Incompatible change: The following conditions apply to enabling the read_only system variable:

Previously, the attempt to enable read_only would return immediately even if explicit locks or transactions were pending, so some data changes could occur for statements executing in the server at the same time. (Bug#11733, Bug#22009)

Incompatible change: Previously, the DATE_FORMAT() function returned a binary string. Now it returns a string with a character set and collation given by character_set_connection and collation_connection so that it can return month and weekday names containing non-ASCII characters. (Bug#22646)

Important: When using MERGE tables the definition of the MERGE table and the MyISAM tables are checked each time the tables are opened for access (including any SELECT or INSERT statement. Each table is compared for column order, types, sizes and associated. If there is a difference in any one of the tables then the statement will fail.

Remote servers for use with the FEDERATED storage engine now can be managed with the new CREATE/ALTER/DROP SERVER syntax.

The --skip-thread-priority option now is enabled by default for binary Mac OS X distributions. Use of thread priorities degrades performance on Mac OS X. (Bug#18526)

Added the --disable-grant-options option to configure. If configure is run with this option, the --bootstrap, --skip-grant-tables, and --init-file options for mysqld are disabled and cannot be used. For Windows, the configure.js script recognizes the DISABLE_GRANT_OPTIONS flag, which has the same effect.

Partitioning of tables using the FEDERATED storage engine is no longer permitted. Attempting to create such a table or to modify an existing table so that is uses both partitioning and FEDERATED now fails with an error. (Bug#22451)

In MySQL 5.1, InnoDB rolls back only the last statement on a transaction timeout. A new option, --innodb_rollback_on_timeout, causes InnoDB to abort and roll back the entire transaction if a transaction timeout occurs (the same behavior as in MySQL 4.1). (Bug#24200)

The Com_create_user status variable was added (for counting CREATE USER statements). (Bug#22958)

The --memlock option relies on system calls that are unreliable on some operating systems. If a crash occurs, the server now checks whether --memlock was specified and if so issues some information about possible workarounds. (Bug#22860)

The default value of the max_connections variable has been increased to 151 in order that Websites running on Apache and using MySQL will not have more processes trying to access MySQL than the default number of connections available.

(The maximum number of Apache processes is determined by the Apache MaxClient, which defaults to 256, but is usually set to 150 in the httpd.conf commonly distributed with Apache. For more information about MaxClient, see http://httpd.apache.org/docs/2.2/mod/mpm_common.html#maxclients.)

(Bug#23883)

The bundled yaSSL library was upgraded to version 1.5.0.

Calling a non-deterministic stored routine when using statement-based replication now throws an error. Formerly, defining such a stored routine would cause an error to be thrown. (Bug#16456)

The (undocumented) UNIQUE_USERS() and and GROUP_UNIQUE_USERS() functions were removed. (Bug#22687)

NDB Cluster: The LockPagesInMainMemory configuration parameter has changed its type and possible values. For more information, see LockPagesInMainMemory. (Bug#25686)

Important: The values true and false are no longer accepted for this parameter. If you were using this parameter and had it set to false in a previous release, you must change it to 0. If you had this parameter set to true, you should instead use 1 to obtain the same behavior as previously, or 2 to take advantage of new functionality introduced with this release described in the section cited above.

mysqld_multi and mysqlaccess looked for option files in /etc even if the --sysconfdir option for configure had been given to specify a different directory. (Bug#24780)

SHOW COLUMNS reported some NOT NULL columns as NULL. (Bug#22377)

Attempts to access a MyISAM table with a corrupt column definition caused a server crash. (Bug#24401)

mysqltest_embedded crashed at startup. (Bug#25890)

Accessing a fixed record format table with a crashed key definition results in server/myisamchk segmentation fault. (Bug#24855)

When opening a corrupted .frm file during a query, the server crashes. (Bug#24358)

If there was insufficient memory to store or update a blob record in a MyISAM table then the table will marked as crashed. (Bug#23196)

