To enable MySQL replication operations to act on individual replication channels, use the FOR CHANNEL clause with the following replication statements:channel
The SOURCE_POS_WAIT() function has a channel parameter.
START REPLICA and STOP REPLICAare disallowed for the group_replication_recovery and group_replication_applier channels. SHOW REPLICA STATUS is also not allowed with the group_replication_applier channel.
FLUSH RELAY LOGS is allowed for the group_replication_applier channel, but if the request is received while a transaction is being applied, the request is not performed until after the transaction ends. The requester must wait while the transaction is completed and the rotation takes place. This prevents transactions from being split, which is not allowed for Group Replication.