17.1.4.1 Configuring Multi-Source Replication

A multi-source replication topology requires at least two masters and one slave configured. In these tutorials, we will assume you have two masters master1 and master2, and a replication slave slavehost. The slave will replicate one database from each of the masters, db1 from master1 and db2 from master2.

Masters in a multi-source replication topology can be configured to use either GTID-based replication, or binary log position-based replication. See Section 17.1.3.4, “Setting Up Replication Using GTIDs” for how to configure a master using GTID-based replication. See Section 17.1.2.1, “Setting the Replication Master Configuration” for how to configure a master using file position based replication.

Slaves in a multi-source replication topology require TABLE repositories for the master info log and relay log info log, which are the default in MySQL 8.0. Multi-source replication is not compatible with file repositories, and the FILE setting for the master_info_repository and relay_log_info_repository system variables is now deprecated.

To modify an existing replication slave that is using a FILE repository for the slave status logs to use TABLE repositories, you can convert the existing replication repositories dynamically by using the mysql client to issue the following statements on the slave:

mysql> STOP SLAVE;
mysql> SET GLOBAL master_info_repository = 'TABLE';
mysql> SET GLOBAL relay_log_info_repository = 'TABLE';

Create a suitable user account on all the masters that the slave can use to connect. You can use the same account on all the masters, 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 replication slave slavehost, use the mysql client to issue these statements on each of the masters:

mysql> CREATE USER 'ted'@'slavehost' IDENTIFIED BY 'password';
mysql> GRANT REPLICATION SLAVE ON *.* TO 'ted'@'slavehost';

For more details, and important information on the default authentication plugin for new users from MySQL 8.0, see Section 17.1.2.3, “Creating a User for Replication”.