MySQL Cluster: More informative error messages are provided when a query is issued against an NDB table that has been modified by another mysqld server. (Bug#6762)

InnoDB: When foreign_key_checks = 0, ALTER TABLE and RENAME TABLE will ignore any type incompatibilities between referencing and referenced columns. Thus, it will be possible to convert the character sets of columns that participate in a foreign key. Be sure to convert all tables before modifying any data! (Bug#9802)

SHOW VARIABLES no longer displays the deprecated log_update system variable. (Bug#9738)

Added support for the BIT data type to the MEMORY, InnoDB, and BDB storage engines.

The behavior controlled by the --innodb-fast-shutdown option now can be changed at runtime by setting the value of the global innodb_fast_shutdown system variable. It now accepts values 0, 1 and 2 (except on Netware where 2 is disabled). If set to 2, then when the MySQL server shuts down, InnoDB will just flush its logs and shut down brutally (and quickly) as if a MySQL crash had occurred; no committed transaction will be lost, but a crash recovery will be done at next startup.

Security Fix: Starting mysqld with --user=non_existent_user caused it to run using the privileges of the account from which it was invoked, including the root account. (Bug#9833)

A memory leak occurred when selecting from a view that contained a subquery. (Bug#10107)

Setting the storage_engine system variable to MEMORY succeeded, but retrieving the variable resulted in a value of HEAP (the old name for the MEMORY storage engine) rather than MEMORY. (Bug#10039)

Queries containing CURRENT_USER() incorrectly were registered in the query cache. (Bug#9796)

Invoking a stored function that returned a value having an ENUM or SET data type caused the server to crash. (Bug#9775)

A string length comparison problem caused mysql to fail when loading dump files containing certain escape sequences containing a backslash character (\). (Bug#9756)

After an internal temporary table became too large in memory and had to be converted to an on-disk table, the error indicator was not cleared and the query failed with error 1023 Can't find record in ''. (Bug#9703)

Use of a subquery that used WITH ROLLUP in the FROM clause of the main query sometimes resulted in a Column cannot be null error. (Bug#9681)

InnoDB: Assertion failures of types ut_a(cursor->old_stored == BTR_PCUR_OLD_STORED) and prebuilt->template_type == 0 could occur when performing multi-table updates. This bug was introduced in 4.1.10 and 4.0.24. (Bug#9670)

A problem with readlinecaused the mysql client to crash when the user pressed Control-R.. (Bug#9568)

Executing LOCK TABLES and then calling a stored procedure caused an error and resulting in the server thinking that no stored procedures exist. (Bug#9566)

The server died with signal 11 if a nonexistent location was specified for the location of the binary log. Now the server exits after printing an appropriate error message. (Bug#9542)

Incorrect results were returned for queries of the form SELECT ... LEFT JOIN ... WHERE EXISTS (subquery), where the subquery selected rows based on an IS NULL condition. (Bug#9516)

A segmentation fault in mysqlcheck occurred when the last table checked in --auto-repair mode returned an error (such as the table being a MERGE table). (Bug#9492)

Within a stored procedure, attempting to execute a multiple-table UPDATE failed with a Table 'tbl_name' was locked with a READ lock and can't be updated error. (Bug#9486)

mysqlshow displayed an incorrect row count for tables. (Bug#9391)

InnoDB: Next-key locking did not allow inserts which did not produce a “phantom”. If the range is of type 'a' <= uniquecolumn, InnoDB lock only the RECORD, if the record with the column value 'a' exists in a CLUSTERED index. This allows inserts before a range. (Bug#9354)

The optimizer did not compute the union of two ranges for the OR operator correctly. (Bug#9348)

Corrected a failure to resolve a column reference correctly for a LEFT JOIN that compared a join column to an IN subquery. (Bug#9338)

OPTIMIZE TABLE was written twice to the binary log when used on InnoDB tables. (Bug#9149)

Multiple-table updates could produce spurious data-truncation warnings if they used a join across columns that are indexed using a column prefix. (Bug#9103)

Invocation of a stored function that returned a value having a BLOB data type caused the server to crash. (Bug#9102)

For stored functions that should return a YEAR value, corrected a failure of the value to be in YEAR format. (Bug#8861)

Selecting from a view containing a subquery caused the server to hang. (Bug#8490)

TIMEDIFF() with a negative time first argument and positive time second argument produced incorrect results. (Bug#8068)

Invocation of a stored function that returned a value having a BIT data type caused the server to crash. (Bug#7648)

SET @var= CAST(NULL AS [INTEGER|CHAR]) now sets the result type of the variable to INTEGER/CHAR. (Bug#6598)

The client/server protocol allowed the server to close the connection before sending the final error message. The problem could show up as a Lost connection to MySQL server error during a query when attempting to connect and access a nonexistent database. (Bug#6387, Bug#9455)

Column references were not properly resolved when an outer join involving a view contained a subquery and the column was used both in the subquery and the outer query. (Bug#6107, Bug#6106)

InnoDB: Prevent ALTER TABLE from changing the storage engine if there are foreign key constraints on the table. (Bug#5574, Bug#5670)