Incompatible Change: The number of function names affected by IGNORE_SPACE was reduced significantly in MySQL 5.1.13, from about 200 to about 30. (For details about IGNORE_SPACE, see Function Name Parsing and Resolution.) This change improves the consistency of parser operation. However, it also introduces the possibility of incompatibility for old SQL code that relies on the following conditions:

For functions that are no longer affected by IGNORE_SPACE as of MySQL 5.1.13, that strategy no longer works. Either of the following approaches can be used if you have code that is subject to the preceding incompatibility:

(Bug #21114)

Incompatible Change: The innodb_buffer_pool_awe_mem_mb system variable has been removed and should no longer be used.

MySQL Cluster: A change in the interfaces for the INFORMATION_SCHEMA.FILES table has made the table accessible to storage engines other than NDB. (Bug #23013)

mysql_upgrade now passes all the parameters specified on the command line to both mysqlcheck and mysql using the upgrade_defaults file. (Bug #20100)

If the user specified the server options --max-connections=N or --table-open-cache=M , a warning would be given in some cases that some values were recalculated, with the result that --table-open-cache could be assigned greater value.

In such cases, both the warning and the increase in the --table-open-cache value were completely harmless. Note also that it is not possible for the MySQL Server to predict or to control limitations on the maximum number of open files, since this is determined by the operating system.

The value of --table-open-cache is no longer increased automatically, and a warning is now given only if some values had to be decreased due to operating system limits. (Bug #21915)

For the CALL statement, stored procedures that take no arguments now can be invoked without parentheses. That is, CALL p() and CALL p are equivalent. (Bug #21462)

mysqldump --single-transaction now uses START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */ rather than BEGIN to start a transaction, so that a consistent snapshot will be used on those servers that support it. (Bug #19660)

Binary distributions of MySQL 5.1.12 were built without support for partitioning. This has been corrected except for NetWare. (Bug #23949)

Performance: InnoDB showed substandard performance with multiple queries running concurrently. (Bug #15815)

Important Change: When installing MySQL on AIX 5.3, you must upgrade AIX to technology level 7 (5300-07) to ensure the required thread libraries are available.

MySQL Cluster: When inserting a row into an NDB table with a duplicate value for a nonprimary unique key, the error issued would reference the wrong key. (Bug #21072)

MySQL Cluster: Multiple node restarts in rapid succession could cause a system restart to fail , or induce a race condition. (Bug #22892, Bug #23210)

MySQL Cluster: Attempting to create a unique constraint with USING HASH on an NDB table caused mysqld to crash. (Bug #21873)

MySQL Cluster: If a node restart could not be performed from the REDO log, no node takeover took place. This could cause partitions to be left empty during a system restart. (Bug #22893)

MySQL Cluster: Aborting a cluster backup too soon after starting it caused a forced shutdown of the data nodes. (Bug #19148)

MySQL Cluster: INSERT ... ON DUPLICATE KEY UPDATE on an NDB table could lead to deadlocks and memory leaks. (Bug #23200)

MySQL Cluster: Backup of a cluster failed if there were any tables with 128 or more columns. (Bug #23502)

MySQL Cluster: The management client command ALL DUMP 1000 would cause the cluster to crash if data nodes were connected to the cluster but not yet fully started. (Bug #23203)

MySQL Cluster: An NDB source file included a memset() call with reversed arguments. (Bug #23169)

MySQL Cluster: Cluster backups failed when there were more than 2048 schema objects in the cluster. (Bug #23499)

MySQL Cluster: Restoring a cluster failed if there were any tables with 128 or more columns. (Bug #23494)

Replication: Transient errors in replication from master to slave may trigger multiple Got fatal error 1236: 'binlog truncated in the middle of event' errors on the slave. (Bug #4053)

Replication: Column names were not quoted properly for replicated views. (Bug #19736)

Disk Data: In the event of an aborted multiple update, the space in the Disk Data log buffer to be freed as a result was actually freed twice, which could eventually lead to a crash. (Bug #23430)

Cluster API: When multiple processes or threads in parallel performed the same ordered scan with exclusive lock and updated the retrieved records, the scan could skip some records, which as a result were not updated. (Bug #20446)

FORMAT(X,D) did not accept a nonconstant value for D. (Bug #48374)

There was a race condition in the InnoDB fil_flush_file_spaces() function. (Bug #24098)

Use of PREPARE with a CREATE PROCEDURE statement that contained a syntax error caused a server crash. (Bug #21856)

The optimizer failed to use equality propagation for BETWEEN and IN predicates with string arguments. (Bug #22753)

Use of a subquery that invoked a function in the column list of the outer query resulted in a memory leak. (Bug #21798)

For a debug server, a reference to an undefined user variable in a prepared statement executed with EXECUTE caused an assertion failure. (Bug #19356)

Several string functions could return incorrect results when given very large length arguments. (Bug #10963)

An unhandled NULL pointer caused a server crash. (Bug #22138)

Incorrect warnings occurred for use of CREATE TABLE ... LIKE or REPAIR TABLE with the log tables. (Bug #21966)

MySQL 5.0.26 introduced an ABI incompatibility, which this release reverts. Programs compiled against 5.0.26 are not compatible with any other version and must be recompiled. (Bug #23427)

If COMPRESS() returned NULL, subsequent invocations of COMPRESS() within a result set or within a trigger also returned NULL. (Bug #23254)

It was not possible to do an atomic rename of the log tables without the possibility of losing rows. Now you can do this:

USE mysql;
CREATE TABLE IF NOT EXISTS general_log2 LIKE general_log;
RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;

