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MySQL Community Server 8.0.2-dmr has been released (part 2/2)





[ This is part 2 of the announcement ]


   Logging Notes

     * These error-logging changes have been made:

          + The server is now more forgiving if it cannot find
            the configured error-message file (specified using
            the lc_messages_dir and lc_messages system
            variable). Previously, the server aborted the
            startup process and exited. Now the server writes a
            message to the error log and defaults to built-in
            English messages. This applies to messages the
            server writes to the error log and sends to clients.

          + Error logging is being rewritten to use the MySQL
            component architecture. Traditional error logging
            now is implemented using built-in components, and
            logging using the system log is a loadable
            component. In addition, a new JSON log writer is
            available. The log components to use are controlled
            by the new log_error_services system variable. For
            more information, see The Error Log
            (http://dev.mysql.com/doc/refman/8.0/en/error-log.html).

   Bugs Fixed

     * Incompatible Change: Plugins such as Group Replication
       and X Plugin now use the mysql.session account added in
       this version. If you are upgrading from a previous
       version 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 ran after a server
       update. (Bug #26042764)
       References: See also: Bug #24311527, Bug #25642343.

     * 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)

     * 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 non-existent 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
       non-existent foreign key. (Bug #25365223)

     * 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)

     * 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: 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: When binlog_checksum=NONE was set on a MySQL
       server after startup, and then Group Replication was
       started, if an error occurred, the server remained in
       RECOVERING state and could not be shut down. (Bug
       #25793366)

     * 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: In a Group Replication setup where circular
       asynchronous replication was implemented between members
       of different replication groups, view change log events
       were repeatedly replicated between the groups with new
       generated GTIDs each time. The fix ensures that view
       change log events are ignored outside the named
       replication group where they occur, and never generate
       new GTIDs. (Bug #25674926)
       References: See also: Bug #26049695, Bug #25928854, Bug
       #25721175.

     * 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: In a setup where single-primary Group
       Replication was combined with asynchronous replication,
       for example with S1 and S2 forming a group and with S2
       and S3 functioning as master and slave, secondaries such
       as S2 were accepting transactions and these could then
       enter the group. The fix prevents secondaries creating an
       asynchronous replication channel when belonging to a
       single-primary group, and Group Replication cannot be
       started when asynchronous replication is running. (Bug
       #25574200)
       References: See also: Bug #26078602.

     * Replication: Group Replication failed to start if the
       super_read_only system variable was enabled. (Bug
       #25481287, Bug #84733)

     * 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: 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 have
       super_read_only=1 in the my.cfg file. Group Replication
       now checks for this setting upon successful start up and
       sets super_read_only=0. This ensures that members which
       do not successfully join a group cannot accept
       transactions. (Bug #25474736, Bug #84728)

     * 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: 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 master/slave replication. The
       fix relaxes some conditions to only be called when commit
       is done and a message has been added to alert you when a
       GTID has already been used. (Bug #25232042)

     * 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)

     * Replication: Interleaved XA 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: Loading and initialization of the Group
       Replication plugin failed if no root account was present.
       (Bug #24311527)

     * 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)

     * Replication: Transmission of large GCS messages could
       take so long the sender appeared to have died. (Bug
       #22671846)

     * Replication: Multi-threaded 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: Issuing SHOW SLAVE STATUS FOR CHANNEL
       'group_replication_recovery' following a restart of a
       server using group replication led to an unplanned
       shutdown. (Bug #85739, Bug #25813258)

     * Replication: Setting an empty filter rule using CHANGE
       REPLICATION FILTER caused issues when running tests with
       UBSan. (Bug #85405, Bug #25702297)

     * 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)

     * 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.

     * 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)

     * 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)

     * 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)

     * 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 server 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)

     * 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)

     * 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)

     * 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
       #25642319, Bug #85224)

     * 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.
       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 any of 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)

     * 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)

     * EXPLAIN for single-table UPDATE or DELETE statements
       could raise an assertion attempting to optimize away
       subqueries. (Bug #23209903)

     * 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)

     * 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 INFILE 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)

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