The SCHEMA and SCHEMAS keywords now are accepted as synonyms for DATABASE and DATABASES.

Added initial support for rudimentary triggers.

Added basic support for read-only server side cursors.

Added --start-datetime, --stop-datetime, --start-position, --stop-position options to mysqlbinlog (makes point-in-time recovery easier).

Made the MySQL server not react to signals SIGHUP and SIGQUIT on Mac OS X 10.3. This is needed because under this OS, the MySQL server receives lots of these signals (reported as Bug #2030).

New --auto-increment-increment and --auto-increment-offset startup options. These allow you to set up a server to generate auto-increment values that don't conflict with another server.

MySQL now by default will check dates and only allow fully correct dates. If you want to MySQL to behave as default, you should enable the new ALLOW_INVALID_DATES SQL mode.

Added STRICT_TRANS_TABLES, STRICT_ALL_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, and TRADITIONAL SQL modes. The TRADITIONAL mode is shorthand for all the preceding modes. When using mode TRADITIONAL, MySQL generates an error if you try to insert a wrong value in a column. It does not adjust the value to the closest possible legal value.

MySQL now remembers which columns were declared to have default values. In STRICT_TRANS_TABLES/STRICT_ALL_TABLES mode, you now get an error if you do an INSERT without specifying all columns that don't have a default value. A side effect of this is that when you do SHOW CREATE for a new table, you will no longer see a DEFAULT value for a column for which you didn't specify a default value.

The compilation flag DONT_USE_DEFAULT_FIELDS was removed because you can get the same behavior by setting the sql_mode system variable to STRICT_TRANS_TABLES.

We now detect too-large floating point numbers during statement parsing and generate an error messages for them.

Renamed the sql_updatable_view_key system variable to updatable_views_with_limit. This variable now can have only two values:

Reverted output format of SHOW TABLES to old pre-5.0.1 format that did not include a table type column. To get the additional column that lists the table type, use SHOW FULL TABLES now.

The mysql_fix_privilege_tables script now initializes the global CREATE VIEW and SHOW VIEW privileges in the user table to the value of the CREATE privilege in that table.

If the server finds that the user table has not been upgraded to include the view-related privilege columns, it treats each account as having view privileges that are the same as its CREATE privilege.

Fixed that mysqlbinlog --read-from-remote-server sometimes couldn't accept two binary logfiles on the command line. (Bug #4507)

Fixed that mysqlbinlog --position --read-from-remote-server had incorrect # at lines. (Bug #4506)

Fixed that CREATE TABLE ... TYPE=HEAP ... AS SELECT... caused replication slave to stop. (Bug #4971)

Fixed that mysql_options(...,MYSQL_OPT_LOCAL_INFILE,...) failed to disable LOAD DATA LOCAL INFILE. (Bug #5038)

Fixed that disable-local-infile option had no effect if client read it from a configuration file using mysql_options(...,MYSQL_READ_DEFAULT,...). (Bug #5073)

Fixed that SET GLOBAL SYNC_BINLOG did not work on some platforms (Mac OS X). (Bug #5064)

Fixed that mysql-test-run failed on the rpl_trunc_binlog test if running test from the installed (the target of 'make install') directory. (Bug #5050)

Fixed that mysql-test-run failed on the grant_cache test when run as Unix user 'root'. (Bug #4678)

Fixed an unlikely deadlock which could happen when using KILL. (Bug #4810)

Fixed a crash when one connection got KILLed while it was doing START SLAVE. (Bug #4827)

Made FLUSH TABLES WITH READ LOCK block COMMIT if server is running with binary logging; this ensures that the binary log position can be trusted when doing a full backup of tables and the binary log. (Bug #4953)

Fixed that the counter of an auto_increment column was not reset by TRUNCATE TABLE is the table was a temporary one. (Bug #5033)

Fixed slave SQL thread so that the SET COLLATION_SERVER... statements it replicates don't advance its position (so that if it gets interrupted before the actual update query, it will later redo the SET). (Bug #5705)

Fixed that if the slave SQL thread found a syntax error in a query (which should be rare, as the master parsed it successfully), it stops. (Bug #5711)

Fixed that if a write to a MyISAM table fails because of a full disk or an exceeded disk quota, it prints a message to the error log every 10 minutes, and waits until disk becomes free. (Bug #3248)

Fixed problem introduced in 4.0.21 where a connection starting a transaction, doing updates, then FLUSH TABLES WITH READ LOCK, then COMMIT, would cause replication slaves to stop complaing about error 1223. Bug surfaced when using the InnoDB innobackup script. (Bug #5949)

Added support for read-only and updatable views based on a single table or other updatable views. View use requires that you upgrade your grant tables to add the view-related privileges. See the section called “Upgrading the Grant Tables”.

Implemented a new “greedy search” optimizer that can significantly reduce the time spent on query optimization for some many-table joins. (You are affected if not only some particular SELECT is slow, but even using EXPLAIN for it takes a noticeable amount of time.) Two new system variables, optimizer_search_depth and optimizer_prune_level, can be used to fine-tune optimizer behavior.

