Functionality added or changed:
Allow spaces in windows service names.
            Changed the default Windows service name for
            mysqld from MySql to
            MySQL. This should not affect usage,
            because service names are not case sensitive.
          
            When you install mysqld as a service on
            Windows systems, mysqld will read startup
            options in option files from the option group with the same
            name as the service name. (Except when the service name is
            MySQL).
          
Bugs fixed:
Fixed Bug#1335 when filesort was never shown in EXPLAIN if query contained ORDER BY NULL clause.
            Fixed invalidation of whole query cache on DROP
            DATABASE. (Bug#1898)
          
            Fixed bug in range optimizer that caused wrong results for
            some not likely AND/OR
            queries. (Bug#1828)
          
            Fixed a crash in ORDER BY when ordering
            by expression and identifier. (Bug#1945)
          
            Fixed a crash in an open HANDLER when an
            ALTER TABLE was executed in a different
            connection. (Bug#1826)
          
            Fixed a bug in trunc* operator of
            full-text search which sometimes caused MySQL not to find
            all matched rows.
          
            Fixed bug in zero prepending to DECIMAL
            column type.
          
            Fixed optimiser bug, introduced in 4.0.16, when
            REF access plan was preferred to more
            efficient RANGE on another column.
          
            Fixed problem when installing a MySQL server as a Windows
            service using a command of the form mysqld
            --install mysql --defaults-file=path-to-file.
          
            Fixed an incorrect result from a query that uses only
            const tables (such as one-row tables) and
            non-constant expression (such as RAND()).
            (Bug#1271)
          
            Fixed bug when the optimiser did not take
            SQL_CALC_FOUND_ROWS into account if
            LIMIT clause was present. (Bug#1274)
          
            mysqlbinlog now asks for a password at
            the console when the -p or
            --password option is used with no argument.
            This is consistent with the way that other clients such
            mysqladmin and
            mysqldump already behave.
            Note: A consequence of this
            change is that it is no longer possible to invoke
            mysqlbinlog as mysqlbinlog -p
            pass_val (with a space between the
            -p option and the following password
            value). (Bug#1595)
          
            Bug accidentally introduced in 4.0.16 where the slave SQL
            thread deleted its replicated temporary tables when
            STOP SLAVE was issued.
          
            In a ``chain'' replication setup
            A->B->C, if 2 sessions on A updated
            temporary tables of the same name at the same time, the
            binary log of B became incorrect,
            resulting in C becoming confused. (Bug#1686)
          
            In a ``chain'' replication setup
            A->B->C, if STOP
            SLAVE was issued on B while it
            was replicating a temporary table from A,
            then when START SLAVE was issued on
            B, the binary log of B
            became incorrect, resulting in C becoming
            confused. (Bug#1240)
          
            When MASTER_LOG_FILE and
            MASTER_LOG_POS were not specified,
            CHANGE MASTER used the coordinates of the
            slave I/O thread to set up replication, which broke
            replication if the slave SQL thread lagged behind the slave
            I/O thread. This caused the slave SQL thread to lose some
            events. The new behaviour is to use the coordinates of the
            slave SQL thread instead. See
            Secção 4.11.8.1, “CHANGE MASTER TO”. (Bug#1870)
          
            Now if integer is stored or converted to
            TIMESTAMP or DATETIME
            value checks of year, month, day, hour, minute and second
            ranges are performed and numbers representing illegal
            timestamps are converted to 0 value. This behaviour is
            consistent with manual and with behaviour of string to
            TIMESTAMP/DATETIME
            conversion. (Bug#1448)
          
            Fixed bug when BIT_AND() and
            BIT_OR() group functions returned
            incorrect value if SELECT used a
            temporary table and no rows were found. (Bug#1790).
          
            BIT_AND() is now unsigned in all
            contexts. This means that it will now return
            18446744073709551615 (= 0xffffffffffffffff) instead of -1 if
            there were no rows in the result.
          
            Fixed bug with BIT_AND() still returning
            signed value for an empty set in some cases. (Bug#1972)
          
            Fixed bug with ^ (XOR) and
            >> (bit shift) still returning
            signed value in some cases. (Bug#1993)
          
Replication: a rare race condition in the slave SQL thread, which could lead to a wrong complain that the relay log is corrupted. (Bug#2011)
            Replication: if an administrative command on a table
            (OPTIMIZE TABLE, REPAIR
            TABLE etc) was run on the slave, this could
            sometimes stop the slave SQL thread (this did not led to any
            corruption; one just had to type START
            SLAVE to get replication going again). (Bug#1858)
          
            Replication: in the slave SQL thread, a multi-table
            UPDATE could produce a wrong complain
            that some record was not found in one table, if the
            UPDATE was preceded by a INSERT
            ... SELECT. (Bug#1701)
          
This is a translation of the MySQL Reference Manual that can be found at dev.mysql.com. The original Reference Manual is in English, and this translation is not necessarily as up to date as the English version.

