SQL Statements for Controlling Replica Servers uuid : interval [: interval ]... uuid : hhhhhhhh - hhhh - hhhh - hhhh - hhhhhhhhhhhh h : [0-9,A-F] interval : n [- n ] ( n  >= 1) START REPLICA | SLAVE  starts one or both of the replication threads. From MySQL 8.0.22, use  START REPLICA  in place of  START SLAVE , which is deprecated from that release. In releases before MySQL 8.0.22, use  START SLAVE . START REPLICA | SLAVE  with no  thread_type  options starts both of the replication threads. The replication I/O thread reads events from the source server and stores them in the relay log. The replication SQL thread reads events from the relay log and executes them.  START REPLICA | SLAVE  requires the REPLICATION_SLAVE_ADMIN  privilege (or the deprecated  SUPER  privilege). If  START REPLICA | SLAVE  succeeds in starting the replication threads, it returns without any error. However, even in that case, it might be that the replication threads start and then later stop (for example, because they do not manage to connect to the source or read its binary log, or some other problem). START REPLICA | SLAVE  does not warn you about this. You must check the replica’s error log for error messages generated by the replication threads, or check that they are running satisfactorily with  SHOW REPLICA | SLAVE STATUS . START REPLICA | SLAVE  causes an implicit commit of an ongoing transaction. See Section 13.3.3, “Statements That Cause an Implicit Commit” . gtid_next  must be set to  AUTOMATIC  before issuing this statement. The optional  FOR CHANNEL  channel  clause enables you to name which replication channel the statement applies to. Providing a  FOR CHANNEL  channel  clause applies the  START REPLICA | SLAVE  statement to a specific replication channel. If no clause is named and no extra channels exist, the statement applies to the default channel. If a  START REPLICA | SLAVE  statement does not have a channel defined when using multiple channels, this statement starts the specified threads for all channels. This statement is disallowed for the  group_replication_recovery  channel. See Section 17.2.2, “Replication Channels”  for more information. You can add  IO_THREAD  and  SQL_THREAD  options to the statement to name which of the threads to start. Note that the Group Replication applier channel ( group_replication_applier ) has no I/O thread, only an SQL thread. Specifying the  IO_THREAD  or  SQL_THREAD  options when you start this channel has no benefit. START REPLICA | SLAVE  supports pluggable user-password authentication with the  USER ,  PASSWORD , DEFAULT_AUTH  and  PLUGIN_DIR  options, as described in the following list: You cannot use the  SQL_THREAD  option when specifying any of  USER ,  PASSWORD ,  DEFAULT_AUTH , or PLUGIN_DIR , unless the  IO_THREAD  option is also provided. • USER : User name. Cannot be set to an empty or null string, or left unset if  PASSWORD  is used. • PASSWORD : Password. • DEFAULT_AUTH : Name of plugin; default is MySQL native authentication. • PLUGIN_DIR : Location of plugin. 2776