create table t2 (a int);
insert into t2 values (1),(2),(3);
create view v2 as select a from t2;
flush status;
select * from v2;
a
1
2
3
show status like '%Created_tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	0
explain select * from v2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	
select * from (select * from t2) T1;
a
1
2
3
show status like '%Created_tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	0
explain select * from (select * from t2) T1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	
drop view v2;
drop table t2;
CREATE TABLE t1(a int);
INSERT INTO t1 values(1),(2);
CREATE TABLE t2(a int);
INSERT INTO t2 values(1),(2);
EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	test.t1.a	1	
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	2	Using where; Using temporary
truncate table performance_schema.events_statements_history_long;
flush status;
CREATE TABLE t3 SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);
# Performance schema should be the same as "Created_tmp_tables" variable below
select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
sum(created_tmp_tables)
2
show status like '%Created_tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	2
drop table t3;
EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	func	1	
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	2	
truncate table performance_schema.events_statements_history_long;
flush status;
CREATE TABLE t3 SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a);
# Performance schema should be the same as "Created_tmp_tables" variable below
select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
sum(created_tmp_tables)
1
show status like '%Created_tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	1
drop table t1,t2,t3;
truncate table performance_schema.events_statements_history_long;
flush status;
# Performance schema should be the same as "Created_tmp_tables" variable below
select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
sum(created_tmp_tables)
0
show status like '%Created_tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	0