Reset table map on rotate events since MySQL mapping is not persisten…

…t and rotate is best approximation we have of detecting server restarts.

pymysqlreplication/binlogstream.py

@@ -160,6 +160,16 @@ def fetchone(self):
            if binlog_event.event_type == ROTATE_EVENT:
                self.log_pos = binlog_event.event.position
                self.log_file = binlog_event.event.next_binlog
                # Table Id in binlog are NOT persistent in MySQL - they are in-memory identifiers
                # that means that when MySQL master restarts, it will reuse same table id for different tables
                # which will cause errors for us since our in-memory map will try to decode row data with
                # wrong table schema.
                # The fix is to rely on the fact that MySQL will also rotate to a new binlog file every time it
                # restarts. That means every rotation we see *could* be a sign of restart and so potentially
                # invalidates all our cached table id to schema mappings. This means we have to load them all 
                # again for each logfile which is potentially wasted effort but we can't really do much better
                # without being broken in restart case
                self.table_map = {}
            elif binlog_event.log_pos:
                self.log_pos = binlog_event.log_pos