point on. If you do not specify a channel and no other channels exist, the statement is applied to the default channel. 

The use of row-based binary logging is strongly recommended when PRIVILEGE_CHECKS_USER  is set, and you can set REQUIRE_ROW_FORMAT  to enforce this. For example, to start privilege checks on the channel channel_1  on a running replica, issue the following statements: 

mysql> STOP REPLICA FOR CHANNEL ’channel_1’; mysql> CHANGE REPLICATION SOURCE TO PRIVILEGE_CHECKS_USER = ’ priv_repl ’@’ %.example.com ’, REQUIRE_ROW_FORMAT = 1, FOR CHANNEL ’channel_1’; mysql> START REPLICA FOR CHANNEL ’channel_1’; 

RELAY_LOG_FILE , RELAY_LOG_POS The relay log file name, and the location in that file, at which the replication SQL thread begins reading from the replica’s relay log the next time the thread starts. RELAY_LOG_FILE  can use either an absolute or relative path, and uses the same base name as SOURCE_LOG_FILE . 

A CHANGE REPLICATION SOURCE TO  statement using RELAY_LOG_FILE , RELAY_LOG_POS , or both options can be executed on a running replica when the replication SQL thread is stopped. Relay logs are preserved if at least one of the replication SQL thread and the replication I/O thread is running. If both threads are stopped, all relay log files are deleted unless at least one of RELAY_LOG_FILE or RELAY_LOG_POS  is specified. For the Group Replication applier channel ( group_replication_applier ), which only has an SQL thread and no I/O thread, this is the case if the SQL thread is stopped, but with that channel you cannot use the RELAY_LOG_FILE  and RELAY_LOG_POS  options. 

REQUIRE_ROW_FORMAT Permits only row-based replication events to be processed by the replication channel. This option prevents the replication applier from taking actions such as creating temporary tables and executing LOAD DATA INFILE  requests, which increases the security of the channel. Group Replication channels are automatically created with REQUIRE_ROW_FORMAT  set, and you cannot change the option for those channels. For more information, see Section 17.3.3, “Replication Privilege Checks” . REQUIRE_ROW_FORMAT  is available as of MySQL 8.0.19. 

REQUIRE_TABLE_PRIMARY_KEY_CHECK Enables a replica to select its own policy for primary key checks. When the option is set to ON  for a replication channel, the replica always uses the value ON  for the sql_require_primary_key system variable in replication operations, requiring a primary key. When the option is set to OFF , the replica always uses the value OFF for the sql_require_primary_key  system variable in replication operations, so that a primary key is never required, even if the source required one. When the REQUIRE_TABLE_PRIMARY_KEY_CHECK option is set to STREAM , which is the default, the replica uses whatever value is replicated from the source for each transaction. 