When updating a table that used a JOIN of the table itself (for example, when building trees) and the table was modified on one side of the expression, the table would either be reported as crashed or the wrong rows in the table would be updated. (Bug#21310)

When SET PASSWORD was written to the binary log double quotes were included in the statement. If the slave was running in with the sql_mode set to ANSI_QUOTES the event would fail and halt the replication process. (Bug#24158)

Using CREATE TABLE ... SELECT and rolling back the transaction would leave an empty table on the master, but the instructions would not be recorded in the binary log and therefore replicated to the slave. This would result in a difference between the master and slave databases. An implicit commit has been added to ensure consistency. (Bug#22865)

When reading from the standard input on Windows, mysqlbinlog opened the input in text mode rather than binary mode and consequently misinterpreted some characters such as Control-Z. (Bug#23735)

No warning was issued for use of the DATA DIRECTORY or INDEX DIRECTORY table options on a platform that does not support them. (Bug#17498)

When a prepared statement failed during the prepare operation, the error code was not cleared when it was reused, even if the subsequent use was successful. (Bug#15518)

mysql_upgrade failed when called with a basedir pathname containing spaces. (Bug#22801)

Hebrew-to-Unicode conversion failed for some characters. Definitions for the following Hebrew characters (as specified by the ISO/IEC 8859-8:1999) were added: LEFT-TO-RIGHT MARK (LRM), RIGHT-TO-LEFT MARK (RLM) (Bug#24037)

If there was insufficient memory available to mysqld, this could sometimes cause the server to hang during startup. (Bug#24751)

Using row-based replication to replicate to a table having at least one extra BIT column with a default value on the slave as compared to the master could cause the slave to fail. (Bug#24490)

Optimizations that are legal only for subqueries without tables and WHERE conditions were applied for any subquery without tables. (Bug#24670)

A query using WHERE unsigned_column NOT IN ('negative_value') could cause the server to crash. (Bug#24261)

A FETCH statement using a cursor on a table which was not in the table cache could sometimes cause the server to crash. (Bug#24117)

CREATE TABLE ... SELECT statements were not rolled back correctly. As part of the fix, such a statement now causes an implicit commit before and after it is executed. However, it does not cause a commit when used to create a temporary table. (Bug#22864)

SSL connections could hang at connection shutdown. (Bug#24148)

The STDDEV() function returned a positive value for data sets consisting of a single value. (Bug#22555)

mysqltest incorrectly tried to retrieve result sets for some queries where no result set was available. (Bug#19410)

mysqltest crashed with a stack overflow. (Bug#24498)

The server was built even when configure was run with the --without-server option. (Bug#23973)

mysqld_error.h was not installed when only the client libraries were built. (Bug#21265)

mysql_install_db did not create the mysql.plugin table if strict SQL mode was enabled. (Bug#24270)

The row count for MyISAM tables was not updated properly, causing SHOW TABLE STATUS to report incorrect values. (Bug#23526)

Using a view in combination with a USING clause caused column aliases to be ignored. (Bug#25106)

Using ALTER TABLE to convert a CSV table containing NULL values to MyISAM resulted in warnings. (Bug#21328)

A view was not handled correctly if the SELECT part contained ‘\Z’. (Bug#24293)

Inserting a row into a table without specifying a value for a BINARY(N) NOT NULL column caused the column to be set to spaces, not zeroes. (Bug#14171)

An assertion failed incorrectly for prepared statements that contained a single-row non-correlated subquery that was used as an argument of the IS NULL predicate. (Bug#25027)

A table created with the ROW_FORMAT = FIXED table option loses the option if an index is added or dropped with CREATE INDEX or DROP INDEX. (Bug#23404)

Dropping a user-defined function sometimes did not remove the UDF entry from the mysql.proc table. (Bug#15439)

The BUILD/check-cpu script did not recognize Celeron processors. (Bug#20061)

