drop table if exists t1, t2;
create table t1 (a int);
insert into t1 values (0),(1),(2),(3);
create table t2 (a int primary key, b int) 
as select a, a as b from t1 where a in (1,2);
explain select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
set optimizer_switch='table_elimination=off';
explain select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
set optimizer_switch='table_elimination=on';
explain select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
set optimizer_switch='table_elimination=default';
explain select t1.a from t1 left join t2 on t2.a=t1.a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
drop table t1, t2;