(Bug #21785, Bug #17544)

At shutdown, Instance Manager told guarded server instances to stop, but did not wait until they actually stopped. (Bug #17486)

FLUSH INSTANCES in Instance Manager triggered an assertion failure. (Bug #19368)

The return value from my_seek() was ignored. (Bug #22828)

The Host column in SHOW PROCESSLIST output was blank when the server was started with the --skip-grant-tables option. (Bug #22723)

Use of a DES-encrypted SSL certificate file caused a server crash. (Bug #21868)

LIKE searches failed for indexed utf8 character columns. (Bug #20471)

mysqldump --xml produced invalid XML for BLOB data. (Bug #19745)

Entries in the slow query log could have an incorrect Rows_examined value. (Bug #12240)

For not-yet-authenticated connections, the Time column in SHOW PROCESSLIST was a random value rather than NULL. (Bug #23379)

The optimizer used the ref join type rather than eq_ref for a simple join on strings. (Bug #22367)

The Handler_rollback status variable sometimes was incremented when no rollback had taken place. (Bug #22728)

The range analysis optimizer did not take into account predicates for which an index could be used after reading const tables. In some cases this resulted in nonoptimal execution plans. (Bug #19579)

OPTIMIZE TABLE with myisam_repair_threads > 1 could result in MyISAM table corruption. (Bug #8283)

WITH ROLLUP could group unequal values. (Bug #20825)

yaSSL-related memory leaks were detected by Valgrind. (Bug #23981)

Lack of validation for input and output TIME values resulted in several problems: SEC_TO_TIME() in some cases did not clip large values to the TIME range appropriately; SEC_TO_TIME() treated BIGINT UNSIGNED values as signed; only truncation warnings were produced when both truncation and out-of-range TIME values occurred. (Bug #11655, Bug #20927)

M % 0 returns NULL, but ( M % 0) IS NULL evaluated to false. (Bug #23411)

Insufficient memory (myisam_sort_buffer_size) could cause a server crash for several operations on MyISAM tables: repair table, create index by sort, repair by sort, parallel repair, bulk insert. (Bug #23175)

If an init_connect SQL statement produced an error, the connection was silently terminated with no error message. Now the server writes a warning to the error log. (Bug #22158)

Some queries that used MAX() and GROUP BY could incorrectly return an empty result. (Bug #22342)

The server did not allocate sufficient memory for some queries for which a DISTINCT to GROUP BY conversion is possible and an ORDER BY clause is present, resulting in a server crash. (Bug #20503)

With sql_mode = TRADITIONAL, MySQL incorrectly aborted on warnings within stored routines and triggers. (Bug #20028)

DELETE IGNORE could hang for foreign key parent deletes. (Bug #18819)

MySQL failed to build on Linux/Alpha. (Bug #23256)

References: This bug was introduced by Bug #21250.

ALTER TABLE was not able to rename a view. (Bug #14959)

FROM_UNIXTIME() did not accept arguments up to POWER(2,31)-1, which it had previously. (Bug #9191)

mysql-test-run did not work correctly for RPM-based installations. (Bug #17194)

A literal string in a GROUP BY clause could be interpreted as a column name. (Bug #14019)

Within a prepared statement, SELECT (COUNT(*) = 1) (or similar use of other aggregate functions) did not return the correct result for statement re-execution. (Bug #21354)

InnoDB crashed when trying to display an error message about a foreign key constraint violation when the two tables are in different schemas. (Bug #23368)

Use of SQL_BIG_RESULT did not influence the sort plan for query execution. (Bug #22781)

The column default value in the output from SHOW COLUMNS or SELECT FROM INFORMATION_SCHEMA.COLUMNS was truncated to 64 characters. (Bug #23037)

The value of the warning_count system variable was not being calculated correctly (also affecting SHOW COUNT(*) WARNINGS). (Bug #19024)

In mysql, invoking connect or \r with very long db_name or host_name parameters caused buffer overflow. (Bug #20894)

A client library crash was caused by executing a statement such as SELECT * FROM t1 PROCEDURE ANALYSE() using a server side cursor on a table t1 that does not have the same number of columns as the output from PROCEDURE ANALYSE(). (Bug #17039)

InnoDB used table locks (not row locks) within stored functions. (Bug #18077)

Within a trigger for a base table, selecting from a view on that base table failed. (Bug #19111)

mysql did not check for errors when fetching data during result set printing. (Bug #22913)

The optimizer sometimes mishandled R-tree indexes for GEOMETRY data types, resulting in a server crash. (Bug #21888)

Within a stored routine, a view definition cannot refer to routine parameters or local variables. However, an error did not occur until the routine was called. Now it occurs during parsing of the routine creation statement.

(Bug #20953)

Statements such as DROP PROCEDURE and DROP VIEW were written to the binary log too late due to a race condition. (Bug #14262)

Range searches on columns with an index prefix could miss records. (Bug #20732)

If a table contains an AUTO_INCREMENT column, inserting into an insertable view on the table that does not include the AUTO_INCREMENT column should not change the value of LAST_INSERT_ID(), because the side effects of inserting default values into columns not part of the view should not be visible. MySQL was incorrectly setting LAST_INSERT_ID() to zero. (Bug #22584)

mysql would lose its connection to the server if its standard output was not writable. (Bug #17583)

The WITH CHECK OPTION for a view failed to prevent storing invalid column values for UPDATE statements. (Bug #16813)

Adding a day, month, or year interval to a DATE value produced a DATE, but adding a week interval produced a DATETIME value. Now all produce a DATE value. (Bug #21811)