SQL Statements for Controlling Replica Servers SOURCE_PORT=3306, SOURCE_LOG_FILE=’source2-bin.001’, SOURCE_LOG_POS=4, SOURCE_CONNECT_RETRY=10; CHANGE REPLICATION SOURCE TO RELAY_LOG_FILE=’replica-relay-bin.006’, RELAY_LOG_POS=4025; The next example shows an operation that is less frequently employed. It is used when the replica has relay log files that you want it to execute again for some reason. To do this, the source need not be reachable. You need only use  CHANGE REPLICATION SOURCE TO  and start the SQL thread ( START REPLICA SQL_THREAD ): Options that you do not specify on a  CHANGE REPLICATION SOURCE TO  statement retain their value, except as indicated in the following discussion. Thus, in most cases, there is no need to specify options that do not change. ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS Makes the replication channel assign a GTID to replicated transactions that do not have one, enabling replication from a source that does not use GTID-based replication, to a replica that does. For a multi-source replica, you can have a mix of channels that use ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS , and channels that do not. The default is  OFF , meaning that the feature is not used. LOCAL  assigns a GTID including the replica’s own UUID (the server_uuid  setting).  uuid  assigns a GTID including the specified UUID, such as the  server_uuid  setting for the replication source server. Using a nonlocal UUID lets you differentiate between transactions that originated on the replica and transactions that originated on the source, and for a multi-source replica, between transactions that originated on different sources. The UUID you choose only has significance for the replica’s own use. If any of the transactions sent by the source do have a GTID already, that GTID is retained. Channels specific to Group Replication cannot use ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS , but an asynchronous replication channel for another source on a server instance that is a Group Replication group member can do so. In that case, do not specify the Group Replication group name as the UUID for creating the GTIDs. To set  ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS  to  LOCAL  or uuid , the replica must have  gtid_mode=ON  set, and this cannot be changed afterwards. This option is for use with a source that has binary log file position based replication, so  MASTER_AUTO_POSITION=1 cannot be set for the channel. Both the replication SQL thread and the replication I/O thread must be stopped before setting this option. A replica set up with ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS on any channel cannot be promoted to replace the replication source server in the event that a failover is required, and a backup taken from the replica cannot be used to restore the replication Important 2762