MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
When a replica has multiple channels and a FOR CHANNEL
option is not
specified, a valid statement generally acts on all available
channels, with some specific exceptions.
channel
For example, the following statements behave as expected for all except certain Group Replication channels:
START SLAVE starts replication
threads for all channels, except the
group_replication_recovery and
group_replication_applier channels.
STOP SLAVE stops replication
threads for all channels, except the
group_replication_recovery and
group_replication_applier channels.
SHOW SLAVE STATUS reports the
status for all channels, except the
group_replication_applier channel.
FLUSH RELAY
LOGS flushes the relay logs for all channels, except
the group_replication_applier channel.
RESET
SLAVE resets all channels.
Use RESET SLAVE with caution as this
statement deletes all existing channels, purges their relay log
files, and recreates only the default channel.
Some replication statements cannot operate on all channels. In
this case, error 1964 Multiple channels exist on the
slave. Please provide channel name as an argument. is
generated. The following statements and functions generate this
error when used in a multi-source replication topology and a
FOR CHANNEL
option is not used to specify which channel to act on:
channel
Note that a default channel always exists in a single source replication topology, where statements and functions behave as in previous versions of MySQL.