MySQL 5.6.4 がリリースされました


MySQL 5.6.4(マイルストーンリリース)は世界でもっともポピュラーなオープンソースデータベースの新バージョンです。


5.6.4はMySQL 5.5の全機能を含んでいます。MySQL 5.6の新機能の概要については、以下の"MySQL 5.6の何が新しくなったのか"を参照してください。

新しいサーバにMySQL 5.6.4をインストールする情報として、以下のMySQLのインストールドキュメントを参照してください。




MySQL Server 5.6は、ダウンロード・ページの「開発版リリース」からソースコード及び多くのプラットフォームのためのバイナリで現在利用可能です。





もしプロダクションレベルのシステムでMySQLを稼動させるならば、MySQL製品、バックアップ、モニタリング、モデリング、開発、管理ツールを含むMySQL Enterprise Editionに注目してください。MySQLのパフォーマンス、セキュリティ、稼働時間を高いレベルで達成します。

D.1.2. Changes in MySQL 5.6.4 (20 December 2011 Milestone 7)

    Condition Handler Changes

      * Incompatible Change: MySQL now supports the GET DIAGNOSTICS
        statement. GET DIAGNOSTICS provides applications a
        standardized way to obtain information from the diagnostics
        area, such as whether the previous SQL statement produced an
        exception and what it was. For more information, see Section, "GET DIAGNOSTICS Syntax."

        In addition several deficiencies in condition handler
        processing rules were corrected so that MySQL behavior is more
        like standard SQL:

           + Block scope is used in determining which handler to
             select. Previously, a stored program was treated as
             having a single scope for handler selection.

           + Condition precedence is more accurately resolved.

           + Diagnostics area clearing has changed. Bug #55843 caused
             handled conditions to be cleared from the diagnostics
             area before activating the handler. This made condition
             information unavailable within the handler. Now condition
             information is available to the handler, which can
             inspect it with the GET DIAGNOSTICS statement. The
             condition information is cleared when the handler exits,
             if it has not already been cleared during handler

           + Previously, handlers were activated as soon as a
             condition occurred. Now they are not activated until the
             statement in which the condition occurred finishes
             execution, at which point the most appropriate handler is
             chosen. This can make a difference for statements that
             raise multiple conditions, if a condition raised later
             during statement execution has higher precedence than an
             earlier condition and there are handlers in the same
             scope for both conditions. Previously, the handler for
             the first condition raised would be chosen, even if it
             had a lower precedence than other handlers. Now the
             handler for the condition with highest precedence is
             chosen, even if it is not the first condition raised by
             the statement.

           + Issues that caused server crashes resulting from
             incorrect handler call stack processing were fixed.

        The work just described involved several condition-handler bug

           + The RETURN statement did not clear the diagnostics area
             as it should have. Now the diagnostics area is cleared
             before executing RETURN. This prevents a condition in a
             nested function call from incorrectly propagating to an
             outer scope. It also means there is no way to return an
             SQL warning from a stored function. This change is not
             backward compatible, but the resulting behavior is more
             like standard SQL.

           + When an SQL HANDLER was activated, the handled condition
             was immediately removed from the diagnostics area.
             Consequently, any SQL diagnostic statement executed in
             the handler was unable to examine the condition that
             triggered the handler.

           + If multiple handlers existed at the same level within a
             stored program, the wrong one could be chosen.

           + If an error occurred in a context where different
             handlers were present at different levels of nesting, an
             outer handler could be chosen rather than the innermost

        For more information, see Section, "Scope Rules for
        Handlers." (Bug #12951117, Bug #38806, Bug #11749343, Bug
        #55852, Bug #11763171, Bug #61392, Bug #12652873, Bug #11660,
        Bug #11745196)

   Fractional Seconds Handling

      * Incompatible Change: MySQL now permits fractional seconds for
        TIME, DATETIME, and TIMESTAMP values, with up to microseconds
        (6 digits) precision. To define a column that includes a
        fractional seconds part, use the syntax type_name(fsp), where
        type_name is TIME, DATETIME, or TIMESTAMP, and fsp is the
        fractional seconds precision. For example:
        CREATE TABLE t1 (t TIME(3), dt DATETIME(6));
        The fsp value, if given, must be in the range 0 to 6. A value
        of 0 signifies that there is no fractional part. If omitted,
        the default precision is 0. (This differs from the standard
        SQL default of 6, for compatibility with previous MySQL
        The following items summarize the implications of this change.
        See also Section 10.3.4, "Fractional Seconds in Time Values."

