6, 284

IS NOT NULL, 330

IS NOT TRUE, 304

IS NULL, 199

IS TRUE, 218

isl file, 568

ISNULL(), 304

IS_NULL(), 166

IS_UUID(), 568

Item_subselect::walk_body(), 330

iterator, 260, 284

iterator executor, 240

Japanese, 499, 525

JOIN, 8

join buffer, 103

joins, 34, 55, 86, 122, 166, 182, 304, 330

join_buffer_size, 182

JOIN_CACHE::join_record(), 304

JSON, 4, 8, 17, 23, 42, 103, 122, 143, 166, 182, 199, 218, 240, 260, 304, 330,

356, 378, 402, 419, 442, 477, 499, 525, 568

json, 442

JSON functions, 356

Json_array, 477, 499

JSON_ARRAYAGG(), 42, 166, 182, 356, 378, 525

JSON_ARRAY_INSERT(), 477

JSON_CONTAINS(), 568

JSON_CONTAINS_PATH(), 525

Json_dom, 477

JSON_EXTRACT(), 143, 477, 568

JSON_INSERT(), 442, 477

JSON_LENGTH(), 143

JSON_MERGE(), 477, 568

JSON_MERGE_PATCH(), 477

JSON_MERGE_PRESERVE(), 477

Json_object, 477

JSON_OBJECT(), 199, 442

Json_object::consume(), 568

JSON_OBJECTAGG(), 42, 304, 356, 378, 525

JSON_OVERLAPS(), 304

Json_path, 419

JSON_PRETTY(), 525

JSON_QUOTE(), 419, 525

JSON_REMOVE(), 499

JSON_REPLACE(), 499

JSON_SCHEMA_VALID(), 23, 240, 260, 304

JSON_SCHEMA_VALIDATION_REPORT(), 240, 284, 304

JSON_SEARCH, 525

620

MySQL 8.0 Release Notes

JSON_SEARCH(), 166, 419, 568

JSON_SET(), 378, 442, 499, 568

JSON_STORAGE_FREE(), 499

JSON_STORAGE_SIZE(), 499

JSON_TABLE, 260

JSON_TABLE(), 103, 122, 218, 240, 260, 304, 356, 378, 402, 419, 442

JSON_TABLE() function, 122

JSON_TYPE(), 568

JSON_UNQUOTE, 525

JSON_UNQUOTE(), 378, 525, 568

JSON_VALUE(), 23, 199, 218

JT_CONST, 442

kana sensitivity, 499

Kerberos, 42, 70, 122, 143, 182, 199, 240

KEY, 218

key sort, 42

keyring, 42, 55, 70, 86, 103, 122, 166, 182, 199, 218, 260, 284, 304, 330, 356,

402, 419, 442

keyring migration, 86, 103, 442

keyring_aws plugin, 70, 260, 284, 304

keyring_aws_region, 284, 304

keyring_component_status Performance Schema table, 55, 166

keyring_encrypted_file plugin, 23, 166, 304, 356, 402, 442

keyring_encrypted_file_password, 260

keyring_file plugin, 23, 166, 419, 525

keyring_hashicorp plugin, 122, 199, 218, 284

keyring_hashicorp_update_config() function, 122

keyring_keys, 330

keyring_oci, 70

keyring_oci plugin, 55, 199

keyring_okv plugin, 103, 356, 402, 525

keyring_operations, 402

keys, 240

KEYWORDS, 284, 419

keywords, 284, 330

KEYWORDS table, 182

KEY_BLOCK_SIZE, 499

KEY_COLUMN_USAGE, 218, 356

key_hint, 199

KILL, 8, 23, 42, 70, 330, 419

KILL QUERY, 240, 260

LAG(), 442

large object data, 402, 442

last (keyword), 499

last_committed, 499

LAST_INSERT_ID(), 122, 330

Last_query_cost, 330

LAST_VALUE(), 419, 442

latch, 499

621

MySQL 8.0 Release Notes

latch debugging, 525

later derived tables, 122

LATERAL, 42, 166, 199, 330, 356

lateral derived tables, 356

lateral joins, 304

latin1, 499, 525

latin1_swedish_ci, 525

launchd, 304

lc_messages, 499

lc_messages_dir, 499

LDAP, 182, 199, 218, 240, 260, 284, 330, 356, 378, 419, 442

ldap.conf, 199

LDML, 419

LEAD(), 442

LEAST(), 218, 260, 304, 419, 442, 568

LEFT JOIN, 55, 70, 166, 284, 304, 419

left outer join, 442

LEFT(), 568

libc, 13

libcurl, 182

libedit, 17, 103, 166, 240

libevent, 218, 378, 568

libmysqlclient, 34

libmysqlclient version, 568

libmysqld, 525, 568

libtirpc, 419

LIBWRAP, 356

licensing, 4

LIKE, 23, 42, 166, 199, 304, 356, 419

LIKE ... ESCAPE, 330

LIKE ESCAPE, 70

LIMIT, 42, 55, 199, 218, 260, 304, 568

limit optimization, 218

LimitNOFILE, 419

LINK_RANDOMIZE, 402

Linux, 143, 419, 442, 499

linux, 304, 330

LIST, 477

literal values, 86, 568

LOAD DATA, 166, 199, 218, 284, 442, 499, 525

LOAD DATA INFILE, 42, 86

LOAD DATA LOCAL, 218, 260

LOAD XML, 218, 499

loadable functions, 103, 143, 166, 182, 260, 304, 330, 419, 477

loading data, 122

LOAD_DATA(), 330

LOAD_FILE() function, 182

LOB, 122, 199, 218, 240, 260, 330, 378, 402, 419, 525

LOB pages, 356

local_infile, 499

LOCATE(), 143, 525

LOCK INSTANCE FOR BACKUP, 419

lock system, 86, 166, 218

LOCK TABLES, 199, 240, 378, 442

622

MySQL 8.0 Release Notes

lock-free hash table, 70

locking, 23, 55, 70, 86, 103, 122, 143, 166, 182, 199, 218, 240, 260, 284, 304,

330, 356, 378, 419, 442, 477, 499, 525, 568

locking read, 525

locks, 143, 199, 330, 356, 378, 499

LOCK_ORDER, 182, 218

LOCK_ORDER tool, 182, 304

lock_wait_timeout, 378

log, 218

