MySQL Replication  /  ...  /  Semisynchronous Replication Administrative Interface

3.9.1 Semisynchronous Replication Administrative Interface

The administrative interface to semisynchronous replication has several components:

  • Two plugins implement semisynchronous capability. There is one plugin for the source side and one for the replica 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 replicas.

    • Rpl_semi_sync_master_status

      Whether semisynchronous replication currently is operational on the source server. The value is 1 if the plugin has been enabled and a commit acknowledgment has not occurred. It is 0 if the plugin is not enabled or the source 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 replica.

    • Rpl_semi_sync_master_yes_tx

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

    • Rpl_semi_sync_slave_status

      Whether semisynchronous replication currently is operational on the replica. This is 1 if the plugin has been enabled and the replication 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 source or replica plugin has been installed with INSTALL PLUGIN.