Added IGNORE option for DELETE statement.

The MySQL source distribution now also includes the MySQL Internals Manual internals.texi.

Added mysql_set_server_option() C API client function to allow multiple statement handling in the server to be enabled or disabled.

The mysql_next_result() C API function now returns -1 if there are no more result sets.

Renamed CLIENT_MULTI_QUERIES connect option flag to CLIENT_MULTI_STATEMENTS. To allow for a transition period, the old option will continue to be recognized for a while.

Require DEFAULT before table and database default character set. This enables us to use ALTER TABLE table_name ... CHARACTER SET=... to change the character set for all CHAR, VARCHAR, and TEXT columns in a table.

Added MATCH ... AGAINST( ... WITH QUERY EXPANSION) and the ft_query_expansion_limit server variable.

Removed unused ft_max_word_len_for_sort server variable.

Full-text search now supports multi-byte character sets and the Unicode utf8 character set. (The Unicode ucs2 character set is not yet supported.)

Phrase search in MATCH ... AGAINST ( ... IN BOOLEAN MODE) no longer matches partial words.

Added aggregate function BIT_XOR() for bitwise XOR operations.

Replication over SSL now works.

The START SLAVE statement now supports an UNTIL clause for specifying that the slave SQL thread should be started but run only until it reaches a given position in the master's binary logs or in the slave's relay logs.

Produce warnings even for single-row INSERT statements, not just for multiple-row INSERT statements. Previously, it was necessary to set SQL_WARNINGS=1 to generate warnings for single-row statements.

Added delimiter (\d) command to the mysql command-line client for changing the statement delimiter (terminator). The default delimiter is semicolon.

CHAR, VARCHAR, and TEXT columns now have lengths measured in characters rather than in bytes. The character size depends on the column's character set. This means, for example, that a CHAR(n) column for a multi-byte character set will take more storage than before. Similarly, index values on such columns are measured in characters, not bytes.

LIMIT no longer accepts negative arguments (they used to be treated as very big positive numbers before).

The DATABASE() function now returns NULL rather than the empty string if there is no database selected.

Added --sql-mode=NO_AUTO_VALUE_ON_ZERO option to suppress the usual behavior of generating the next sequence number when zero is stored in an AUTO_INCREMENT column. With this mode enabled, zero is stored as zero; only storing NULL generates a sequence number.

Warning: Incompatible change! Client authentication now is based on 41-byte passwords in the user table, not 45-byte passwords as in 4.1.0. Any 45-byte passwords created for 4.1.0 must be reset after running the mysql_fix_privilege_tables script.

Added MySQL Server option and global variable 'secure-auth' that disallows authentication for accounts that have old (pre-4.1.1) passwords.

Added MySQL command line client option 'secure-auth'. If this option is set, client will refuse to send password in old (pre-4.1.1) format.

Warning: Incompatible change! Renamed the C API mysql_prepare_result() function to mysql_get_metadata() as the old name was confusing.

Added DROP USER 'username'@'hostname' statement to drop an account that has no privileges.

The interface to aggregated UDF functions has changed a bit. You must now declare a xxx_clear() function for each aggregate function XXX().

The CONCAT_WS() function no longer skips empty strings.

Added new ADDTIME(), DATE(), DATEDIFF(), LAST_DAY(), MAKEDATE(), MAKETIME(), MICROSECOND(), SUBTIME(), TIME(), TIMEDIFF(), TIMESTAMP(), UTC_DATE(), UTC_TIME(), UTC_TIMESTAMP(), and WEEKOFYEAR() functions.

Added new syntax for ADDDATE() and SUBDATE(). The second argument now may be a number representing the number of days to be added to or subtracted from the first date argument.

Added new type values DAY_MICROSECOND, HOUR_MICROSECOND, MINUTE_MICROSECOND, SECOND_MICROSECOND, and MICROSECOND for DATE_ADD(), DATE_SUB(), and EXTRACT().

Added new %f microseconds format specifier for DATE_FORMAT() and TIME_FORMAT().

All queries in which at least one SELECT does not use indexes properly now are written to the slow query log when long log format is used.

It is now possible to create a MERGE table from MyISAM tables in different databases. Formerly, all the MyISAM tables had to be in the same database, and the MERGE table had to be created in that database as well.

Added new COMPRESS(), UNCOMPRESS(), and UNCOMPRESSED_LENGTH() functions.

When doing SET sql_mode='mode' for a complex mode (like ANSI), we now update the sql_mode variable to include all the individual options implied by the complex mode.

Added the OLAP (On-Line Analytical Processing) function ROLLUP, which provides summary rows for each GROUP BY level.

Added SQLSTATE codes for all server errors.

Added mysql_sqlstate() and mysql_stmt_sqlstate() C API client functions that return the SQLSTATE error code for the last error.

TIME columns with hour values greater than 24 were returned incorrectly to the client.

ANALYZE, OPTIMIZE, REPAIR, and FLUSH statements are now stored in the binary log and thus replicated to slaves. This logging does not occur if the optional NO_WRITE_TO_BINLOG keyword (or its alias LOCAL) is given. Exceptions are that FLUSH LOGS, FLUSH MASTER, FLUSH SLAVE, and FLUSH TABLES WITH READ LOCK are not logged in any case. For a syntax example, see 項4.6.4. 「FLUSH 構文」.