           + For TIME, DATETIME, and TIMESTAMP columns, the encoding
             and storage requirements in new tables differ from such
             columns in tables created previously because these types
             now include a fractional seconds part.

           + Syntax for temporal literals now produces temporal
             values: DATE 'str', TIME 'str', and TIMESTAMP 'str', and
             the ODBC-syntax equivalents. Previously, the temporal
             type keyword was ignored and these constructs produced
             the string value.

           + Functions that take temporal arguments accept values with
             fractional seconds. Return values from temporal functions
             include fractional seconds as appropriate.

           + Three INFORMATION_SCHEMA tables, COLUMNS, PARAMETERS, and
             ROUTINES, now have a DATETIME_PRECISION column. Its value
             is the fractional seconds precision for TIME, DATETIME,
             and TIMESTAMP columns, and NULL for other data types.

           + The C API accommodates fractional seconds as follows:
                o In the MYSQL_FIELD column metadata structure, the
                  decimals member indicates the fractional seconds
                  precision for TIME, DATETIME, and TIMESTAMP columns.
                  Clients can determine whether a result set temporal
                  column has a fractional seconds part by checking for
                  a nonzero decimals value in the corresponding
                  MYSQL_FIELD structure. Previously, the decimals
                  member indicated the precision for numeric columns
                  and was zero otherwise.
                o In the MYSQL_TIME structure used for the binary
                  protocol, the second_part member indicates the
                  microseconds part for TIME, DATETIME, and TIMESTAMP
                  columns. Previously, the second_part member was
        In some cases, previously accepted syntax may produce
        different results. The following items indicate where existing
        code may need to be changed to avoid problems:

           + Some expressions produce results that differ from
             previous results. Examples: The timestamp system variable
             returns a value that includes a microseconds fractional
             part rather than an integer. Functions that return a
             result that includes the current time (such as CURTIME(),
             SYSDATE(), or UTC_TIMESTAMP()) interpret an argument as
             an fsp value and the return value includes a fractional
             seconds part of that many digits. Previously, these
             functions permitted an argument but ignored it.

           + TIME values are converted to DATETIME by adding the time
             to the current date. (This means that the date part of
             the result differs from the current date if the time
             value is outside the range from '00:00:00' to
             '23:59:59'.) Previously, conversion of TIME values to
             DATETIME was unreliable. See Section 10.3.5, "Conversion
             Between Date and Time Types."

           + TIMESTAMP(N) was permitted in old MySQL versions, but N
             was a display width rather than fractional seconds
             precision. Support for this behavior was removed in MySQL
             5.5.3, so applications that are reasonably up to date
             should not be subject to this issue. Otherwise, code must
             be rewritten.

        There may be problems replicating from a master server that
        understands fractional seconds to an older slave that does

           + For CREATE TABLE statements containing columns that have
             an fsp value greater than 0, replication will fail due to
             parser errors.

           + Statements that use temporal data types with an fsp value
             of 0 will work for with statement-based logging but not
             row-based logging. In the latter case, the data types
             have binary formats and type codes on the master that
             differ from those on the slave.

