id	select_type	table		type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY		<derived2>	system	NULL	NULL		NULL	NULL	1	"Using filesort"
1	PRIMARY		<derived3>	system	NULL	NULL		NULL	NULL	1
1	PRIMARY		my_table	ALL	NULL	NULL		NULL	NULL	32594440
3	DERIVED		NULL		NULL	NULL	NULL		NULL	NULL	NULL	"No tables used"
2	DERIVED		NULL		NULL	NULL	NULL		NULL	NULL	NULL	"No tables used"