Warning: Incompatible change! C API change: mysql_shutdown() now requires a second argument. This is a source-level incompatibility that affects how you compile client programs; it does not affect the ability of compiled clients to communicate with older servers. See mysql_shutdown().

A stored procedure is no longer “global.” That is, it now belongs to a specific database:

See Chapter 20, Stored Procedures and Functions.

Fixed SHOW TABLES output field name and values according to standard. Field name changed from Type to table_type, values are BASE TABLE, VIEW and ERROR. (Bug #4603)

Added the sql_updatable_view_key system variable.

Added the --replicate-same-server-id server option.

Added Last_query_cost status variable that reports optimizer cost for last compiled query.

Added the --to-last-log option to mysqlbinlog, for use in conjunction with --read-from-remote-server.

Added the --innodb-safe-binlog server option, which adds consistency guarantees between the content of InnoDB tables and the binary log. See the section called “The Binary Log”.

OPTIMIZE TABLE for InnoDB tables is now mapped to ALTER TABLE instead of ANALYZE TABLE.

sync_frm is now a settable global variable (not only a startup option).

For replication of MEMORY (HEAP) tables: Made the master automatically write a DELETE FROM statement to its binary log when a MEMORY table is opened for the first time since master's startup. This is for the case where the slave has replicated a non-empty MEMORY table, then the master is shut down and restarted: the table is now empty on master; the DELETE FROM empties it on slave too. Note that even with this fix, between the master's restart and the first use of the table on master, the slave still has out-of-date data in the table. But if you use the --init-file option to populate the MEMORY table on the master at startup, it ensures that the failing time interval is zero. (Bug #2477)

When a session having open temporary tables terminates, the statement automatically written to the binary log is now DROP TEMPORARY TABLE IF EXISTS instead of DROP TEMPORARY TABLE, for more robustness.

The MySQL server now returns an error if SET SQL_LOG_BIN is issued by a user without the SUPER privilege (in previous versions it just silently ignored the statement in this case).

Changed that when the MySQL server has binary logging disabled (that is, no --log-bin option was used), then no transaction binary log cache is allocated for connections. This should save binlog_cache_size bytes of memory (32KB by default) for every connection.

Added the sync_binlog=N global variable and startup option, which makes the MySQL server synchronize its binary log to disk (fdatasync()) after every Nth write to the binary log.

Changed the slave SQL thread to print less useless error messages (no more message duplication; no more messages when an error is skipped because of slave-skip-errors).

DROP DATABASE IF EXISTS, DROP TABLE IF EXISTS, single-table DELETE, and single-table UPDATE now are written to the binary log even if they changed nothing on the master (for example, even if a DELETE matched no rows). The old behavior sometimes caused bad surprises in replication setups.

Replication and mysqlbinlog now have better support for the case that the session character set and collation variables are changed within a given session. See the section called “Replication Features and Known Problems”.

Killing a CHECK TABLE statement does not result in the table being marked as “corrupted” any more; the table remains as if CHECK TABLE had not even started. See KILL.

Strange results with index (x, y) ... WHERE x=val_1 AND y>=val_2 ORDER BY pk; (Bug #3155)

Subquery and order by (Bug #3118)

ALTER DATABASE caused the client to hang if the database did not exist. (Bug #2333)

SLAVE START (which is a deprecated syntax, START SLAVE should be used instead) could crash the slave. (Bug #2516)

Multiple-table DELETE statements were never replicated by the slave if there were any --replicate-*-table options. (Bug #2527)

The MySQL server did not report any error if a statement (submitted through mysql_real_query() or mysql_stmt_prepare()) was terminated by garbage characters. This can happen if you pass a wrong length parameter to these functions. The result was that the garbage characters were written into the binary log. (Bug #2703)

Replication: If a client connects to a slave server and issues an administrative statement for a table (for example, OPTIMIZE TABLE or REPAIR TABLE), this could sometimes stop the slave SQL thread. This does not lead to any corruption, but you must use START SLAVE to get replication going again. (Bug #1858)

Made clearer the error message that one gets when an update is refused because of the --read-only option. (Bug #2757)

Fixed that --replicate-wild-*-table rules apply to ALTER DATABASE when the table pattern is %, as is already the case for CREATE DATABASE and DROP DATABASE. (Bug #3000)

Fixed that when a Rotate event is found by the slave SQL thread in the middle of a transaction, the value of Relay_Log_Pos in SHOW SLAVE STATUS remains correct. (Bug #3017)

Corrected the master's binary log position that InnoDB reports when it is doing a crash recovery on a slave server. (Bug #3015)

Changed the column Seconds_Behind_Master in SHOW SLAVE STATUS to never show a value of −1. (Bug #2826)

Changed that when a DROP TEMPORARY TABLE statement is automatically written to the binary log when a session ends, the statement is recorded with an error code of value zero (this ensures that killing a SELECT on the master does not result in a superfluous error on the slave). (Bug #3063)

Changed that when a thread handling INSERT DELAYED (also known as a delayed_insert thread) is killed, its statements are recorded with an error code of value zero (killing such a thread does not endanger replication, so we thus avoid a superfluous error on the slave). (Bug #3081)

Fixed deadlock when two START SLAVE commands were run at the same time. (Bug #2921)

Fixed that a statement never triggers a superfluous error on the slave, if it must be excluded given the --replicate-* options. The bug was that if the statement had been killed on the master, the slave would stop. (Bug #2983)

The --local-load option of mysqlbinlog now requires an argument.