           + Some expression results will differ on master and slave.
             For example, expressions that involve the timestamp
             system variable or functions that return the current time
             have different results, as described earlier.
            (Bug #8523, Bug #11745064)

   Optimizer Features

      * These query optimizer improvements were implemented:

           + The optimizer detects and optimizes away these useless
             query parts within IN/ALL/SOME/EXISTS subqueries:

                o DISTINCT
                o GROUP BY, if there is no HAVING clause and no
                  aggregate functions
                o ORDER BY, which has no effect because LIMIT is not
                  supported in these subqueries

    Performance Schema Notes

      * The Performance Schema has these additions:

           + The Performance Schema now permits instrument and
             consumer configuration at server startup, which
             previously was possible only at runtime using UPDATE
             statements for the setup_instruments and setup_consumers
             tables. This change was made because configuration at
             runtime is too late to disable instruments that have
             already been initialized during server startup. For
             example, the wait/sync/mutex/sql/LOCK_open mutex is
             initialized once during server startup, so attempts to
             disable the corresponding instrument at runtime have no

             To control an instrument at server startup, use an option
             of this form:


             Here, instrument_name is an instrument name such as
             wait/sync/mutex/sql/LOCK_open, and value is one of these

                o off, false, or 0: Disable the instrument
                o on, true, or 1: Enable and time the instrument
                o counted: Enable and count (rather than time) the

             Each --performance_schema_instrument option can specify
             only one instrument name, but multiple instances of the
             option can be given to configure multiple instruments. In
             addition, patterns are permitted in instrument names to
             configure instruments that match the pattern. To
             configure all condition synchronization instruments as
             enabled and counted, use this option:


             To disable all instruments, use this option:

             Longer instrument name strings take precedence over
             shorter pattern names, regardless of order. For
             information about specifying patterns to select
             instruments, see Section, "Naming Instruments
             or Consumers for Filtering Operations."

             An unrecognized instrument name is ignored. It is
             possible that a plugin installed later may create the
             instrument, at which time the name is recognized and

             To control a consumer at server startup, use an option of
             this form:


             Here, consumer_name is a consumer name such as
             events_waits_history, and value is one of these values:

                o off, false, or 0: Do not collect events for the
                o on, true, or 1: Collect events for the consumer

             For example, to enable the events_waits_history consumer,
             use this option:


             The permitted consumer names can be found by examining
             the setup_consumers table. Patterns are not permitted.
             Along with the preceding changes to permit configuration
             at server startup, the default instrument and consumer
             configuration has changed. Previously, all instruments
             and consumers were enabled by default. Now, instruments
             are disabled except the statement, I/O, and idle
             instruments. Consumers are disabled except the global,
             thread, and statement consumers. These changes produce a
             default configuration with minimal overhead.

           + Tables that have an EVENT_ID column now also have an
             END_EVENT_ID column to support determination of nested
             event relationships:

                o events_waits_current, events_waits_history,

                o events_stages_current, events_stages_history,

                o events_statements_current,

             As before, EVENT_ID is populated with the thread current
             event counter when an event starts. In addition,
             END_EVENT_ID is NULL until the event ends, at which point
             it is set to the new thread current event counter. This
             permits the relationship "event A is included in event B"
             to be determined using the following expression, without
             having to follow each inclusion relationship using


           + The Performance Schema aggregates file I/O operations in
             two places, the events_waits_summary_xxx tables and the
             file_summary_xxx tables. It was possible to join the
             events_waits_summary_global_by_event_name table to the
             file_summary_by_event_name by using the EVENT_NAME
             column. However, it was not possible to do the same with
             the events_waits_summary_by_instance and
             file_summary_by_instance tables because the former uses
             OBJECT_INSTANCE_BEGIN as the instance identifier and the
             latter uses FILE_NAME. This means that it was possible to
             obtain both file I/O latency and usage per file, but not
             to correctly correlate latency to usage when there was
             more than one form of file (such as multiple redo logs,
             table files, and so forth).

             To address this issue, the file_summary_by_instance table
             now has an OBJECT_INSTANCE_BEGIN column. In addition,
             both file_summary_by_instance and
             file_summary_by_event_name have additional aggregation
             columns (such as timer wait information), which in many
             cases makes it possible to obtain the desired summary
             information without need for a join at all.

