MHA clears relaylog (purge_relay_logs)

MHA clears relaylog (purge_relay_logs)

By default, the slave database's relay logs in the MySQL database will be automatically deleted after the SQL thread is executed. However, in the MHA scenario, the recovery of some lagging slave databases depends on the relay logs of other slave databases. Therefore, disable the automatic deletion function and regularly clean up the database. Pay attention to the overhead of replication delayed resources when clearing excessive relay logs. MHA can use the purge_relay_logs script and cronjob to complete this task. The details are as follows.

1. Features of purge_relay_logs

2. purge_relay_logs usage and Related Parameters

### Parameter description

3. Customize and clear relay log cronjob

4. Manual cleanup example