All the procedures explained previously also apply to multisource replication. The difference is that, with multisource replication, each slave associates each master-slave connection to a unique ID. This allows the replication commands and the configuration variables to refer to a particular master.

For example, we generally do not want to start or stop all the I/O threads, but only one of them.

Thus, all replication-related SQL statements support a parameter that specifies which connection they refer to. For example:

Also, it is possible to start or stop all the slave I/O threads using the following syntax:

When the connection name is not specified in a command, and the ALL keyword is not present, the default connection is used. Initially, it is an empty string. It can be changed or read with the @@default_master_connection server variable:

MariaDB [(none)]> SELECT @@default_master_connection;
+-----------------------------+
| @@default_master_connection |
+-----------------------------+
|                             |
+-----------------------------+
1 row in set (0.00 sec)

Also the variables used for filtering connections, by default, refer to the default connection. The following syntax can be used to specify a filter for a certain connection:

connection_name.variable_name

For example, to only replicate db via the connection master1 and all databases via other connections, we can use:

SET GLOBAL master1.replicate_do_db = '';