log buffer, 402, 568

log rotation, 525

log system lock, 199

log writer, 182

log writer threads, 199

log-error, 356

logging, 34, 42, 70, 86, 122, 143, 166, 182, 199, 218, 240, 260, 284, 304, 330,

356, 378, 402, 419, 442, 477, 499, 525, 568

logical backup, 103

log_bin_trust_function_creators, 23

log_builtin_as_identified_by_password, 419

log_error_services, 70, 218, 477, 499

log_error_suppression_list, 378

log_error_verbosity, 218, 442, 477

log_filter_dragnet, 442

log_filter_internal, 442

log_free_check(), 166

log_raw, 260

log_sink_internal, 442

log_sink_json, 240

log_sink_syseventlog, 378

log_slow_extra, 356

log_statements_unsafe_for_binlog, 23

log_status, 419

log_syslog, 378

log_syslog_facility, 378

log_syslog_include_pid, 378

log_syslog_tag, 378

log_warnings, 477

long messages, 284

long semaphore wait, 70, 86, 103, 260

loose index scan, 8, 122

Loose Index Scan, 442

lowercase_table_names, 356, 378

lower_case_table_names, 199, 260, 304, 356, 419

low_priority_updates system variable, 122

LPAD(), 34, 260, 378

LRU mutex, 143

LWG-3865, 17

lz4, 143

LZ4, 240

lz4_decompress, 568

623

MySQL 8.0 Release Notes

macce, 103

macOS, 143, 240, 260, 304, 330, 378, 402, 419, 442

macroman, 103

maintainer mode, 8

MAKETIME(), 34

mandatory_roles, 122, 260

mask_ssn(), 86

master key rotation, 284

MASTER_COMPRESSION_ALGORITHMS, 42

MATCH, 143

MATCH(), 42, 103

materialization, 182, 284

materialized tables, 55, 442

MAX(), 86, 260, 304, 442

maximum prefix, 42

max_allowed_packet, 477

max_connections, 260, 477

max_delayed_threads system variable, 122

max_error_count, 477

max_error_count system variable, 122

max_execution_time, 70, 378

MAX_EXECUTION_TIME, 260

max_join_size, 42

max_length_for_sort_data, 240, 525

max_prepared_stmt_count, 284

MAX_SIZE_LOG_EVENT_STATUS, 55

max_sort_length, 199

max_tmp_tables, 477

MAX_USER_CONNECTIONS, 240

mbind, 378

MBRContains(), 103, 477, 499

MBRCoveredBy(), 477, 499

MBRCovers(), 477, 499

MBRDisjoint(), 477, 499

MBREquals(), 477, 499

MBRIntersects(), 477, 499

MBROverlaps(), 442, 477, 499

MBRTouches(), 477, 499

MBRWithin(), 477, 499

mbr_utils.cc, 122

MD5() encryption function, 13

MeCab, 284, 304, 402, 442

mecab_charset, 122

MEMBER, 260

MEMBER OF(), 23, 260, 304

memcached, 143, 240, 284, 304, 378, 402, 442, 477, 499, 525, 568

memory, 103, 499, 525

MEMORY, 378, 442

memory allocation, 143, 442

memory allocator, 103

memory management, 103

memory usage, 86, 103

624

MySQL 8.0 Release Notes

memory_summary_global_by_event_name, 182

mem_heap_alloc(), 86

MEM_ROOT, 23, 284

MERGE, 240, 378, 568

MESSAGE_TEXT, 13

metadata, 356, 499, 568

metadata locking, 442

metadata logging, 304

metadata_locks table, 143

metadata_locks_cache_size, 378

metadata_locks_hash_instances, 378

Microsoft Windows, 8, 13, 23, 34, 42, 55, 86, 103, 122, 143, 166, 182, 199, 260,

304, 330, 356, 378, 402, 419, 442, 499, 525, 568

MIN(), 86, 304

min_examined_row_limit system variable, 122

monitor thread, 86

MRR, 8, 143

MSVC, 330

MTR_PORT_EXCLUDE, 218

MTR_UNIQUE_IDS_DIR, 330

MTS, 442, 477, 499, 525

multi-source, 499

multi-value indexes, 8

multi-valued index, 70

multi-valued indexes, 86, 103, 122, 166, 182, 199, 304

multifactor authentication (MFA), 17, 42, 122

multithreaded slave, 477, 499, 525

multithreading for replica servers, 122

multi_range_count, 477

mutex, 143, 284, 304, 356, 402, 568

MVCC, 199, 356, 378, 477

MyISAM, 4, 55, 402

myisam_repair_threads, 70, 86

myisam_use_mmap, 442

MySQL Enterprise Encryption, 34, 55, 70

MySQL NDB ClusterJ, 4, 8

mysql-test-run.pl, 199, 218, 330, 499, 525, 568

mysql-test.run.pl, 525

mysql.gtid_executed, 442, 499

mysql.innodb_table_stats.table_name, 568

mysql.plugin, 304

mysql.session, 402

mysql.session account, 499

mysqladmin, 240, 330

mysqladmin flush-hosts command, 182

mysqlbinlog, 23, 34, 304, 356, 477, 499

mysqlcheck, 55

mysqld, 378

mysqld-auto.cnf, 378, 419

mysqldump, 8, 23, 34, 42, 70, 86, 103, 182, 218, 240, 284, 304, 356, 378, 402,

442, 477, 499, 525, 568

mysqldump command, 166

mysqld_multi, 34, 356

mysqld_safe, 86, 218, 356, 525

625

MySQL 8.0 Release Notes

mysqld_safe.pid, 525

mysqlimport, 34, 199

mysqlpump, 23, 34, 55, 86, 166, 182, 199, 240, 260, 284, 304, 330, 356, 402, 419,

