MySQL 9.0 Reference Manual Including MySQL NDB Cluster 9.0
The plugins for semisynchronous replication expose a number of
status variables that enable you to monitor their operation. To
check the current values of the status variables, use
SHOW STATUS:
mysql> SHOW STATUS LIKE 'Rpl_semi_sync%';
All
Rpl_semi_sync_
status variables are described at
Section 7.1.10, “Server Status Variables”. Some examples are:
xxx
The number of semisynchronous replicas that are connected to the source server.
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.
The number of commits that were not acknowledged successfully by a replica.
The number of commits that were acknowledged successfully by a replica.
Whether semisynchronous replication currently is operational on the replica. This is 1 if the plugin has been enabled and the replication I/O (receiver) thread is running, 0 otherwise.
When the source switches between asynchronous or semisynchronous
replication due to commit-blocking timeout or a replica catching
up, it sets the value of the
Rpl_semi_sync_source_status
status variable appropriately. Automatic fallback from
semisynchronous to asynchronous replication on the source means
that it is possible for the
rpl_semi_sync_source_enabled
system variable to have a value of 1 on the source side even
when semisynchronous replication is in fact not operational at
the moment. You can monitor the
Rpl_semi_sync_source_status
status variable to determine whether the source currently is
using asynchronous or semisynchronous replication.