        If you upgrade to this release of MySQL from an earlier
        version, you must run mysql_upgrade (and restart the server)
        to incorporate these changes into the performance_schema

        For more information, see Chapter 19, "MySQL Performance

    Functionality Added or Changed

      * Replication: Previously, replication slaves could connect to
        the master server only through master accounts that use native
        authentication. Now replication slaves can also connect
        through master accounts that use nonnative authentication if
        the required client-side plugin is installed on the slave side
        in the directory named by the slave plugin_dir system
        variable. (Bug #12897501)

      * The optimizer trace capability now tracks temporary tables
        created by the server during statement execution. (Bug

      * Performance of metadata locking operations on Windows XP
        systems was improved by instituting a cache for metadata lock
        objects. This permits the server to avoid expensive operations
        for creation and destruction of synchronization objects on XP.
        A new system variable, metadata_locks_cache_size, permits
        control over the size of the cache. The default size is 1024.
        (Bug #12695572)

      * Upgrading from an Advanced GPL RPM package to an Advanced RPM
        package did not work. Now on Linux it is possible to use rpm
        -U to replace any installed MySQL product by any other of the
        same release family. It is not necessary to remove the old
        produce with rpm -e first. (Bug #11886309)

      * The make_win_bin_dist script is no longer used and has been
        removed from MySQL distributions and the manual. (Bug #58241)

      * MEMORY table creation time is now available in the CREATE_TIME
        column of the INFORMATION_SCHEMA.TABLES table and the
        Create_time column of SHOW TABLE STATUS output. (Bug #51655,
        Bug #11759349)

      * Previously, MySQL servers from 5.1 and up refused to open
        ARCHIVE tables created in 5.0 because opening them caused a
        server crash. The server now can open 5.0 ARCHIVE tables, and
        REPAIR TABLE updates them to the format used in 5.6. However,
        the recommended upgrade procedure is still to dump 5.0 ARCHIVE
        tables before upgrading and reload them after upgrading. (Bug
        #48633, Bug #11756687)

      * The MySQL code base was changed to permit use of the C++
        Standard Library and to enable exceptions and runtime type
        information (RTTI). This change has the following

           + Libraries and executables depend on some C++ standard
             library. On Linux, this has not been the case previously.
             On Solaris, the default dependency has changed from the
             default library to libstlport, which is now included with
             binary distributions for users whose system does not have

           + The -fno-rtti and -fno-exceptions options are no longer
             used to build plugins, such as storage engines. Users who
             write their own plugins should omit these options if they
             were using tem.

           + C++ users who compile from source should set CXX to a C++
             compiler rather than a C compiler. For example, use g++
             rather than gcc. This includes the server as well as
             client programs.

           + mysql_config now has a --cxxflags option. This is like
             the --cflags option, but produces flags appropriate for a
             C++ compiler rather than a C compiler.

           + User-defined functions can be written in C++ using
             standard library features.

      * New optimizations apply to read-only InnoDB transactions. See
        Section, "Optimizations for Read-Only Transactions"
        for details. The new optimizations make autocommit more
        applicable to InnoDB queries than before, as a way to signal
        that a transaction is read-only because it is a
        single-statement SELECT.

      * You can now set the InnoDB page size for uncompressed tables
        to 8KB or 4KB, as an alternative to the default 16KB. This
        setting is controlled by the innodb_page_size configuration
        option. You specify the size when creating the MySQL instance.
        All InnoDB tablespaces within an instance share the same page
        size. Smaller page sizes can help to avoid redundant or
        inefficient I/O for certain combinations of workload and
        storage devices, particularly SSD devices with small block

      * MySQL now supports FULLTEXT indexes for InnoDB tables. The
        core syntax is very similar to the FULLTEXT capability from
        earlier releases, with the CREATE TABLE and CREATE INDEX
        statements, and MATCH() ... AGAINST() clause in the SELECT
        statement. The new @ operator allows proximity searches for
        terms that are near each other in the document. The detailed
        search processing is controlled by a new set of configuration
        options: innodb_ft_enable_stopword,
        innodb_ft_user_stopword_table, innodb_ft_cache_size,
        innodb_ft_min_token_size, and innodb_ft_max_token_size. You
        can monitor the workings of the InnoDB full-text search system
        by querying new INFORMATION_SCHEMA tables:
        innodb_ft_default_stopword, innodb_ft_index_table,
        innodb_ft_index_cache, innodb_ft_config, innodb_ft_deleted,
        and innodb_ft_being_deleted.

