The handling of BIT columns has been improved, and should now be much more reliable in a number of cases. (Bug#11572, Bug#11091, Bug#10617)

Recursion in stored routines is now disabled because it was crashing the server. We plan to modify stored routines to allow this to operate safely in a future release. (Bug#11394)

An attempt to create a TIMESTAMP column with a display width (for example, TIMESTAMP(6)) now results in a warning. Display widths have not been supported for TIMESTAMP since MySQL 4.1. (Bug#10466)

mysql_real_escape_string() API function now respects NO_BACKSLASH_ESCAPES SQL mode. (Bug#10214)

InnoDB: Made CHECK TABLE killable. (Bug#9730)

InnoDB: Make innodb_thread_concurrency = 20 by default. Bypass the concurrency checking if the setting is greater than or equal to 20.

InnoDB: Various optimizations. Removed unreachable debug code from nondebug builds. Added hints for the branch predictor in gcc. Made assertions occupy less space.

InnoDB: When creating or extending an InnoDB data file, at most one megabyte at a time is allocated for initializing the file. Previously, InnoDB allocated and initialized 1 or 8 megabytes of memory, even if only a few 16-kilobyte pages were to be written. This improves the performance of CREATE TABLE in innodb_file_per_table mode.

MySQL Cluster: When trying to open a table that could not be discovered or unpacked, the cluster returned error codes which the MySQL server falsely interpreted as operating system errors. (Bug#10365)

The --master-data option for mysqldump resulted in no error if the binary log was not enabled. Now an error occurs unless the --force option is given. (Bug#11678)

When a table had a primary key containing a BLOB column, creation of another index failed with the error BLOB/TEXT column used in key specification without keylength, even when the new index did not contain a BLOB column. (Bug#11657)

Incorrect results when using GROUP BY ... WITH ROLLUP on a VIEW. (Bug#11639)

MySQL would not compile correctly on QNX due to missing rint() function. (Bug#11544)

A SELECT DISTINCT col_name would work correctly with a MyISAM table only when there was an index on col_name. (Bug#11484)

Using CONCAT_WS() on a column set NOT NULL caused incorrect results when used in a LEFT JOIN. (Bug#11469)

Temporary tables were created in the data directory instead of tmpdir. (Bug#11440)

Running a CHECK TABLES on multiple views crashed the server. (Bug#11337)

Manually inserting a row with host='' into mysql.tables_priv and performing a FLUSH PRIVILEGES would cause the server to crash. (Bug#11330)

Wrong comparison method used in VIEW when relaxed date syntax used (for example, 2005.06.10). (Bug#11325)

Signed BIGINT would not accept -9223372036854775808 as a DEFAULT value. (Bug#11215)

Optimizer performed range check when comparing unsigned integers to negative constants, could cause errors. (Bug#11185)

A cursor using a query with a filter on a DATE or DATETIME column would cause the server to crash server after the data was fetched. (Bug#11172)

The mysql_config script did not handle symbolic linking properly. (Bug#10986)

mysqldump failed when reloading a view if the view was defined in terms of a different view that had not yet been reloaded. mysqldump now creates a dummy table to handle this case. (Bug#10927)

If a prepared statement cursor is opened but not completely fetched, attempting to open a cursor for a second prepared statement will fail. (Bug#10794)

Combining cursors and subqueries could cause server crash or memory leaks. (Bug#10736)

Instances of the VAR_SAMP() function in view definitions were converted to VARIANCE(). This is incorrect because VARIANCE() is the same as VAR_POP(), not VAR_SAMP(). (Bug#10651)

DES_ENCRYPT() and DES_DECRYPT() require SSL support to be enabled, but were not checking for it. Checking for incorrect arguments or resource exhaustion was also improved for these functions. (Bug#10589)

For MEMORY tables, it was possible for updates to be performed using outdated key statistics when the updates involved only very small changes in a very few rows. This resulted in the random failures of queries such as UPDATE t SET col = col + 1 WHERE col_key = 2; where the same query with no WHERE clause would succeed. (Bug#10178)

When used in joins, SUBSTRING() failed to truncate to zero those string values that could not be converted to numbers. (Bug#10124)

Views did not use indexes on all appropriate queries. (Bug#10031)

Closing a cursor that was already closed would cause MySQL to hang. (Bug#9814)

The server would lose table-level CREATE VIEW and SHOW VIEW privileges following a FLUSH PRIVILEGES or server restart. (Bug#9795)

mysqldump --xml did not format NULL column values correctly. (Bug#9657)

The --no-data option for mysqldump was being ignored if table names were given after the database name. (Bug#9558)

Clients would hang following some errors with stored procedures. (Bug#9503)

mysqldump could crash for illegal or nonexistent table names. (Bug#9358)

A compression algorithm issue caused myisampackto fail for very large data sets (where the total size of all records in a single column was on the order of 3 GB or more) on 64-bit platforms. (A fix for other platforms was made in MySQL 5.0.6.) (Bug#8321)

The ENCRYPT() and SUBSTRING_INDEX() functions would cause errors when used with a VIEW. (Bug#7024)

SHOW CREATE VIEW did not take the ANSI SQL mode into account when quoting identifiers. (Bug#6903)

In strict mode, an INSERT into a view that did not include a value for a NOT NULL column but that did include a WHERE test on the same column would succeed, This happened even though the INSERT should have been prevented due to the failure to supply a value for the NOT NULL column. (Bug#6443)