A multi-source replication topology requires at least two sources
      and one replica configured. In these tutorials, we assume that you
      have two sources source1 and
      source2, and a replica
      replicahost. The replica replicates one
      database from each of the sources, db1 from
      source1 and db2 from
      source2.
    
Sources in a multi-source replication topology can be configured to use either GTID-based replication, or binary log position-based replication. See Section 19.1.3.4, “Setting Up Replication Using GTIDs” for how to configure a source using GTID-based replication. See Section 19.1.2.1, “Setting the Replication Source Configuration” for how to configure a source using file position based replication.
      Replicas in a multi-source replication topology require
      TABLE repositories for the replica's connection
      metadata repository and applier metadata repository, which are the
      default in MySQL 9.4. Multi-source replication is not
      compatible with the deprecated alternative file repositories.
    
      Create a suitable user account on all the sources that the replica
      can use to connect. You can use the same account on all the
      sources, or a different account on each. If you create an account
      solely for the purposes of replication, that account needs only
      the REPLICATION SLAVE privilege.
      For example, to set up a new user, ted, that
      can connect from the replica replicahost, use
      the mysql client to issue these statements on
      each of the sources:
    
mysql> CREATE USER 'ted'@'replicahost' IDENTIFIED BY 'password';
mysql> GRANT REPLICATION SLAVE ON *.* TO 'ted'@'replicahost';For more information about the default authentication plugin for new users, see Section 19.1.2.3, “Creating a User for Replication”.