I'm trying to understand when/where using relay log is beneficial. According the documentation, mysql captures and writes events from the master's binary log as the result of the I/O thread. Then, the SQL thread executes the statements from the slave relay log.

Currently, I have the relay logs disabled on the slave but it hasn't affected replication. It still performs well.

If replication requires the SQL thread to read statements from the relay log so they can be executed, why is it still working without a relay log?

Thanks