Some problems uncovered by Valgrind were fixed. (Bug#25396)

mysql_fix_privilege_tables did not handle a password containing embedded space or apostrophe characters. (Bug#17700)

On Windows, the SLEEP() function could sleep too long, especially after a change to the system clock. (Bug#14094, Bug#17635, Bug#24686)

In the INFORMATION_SCHEMA.KEY_COLUMN_USAGE table, the value displayed for the REFERENCED_TABLE_NAME column was the table name as encoded for disk storage, not the actual table name. (Bug#25026)

Changing the value of MI_KEY_BLOCK_LENGTH in myisam.h and recompiling MySQL resulted in a myisamchk that saw existing MyISAM tables as corrupt. (Bug#22119)

A stored routine containing semicolon in its body could not be reloaded from a dump of a binary log. (Bug#20396)

For SET, SELECT, and DO statements that invoked a stored function from a database other than the default database, the function invocation could fail to be replicated. (Bug#19725)

For ENUM columns defined such that enumeration values contained commas, the commas were mapped to 0xff. (Bug#24660)

Upgrade note: The fix for this problem affects tables containing ENUM columns that actually do have 0xff in enumeration values. Such tables should be dumped using mysqldump with the current server before upgrading to MySQL 5.1.15 or higher and reloading the tables.

SET lc_time_names = value allowed only exact literal values, not expression values. (Bug#22647)

Changes to the lc_time_names system variable were not replicated. (Bug#22645)

SELECT ... FOR UPDATE, SELECT ... LOCK IN SHARE MODE, DELETE, and UPDATE statements executed using a full table scan were not releasing locks on rows that did not satisfy the WHERE condition. (Bug#20390)

A stored procedure, executed from a connection using a binary character set, and which wrote multibyte data, would write incorrectly escaped entries to the binary log. This caused syntax errors, and caused replication to fail. (Bug#23619, Bug#24492)

mysqldump --order-by-primary failed if the primary key name was an identifier that required quoting. (Bug#13926)

Re-execution of CREATE DATABASE, CREATE TABLE, and ALTER TABLE statements in stored routines or as prepared statements caused incorrect results. (Bug#22060)

The internal functions for table preparation, creation, and alteration were not re-execution friendly, causing problems in code that: repeatedly altered a table; repeatedly created and dropped a table; opened and closed a cursor on a table, altered the table, and then reopened the cursor. (Bug#4968, Bug#6895, Bug#19182, Bug#19733)

A workaround was implemented to avoid a race condition in the NPTL pthread_exit() implementation. (Bug#24507)

The Instance Manager DROP INSTANCE command did not work. (Bug#23476)

The Instance Manager STOP INSTANCE command took too much time and caused Instance Manager to be unresponsive. (Bug#23215)

The Instance Manager STOP INSTANCE command could not be applied to instances in the Crashed, Failed, or Abandoned state. (Bug#22306)

Instance Manager could crash during shutdown. (Bug#19044)

A deadlock could occur, with the server hanging on Closing tables, with a sufficient number of concurrent INSERT DELAYED, FLUSH TABLES, and ALTER TABLE operations. (Bug#23312)

A user-defined variable could be assigned an incorrect value if a temporary table was employed in obtaining the result of the query used to determine its value. (Bug#16861)

The optimizer removes expressions from GROUP BY and DISTINCT clauses if they happen to participate in expression = constant predicates of the WHERE clause, the idea being that, if the expression is equal to a constant, then it cannot take on multiple values. However, for predicates where the expression and the constant item are of different result types (for example, when a string column is compared to 0), this is not valid, and can lead to invalid results in such cases. The optimizer now performs an additional check of the result types of the expression and the constant; if their types differ, then the expression is not removed from the GROUP BY list. (Bug#15881)

Referencing an ambiguous column alias in an expression in the ORDER BY clause of a query caused the server to crash. (Bug#25427)

