Performance: The query cache now checks whether a SELECT statement begins with SQL_NO_CACHE to determine whether it can skip checking for the query result in the query cache. This is not supported when SQL_NO_CACHE occurs within a comment. (Bug#37416)

The libedit library was upgraded to version 2.11. (Bug#42433)

Performance: For an InnoDB table, DROP TABLE or ALTER TABLE ... DISCARD TABLESPACE could take a long time or cause a server crash. (Bug#39939)

Replication: Server IDs greater than 2147483647 (2³² – 1) were represented by negative numbers in the binary log. (Bug#37313)

Replication: The --replicate-*-table options were not evaluated correctly when replicating multi-table updates.

As a result of this fix, replication of multi-table updates no longer fails when an update references a missing table but does not update any of its columns. (Bug#37051)

Replication: When its disk becomes full, a replication slave may wait while writing the binary log, relay log or MyISAM tables, continuing after space has been made available. The error message provided in such cases was not clear about the frequency with which checking for free space is done (once every 60 seconds), and how long the server waits after space has been freed before continuing (also 60 seconds); this caused users to think that the server had hung.

These issues have been addressed by making the error message clearer, and dividing it into two separate messages:

(Bug#22082)

On 32-bit Windows, mysqld could not use large buffers due to a 2GB user mode address limit. (Bug#43082)

The use by libedit of the __weak_reference() macro caused compilation failure on FreeBSD. (Bug#42817)

Tables could enter open table cache for a thread without being properly cleaned up, leading to a server crash. (Bug#42419)

mysqldumpslow parsed the --debug and --verbose options incorrectly. (Bug#42027)

String reallocation could cause memory overruns. (Bug#41868)

Queries that used the loose index scan access method could return no rows. (Bug#41610)

In InnoDB recovery after a server crash, rollback of a transaction that updated a column from NULL to NULL could cause another crash. (Bug#41571)

If InnoDB reached its limit on the number of concurrent transactions (1023), it wrote a descriptive message to the error log but returned a misleading error message to the client, or an assertion failure occurred. (Bug#41529)

Use of SELECT * allowed users with rights to only some columns of a view to access all columns. (Bug#41354)

The server did not robustly handle problems hang if a table opened with HANDLER needed to be re-opened because it had been altered to use a different storage engine that does not support HANDLER. The server also failed to set an error if the re-open attempt failed. These problems could cause the server to crash or hang. (Bug#41110, Bug#41112)

For prepared statements, multibyte character sets were not taking into account when calculating max_length for string values and mysql_stmt_fetch() could return truncated strings. (Bug#41078)

The mysql_change_user() C API function changed the value of the sql_big_selects session variable. (Bug#40363)

See also Bug#20023.

For a view that references a table in another database, mysqldump wrote the view name qualified with the current database name. This makes it impossible to reload the dump file into a different database. (Bug#40345)

perror did not produce correct output for error codes 153 to 163. (Bug#39370)

Comparisons between row constructors, such as (a, b) = (c, d) resulted in unnecessary Illegal mix of collations errors for string columns. (Bug#37601)

An argument to the MATCH() function that was an alias for an expression other than a column name caused a server crash. (Bug#36737)

For DROP FUNCTION with names that were qualified with a database name, the database name was handled in case-sensitive fashion even with lower_case_table_names set to 1. (Bug#33813)

mysqldump --compatible=mysql40 emitted statements referring to the character_set_client system variable, which is unknown before MySQL 4.1. Now the statements are enclosed in version-specific comments. (Bug#33550)

Use of MBR spatial functions such as MBRTouches() with columns of InnoDB tables caused a server crash rather than an error. (Bug#31435)

The mysql client mishandled input parsing if a delimiter command was not first on the line. (Bug#31060)

For installation on Solaris using pkgadd packages, the mysql_install_db script was generated in the scripts directory, but the temporary files used during the process were left there and not deleted. (Bug#31052)

SHOW PRIVILEGES listed the CREATE ROUTINE privilege as having a context of Functions,Procedures, but it is a database-level privilege. (Bug#30305)

SHOW TABLE STATUS could fail to produce output for tables with non-ASCII characters in their name. (Bug#25830)

Floating-point numbers could be handled with different numbers of digits depending on whether the text or prepared-statement protocol was used. (Bug#21205)

Incorrect length metadata could be returned for LONG TEXT columns when a multibyte server character set was used. (Bug#19829)

ROUND() sometimes returned different results on different platforms. (Bug#15936)