442, 477, 499, 525

mysqlslap, 240

mysqltest, 218, 442, 499, 525, 568

mysqltest_safe_process, 330

mysqlxtest, 442, 499

mysqlxtext, 402

mysqlx_bind_address, 199

mysqlx_interactive_timeout, 442

mysqlx_read_timeout, 442

mysqlx_wait_timeout, 442

mysqlx_write_timeout, 442

mysql_bind_param() C API function, 34, 182

mysql_config, 260, 419, 525

mysql_config_editor, 525

mysql_config_editor command, 166, 182

mysql_current_thread_reader component service, 304

mysql_fetch_row_nonblocking(), 218, 330

mysql_fetch_row_nonblocking() C API function, 218

MYSQL_FIREWALL plugin, 13

mysql_free_result_nonblocking(), 330

MYSQL_GROUP_SUFFIX, 442

MYSQL_HOME, 330

mysql_insert_id(), 525

mysql_install_db, 330, 568

mysql_install_plugin, 378

mysql_list_fields(), 122

mysql_migrate_keyring, 143

mysql_migrate_keyring utility, 166

mysql_native_password, 4, 442

mysql_native_password plugin, 23

mysql_next_result_nonblocking(), 330

mysql_num_rows(), 218

mysql_options(), 218, 499

mysql_options() C API function, 70, 218

MYSQL_OPT_COMPRESS, 42

MYSQL_OPT_COMPRESSION_ALGORITHMS, 42, 218

MYSQL_OPT_LOAD_DATA_LOCAL_DIR, 199, 218

MYSQL_OPT_LOCAL_INFILE, 218

MYSQL_OPT_RECONNECT, 23, 70

MYSQL_OPT_SSL_MODE, 499

MYSQL_OPT_ZSTD_COMPRESSION_LEVEL, 218

mysql_plugin, 568

MYSQL_PWD, 284

mysql_query_attribute_string() function, 182

mysql_real_connect(), 42, 218

mysql_real_connect() C API function, 199

mysql_real_connect_dns_srv() C API function, 199

mysql_real_connect_nonblocking(), 218, 330

mysql_real_connect_nonblocking() C API function, 240

mysql_real_query_nonblocking(), 330

mysql_refresh() function, 182

626

MySQL 8.0 Release Notes

mysql_reset_server_public_key(), 442

mysql_result_metadata(), 378

mysql_secure_installation, 330, 402, 525

MYSQL_SERVER_PUBLIC_KEY, 419

mysql_service_udf_registration service, 499

mysql_service_udf_registration_aggregate service, 499

mysql_shutdown(), 525, 568

mysql_ssl_rsa_setup, 23, 330, 442

mysql_ssl_set() C API function, 17

mysql_stmt_close(), 499

mysql_stmt_errno(), 499

mysql_stmt_error(), 499

mysql_stmt_sqlstate(), 499

mysql_store_result(), 218

mysql_store_result_nonblocking(), 330

mysql_string component, 499

mysql_udf_metadata component service, 260

mysql_upgrade, 330, 419, 442, 499

mysql_upgrade_info, 304

mysql_use_result(), 218

MYSQL_VERSION file, 199

mysys, 568

my_bool, 525

my_init(), 499

my_row_id, 166

my_time.cc, 55

my_ulonglong, 284

m_flush_bit, 70

named_pipe_full_access_group, 330, 356

NAME_CONST(), 218

natural joins, 42

NDB Client Programs, 378

NDB Cluster, 23, 34, 240, 260, 284, 304, 330, 378, 568

ndb_binlog_index, 568

ndb_cache_check_time, 477

negation, 122, 218

nested joins, 260

network namespaces, 182, 199

NETWORK_NAMESPACE, 199

ngram, 402, 477

NO ACTION, 477

NO PAD collations, 304, 356, 499, 525

nondeterministic, 260

NOOP, 442

NOT EXISTS, 304

NOT IN, 143, 304

NOT NULL, 419, 442

NOTIFY_SOCKET, 260, 419

NOWAIT, 143, 199, 525

NO_AUTO_CREATE_USER, 419

NO_AUTO_VALUE_ON_ZERO, 284

627

MySQL 8.0 Release Notes

NO_ENGINE_SUBSTITUTION, 402

NO_HASH_JOIN, 260

NO_INDEX_MERGE, 525

NO_MERGE, 568

NO_SKIP_SCAN, 55

NO_ZERO_DATE, 419

NTH_VALUE(), 442

NTILE(), 34

NULL, 8, 17, 34, 70, 86, 103, 143, 182, 199, 218, 240, 304, 330, 402, 419, 442,

477, 525, 568

null pointer, 70, 86

NULL-safe, 86

null-safe equals, 55

NULLIF(), 143, 166, 378, 499

NUMA, 103, 182, 378, 499, 568

numeric data types, 284

offline_mode, 8, 356

OFFSET, 304, 330

old-style-user-limits, 70

old_passwords, 419, 442

ON DUPLICATE KEY UPDATE, 86, 260, 442, 525

ON EMPTY, 240

ON ERROR, 240

one_or_all, 525

online DDL, 8, 86, 103, 122, 356, 402, 419, 442

only_full_group_by, 419

ONLY_FULL_GROUP_BY, 525

open files limit, 143

opening tables, 13

OpenSSL, 23, 55, 70, 86, 103, 122, 166, 182, 218, 240, 260, 284, 304, 330, 356,

378, 402, 419, 442, 499, 525

openssl_udf plugin, 70

open_files_limit, 260

operators, 356, 568

optimization, 330

OPTIMIZE PARTITION, 499

OPTIMIZE TABLE, 199, 378

optimizer, 122, 166, 199, 218, 240, 304, 356, 378, 402, 442, 477, 499, 525, 568

optimizer hints, 240, 304, 477, 525, 568

optimizer statistics, 260

optimizer trace, 103, 122, 166

optimizer_search_depth, 166

optimizer_switch, 218, 304, 477

optimizer_trace_max_mem_size, 442

optimizer_trace_offset, 419

options, 42, 55, 70, 86, 103, 122, 143, 199, 218, 240, 260, 284, 304, 330, 356,

378, 402, 419, 442, 477, 499, 525, 568

OR, 23, 122, 260

ORDER BY, 13, 17, 23, 34, 42, 55, 70, 86, 122, 143, 182, 199, 218, 240, 284,

304, 330, 356, 402, 442, 525

ORDER BY DESC, 23

628

MySQL 8.0 Release Notes

ordered index scans, 34

original_commit_timestamp, 356, 499

os_event, 122

outer joins, 330, 356

outer references, 86, 240

OVER(), 8

Packaging, 8, 23, 70, 103, 199, 402, 442, 525

packaging, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166, 182, 199,

218, 240, 260, 284, 304, 330, 356, 356, 378, 402, 419, 442, 477, 499, 525, 568

PAD SPACE, 260

PAD SPACE collations, 304, 525

padding, 122

PAD_CHAR_TO_FULL_LENGTH, 378

page, 568

page allocation, 103

page cleaner, 568

page cleaner thread, 86, 304, 525

page compression, 86, 122, 182, 199, 419, 477, 499

page flushing, 166, 182, 199, 284, 477

page tracker, 240

page tracking, 86, 260, 330

parallel index read, 304, 356

parallel read, 182, 240, 260

parallel read threads, 199, 218

parallel scan, 122

parallelization, 442, 525

Parallel_reader interface, 199

parser, 70, 199, 218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525,

568

parser_max_mem_size, 378

partial indexes, 419

partial revokes, 330

partial update, 442, 499

partial updates, 442, 477

partial_revokes, 182

partial_revokes system variable, 218

PARTITION, 13

partition, 477, 568

PARTITION BY, 13

partition handler, 86

partition ID, 477

partition pruning, 86

Partitioning, 34, 55, 86, 103, 143, 166, 182, 218, 260, 304, 330, 356, 378, 402, 419,

