Fixed range optimizer bug: SELECT * FROM table_name
            WHERE key_part1 >= const AND (key_part2 = const OR
            key_part2 = const). The bug was that some rows
            could be duplicated in the result.
          
            Running myisamchk without
            -a updated the index distribution
            incorrectly.
          
            SET SQL_LOW_PRIORITY_UPDATES=1 was
            causing a parse error.
          
            You can now update index columns that are used in the
            WHERE clause. UPDATE tbl_name
            SET KEY=KEY+1 WHERE KEY > 100
          
Date handling should now be a bit faster.
            Added handling of fuzzy dates (dates where day or month is
            0), such as '1999-01-00'.
          
            Fixed optimization of SELECT ... WHERE
            key_part1=const1 AND key_part_2=const2 AND key_part1=const4
            AND key_part2=const4; indextype should be
            range instead of ref.
          
            Fixed egcs 1.1.2 optimizer bug (when
            using BLOB values) on Linux Alpha.
          
            Fixed problem with LOCK TABLES combined
            with DELETE FROM table.
          
            MyISAM tables now allow keys on
            NULL and BLOB/TEXT
            columns.
          
            The following join is now much faster: SELECT ...
            FROM t1 LEFT JOIN t2 ON ... WHERE t2.not_null_column IS
            NULL.
          
            ORDER BY and GROUP BY
            can be done on functions.
          
            Changed handling of 'const_item' to allow handling of
            ORDER BY RAND().
          
            Indexes are now used for WHERE key_column =
            function.
          
            Indexes are now used for WHERE key_column =
            col_name even if the columns are not identically
            packed.
          
            Indexes are now used for WHERE col_name IS
            NULL.
          
            Changed heap tables to be stored in low_byte_first order (to
            make it easy to convert to MyISAM tables)
          
            Automatic change of HEAP temporary tables
            to MyISAM tables in case of ``table is
            full'' errors.
          
            Added --init-file=file_name option to
            mysqld.
          
            Added COUNT(DISTINCT value, [value,
            ...]).
          
            CREATE TEMPORARY TABLE now creates a
            temporary table, in its own namespace, that is automatically
            deleted if connection is dropped.
          
            New reserved words (required for CASE):
            CASE, THEN, WHEN, ELSE and END.
          
            New functions EXPORT_SET() and
            MD5().
          
Support for the GB2312 Chinese character set.
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.