New global variable RELAY_LOG_PURGE to enable or disable automatic relay log purging.

LOAD DATA now produces warnings that can be fetched with SHOW WARNINGS.

Added support for syntax CREATE TABLE table2 (LIKE table1) that creates an empty table table2 with a definition that is exactly the same as table1, including any indexes.

CREATE TABLE table_name (...) TYPE=storage_engine now generates a warning if the named storage engine is not available. The table is still created as a MyISAM table, as before.

Most subqueries are now much faster than before.

Added PURGE BINARY LOGS as an alias for PURGE MASTER LOGS.

Disabled the PURGE LOGS statement that was added in in version 4.1.0. The statement now should be issued as PURGE MASTER LOGS or PURGE BINARY LOGS.

Added SHOW BDB LOGS as an alias for SHOW LOGS.

Added SHOW MASTER LOGS (which had been deleted in version 4.1.0) as an alias for SHOW BINARY LOGS.

Added Slave_IO_State and Seconds_Behind_Master columns to the output of SHOW SLAVE STATUS. Slave_IO_State indicates the state of the slave I/O thread, and Seconds_Behind_Master indicates the number of seconds by which the slave is late compared to the master.

--lower-case-table-names=1 now also makes aliases case insensitive. (Bug#534)

Fixed merging types and length of result set columns for UNION operations. The types and lengths now are determined taking into account values for all SELECT statements in the UNION, not just the first SELECT.

Fixed a bug in privilege handling that caused connections from certain IP addresses to be assigned incorrect database-level privileges. A connection could be assigned the database privileges of the previous successful authentication from one of those IP addresses, even if the IP address username and database name were different. (Bug#1636)

Error-handling functions were not called properly when an error resulted from [CREATE | REPLACE| INSERT] ... SELECT statements.

HASH, BTREE, RTREE, ERRORS, and WARNINGS no longer are reserved words. (Bug#724)

Fix for bug in ROLLUP when all tables were const tables. (Bug#714)

Fixed a bug in UNION that prohibited NULL values from being inserted into result set columns where the first SELECT of the UNION retrieved NOT NULL columns.

Fixed name resolution of columns of reduced subqueries in unions. (Bug#745)

Fixed memory overrun in subqueries in select list with WHERE clause bigger than outer query WHERE clause. (Bug#726)

Fixed a bug that caused MyISAM tables with FULLTEXT indexes created in 4.0.x to be unreadable in 4.1.x.

Fixed a data loss bug in REPAIR TABLE ... USE_FRM when used with tables that contained TIMESTAMP columns and were created in 4.0.x.

Fixed reduced subquery processing in ORDER BY/GROUP BY clauses. (Bug#442)

Fixed name resolution of outer columns of subquery in INSERT/REPLACE statements. (Bug#446)

Fixed bug in marking columns of reduced subqueries. (Bug#679)

Fixed a bug that made CREATE FULLTEXT INDEX syntax illegal.

Fixed a crash when a SELECT that required a temporary table (marked by Using temporary in EXPLAIN output) was used as a derived table in EXPLAIN command. (Bug#251)

Fixed a rare table corruption bug in DELETE from a big table with a new (created by MySQL-4.1) full-text index.

LAST_INSERT_ID() now returns 0 if the last INSERT statement didn't insert any rows.

Fixed missing last character in function output. (Bug#447)

Fixed a rare replication bug when a transaction spanned two or more relay logs, and the slave was stopped while executing the part of the transaction that was in the second or later relay log. Then replication would resume at the beginning of the second or later relay log, which was incorrect. (It should resume at BEGIN, in the first relay log.) (Bug#53)

CONNECTION_ID() now is properly replicated. (Bug#177)

The new PASSWORD() function in 4.1 is now properly replicated. (Bug#344)

Fixed a bug with double freed memory.

Fixed a crashing bug in UNION operations that involved temporary tables.

Fixed a crashing bug in DERIVED TABLES when EXPLAIN is used on a DERIVED TABLES with a join.

Fixed a crashing bug in DELETE with ORDER BY and LIMIT caused by an uninitialized array of reference pointers.

Fixed a bug in the USER() function caused by an error in the size of the allocated string.

Fixed a crashing bug when attempting to create a table containing a spatial (GIS) column with a storage engine that does not support spatial types.

Fixed a crashing bug in UNION caused by the empty select list and a non-existent column being used in some of the individual SELECT statements.

Fixed a replication bug with a 3.23 master and a 4.0 slave: The slave lost the replicated temporary tables if FLUSH LOGS was issued on the master. (Bug#254)

Fixed a security bug: A server compiled without SSL support still allowed connections by users that had the REQUIRE SSL option specified for their accounts.

When an undefined user variable was used in a updating query on the master (such as INSERT INTO t VALUES(@a), where @a had never been set by this connection before), the slave could replicate the query incorrectly if a previous transaction on the master used a user variable of the same name. (Bug#1331)

Fixed bug with prepared statements: Using the ? prepared statement parameter as the argument to certain functions or statement clauses caused a server crash when mysql_prepare() was invoked. (Bug#1500)

Fixed bug with prepared statements: after call to mysql_stmt_prepare placeholders became allowed in all consequent statements, even if they are not prepared (Bug#1946)