442, 477, 499, 525, 568

partitioning, 122, 166, 260, 284, 356, 402, 442, 477, 499, 525

password expiration, 442

password history, 477

password verification, 378

PASSWORD(), 330, 419, 442

passwords, 260, 284, 356, 378, 477

password_history, 477

629

MySQL 8.0 Release Notes

PASSWORD_LOCK_TIME, 260

password_require_current, 378

password_reuse_interval, 477

PATH, 378

path expressions, 477

paths, 568

PERCENT_RANK(), 34

perdicate elimination, 356

Performance, 13, 17, 143, 218, 240, 477, 499

performance, 402, 568

Performance Schema, 4, 8, 34, 42, 55, 70, 86, 103, 122, 143, 166, 182, 199,

218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

PERFORMANCE_SCHEMA.DATA_LOCKS, 330

performance_schema.events_statements_summary_by_digest, 304

performance_schema.procsslist, 86

performance_schema.threads, 86

performance_schema_max_cond_classes, 122

performance_schema_max_mutex_classes, 477

performance_schema_max_thread_classes system variable, 166

performance_schema_max_thread_instances system variable, 166

performance_schema_show_processlist, 199

Performansce Schema, 103

perform_order_index, 4

PERIOD_ADD(), 330, 442

PERIOD_DIFF(), 442

perror, 419

PERSIST, 330

persisted variables, 122, 419

PERSIST_ONLY, 330

persist_only_admin_x509_subject, 356

PERSIST_RO_VARIABLES_ADMIN, 402, 499

PERSIST_RO_VARIABLES_ADMIN privilege, 477

pid_file, 356

PIPES_AS_CONCAT, 284

pkg-config, 525

pluggable authentication, 17, 143, 330, 356, 419, 442, 477, 499

plugin service, 477

plugins, 13, 17, 23, 34, 42, 70, 122, 143, 166, 182, 199, 218, 240, 260, 284,

304, 330, 356, 378, 402, 419, 442, 477, 499, 525

plugin_registry_service, 525

pointers, 23, 55, 477

posix_fallocate(), 182

precision, 122

prefer_ordering_index, 143, 218

prefetch chache, 103

prefixes, 378, 419

preload_buffer_size system variable, 122

PREPARE, 17, 166, 402

prepared statements, 4, 8, 13, 34, 42, 55, 70, 86, 103, 122, 143, 166, 166,

182, 199, 240, 284, 304, 330, 356, 402, 419, 442, 499, 568

primary key, 122, 378

PRIMARY KEY, 143

primary key extensions, 182

primary passwords, 356

630

MySQL 8.0 Release Notes

print_identified_with_as_hex, 304

privileges, 4, 34, 42, 55, 70, 103, 122, 143, 166, 182, 199, 218, 240, 260, 284,

304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

proc table, 568

procedure, 568

PROCEDURE ANALYSE(), 525

processlist, 199

PROP_SUBQUERY, 34

Protobuf, 218, 260, 284, 304

protocol_compression_algorithms, 218

proxies_priv table, 568

PROXY, 499

pruning, 4, 330, 568

pseudo_slave_mode, 356

pseudo_thread_id, 356

PS_CURRENT_THREAD_ID(), 260, 330

ps_setup_reset_to_default(), 240

PS_THREAD_ID(), 260, 330

punch hole, 143

purge, 70, 86, 103, 122, 143, 182, 218, 260, 330, 356, 568

pushdown, 182, 199, 330

Qcache_free_blocks, 477

Qcache_free_memory, 477

Qcache_hits, 477

Qcache_inserts, 477

Qcache_lowmem_prunes, 477

Qcache_not_cached, 477

Qcache_queries_in_cache, 477

Qcache_total_blocks, 477

query attributes, 143, 182

query cache, 477, 499, 525

query caching, 17

query cost, 284, 304, 330, 419

query end, 199

query rewrite plugin, 122

query rewrite plugins, 122, 330, 402, 499

query_attributes component, 182

query_cache_limit, 477

query_cache_min_res_unit, 477

query_cache_size, 477, 525

query_cache_type, 477

query_cache_wlock_invalidate, 477

query_digest audit log function, 143

query_prealloc_size, 86

QUICK_GROUP_MIN_MAX_SELECT, 442

QUOTE, 17

QUOTE(), 17, 330, 442, 525

quoting, 477

R-tree, 240, 419, 525

631

MySQL 8.0 Release Notes

race condition, 568

RAND(), 199, 240

random generator functions, 70

random password generation, 284

RANDOM_BYTES(), 23, 34

range, 419

range access, 42, 442

range checks, 86

range expressions, 122

range frames, 330, 356

range index access, 356

range indexes, 103

RANGE INTERVAL, 103

range optimization, 34

range optimizer, 86, 122, 199

range scans, 103

ranges, 499

range_optimizer_max_mem_size, 378

RANK(), 8

RAPID, 304

rapidjson, 240, 525

RapidJSON, 378, 525

raw disk partition, 199

rbr_exec_mode, 356

READ ONLY, 199

read-ahead, 525

READ-COMMITTED, 103

READ_BACKUP, 240

read_only, 199, 260, 499

read_only system variable, 103, 143

REAL, 304

receiver thread, 499

records_in_range, 17

recovery, 55, 70, 86, 103, 122, 143, 166, 260, 284, 304, 330, 402, 419, 442, 477,

499, 525, 568

recursion, 122, 284

rec_convert_dtuple_to_rec_old(), 86

rec_get_instant_row_version_old(), 70

rec_get_offsets(), 143

redo, 356, 378

redo log, 70, 103, 199, 218, 284, 330, 356, 378, 419, 442, 499, 525

redo log archiving, 199, 304

redo log format, 240

redo logs, 17, 240

ref access, 356, 442

reference counts, 4

references, 42

regex, 330

regexp, 419

REGEXP, 442

regexp functions, 330, 356

regexp::EvalExprToCharset(), 378

REGEXP_INSTR(), 122, 402, 442

REGEXP_LIKE(), 402, 442

632

MySQL 8.0 Release Notes

REGEXP_REPLACE(), 182, 304, 402, 442

regexp_stack_limit, 442

REGEXP_SUBSTR(), 218, 304, 402, 442

regexp_time_limit, 442

regular accounts, 330

regular expression functions, 182

regular expressions, 419, 442

regular sessions, 330

relay log, 4, 34, 499, 525

relay_log_space_limit, 42

RELOAD privilege, 182

rematerialization, 284

removing WHERE, 240

RENAME, 304

RENAME COLUMN, 55, 103, 477

RENAME TABLE, 284, 304, 330, 356, 378, 419, 499, 525

RENAME USER, 199, 402, 419

REPAIR, 304

REPEAT(), 304, 568

REPEATABLE-READ, 499

REPLACE, 402, 419, 442

REPLACE(), 260, 378, 477, 525, 568

replace_index_subquery(), 199

replace_numeric_round, 499

Replication, 4, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166, 182, 199,

218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442, 477, 499, 525, 568

replication, 55, 182, 442, 477, 568

replication filtering, 55

replication_applier_status_by_worker, 477, 499

replication_connection_configuration, 199, 442

replication_group_communication_information, 42

replica_parallel_type, 86, 122

replica_parallel_workers, 70, 122

replica_preserve_commit_order, 122

REPRODUCIBLE_BUILD, 402

require_row_format, 55

REQUIRE_TABLE_PRIMARY_KEY_CHECK, 42

reserved accounts, 199, 402, 442, 499

reserved words, 284, 525, 568

RESET PERSIST, 42, 356, 402, 419, 525

RESET QUERY CACHE, 477

resolveip, 356

resolver, 122, 240

resolve_stack_dump, 356

resource allocation, 103, 240

resource groups, 42, 55, 284, 356, 477

resource usage, 568

RESTART, 304, 402, 419, 442

restart, 499

restore_last_record(), 304

RESTRICT, 477

RETAIN CURRENT PASSWORD, 356

return values, 122

633

MySQL 8.0 Release Notes

REVOKE, 70, 442

Rewriter plugin, 55

RFC 7159, 477

RIGHT JOIN, 199

RIGHT(), 568

RLIKE, 442

roles, 122, 182, 199, 218, 240, 260, 284, 304, 330, 378, 402, 419, 442, 477, 499, 525,