Fixed a segmentation fault when running LOAD DATA FROM MASTER after RESET SLAVE. (Bug #2922)

mysqlbinlog --read-from-remote-server read all binary logs following the one that was requested. It now stops at the end of the requested file, the same as it does when reading a local binary log. There is an option --to-last-log to get the old behavior. (Bug #3204)

Fixed mysqlbinlog --read-from-remote-server to print the exact positions of events in the "at #" lines. (Bug #3214)

Fixed a rare error condition that caused the slave SQL thread spuriously to print the message Binlog has bad magic number and stop when it was not necessary to do so. (Bug #3401)

Fixed mysqlbinlog not to forget to print a USE statement under rare circumstances where the binary log contained a LOAD DATA INFILE statement. (Bug #3415)

Fixed a memory corruption when replicating a LOAD DATA INFILE when the master had version 3.23. (Bug #3422)

Multiple-table DELETE statements were always replicated by the slave if there were some --replicate-*-ignore-table options and no --replicate-*-do-table options. (Bug #3461)

Fixed a crash of the MySQL slave server when it was built with --with-debug and replicating itself. (Bug #3568)

Fixed that in some replication error messages, a very long query caused the rest of the message to be invisible (truncated), by putting the query last in the message. (Bug #3357)

If server-id was not set using startup options but with SET GLOBAL, the replication slave still complained that it was not set. (Bug #3829)

mysql_fix_privilege_tables didn't correctly handle the argument of its --password=# option. (Bug #4240)

Fixed potential memory overrun in mysql_real_connect() (which required a compromised DNS server and certain operating systems). (Bug #4017)

During the installation process of the server RPM on Linux, mysqld was run as the root system user, and if you had --log-bin=<somewhere_out_of_var_lib_mysql> it created binary log files owned by root in this directory, which remained owned by root after the installation. This is now fixed by starting mysqld as the mysql system user instead. (Bug #4038)

Made DROP DATABASE honor the value of lower_case_table_names. (Bug #4066)

The slave SQL thread refused to replicate INSERT ... SELECT if it examined more than 4 billion rows. (Bug #3871)

mysqlbinlog didn't escape the string content of user variables, and did not deal well when these variables were in non-ASCII character sets; this is now fixed by always printing the string content of user variables in hexadecimal. The character set and collation of the string is now also printed. (Bug #3875)

Fixed incorrect destruction of expression that led to a server crash on complex AND/OR expressions if query was ignored (either by a replication server because of --replicate-*-table rules, or by any MySQL server because of a syntax error). (Bug #3969, Bug #4494)

If CREATE TEMPORARY TABLE t SELECT failed while loading the data, the temporary table was not dropped. (Bug #4551)

Fixed that when a multiple-table DROP TABLE failed to drop a table on the master server, the error code was not written to the binary log. (Bug #4553)

When the slave SQL thread was replicating a LOAD DATA INFILE statement, it didn't show the statement in the output of SHOW PROCESSLIST. (Bug #4326)

The KILL statement now takes CONNECTION and QUERY modifiers. The first is the same as KILL with no modifier (it kills a given connection thread). The second kills only the statement currently being executed by the connection.

Added TIMESTAMPADD() and TIMESTAMPDIFF() functions.

Added WEEK and QUARTER values as INTERVAL arguments for the DATE_ADD() and DATE_SUB() functions.

New binary log format that enables replication of these session variables: sql_mode, SQL_AUTO_IS_NULL, FOREIGN_KEY_CHECKS (which was already replicated since 4.0.14, but here it's done more efficiently and takes less space in the binary logs), UNIQUE_CHECKS. Other variables (like character sets, SQL_SELECT_LIMIT, ...) will be replicated in upcoming 5.0.x releases.

Implemented Index Merge optimization for OR clauses. See the section called “Index Merge Optimization”.

Basic support for stored procedures (SQL:2003 style). See Chapter 20, Stored Procedures and Functions.

Added SELECT INTO list_of_vars, which can be of mixed (that is, global and local) types. See SELECT INTO Statement.

Easier replication upgrade (5.0.0 masters can read older binary logs and 5.0.0 slaves can read older relay logs). See the section called “Replication Compatibility Between MySQL Versions” for more details). The format of the binary log and relay log is changed compared to that of MySQL 4.1 and older.

Important note: If you upgrade to MySQL 4.1.1 or higher, it is difficult to downgrade back to 4.0 or 4.1.0! That is because, for earlier versions, InnoDB is not aware of multiple tablespaces.