Incompatible Change: The obsolete constructs in the following table have been removed. Use the equivalents shown in the table's second column instead. Existing applications that depend on the obsolete constructs should be converted to make use of the current equivalents as soon as possible.

Cluster Replication: Replication: A replication heartbeat mechanism has been added to facilitate monitoring. This provides an alternative to checking log files, making it possible to detect in real time when a slave has failed.

Configuration of heartbeats is done via a new MASTER_HEARTBEAT_PERIOD = interval clause for the CHANGE MASTER TO statement (see Section 12.6.2.1, “CHANGE MASTER TO Syntax”); monitoring can be done by checking the values of the status variables Slave_heartbeat_period and Slave_received_heartbeats (see Section 5.1.7, “Server Status Variables”).

The addition of replication heartbeats addresses a number of issues:

(Bug#20435, Bug#29309, Bug#30932)

Replication: The global server variable sync_relay_log is introduced for use on replication slaves. Setting this variable to a nonzero integer value N causes the slave to synchonize the relay log to disk after every N events. Setting its value to 0 allows the operation system to handle syncronization of the file. The action of this variable, when enabled, is analogous to how the sync_binlog variable works with regard to binary logs on a replication master.

The global server variables sync_master_info and sync_relay_log_info are introduced for use on replication slaves to control synchronization of, respectively, the master.info and relay.info files.

In each case, setting the variable to a nonzero integer value N causes the slave to synchonize the corresponding file to disk after every N events. Setting its value to 0 allows the operation system to handle syncronization of the file instead.

The actions of these variables, when enabled, are analogous to how the sync_binlog variable works with regard to binary logs on a replication master.

An additional system variable relay_log_recovery is also now available. When enabled, this variable causes a replication slave to discard relay log files obtained from the replication master following a crash.

These variables can also be set in my.cnf, or by using the --sync-relay-log, --sync-master-info, --sync-relay-log-info, and --relay-log-recovery server options.

For more information, see Section 16.1.3.3, “Replication Slave Options and Variables”. (Bug#31665, Bug#35542, Bug#40337)

Replication: Because SHOW BINLOG EVENTS cannot be used to read events from relay log files, a new SHOW RELAYLOG EVENTS statement has been added for this purpose. (Bug#28777)

Replication: In circular replication, it was sometimes possible for an event to propagate such that it would be reapplied on all servers. This could occur when the originating server was removed from the replication circle and so could no longer act as the terminator of its own events, as normally happens in circular replication.

In order to prevent this from occurring, a new IGNORE_SERVER_IDS option is introduced for the CHANGE MASTER TO statement. This option takes a list of replication server IDs; events having a server ID which appears in this list are ignored and not applied. For more information, see Section 12.6.2.1, “CHANGE MASTER TO Syntax”. (Bug#25998)

See also Bug#27808.

The Multi-Range Read access method does not work reliably for InnoDB and has been disabled for InnoDB tables. (Bug#45029)

The deprecated mysql_fix_privilege_tables script has been removed. (Bug#42589)

If the value of the --log-warnings option is greater than 1, the server now writes access-denied errors for new connection attempts to the error log (for example, if a client user name or password is incorrect). (Bug#25822)

TRUNCATE TABLE now is allowed for a table for which a WRITE lock has been acquired with LOCK TABLES. (Bug#20667)

See also Bug#46452.

mysqladmin now allows the password value to be omitted following the password command. In this case, mysqladmin prompts for the password value, which enables you to avoid specifying the password on the command line. Omitting the password value should be done only if password is the final command on the mysqladmin command line. Otherwise, the next argument is taken as the password. (Bug#5724)

mysql_upgrade now has an --upgrade-system-tables option that causes only the system tables to be upgraded. With this option, data upgrades are not performed.

Most statements that previously caused an implicit commit before executing now also cause an implicit commit after executing. Also, the FLUSH statement and mysql_refresh() C API function now cause an implicit commit. See Section 12.4.3, “Statements That Cause an Implicit Commit”.

The CREATE TABLESPACE privilege has been introduced. This privilege exists at the global (superuser) level and enables you to create, alter, and drop tablespaces and logfile groups.

When the server detects MyISAM table corruption, it now writes additional information to the error log, such as the name and line number of the source file, and the list of threads accessing the table. Example: Got an error from thread_id=1, mi_dynrec.c:368. This is useful information to include in bug reports.

Parser performance was improved for identifier scanning and conversion of ASCII string literals.