568

ROLES_GRAPHML(), 419

ROLE_COLUMN_GRANTS, 260

role_edges, 218

ROLE_ROUTINE_GRANTS, 260

ROLE_TABLE_GRANTS, 260

rollback, 260, 330, 378, 442, 568

rollback segment, 240

rollback segments, 143, 284, 499, 525

rollbacks, 143

ROLLUP, 13, 23, 34, 86, 103, 122, 143, 182, 199, 218, 304, 330, 356, 378, 419,

442, 525

root, 166

Rotate_log_event, 499

ROUND(), 199

rounding, 122

row comparison, 23

row format, 143, 199, 568

row size, 86

row-based, 525

row-based replication, 419, 442

ROW_COUNT(), 34

ROW_FORMAT, 304, 442, 499, 525

row_table_add_foreign_constraints(), 477

RPAD(), 34, 182, 378

RPC, 356, 419

rpcgen, 419

RPM, 499

Russian, 477

rw_lock_stats counter, 166

SAFE_MUTEX, 477

sandbox mode, 122

SASL LDAP plugin, 70

savepoints, 378

SCHEMATA_EXTENSIONS, 199

scientific notation, 240

scope, 477

SCRAM-SHA-256, 182

scramble generator, 34

SDI, 166

secondary engines, 260

secondary indexes, 103, 143

secondary passwords, 356

secure_auth, 477

634

MySQL 8.0 Release Notes

secure_file_priv, 525

secure_file_priv system variable, 182

security, 17, 23, 34, 199, 260, 284, 330, 356, 378, 499

SELECT, 13, 55, 86, 240, 356, 378, 419, 525

SELECT COUNT(*), 8, 143, 166, 182, 240

SELECT INTO DUMPFILE, 199

SELECT INTO OUTFILE, 199

select_into_buffer_size, 199

select_into_buffer_size system variable, 122

select_into_disk_sync, 199

select_into_disk_sync_delay, 199

select_into_disk_sync_delay system variable, 122

select_lex, 378

semijoin, 199, 304, 442

semijoins, 70, 240, 260, 284, 304, 330

semisynchronous replication, 182

send buffer, 284

SENSITIVE_VARIABLES_OBSERVER, 70

SERIAL, 103

serialization, 442

serialized dictionary information (SDI), 260, 284, 304, 330, 378, 419, 442, 477, 499

