When a server shuts down and restarts, its MEMORY (HEAP) tables become empty. To replication this effect to slaves, the first time that the master uses a given MEMORY table after startup, it logs an event that notifies the slaves that the table needs to be emptied by writing a DELETE statement for that table to the binary log. See Section 13.4, “The MEMORY (HEAP) Storage Engine”, for more information about MEMORY tables.