Some CASE statements inside stored routines could lead to excessive resource usage or a crash of the server. (Bug#24854, Bug#19194)

Some joins in which one of the joined tables was a view could return erroneous results or crash the server. (Bug#24345)

OPTIMIZE TABLE tried to sort R-tree indexes such as spatial indexes, although this is not possible (see 項12.5.2.5. 「OPTIMIZE TABLE 構文」). (Bug#23578)

User-defined variables could consume excess memory, leading to a crash caused by the exhaustion of resources available to the MEMORY storage engine, due to the fact that this engine is used by MySQL for variable storage and intermediate results of GROUP BY queries. Where SET had been used, such a condition could instead give rise to the misleading error message You may only use constant expressions with SET, rather than Out of memory (Needed NNNNNN bytes). (Bug#23443)

InnoDB: During a restart of the MySQL Server that followed the creation of a temporary table using the InnoDB storage engine, MySQL failed to clean up in such a way that InnoDB still attempted to find the files associated with such tables. (Bug#20867)

Under some circumstances, a REORGANIZE PARTITION statement could crash mysqld. (Bug#24502)

A multi-table DELETE QUICK could sometimes cause one of the affected tables to become corrupted. (Bug#25048)

A compressed MyISAM table that became corrupted could crash myisamchk and possibly the MySQL Server. (Bug#23139)

Using INSTALL PLUGIN followed by a restart of the server caused an error due to memory not being properly initialized. (Bug#22694)

A crash of the MySQL Server could occur when unpacking a BLOB column from a row in a corrupted MyISAM table. This could happen when trying to repair a table using either REPAIR TABLE or myisamchk; it could also happen when trying to access such a 「broken」 row using statements like SELECT if the table was not marked as crashed. (Bug#22053)

The FEDERATED storage engine did not support the euckr character set. (Bug#21556)

The FEDERATED storage engine did not support the utf8 character set. (Bug#17044)

mysql_upgrade failed if the --password (or -p) option was given. (Bug#24896)

For a nonexistent table, DROP TEMPORARY TABLE failed with an incorrect error message if read_only was enabled. (Bug#22077)

The code for generating USE statements for binary logging of CREATE PROCEDURE statements resulted in confusing output from mysqlbinlog for DROP PROCEDURE statements. (Bug#22043)

The REPEAT() function could return NULL when passed a column for the count argument. (Bug#24947)

Accuracy was improved for comparisons between DECIMAL columns and numbers represented as strings. (Bug#23260)

InnoDB crashed while performing XA recovery of prepared transactions. (Bug#21468)

ROW_COUNT() did not work properly as an argument to a stored procedure. (Bug#23760)

It was possible to use DATETIME values whose year, month, and day parts were all zeroes but whose hour, minute, and second parts contained nonzero values, an example of such an illegal DATETIME being '0000-00-00 11:23:45'. (Bug#21789)

It was possible to set the backslash character (「 \ 」) as the delimiter character using DELIMITER, but not actually possible to use it as the delimiter. (Bug#21412)

ALTER ENABLE KEYS or ALTER TABLE DISABLE KEYS combined with another ALTER TABLE option other than RENAME TO did nothing. In addition, if ALTER TABLE was used on a table having disabled keys, the keys of the resulting table were enabled. (Bug#24395)

An ALTER TABLE statement that used a RENAME clause in combination with a MODIFY or CHANGE that did not actually change the table (for example, when it changed a column's type from INT to INT). The behavior caused by this bug differed according to whether or not the storage engine used by the table was transactional or non-transactional. For transactional tables (such as those using the InnoDB storage engine), the statement simply failed; for non-transactional tables (such as those using the MyISAM storage engine), the ALTER TABLE statement succeeding renaming the table, but subsequent SELECT statements against the renamed table would fail. (Bug#22369)

Queries of the form SELECT ... WHERE string = ANY(...) failed when the server used a single-byte character set and the client used a multi-byte character set. (Bug#20835)