server ID, 42

server initialization, 419

session categories, 330

session temporary tablespace, 166

session tracking, 86

SESSION_STATUS, 525

session_track_gtids, 23

SESSION_VARIABLES, 525

SESSION_VARIABLES_ADMIN privilege, 356

SET, 8, 122, 218, 499

SET DEFAULT ROLE, 442

SET GLOBAL, 499

set operations, 34

SET PASSWORD, 86, 330, 356, 419

SET PERSIST, 240, 260, 284, 356, 419, 442, 477, 499, 568

SET PERSIST_ONLY, 260, 284, 304, 330, 356, 402, 419, 442, 499

SET PERSIST_ONLY statement, 143

SET RESOURCE GROUP, 356

SET ROLE, 330, 402

SET statement, 122, 182, 378

setuid, 402

setup_instruments, 477

setup_threads, 477

set_parse_error_message, 103

SET_USER_ID, 199

SET_VAR, 199, 442, 477

sha256 cache, 442

sha256_password, 330, 442, 477

sha256_password_auth_client_nonblocking(), 42

sha256_password_auto_generate_rsa_keys, 442

shared-memory connections, 182

SHOW, 86, 284

SHOW CHARACTER SET, 218

635

MySQL 8.0 Release Notes

SHOW COLLATION, 218

SHOW COLUMNS, 182, 218, 240, 284, 477, 499

SHOW CREATE EVENT statement, 143

SHOW CREATE PROCEDURE statement, 143

SHOW CREATE TABLE, 166, 260, 284, 356, 378, 402, 419, 442, 499, 568

SHOW CREATE TABLE statement, 166

SHOW CREATE TRIGGER, 218, 330

SHOW CREATE USER, 304, 402, 477, 568

SHOW CREATE USER statement, 166

SHOW CREATE VIEW, 240, 477

SHOW CREATE VIEW statement, 166

SHOW ENGINE INNODB MUTEX, 199

SHOW ENGINE INNODB STATUS, 166, 568

SHOW ENGINE PERFORMANCE SCHEMA STATUS statement, 166

SHOW EVENTS, 218

SHOW FUNCTION STATUS, 218

SHOW GRANTS, 122, 218, 260, 402, 419

SHOW INDEX, 499

SHOW INDEXES, 378

SHOW KEYS, 218

SHOW PLUGINS, 442

SHOW PROCEDURE STATUS, 218

SHOW PROCESSLIST, 103, 166, 199, 284, 419

SHOW RELAYLOG EVENTS, 499

SHOW REPLICA STATUS, 199

SHOW SCHEMAS, 218

SHOW SLAVE STATUS, 419, 442, 499

SHOW TABLE STATUS, 103, 218, 402, 442

SHOW TABLE STATUS statement, 182

SHOW TABLES, 218, 499

SHOW TRIGGERS, 218

show_create_table_verbosity, 419

SHOW_ENGINE_INNODB_STATUS, 42

show_old_temporals system variable, 122

SHOW_ROUTINE, 240

shutdown, 55, 86, 166, 199, 218, 284, 402, 419, 499

SHUTDOWN, 304, 568

SIGHUP, 240, 260, 356

signals, 356, 402

signed variables, 86

signedness, 218

SIGUSR1, 260

single user mode, 240

SKIP LOCKED, 199, 525

Skip Scan, 378

skip-slave-start, 499

skip_name_resolve, 330, 356

skip_networking, 477

slave, 568

slave applier, 499

slave_compressed_protocol, 42

Slave_heartbeat_period, 525

Slave_last_heartbeat, 525

slave_master_info, 199

636

MySQL 8.0 Release Notes

slave_pending_jobs_size_max, 402, 499

Slave_received_heartbeats, 525

Slave_retried_transactions, 525

slave_rows_search_algorithms, 284

Slave_running, 525

slave_skip_errors, 499

slow query log, 86, 260, 356

slow shutdown, 240, 568

Solaris, 240, 356, 378, 419, 499, 525, 568

sort, 143, 199, 525

sort buffer, 330

sort elimination, 304

sort keys, 378

sorting, 103, 240, 284

sort_buffer_length, 199

sort_buffer_size, 284

source code, 86

source_heartbeat_period, 42

space ID, 218

SPACE(), 34, 122

space_id, 568

SPATIAL, 402

spatial index, 304, 378, 442, 477

spatial indexes, 4, 70, 240, 260

spill to disk, 260

spin lock polling, 330

SQL, 499

SQL syntax, 568

sql_auto_is_null, 330

SQL_BIG_RESULT, 55

sql_buffer_result, 477

SQL_CACHE, 477, 568

SQL_CALC_FOUND_ROWS, 304

sql_help.cc, 122

sql_log_bin, 356, 477

sql_log_off, 356

sql_mode, 356, 378, 402, 419, 499, 525

SQL_NO_CACHE, 442, 477, 568

sql_require_primary_key, 284, 330, 356, 378

sql_safe_updates, 378

SQL_SMALL_RESULT, 55

SRID attribute, 477

SRS, 42

Srv_session, 330

SSL, 8, 13, 17, 23, 34, 42, 55, 70, 86, 103, 122, 143, 166, 182, 218, 240,

284, 304, 330, 356, 378, 402, 419, 442, 499, 525

SSL session, 86

ssl-fips-mode, 122

ssl_fips_mode, 378

stack, 86

stack size, 525

standard monitor, 419

standards compliance, 218, 284

START GROUP_REPLICATION, 13

637

MySQL 8.0 Release Notes

START TRANSACTION, 199

start-position, 34

startup, 55, 122, 143, 182, 260, 284, 304, 330, 378, 402, 419, 442, 499, 568

startup configuration, 419

statement event tables, 86

statement summary tables, 86

STATEMENT_DIGEST(), 304, 442

statement_digest(), 304

STATEMENT_DIGEST_TEXT(), 304, 442

statement_digest_text(), 304

statistics, 525, 568

status variables, 260

status_by_thread, 304

status_variable_registration service, 499

std::vector, 499

STOP REPLICA, 42

STOP SLAVE, 42

storage, 143

storage engine attributes, 218

storage engine initailization, 284

storage engines, 568

stored functions, 4, 17, 70, 103, 122, 260

stored objects, 199, 240

stored procedures, 13, 55, 70, 103, 122, 166, 199, 330, 378, 402, 442

stored programs, 13, 17, 42, 103, 122, 143, 166, 182, 240, 260, 304, 356, 402, 419,

