13.4.1.2 RESET MASTER Statement

RESET MASTER

Warning

Use this statement with caution to ensure you do not lose any wanted binary log file data and GTID execution history.

RESET MASTER requires the RELOAD privilege.

For a server where binary logging is enabled (log_bin is ON), RESET MASTER deletes all existing binary log files and resets the binary log index file, resetting the server to its state before binary logging was started. A new empty binary log file is created so that binary logging can be restarted.

For a server where GTIDs are in use (gtid_mode is ON), issuing RESET MASTER resets the GTID execution history. The value of the gtid_purged system variable is set to an empty string (''), the global value (but not the session value) of the gtid_executed system variable is set to an empty string, and the mysql.gtid_executed table is cleared (see mysql.gtid_executed Table). If the GTID-enabled server has binary logging enabled, RESET MASTER also resets the binary log as described above. Note that RESET MASTER is the method to reset the GTID execution history even if the GTID-enabled server is a replica where binary logging is disabled; RESET SLAVE has no effect on the GTID execution history. For more information on resetting the GTID execution history, see Resetting the GTID Execution History.

Important

The effects of RESET MASTER differ from those of PURGE BINARY LOGS in 2 key ways:

1. RESET MASTER removes all binary log files that are listed in the index file, leaving only a single, empty binary log file with a numeric suffix of .000001, whereas the numbering is not reset by PURGE BINARY LOGS.

2. RESET MASTER is not intended to be used while any replicas are running. The behavior of RESET MASTER when used while replicas are running is undefined (and thus unsupported), whereas PURGE BINARY LOGS may be safely used while replicas are running.

See also Section 13.4.1.1, “PURGE BINARY LOGS Statement”.

RESET MASTER can prove useful when you first set up the source and the replica, so that you can verify the setup as follows:

1. Start the source and replica, and start replication (see Section 16.1.2, “Setting Up Binary Log File Position Based Replication”).

2. Execute a few test queries on the source.

3. Check that the queries were replicated to the replica.

4. When replication is running correctly, issue STOP SLAVE followed by RESET SLAVE on the replica, then verify that any unwanted data no longer exists on the replica.

5. Issue RESET MASTER on the source to clean up the test queries.

After verifying the setup, resetting the source and replica and ensuring that no unwanted data or binary log files generated by testing remain on source or replica, you can start the replica and begin replicating.