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MySQL Replication  /  ...  /  Semisynchronous Replication Administrative Interface

3.8.1 Semisynchronous Replication Administrative Interface

The administrative interface to semisynchronous replication has several components:

  • Two plugins implement semisynchronous capability. There is one plugin for the master side and one for the slave side.

  • System variables control plugin behavior. Some examples:

    All rpl_semi_sync_xxx system variables are described at Server System Variables.

  • Status variables enable semisynchronous replication monitoring. Some examples:

    • Rpl_semi_sync_master_clients

      The number of semisynchronous slaves.

    • Rpl_semi_sync_master_status

      Whether semisynchronous replication currently is operational on the master. The value is 1 if the plugin has been enabled and a commit acknowledgment has occurred. It is 0 if the plugin is not enabled or the master has fallen back to asynchronous replication due to commit acknowledgment timeout.

    • Rpl_semi_sync_master_no_tx

      The number of commits that were not acknowledged successfully by a slave.

    • Rpl_semi_sync_master_yes_tx

      The number of commits that were acknowledged successfully by a slave.

    • Rpl_semi_sync_slave_status

      Whether semisynchronous replication currently is operational on the slave. This is 1 if the plugin has been enabled and the slave I/O thread is running, 0 otherwise.

    All Rpl_semi_sync_xxx status variables are described at Server Status Variables.

The system and status variables are available only if the appropriate master or slave plugin has been installed with INSTALL PLUGIN.