442, 477, 499, 568

stored routines, 23, 55, 442

STRAIGHT_JOIN, 240, 568

strict mode, 330

STRICT_TRANS_TABLES, 330

string, 86, 442

string data types, 218

string functions, 55

strings, 143, 330

STR_TO_DATE(), 17, 199, 284

ST_Area(), 378, 442

ST_AsBinary(), 525

ST_AsGeoJSON(), 442, 568

ST_AsText(), 442, 525

ST_AsWKB(), 304, 525

ST_AsWKT(), 525

ST_Buffer(), 442

ST_Buffer() function, 143

ST_Centroid(), 442

ST_Collect() function, 166

ST_Contains(), 240, 477, 499

ST_ConvexHull(), 442

ST_Crosses(), 442, 477, 499

ST_Difference(), 442

ST_Difference() function, 143

ST_Dimension(), 442

ST_Disjoint(), 477, 499

ST_Distance(), 284, 356

ST_Distance_Sphere(), 442

638

MySQL 8.0 Release Notes

ST_EndPoint(), 442

ST_Envelope(), 442

ST_Equals(), 477, 499

ST_ExteriorRing(), 442

ST_FrechetDistance() function, 182

ST_GeoHash(), 442

ST_GeomCollFromText(), 442, 525

ST_GeomCollFromTXT(), 442

ST_GeomCollFromTxt(), 442, 525

ST_GeomCollFromWKB(), 442, 525

ST_GeometryCollectionFromText(), 442, 525

ST_GeometryCollectionFromWKB(), 442, 525

ST_GeometryFromText(), 442, 525

ST_GeometryFromWKB(), 442, 525

ST_GeometryN(), 442

ST_GeometryType(), 419, 442

ST_GeomFromGeoJSON(), 442, 568

ST_GeomFromText(), 442, 525

ST_GeomFromWKB(), 442, 525

ST_HausdorffDistance() function, 182

ST_InteriorRingN(), 442

ST_Intersection(), 442

ST_Intersection() function, 122

ST_Intersects(), 477, 499

ST_IsClosed(), 442

ST_IsEmpty(), 442

ST_IsSimple(), 442

ST_IsValid(), 419, 442

ST_Latitude(), 402

ST_Length(), 330, 442

ST_LineFromText(), 442, 525

ST_LineFromWKB(), 442, 525

ST_LineInterpolatePoint() function, 166

ST_LineInterpolatePoints() function, 166

ST_LineStringFromText(), 442

ST_LinestringFromText(), 525

ST_LineStringFromWKB(), 442

ST_LinestringFromWKB(), 525

ST_Longitude(), 402

ST_MakeEnvelope(), 442

ST_MLineFromText(), 442, 525

ST_MLineFromWKB(), 442, 525

ST_MPointFromText(), 442, 525

ST_MPointFromWKB(), 442, 525

ST_MPolyFromText(), 442, 525

ST_MPolyFromWKB(), 442, 525

ST_MultiLineStringFromText(), 442

ST_MultiLinestringFromText(), 525

ST_MultiLineStringFromWKB(), 442

ST_MultiLinestringFromWKB(), 525

ST_MultiPointFromText(), 442, 525

ST_MultiPointFromWKB(), 442, 525

ST_MultiPolygonFromText(), 442, 525

ST_MultiPolygonFromWKB(), 442, 525

639

MySQL 8.0 Release Notes

ST_NumGeometries(), 442

ST_NumInteriorRing(), 442

ST_NumInteriorRings(), 442

ST_NumPoints(), 442

ST_Overlaps(), 477, 499

ST_PointAtDistance() function, 166

ST_PointFromGeoHash(), 442

ST_PointFromText(), 442, 525

ST_PointFromWKB(), 442, 525

ST_PointN(), 442

ST_PolyFromText(), 442, 525

ST_PolyFromWKB(), 442, 525

ST_PolygonFromText(), 442, 525

ST_PolygonFromWKB(), 442, 525

ST_Simplify(), 378, 442

ST_SPATIAL_REFERENCE_SYSTEMS, 442

st_spatial_reference_systems, 442

ST_SRID(), 568

ST_StartPoint(), 442

ST_SwapXY(), 442, 525

ST_SymDifference(), 442

ST_SymDifference() function, 122

ST_Touches(), 477, 499

ST_Transform(), 42, 378

ST_TRANSFORM(), 70

ST_Union(), 442

ST_Union() function, 143

ST_UNITS_OF_MEASURE, 330, 356

ST_Validate(), 378, 442

ST_Within(), 477, 499

ST_X(), 402, 442, 568

ST_Y(), 402, 442, 568

subqueries, 8, 13, 23, 34, 42, 70, 86, 103, 122, 166, 182, 199, 218, 240, 260,

284, 304, 330, 356, 378, 419, 442

subquery, 240

subquery materialization, 260

subquery_to_derived, 23, 34, 122, 182, 199, 218

subselects, 8, 103, 304

SUBSTR(), 103, 568

SUBSTRING_INDEX(), 260, 568

suitably aligned types, 103

SUM(), 304, 378, 525

SUPER privilege, 356, 402, 477, 525

super_read_only, 199, 260, 284

super_read_only system variable, 103, 143

SyncFileIO::execute, 86

sync_array_detect_deadlock, 103

sync_binlog, 378

sync_frm, 568

sync_relay_log_info, 23

sys schema, 240, 260, 284, 330, 419

sys.diagnostics(), 284

sys.format_bytes(), 260, 330

sys.format_time(), 260, 330

640

MySQL 8.0 Release Notes

sys.processlist, 284

sys.ps_is_consumer_enabled(), 284

sys.ps_thread_id(), 260, 330

sys.schema_index_statistics, 284

sys.schema_unused_indexes, 284

sys.session, 284

sys.version, 284

syseventlog.facility, 378

syseventlog.include_pid, 378

syseventlog.tag, 378

sysschema.processlist, 86

sysschema.x$processlist, 86

system accounts, 330

system database, 330

system sessions, 330

system tablespace, 182, 304

system variables, 55, 70, 86, 356

systemd, 199, 260, 284, 419

system_time_zone system variable, 143

SYSTEM_USER, 199

SYSTEM_VARIABLES_ADMIN, 402, 499

SYSTEM_VARIABLES_ADMIN privilege, 356, 477

table encryption, 330

table functions, 442

table locks, 402

table references, 260

table share, 166

TABLE statement, 260

table statistics, 103, 442, 477

table value constructors, 260

tablespace, 182, 442, 477, 525, 568

TABLESPACE, 442

tablespace encryption, 182, 378, 402, 499, 525

tablespace file, 143

tablespace file size, 260

tablespace import, 240, 260, 284, 419

tablespace path validation, 218

tablespace size limit, 70

TABLESPACES, 199

tablespaces, 442, 499

tables_priv table, 568

table_definition_cache, 442

TABLE_ENCRYPTION_ADMIN, 260, 330

table_encryption_privilege_check, 330

table_io_waits_summary_by_index_usage, 284

TABLE_LIST, 260

table_open_cache, 442

tcmalloc, 4, 218

tcmalloc(), 4

Telemetry traces, 34

telemetry_log plugin, 34

641

MySQL 8.0 Release Notes

TELEMETRY_LOG_ADMIN, 34

temporal data types, 284, 442

temporal functions, 166

temporary directory, 442

temporary table, 103

temporary tables, 34, 42, 122, 260, 378, 419, 442, 499, 525, 568

temporary tablespace, 378

TempTable, 86, 122

TempTable storage engine, 143, 166, 182, 199, 218, 260, 284, 330, 356, 378, 419, 477

temptable::Allocator, 356

temptable_max_mmap system variable, 182

temptable_max_ram, 182

temptable_use_mmap, 143

Temp_table_param, 240

terminology, 34

test suite, 70, 86, 199, 218, 240, 477, 499, 525, 568

tests, 86

text protocol, 260

thread management, 568

thread pool plugin, 55, 103, 182, 218, 260, 356, 419

thread switching, 330

threads, 499

thread_cache_size, 330

THREAD_ID, 42

thread_mutex, 378

thread_pool, 330

thread_pool plugin, 218, 260, 284, 304

thread_pool_max_active_query_threads system variable, 260

thread_pool_transaction_delay, 55

thread_stack, 122, 402

TIME, 86, 199, 402

time zone offset, 260

time zone offsets, 103

time zone support, 143

time zones, 86

timeouts, 42

TIMESTAMP, 86, 143, 199, 304, 442, 499

TIMESTAMPADD(), 284

time_format, 477

TIME_TRUNCATE_FRACTIONAL, 525

time_zone, 304

TLS, 34, 86, 143, 218, 304, 330

TLS v1.0, 103

TLS v1.1, 103

TLSv1, 143

TLSv1.1, 143

TLSv1.3, 330

tls_channel_status, 218

tls_version, 103

tmp_table_size, 103

to (keyword), 499

TO_SECONDS(), 330

tp_thread_state table, 42

TP_THREAD_TYPE, 42

642

MySQL 8.0 Release Notes

trace log, 86

transaction, 477

transaction locks, 477

transactions, 143, 166, 182, 378, 442, 477, 499, 525

transaction_isolation, 477

transaction_prealloc_size, 86

transaction_read_only, 477

transaction_write_set_extraction, 356

transportable tablespace, 402, 499, 568

TREE, 284, 330

triggers, 70, 86, 103, 166, 304, 402, 442, 499, 525

TRIM(), 143, 260

trivial conditions, 356

TRUNCATE, 122, 402

TRUNCATE PARTITION, 86, 402, 568

TRUNCATE TABLE, 55, 166, 182, 402, 419, 442, 499, 525, 568

TRUNCATE(), 182, 199

truncation, 525

TRX_FORCE_ROLLBACK_ASYNC, 143

trx_sys, 143

trx_t::is_recovered, 143

trx_undo_prev_version_build(), 55

tuning, 477

two-phase commit, 568

tx_isolation, 477

tx_read_only, 477

type comparisons, 218

type conversion, 55, 260, 330, 442, 568

type conversions, 42

type handling, 103

type-checking, 143

types, 34, 42

UBSAN, 166, 182, 218, 284, 304, 378, 419, 525

UBSan, 218, 304, 499

ucs2, 103

UDF, 23

UDFs, 34, 122

udf_example, 442

uint64_t, 284

ULLONG_MAX, 218

UMASK, 442

UMASK_DIR, 442

Undefined Behavior Sanitizer, 182, 218, 284, 304, 378, 419

underflow, 284

undo, 240, 499

undo log, 182, 330, 356, 378, 442, 525

undo log encryption, 304, 330

undo tablespace, 122, 143, 166, 182, 199, 218, 240, 260, 284, 304, 330, 356, 378, 419,