Performance: The InnoDB adaptive hash latch is released (if held) for serveral potentially long-running operations. This improves throughput for other queries if the current query is removing a temporary table, changing a temporary table from memory to disk, using CREATE TABLE ... SELECT, or performing a MyISAM repair on a table used within a transaction. (Bug#32149)

Security Fix: The server crashed if an account with the CREATE ROUTINE privilege but not the EXECUTE privilege attempted to create a stored procedure. (Bug#44798)

Security Fix: The server crashed if an account without the proper privileges attempted to create a stored procedure. (Bug#44658)

Incompatible Change: CHECK TABLE ... FOR UPGRADE did not check for collation changes made in MySQL 6.0.1 and 6.0.5 to latin2_czech_cs (Bug#25420) or collation changes made in MySQL 6.0.6 to big5_chinese_ci, cp866_general_ci, gb2312_chinese_ci, and gbk_chinese_ci. This also affects mysqlcheck and mysql_upgrade, which cause that statement to be executed. See Section 2.12.3, “Checking Whether Table Indexes Must Be Rebuilt”. (Bug#40054)

Incompatible Change: If a data definition language (DDL) statement occurred for a table that was being used by another session in an active transaction, statements could be written to the binary log in the wrong order. For example, this could happen if DROP TABLE occurred for a table being used in a transaction. This is now prevented by deferring release of metadata locks on tables used within a transaction until the transaction ends.

This bug fix results in some incompatibilities with previous versions:

(Bug#989, Bug#39675)

Partitioning: The cardinality of indexes on partitioned tables was calculated using the first partition in the table, which could result in suboptimal query execution plans being chosen. Now the partition having the most records is used instead, which should result in better use of indexes and thus improved performance of queries against partitioned tables in many if not most cases. (Bug#44059)

Partitioning: After attempting to create a duplicate index on a partitioned table (and having the attempt fail as expected), a subsequent attempt to create a new index on the table caused the server to hang. (Bug#40181)

Partitioning: Truncating a partitioned MyISAM table did not reset the AUTO_INCREMENT value. (Bug#35111)

Partitioning: Portions of the partitioning code were refactored in response to potential regression issues uncovered while working on the fix for Bug#31210. (Bug#32115)

See also Bug#40281.

Replication: When using row-based replication, the incomplete logging of a group of events involving both transaction and non-transactional tables could cause STOP SLAVE to hang. (Bug#45940)

See also Bug#319, Bug#38205.

Replication: Failures while flushing the relay log were not always reported. (Bug#45820)

Replication: The internal function get_master_version_and_clock() (defined in sql/slave.cc) ignored errors and passed directly when queries failed, or when queries succeeded but the result retrieved was empty. Now this function tries to reconnect the master if a query fails due to transient network problems, and to fail otherwise. The I/O thread now prints a warning if the same system variables do not exist on master (in the event the master is a very old version of MySQL, compared to the slave.) (Bug#45214)

Replication: START SLAVE succeeded even if the I/O thread did not connect to the master. (Bug#44830)

Replication: The server failed to start when using the --log-slave-updates option without also using the --log-bin option. Now in such cases, only a warning message is generated. (Bug#44663)

Replication: An extraneous debug message was written repeatedly to the slave error log, which could eventually lead to premature exhaustion of disk space. (Bug#43647)

Replication: When the logging format was set without binary logging being enabled, the server failed to start. Now in such cases, the server starts successfully, binlog_format is set, and a warning is logged instead of an error. (Bug#42928)

Replication: An error message relating to permissions required for SHOW SLAVE STATUS was confusing. (Bug#34227)

A CREATE TABLE attempt for a table that had been opened with HANDLER caused an assertion failure because CREATE TABLE did not close any open handlers for the table. (Bug#47107)

The test suite was missing from RPM packages. (Bug#46834)

For debug builds, an assertion failure could result from concurrent execution of statements involving stored functions or triggers that were using several tables and DDL statements that affected those tables. (Bug#46748)

The server crashed for attempts to drop a trigger for which the subject table was shadowed by a temporary table with the same name. (Bug#46747)

Deadlock could occur when executing transactions containing data-modifying statements at the same time as FLUSH TABLES WITH READ LOCK or SET read_only=1 statements. (Bug#46673)

Selecting from a MERGE table with a corrupted child MyISAM table could cause a server crash when the server attempted to automatically repair the child table. (Bug#46610)

The server could crash attempting to flush privileges after receipt of a SIGHUP signal. (Bug#46495)

When running the test suite with Valgrind the archive_aio_posix test case took approximately 60 minutes to complete, causing the test suite to fail due to timeout. (Bug#46461)

HANDLER OPEN followed by TRUNCATE TABLE could cause a server crash. (Bug#46452)

See also Bug#20667.

The server crashed if a shutdown occurred while a connection was idle. This happened because of a NULL pointer dereference while logging to the error log. (Bug#46267)

After an error such as a table-full condition, INSERT IGNORE could cause an assertion failure for debug builds. (Bug#46075)

Deadlock could occur for INFORMATION_SCHEMA queries when execution attempted to open a table or its .frm file. (Bug#46044)

Improperly closing tables when INSERT DELAYED needed to reopen tables could cause an assertion failure. (Bug#45949)

For an IPv6-enabled MySQL server, privileges specified using standard IPv4 addresses for hosts were not matched (only IPv4-mapped addresses were handled correctly).

As part of the fix for this bug, a new build option --disable-ipv6 has been introduced. Compiling MySQL with this option causes all IPv6-specific code in the server to be ignored.