    Bugs Fixed

      * Incompatible Change: Replication: The statements in the
        following list are now marked as unsafe for statement-based
        replication. This is due to the fact that each of these
        statements depends on the results of a SELECT statement whose
        order cannot always be determined. When using STATEMENT
        logging mode, a warning is issued in the binary log for any of
        these statements; when using MIXED logging mode, the statement
        is logged using the row-based format.

           + REPLACE ... SELECT
           + INSERT IGNORE ... SELECT
           + UPDATE IGNORE

        When upgrading, you should note the use of these statements in
        your applications, keeping in mind that a statement that
        inserts or replaces rows obtained from a SELECT can take up
        many times as much space in the binary log when logged using
        row-based format than when only the statement itself is
        logged. Depending on the number and size of the rows selected
        and inserted (or replaced) by any such statements, the
        difference in size of the binary log after the logging of
        these statements is switched from statement-based to row-based
        can potentially be several orders of magnitude. See Section, "Advantages and Disadvantages of Statement-Based and
        Row-Based Replication." (Bug #11758262, Bug #50439)

      * Incompatible Change: Previously, "Aborted connection" errors
        were written to the error log based on the session value of
        log_warnings, which permitted users with minimal privileges to
        cause many messages to be written to the log unless restricted
        by the MAX_CONNECTIONS_PER_HOUR resource limit. Now this
        logging is based on the global log_warnings variable. There
        are no remaining uses of the session log_warnings variable, so
        it has been removed that the variable has only a global value.
        (Bug #53466, Bug #11761014)

      * Important Change: InnoDB Storage Engine: Data from BLOB
        columns could be lost if the server crashed at a precise
        moment when other columns were being updated in an InnoDB
        table. (Bug #12704861)

      * InnoDB Storage Engine: This fix improves the performance of
        instrumentation code for InnoDB buffer pool operations. (Bug
        #12950803, Bug #62294)

      * InnoDB Storage Engine: Unused functions were removed from the
        internal InnoDB code related to mini-transactions, to clarify
        the logic. (Bug #12626794, Bug #61240)

      * InnoDB Storage Engine: Lookups using secondary indexes could
        give incorrect matches under a specific set of conditions. The
        conditions involve an index defined on a column prefix, for a
        BLOB or other long column stored outside the index page, with
        a table using the Barracuda file format. (Bug #12601439)

      * InnoDB Storage Engine: This fix corrects cases where the MySQL
        server could hang or abort with a long semaphore wait message.
        (This is a different issue than when these symptoms occurred
        during a CHECK TABLE statement.) (Bug #11766591, Bug #59733)

      * Partitioning: CHECKSUM TABLE returned 0 for a partitioned
        table unless the statement was used with the EXTENDED option.
        (Bug #11933226, Bug #60681)

      * Partitioning: Error 1214 (ER_TABLE_CANT_HANDLE_FT), given when
        trying to use a FULLTEXT index with a partitioned table,
        displayed the misleading text The used table type doesn't
        support FULLTEXT indexes was misleading and has been replaced
        which shows the more accurate FULLTEXT index is not supported
        for partitioned tables. (Bug #11763825, Bug #56590)

      * Replication: The value set for the slave_parallel_workers
        system variable (or the corresponding --slave-parallel-workers
        server option) was not always honored correctly; in such cases
        a random value was used. (Bug #13334470)

      * Replication: Several warnings and informational messages were
        revised for typographic errors and clarity. (Bug #12947248,
        Bug #12978113)

      * Replication: A replication master could send damaged events to
        slaves after the binary log disk on the master became full. To
        correct this issue, only complete events are now pushed by the
        master dump thread to the slave I/O thread. In addition, the
        error text that the master sends to the slave when an
        incomplete event is found now states that the incomplete event
        may have been caused by running out of disk space on the
        master, and provides coordinates of the first and the last
        event bytes read. (Bug #11747416, Bug #32228)

