MySQL 9.0 Release Notes
There is a lot of automation built into the Group Replication plugin. Nonetheless, you might sometimes need to understand what is happening behind the scenes. This is where the instrumentation of Group Replication and Performance Schema becomes important. The entire state of the system (including the view, conflict statistics and service states) can be queried through Performance Schema tables. The distributed nature of the replication protocol and the fact that server instances agree and thus synchronize on transactions and metadata makes it simpler to inspect the state of the group. For example, you can connect to a single server in the group and obtain both local and global information by issuing select statements on the Group Replication related Performance Schema tables. For more information, see Section 20.4, “Monitoring Group Replication”.