File: table_elim_debug.result

package info (click to toggle)
mariadb 1%3A11.8.2-1
  • links: PTS, VCS
  • area: main
  • in suites: trixie
  • size: 765,428 kB
  • sloc: ansic: 2,382,827; cpp: 1,803,532; asm: 378,315; perl: 63,176; sh: 46,496; pascal: 40,776; java: 39,363; yacc: 20,428; python: 19,506; sql: 17,864; xml: 12,463; ruby: 8,544; makefile: 6,059; cs: 5,855; ada: 1,700; lex: 1,193; javascript: 1,039; objc: 80; tcl: 73; awk: 46; php: 22
file content (22 lines) | stat: -rw-r--r-- 1,061 bytes parent folder | download | duplicates (13)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
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;