      * A derived table with more than 64 columns caused a server
        crash. (Bug #13354889)

      * Writes to the slow log involved a call to thd->current_utime()
        even if no log entries ended up being written, unnecessarily
        reducing performance. (Bug #13326965)

      * Rounding DBL_MAX returned DBL_MAX, not 'inf'. (Bug #13261955)

      * Access privileges were checked for each stored program
        instruction, even if the instruction used no tables, resulting
        in reduced performance. (Bug #13251277)

      * The error message for ER_EVENT_CANNOT_ALTER_IN_THE_PAST was
        incorrect. (Bug #13247871)

      * During the table-opening process, memory was allocated and
        later freed that was needed view loading, even for statements
        that did not use views. These unnecessary allocation and free
        operations are no longer done. (Bug #13116518)

      * Subqueries with OUTER JOIN could return incorrect results if
        the subquery referred to a column from another SELECT. (Bug

      * The Performance Schema nested some network I/O events within
        the wrong statement. (Bug #12981100)

      * mysql_plugin mishandled the --plugin-ini, --mysqld, and
        --my-print-defaults options under some circumstances. (Bug

      * mysql_plugin returned the wrong error code from failed server
        bootstrap execution. (Bug #12968567)

      * Internal conversion of zero to binary and back could yield a
        result with incorrect precision. (Bug #12911710)

      * Valgrind warnings generated by filesort operations were fixed.
        (Bug #12856915)

      * Partitioning: Using ALTER TABLE to remove partitioning from a
        valid MyISAM table could corrupt it. (Bug #52599, Bug

      * An IN-to-EXISTS subquery transformation could yield incorrect
        results if the outer value list contained NULL. (Bug

      * With index condition pushdown enabled, STRAIGHT_JOIN queries
        could produce incorrect results. (Bug #12822678, Bug

      * The result of ROUND() was incorrect for certain numbers. (Bug

      * A warning resulting from use of SPACE() referred to REPEAT()
        in the warning message. (Bug #12735829)

      * IN and EXISTS subqueries with DISTINCT and ORDER BY could
        return incorrect results. (Bug #12709738)

      * Several improvements were made to the libedit library bundled
        with MySQL distributions, and that is available for all
        platforms that MySQL supports except Windows.

           + Navigation keys did not work for UTF-8 input.

           + Word navigation and delete operations did not work for
             UTF-8 input with Cyrillic characters.

           + Nonlatin characters were corrupted in overwrite mode for
             UTF-8 input.

           + Long queries caused the statement history file to become

           + The Alt key caused history operations to fail.

        (Bug #12605400, Bug #12613725, Bug #12618092, Bug #12624155,
        Bug #12617651, Bug #12605388)

      * SELECT SQL_BUFFER_RESULT query results included too many rows
        if a GROUP BY clause was optimized away. (Bug #12578908)

      * mysqldump --all-databases did not dump the replication log
        tables. (They could be dumped only by naming them explicitly
        when invoking mysqldump, and using the --master-data option.)

        As a result of the fix for this problem, it is now possible to
        execute statements requiring read locks on the replication log
        tables at any time, while any statements requiring a write
        lock on either or both of these tables are disallowed whenever
        replication is in progress. For more information, see Section
        15.2.2, "Replication Relay and Status Logs." (Bug #12402875,
        Bug #60902)

      * mysqld_safe did not properly check for an already running
        instance of mysqld. (Bug #11878394)

      * Replication: --replicate-rewrite-db=from_name->to_name did not
        work correctly when the name of the source database
        (from_name) consisted of only a single character. (Bug #34332,
        Bug #11747866)

      * If index condition pushdown access was chosen and then
        abandoned, some variables were not cleared, leading to
        incorrect query results. (Bug #62533)