A partitioned table that used the DATA DIRECTORY option, where the data directory was the same as the directory in which the table definition file resided, became corrupted following ALTER TABLE ENGINE=ARCHIVE. This was actually due to an issue with the ARCHIVE storage engine, and not with partitioned tables in general. (Bug#22634)

NDB Cluster (Cluster APIs): Deletion of an Ndb_cluster_connection object took a very long time. (Bug#25487)

NDB Cluster (Replication): Certain errors in replication setups could lead to subsequent node failures. (Bug#25755)

NDB Cluster (Replication): Connecting a mysqld to a cluster where not all nodes were running, starting the remaining cluster nodes, and then disconnecting from the cluster caused the mysqld process to crash. (Bug#25387)

NDB Cluster (Replication): Connecting an API node to the cluster during a node restart while performing database operations could cause the restarting node to fail. (Bug#25329)

NDB Cluster (Disk Data): Following 3 or more missed local checkpoints by a cluster node, a restart of the node caused incorrect undo information to be used for Disk Data tables. (Bug#25636)

NDB Cluster (Disk Data): Issuing a TRUNCATE statement on a Disk Data table caused the table to become an in-memory table. (Bug#25296)

NDB Cluster (Disk Data): Changing a column specification on a Disk Data table caused the table to become an in-memory table. (Bug#24667)

NDB Cluster: It was not possible to create an NDB table with a key on two VARCHAR columns where both columns had a storage length in excess of 256. (Bug#25746)

NDB Cluster: Hosts in clusters with a large number of nodes could experience excessive CPU usage while obtaining configuration data. (Bug#25711)

NDB Cluster: In some circumstances, shutting down the cluster could cause connected mysqld processes to crash. (Bug#25668)

NDB Cluster: Non-32-bit, non-aligned columns were not handled correctly in explicitly partitioned NDB tables. (Bug#25587)

NDB Cluster: Some aggregate queries such as SELECT COUNT(*) performed a table scan on NDB tables rather than checking table statistics, causing such queries to perform much more slowly in MySQL Cluster 5.1 than in 5.0. (Bug#25567)

NDB Cluster: Memory allocations for TEXT columns were calculated incorrectly, resulting in space being wasted and other issues. (Bug#25562)

NDB Cluster: The failure of a master node during a node restart could lead to a resource leak, causing later node failures. (Bug#25554)

NDB Cluster: The failure of a node during a local checkpoint could lead to other node failures. (Bug#25468)

NDB Cluster: A node shutdown occurred if the master failed during a commit. (Bug#25364)

NDB Cluster: Creating a non-unique index with the USING HASH clause silently created an ordered index instead of issuing a warning. (Bug#24820)

NDB Cluster: The management server did not handle logging of node shutdown events correctly in certain cases. (Bug#22013)

NDB Cluster: A potential memory leak in the NDB storage engine's handling of file operations was uncovered. (Bug#21858)

NDB Cluster: When stopping and restarting multiple data nodes, the last node to be restarted would sometimes hang in Phase 100. (Bug#19645)

NDB Cluster (NDB API): Invoking the NdbTransaction::execute() method using execution type Commit and abort option AO_IgnoreError could lead to a crash of the transaction coordinator (DBTC). (Bug#25090)

NDB Cluster (NDB API): A unique index lookup on a non-existent tuple could lead to a data node timeout (error 4012). (Bug#25059)

NDB Cluster (NDB API): Due to an error in the computation of table fragment arrays, some transactions might not be executed from the correct starting point. (Bug#24914)

NDB Cluster (Replication): Following a restart of the master cluster, the latest GCI was set to 0 upon reconnection to the slave. (Bug#21806)

NDB Cluster (Disk Data): A MEDIUMTEXT column of a Disk Data table was stored in memory rather than on disk, even if the column was not indexed. (Bug#25001)

NDB Cluster (Disk Data): Performing a node restart with a newly dropped Disk Data table could lead to failure of the node during the restart. (Bug#24917)