(Bug#45606)

See also Bug#38247, Bug#43006, Bug#45283, Bug#45584.

The hostname cache failed to work correctly. (Bug#45584)

See also Bug#38247, Bug#43006, Bug#45283, Bug#45606.

A Windows Installation using the GUI installer would fail with:

MySQL Server 5.1 Setup Wizard ended prematurely

The wizard was interrupted before MySQL Server 5.1. could be completely installed.

Your system has not been modified. To complete installation at another time, please run
setup again.

Click Finish to exit the wizard

This was due to an step in the MSI installer that could fail to execute correctly on some environments. (Bug#45418)

NULL values were not grouped properly for some joins containing GROUP BY. (Bug#45267)

Killing a delayed-insert thread could cause a server crash. (Bug#45067)

Execution of FLUSH TABLES or FLUSH TABLES WITH READ LOCK concurrently with LOCK TABLES resulted in deadlock. (Bug#45066)

ALTER TABLE ... ADD COLUMN for a table with multiple foreign keys caused a server crash. (Bug#45052)

If a session had a table locked with LOCK TABLES for both READ and WRITE, ALTER TABLE could fail. (Bug#45035)

The mysql_real_connect() C API function only attempted to connect to the first IP address returned for a hostname. This could be a problem if a hostname mapped to multiple IP address and the server was not bound to the first one returned. Now mysql_real_connect() attempts to connect to all IPv4/6 addresses that a domain name maps to. (Bug#45017)

mysqld_safe could fail to find the logger program. (Bug#44736)

Some Perl scripts in AIX packages contained an incorrect path to the perl executable. (Bug#44643)

For debug builds, executing a stored procedure as a prepared statement could sometimes cause an assertion failure. (Bug#44521)

A natural join of INFORMATION_SCHEMA tables could cause an assertion failure. (Bug#43834)

Queries executed using index condition pushdown could return incorrect results because the condition could evaluate to an unexpected result. (Bug#43600)

The server crashed if invoked with the --verbose and --help options. (Bug#43533)

HANDLER statements are now disallowed if a table lock has been acquired with LOCK TABLES. (Bug#43272)

Redefining a trigger could cause an assertion failure. (Bug#43054)

The IPv6 loopback address ::1 was interpeted as a hostname rather than a numeric IP address.

In addition, the IPv6-enabled server on Windows interpeted the hostname localhost as ::1 only, which failed to match the default root@127.0.0.1 entry in the mysql.user privilege table. (Bug#43006)

See also Bug#38247, Bug#45283, Bug#45584, Bug#45606.

The server could crash if an attempt to open a MERGE table child MyISAM table failed. (Bug#42862)

The named_pipe system variable was not properly defined in Windows. For example, SHOW VARIABLES did not display the variable. (Bug#42173)

The patch for Bug#10374 broke named-pipe and shared-memory connections on Windows. (Bug#41860)

Premature metadata lock downgrade for CREATE TABLE ... SELECT could result in an inconsistent binary log or failure with an ER_CANT_LOCK error. (Bug#41425)

Plugin shutdown could lead to an assertion failure caused by using an already destroyed mutex in the metadata locking subsystem. (Bug#39674)

Concurrent connections executing FLUSH TABLES and at least two statements using the same table could cause all three connections to stall with 100% CPU utilization. (Bug#38661)

Valgrind warnings that occurred for SHOW TABLE STATUS with InnoDB tables were silenced. (Bug#38479)

mysqlbinlog had a memory leak in its option-processing code. (Bug#38468)

Use of GET_LOCK() within an Event Manager event could cause a server crash. (Bug#37774)

Valgrind warnings that occurred when reading spatial indexes were silenced. (Bug#37066)

For its warning count, the mysql_info() C API function could print the number of truncated data items rather than the number of warnings. (Bug#34898)

The LAST_DAY() and MAKEDATE() functions could return NULL, but the result metadata indicated NOT NULL. Thanks to Hiromichi Watari for the patch to fix this bug. (Bug#33629)

Instance Manager (mysqlmanager) has been removed, but a reference to it still appeared in the mysql.server script. (Bug#33472)

A statement that caused a circular wait among statements did not return a deadlock error. Now the server detects deadlock and returns ER_LOCK_DEADLOCK. (Bug#22876)

Renaming a column that appeared in a foreign key definition did not update the foreign key definition with the new column name. (Bug#21704)

For INSERT DELAYED statements issued for a table while an ALTER TABLE operation on the table was in progress, the server could return a spurious Server shutdown in progress error. (Bug#18484)

The character set was not being properly initialized for CAST() with a type such as CHAR(2) BINARY, which resulted in incorrect results or a server crash. (Bug#17903)

If a connection was waiting for a GET_LOCK() lock or a SLEEP() call, and the connection aborted, the server did not detect this and thus did not close the connection. This caused a waste of system resources allocated to dead connections. Now the server checks such a connection every five seconds to see whether it has been aborted. If so, the connection is killed (and any lock request is aborted). (Bug#10374)