id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	184	Using where
1	PRIMARY	t2	eq_ref	PRIMARY	PRIMARY	54	iq_test_inte.t1.id,const	1	Using where
2	UNION	t1	ALL	PRIMARY	NULL	NULL	NULL	184	Using where
2	UNION	t2	eq_ref	PRIMARY	PRIMARY	54	iq_test_inte.t1.id,const	1	Using where
3	DEPENDENT SUBQUERY	i18n_message	unique_subquery	PRIMARY	PRIMARY	54	func,const	1	Using index; Using where