NDB Cluster (Disk Data): When restoring from backup a cluster containing any Disk Data tables with hidden primary keys, a node failure resulted which could lead to a crash of the cluster. (Bug#24166)

NDB Cluster (Disk Data): Repeated CREATE, DROP, or TRUNCATE in various combinations with system restarts between these operations could lead to the eventual failure of a system restart. (Bug#21948)

NDB Cluster (Disk Data): Extents that should have been available for re-use following a DROP TABLE operation were not actually made available again until after the cluster performed a local checkpoint. (Bug#17605)

NDB Cluster: Under certain rare circumstances, local checkpoints were not performed properly, leading to an inability to restart one or more data nodes. (Bug#24664)

NDB Cluster (NDB API): When using the NdbTransaction::execute() method, a very long timeout (greater than 5 minutes) could result if the last data node being polled was disconnected from the cluster. (Bug#24949)

NDB Cluster: When a data node was shut down using the management client STOP command, a connection event (NDB_LE_Connected) was logged instead of a disconnection event (NDB_LE_Disconnected). (Bug#22773)

NDB Cluster: SELECT statements with a BLOB or TEXT column in the selected column list and a WHERE condition including a primary key lookup on a VARCHAR primary key produced empty result sets. (Bug#19956)

NDB Cluster: ndb_config failed when trying to use 2 management servers and node IDs. (Bug#23887)

STR_TO_DATE() returned NULL if the format string contained a space following a non-format character. (Bug#22029)

yaSSL crashed on pre-Pentium Intel CPUs. (Bug#21765)

Selecting into variables sometimes returned incorrect wrong results. (Bug#20836)

Inserting DEFAULT into a column with no default value could result in garbage in the column. Now the same result occurs as when inserting NULL into a NOT NULL column. (Bug#20691)

mysql_fix_privilege_tables.sql altered the table_privs.table_priv column to contain too few privileges, causing loss of the CREATE VIEW and SHOW VIEW privileges. (Bug#20589)

A server crash occurred when using LOAD DATA to load a table containing a NOT NULL spatial column, when the statement did not load the spatial column. Now a NULL supplied to NOT NULL column error occurs. (Bug#22372)

Unsigned BIGINT values treated as signed values by the MOD() function. (Bug#19955)

Compiling PHP 5.1 with the MySQL static libraries failed on some versions of Linux. (Bug#19817)

The DELIMITER statement did not work correctly when used in an SQL file run using the SOURCE statement. (Bug#19799)

VARBINARY column values inserted on a MySQL 4.1 server had trailing zeroes following upgrade to MySQL 5.0 or later. (Bug#19371)

Subqueries of the form NULL IN (SELECT ...) returned invalid results. (Bug#8804, Bug#23485)

The --extern option for mysql-test-run.pl did not function correctly. (Bug#24354)

ALTER TABLE statements that performed both RENAME TO and {ENABLE|DISABLE} KEYS operations caused a server crash. (Bug#24089)

The MySQL 5.1.12 binaries for Windows were missing the FEDERATED, EXAMPLE, and BLACKHOLE storage engines. (Bug#23900)

myisampack wrote to unallocated memory, causing a crash. (Bug#17951)

Some small double precision numbers (such as 1.00000001e-300) that should have been accepted were truncated to zero. (Bug#22129)

The mysql.server script used the source command, which is less portable than the . command; it now uses . instead. (Bug#24294)

DATE_ADD() requires complete dates with no 「zero」 parts, but sometimes did not return NULL when given such a date. (Bug#22229)

Using FLUSH TABLES in one connection while another connection is using HANDLER statements caused a server crash. (Bug#21587)

FLUSH LOGS or mysqladmin flush-logs caused a server crash if the binary log was not open. (Bug#17733)

On HP-UX, mysqltest (non-thread-safe) crashed due to being linked against a thread-safe libmysys library. (Bug#23984)