      * For a lower_case_table_names value of 1 or 2 and a database
        having a mixed-case name, calling a stored function using a
        fully qualified name including the database name failed. (Bug
        #60347, Bug #11840395)

      * mysql_upgrade did not upgrade the system tables or create the
        mysql_upgrade_info file when run with the --write-binlog or
        --skip-write-binlog option. (Bug #60223, Bug #11827359)

      * A multiple-table UPDATE statement required the UPDATE
        privilege on a view which was only read if the view was
        processed using the merge algorithm. (Bug #59957, Bug

      * When a join operation contained a view, the optimizer
        sometimes failed to associate the view's WHERE clause
        with the first table or view in a join when it was
        possible to do so, resulting in a less efficient query.
        (Bug #59696, Bug #11766559)

      * An assertion was raised when selecting from a view that
        selects from a view that used a user-defined function that had
        been deleted. (Bug #59546, Bug #11766440)

      * The help message for mysql_install_db did not indicate that it
        supports the --defaults-file, --defaults-extra-file and
        --no-defaults options. (Bug #58898, Bug #11765888)

      * mysql_install_db printed the --skip-grant-tables server option
        as --skip-grant in one of its error messages. (Bug #58534, Bug

      * An assertion designed to detect zero-length sort keys also was
        raised when the entire key set fit in memory. (Bug #58200, Bug

      * During optimization, ZEROFILL values may be converted to
        string constants. However, CASE expressions did not handle
        switching data types after the planning stage, leading to CASE
        finding a null pointer instead of its argument. (Bug #57135,
        Bug #11764313)

      * If a plugin was uninstalled, thread local variables for plugin
        variables of string type with wth PLUGIN_VAR_MEMALLOC flag
        were not freed. (Bug #56652, Bug #11763882)

      * Deadlock could occur when these four things happened at the
        same time: 1) An old dump thread was waiting for the binary
        log to grow. 2) The slave server that replicates from the old
        dump thread tried to reconnect. During reconnection, the new
        dump thread tried to kill the old dump thread. 3) A KILL
        statement tried to kill the old dump thread. 4) An INSERT
        statement caused a binary log rotation. (Bug #56299, Bug

      * myisampack could create corrupt FULLTEXT indexes when
        compressing tables. (Bug #53646, Bug #11761180)

      * The SQL_BIG_RESULT modifier could change the results for
        queries that included a GROUP BY clause. (Bug #53534, Bug

      * ARCHIVE tables with NULL columns could cause server crashes or
        become corrupt under concurrent load. (Bug #51252, Bug

      * InnoDB used incorrect identifier quoting style in an error
        message that resulted in an error if a user followed the
        suggestion in the message. (Bug #49556, Bug #11757503)

      * OPTIMIZE TABLE could corrupt MyISAM tables if myisam_use_mmap
        was enabled. (Bug #49030, Bug #11757032)

      * A query that selected a GROUP_CONCAT() function result could
        return different values depending on whether an ORDER BY of
        the function result was present. (Bug #41090, Bug #11750518)

      * A linking problem prevented the FEDERATED storage engine
        plugin from loading. (Bug #40942, Bug #11750417)

      * Subqueries could return incorrect results when materialization
        was enabled. (Bug #40037, Bug #11749901, Bug #12705660, Bug

      * For debug builds, an assertion could be raised for ALTER
        statements that performed a RENAME operation. This occurred
        for storage engine handlertons that exposed the
        HTON_FLUSH_AFTER_RENAME flag. (Bug #38028, Bug #11749050)

      * The estimate of space required for filesort operations could
        be too high, resulting in inefficient initialization. (Bug
        #37359, Bug #11748783)

      * An ALTER TABLE that included an ADD ... AFTER operation to add
        a new column after a column that had been modified earlier in
        the statement failed to find the existing column. (Bug #34972,
        Bug #11748057)

      * For FEDERATED tables, loss of connection to the remote table
        during some insert operations could cause a server crash. (Bug
        #34660, Bug #11747970)

      * For some queries, the index_merge access method was used even
        when more expensive then ref access. (Bug #32254, Bug