Mysql：Changes in MySQL 5.6.9 (2012-12-11, Release Candidate)：GTID-based variables have been 【renamed】

Changes in MySQL 5.6.9 (2012-12-11, Release Candidate)

Functionality Added or Changed

• Incompatible Change; Replication: A number of variable and other names relating to GTID-based replication have been changed, with a view to making these names more appropriate and meaningful. The old names are no longer supported.

  The features so renamed are shown in the following list:

  • The disable_gtid_unsafe_statements system variable has been renamed enforce_gtid_consistency.

  • The gtid_done server system variable has been renamed gtid_executed.

    The gtid_lost server system variable has been renamed gtid_purged; in addition, this variable is no longer read-only.

  • The SQL_THREAD_WAIT_AFTER_GTIDS() function has been renamed WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS().

  For more information, see Replication with Global Transaction Identifiers, and Global Transaction ID Options and Variables. (Bug #14775984)

• Microsoft Windows: Windows Vista, Windows Server 2008, and newer support native symbolic linking using the mklink command. This makes the MySQL Server implementation of database symbolic links using .sym files redundant, so that mechanism is now deprecated and will be removed in a future MySQL release. See Using Symbolic Links for Databases on Windows.

• For client connections restrictd by the server because the client account password is expired, the server now permits SET PASSWORD only if the account named in the statement matches the account used by the client. (Bug #14807074)

  References: See also: Bug #14698309.

• The server now provides thread information (for SHOW PROCESSLIST) to indicate the progress of in-place ALTER TABLE operations:

  • preparing for alter table

    The server is preparing to execute an in-place ALTER TABLE.

  • altering table

    The server is in the process of executing an in-place ALTER TABLE.

  • committing alter table to storage engine

    The server has finished an in-place ALTER TABLE and is committing the result.

  (Bug #14790408)

• InnoDB automatically extends each secondary index by appending the primary key columns to it. Previously, the optimizer did not take into account the primary key columns of the extended secondary index when determining how and whether to use that index. Now the optimizer takes the primary key columns into account, which can result in more efficient query execution plans and better performance.

  The optimizer can use extended secondary keys for ref, range, and index_merge index access, for Loose Index Scan, for join and sorting optimization, and for MIN()/MAX() optimization.

  The new use_index_extensions flag of the optimizer_switch system variable permits control over whether the optimizer takes the primary key columns into account when determining how to use an InnoDB table's secondary indexes. By default, use_index_extensions is enabled. To check whether disabling use of index extensions will improve performance, use this statement:

  SET optimizer_switch = 'use_index_extensions=off';

  For more information, see Use of Index Extensions. (Bug #62025, Bug #12814559, Bug #56714, Bug #11763940)

• mysqld now writes dates to the error log in ISO (YYYY-MM-DD hh:mm:ss) format. It also includes its process ID following the date. Thanks to Davi Arnaut for the patch. (Bug #56240, Bug #11763523)