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ReplicationFeatures/SemiSyncReplication

Contents 1 SEMI-SYNCHRONOUS REPLICATION 2 Provides: 3 Use case: 4 User interface: 5 Modifications made by MySQL: 6 References: 7 Associated issues: 8 Downloads: 9 Thanks:

[edit] SEMI-SYNCHRONOUS REPLICATION

Feature preview from a contributed patch from Mark Callaghan and Wei Li, Google, that was modified by Zhenxing He, MySQL Replication Team.

[edit] Provides:

A facility for highly available replication. If the master crash after having committed a transaction, the slave is guaranteed to have receive it.

[edit] Use case:

If the master crash, the slave can be instantly promoted to substitute the old master. The slave has all the master's transactions either in its relay-log or already applied.

[edit] User interface:

• the server startup options:

 master:
    --rpl_semi_sync_enabled=1|0
    --rpl_semi_sync_timeout= timeout value in seconds
 slave:
    --rpl_semi_sync_slave_enabled=1|0

• run time facilities:

 master:
    set global rpl_semi_sync_enabled=1|0;
    show status like 'Rpl_semi_sync_clients';
    show status like 'Rpl_semi_sync_status';
    show status like 'Rpl_semi_sync_no_tx';
    show status like 'Rpl_semi_sync_yes_tx';
 slave:
    set global rpl_semi_sync_slave_enabled = 1|0;
    show status like 'Rpl_semi_sync_slave_status';

[edit] Modifications made by MySQL:

• Converted MySQL 5.0 google patch to MySQL 5.1
• Made it storage engine independent (removed modifications to InnoDB)
• Made RESET MASTER reset semi-sync master status
• Modularized code (work in progress)

[edit] References:

• http://code.google.com/p/google-mysql-tools/wiki/SemiSyncReplication
• http://code.google.com/p/google-mysql-tools/wiki/SemiSyncReplicationDesign
• WL#1720 Semi-synchronous replication

[edit] Associated issues:

• Recovery based on the global transaction identifier.

[edit] Downloads:

• Linux binary: http://downloads.mysql.com/forge/replication_features_preview/mysql-5.1.24-with-semi-sync-repl-linux-i686.tar.gz
• Source code: http://downloads.mysql.com/forge/replication_features_preview/mysql-5.1.24-with-semi-sync-repl.tar.gz

[edit] Thanks:

Mark Callaghan and Wei Li from Google whose original patch for 5.0 was converted by Zhenxing He MySQL Replication Team.