442, 477, 525, 568

UNHEX(), 218

UNICODE, 103

643

MySQL 8.0 Release Notes

Unicode, 304, 330, 477, 499, 525, 568

UNINSTALL COMPONENT, 419, 442, 568

UNINSTALL PLUGIN, 304

UNION, 34, 42, 55, 86, 103, 166, 218, 240, 304, 356, 378, 402, 419, 442, 525, 568

UNION ALL, 284

UNION statement, 143

UNIQUE, 86, 304, 419

Unique::io_cache, 378

UNIV_INLINE, 143

UNIV_INNOCHECKSUM, 568

UNIV_MATERIALIZE, 143

UNIX_TIMESTAMP(), 103, 260, 442

UNSIGNED, 284, 304

UPDATE, 86, 103, 199, 218, 240, 304, 356, 402, 442, 525

UPDATE HISTOGRAM, 122

UpdateXML(), 4, 304

upgrade, 23, 42, 55, 70, 103, 122, 166, 182, 199, 218, 240, 260, 284, 304, 330,

378, 402, 419, 442

UPGRADE DATA DIRECTORY NAME, 55

upgrades, 4, 42, 143, 166, 260, 284, 304, 330, 356, 442, 477, 499, 525

upgrading, 260

usability, 525

user table, 568

user variables, 42, 86, 103, 330, 378

user-defined functions, 42

user-defined variables, 166

USER_ATTRIBUTES, 199

user_defined_functions, 182

user_defined_functions table, 499

user_variables, 442

use_invisible_indexes, 199, 477

USE_LD_LLD, 330

Using index, 260

ut::aligned, 143

UTC, 199

UTF, 166

UTF-16, 34, 525

utf32, 86, 356, 419

UTF32, 284

utf8, 378, 419, 442

utf8 character set, 143, 166

utf8mb3, 378, 419

utf8mb3 character set, 143, 166

utf8mb4, 260, 304, 330, 378, 419, 477, 499, 525

utf8mb4_0900_ai_ci, 525, 568

utf8mb4_0900_as_ci, 499

utf8mb4_0900_bin, 304

utf8mb4_general_ci, 525

utf8mb4_ja_0900_as_cs_ks, 499

utf8mb4_ru_0900_ai_ci, 477

utf8mb4_ru_0900_as_cs, 477

utf8mb4_zh_0900_as_cs, 330

ut_allocator, 143

ut_allocator(), 143

644

MySQL 8.0 Release Notes

UT_DELETE, 143

ut_list, 143

UT_LOCATION_HERE, 70

ut_rnd_ulint_counter, 568

ut_time(), 103

UUID(), 477

UUIDs, 568

UUID_TO_BIN(), 568

Valgrind, 55, 86, 240, 477, 568

valgrind, 240

validate_password, 356, 402, 419, 442

validate_password component, 23

validate_password plugin, 568

VALUES, 8, 86, 122, 182

VALUES statement, 86, 260

VALUES(), 240

VARCHAR, 86, 199

variable conversions, 103

variables, 356

variables_by_thread, 356

variables_info, 356, 419, 442, 477

VARIANCE(), 419

Variance-Aware Transaction Scheduling (VATS), 442, 477

VAR_POP(), 419

VAR_SAMP(), 419

version comments, 23

VERSION file, 199

version table, 499

version_compile_zlib, 419

version_tokens plugin, 525

version_tokens_session, 304

view references, 330

views, 13, 23, 34, 42, 55, 70, 86, 122, 143, 182, 199, 260, 356, 442, 525, 568

View_change_log_event, 42

VIEW_ROUTINE_USAGE, 378

VIEW_TABLE_USAGE, 378

virtual column, 166

virtual columns, 122, 143, 166, 240, 284, 304, 330, 356, 402, 419, 442, 477, 499, 525,

568

virtual indexes, 330, 419, 525, 568

virtual memory, 55

Visual C++ Redistributable, 525

Visual Studio, 13, 166

WAIT_FOR_EXECUTED_GTID_SET(), 34

wait_timeout system variable, 166

walk and replace, 143

WalkAndReplace(), 122

warnings, 378

WebAuthn pluggable authentication, 17

645

MySQL 8.0 Release Notes

weedout, 240, 260, 284

WEIGHT_STRING(), 218, 442, 525

WHERE, 260, 284, 304

WHERE_CONDITION optimization, 182

whitespace, 499

widen_fraction, 330

wildcards, 17, 304, 477

window function, 34

window functions, 13, 17, 23, 34, 42, 86, 122, 143, 166, 182, 199, 284, 330, 356,

378, 402, 419, 442, 477, 499

windowing functions, 13, 42, 103, 304, 330, 356, 442

windowing_use_high_precision, 419

windows, 13, 17, 70

Windows, 304, 356

Windows 32-bit, 70

WITH, 525

WITH ADMIN, 304

WITH ADMIN OPTION, 218

WITH CHECK OPTION, 86

WITH RECURSIVE, 260

WITH ROLLUP, 182, 218, 402

WITH_AUTHENTICATION_CLIENT_PLUGINS CMake option, 143

WITH_DEFAULT_FEATURE_SET, 199

WITH_EDITLINE, 419

WITH_GMOCK, 378

WITH_GMOCK CMake option, 143

WITH_ICU, 182, 419, 442

WITH_INNODB_EXTRA_DEBUG, 419

WITH_JEMALLOC, 330

WITH_LIBEVENT, 218, 419

WITH_LOCK_ORDER, 304

WITH_LSAN, 330

WITH_LTO, 240, 260, 378

WITH_LZ4, 419

WITH_LZMA, 330, 442

WITH_MYSQLX, 330

WITH_PACKAGE_FLAGS CMake option, 143

WITH_PROTOBUF, 419

WITH_RAPIDJSON, 378

WITH_RE2, 284, 442

WITH_ROUTER, 330

WITH_SSL, 260, 419, 442

WITH_SYSTEMD_DEBUG, 199

WITH_SYSTEM_LIBS, 419

WITH_TCMALLOC, 199

WITH_UNIT_TESTS CMake option, 143

WITH_VALGRIND, 70

WITH_WIN_JEMALLOC, 42

WITH_ZLIB, 419

WITH_ZSTD, 23, 199

wolfSSL, 284, 419

WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE, 42

WSAPoll, 55

646

MySQL 8.0 Release Notes

X DevAPI, 304, 356

X Plugin, 356, 419

X Protocol, 86, 143, 182, 199, 218, 240, 260, 284, 304, 330, 356, 378, 402, 419, 442,

477, 525, 568

X509, 442

XA, 34, 143, 166, 199, 260, 284, 378, 419, 442, 499, 525, 568

XA RECOVER, 499

XA statement, 284

XA transaction, 182

XA transactions, 55, 260, 378, 442, 499, 525, 568

XA Transactions, 182

XA_RECOVER_ADMIN, 499

XDR, 356

XML, 525

XOR, 13

XPath syntax, 499

yassl, 378, 402

yaSSL, 419, 442, 477, 525

yaSSL support, 23

YEAR, 55, 122, 166, 199, 260, 304, 356, 378

YEAR(), 356

Yum repository, 442

YYYYMMDD, 419

zero-length columns, 8

ZEROFILL, 260, 284, 304

zlib, 42, 419, 477

zlib_decompress, 568

zstd, 260

647

648