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drop table if exists t0, t1, t2, t3;
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (
a int,
b int
);
insert into t1 values (1,1),(1,1),(2,2);
create table t2 (
a int,
b int,
key(b)
);
insert into t2 select a, a/2 from t0;
select * from t1;
a b
1 1
1 1
2 2
select * from t2;
a b
0 0
1 1
2 1
3 2
4 2
5 3
6 3
7 4
8 4
9 5
explain select * from t2 where b in (select a from t1);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Start temporary
1 PRIMARY t2 ref b b 5 test.t1.a 2 End temporary
select * from t2 where b in (select a from t1);
a b
1 1
2 1
3 2
4 2
create table t3 (
a int,
b int,
key(b),
pk1 char(200), pk2 char(200), pk3 char(200),
primary key(pk1, pk2, pk3)
) engine=innodb;
insert into t3 select a,a, a,a,a from t0;
explain select * from t3 where b in (select a from t1);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Start temporary
1 PRIMARY t3 ref b b 5 test.t1.a 1 End temporary
select * from t3 where b in (select a from t1);
a b pk1 pk2 pk3
1 1 1 1 1
2 2 2 2 2
set @save_max_heap_table_size= @@max_heap_table_size;
set max_heap_table_size=16384;
set @save_join_buffer_size = @@join_buffer_size;
set join_buffer_size= 8000;
Warnings:
Warning 1292 Truncated incorrect join_buffer_size value: '8000'
drop table t3;
create table t3 (
a int,
b int,
key(b),
pk1 char(200), pk2 char(200),
primary key(pk1, pk2)
) engine=innodb;
insert into t3 select
A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a
from t0 A, t0 B where B.a <5;
explain select * from t3 where b in (select a from t0);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t0 ALL NULL NULL NULL NULL 10 Start temporary
1 PRIMARY t3 ref b b 5 test.t0.a 1 End temporary
select * from t3 where b in (select A.a+B.a from t0 A, t0 B where B.a<5);
a b pk1 pk2
0 0 0 0
1 1 1 1
2 2 2 2
3 3 3 3
4 4 4 4
5 5 5 5
6 6 6 6
7 7 7 7
8 8 8 8
9 9 9 9
10 10 10 10
11 11 11 11
12 12 12 12
13 13 13 13
set join_buffer_size= @save_join_buffer_size;
set max_heap_table_size= @save_max_heap_table_size;
explain select * from t1 where a in (select b from t2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 index b b 5 NULL 10 Using index; LooseScan
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer
select * from t1;
a b
1 1
1 1
2 2
select * from t1 where a in (select b from t2);
a b
1 1
1 1
2 2
drop table t1, t2, t3;
set @save_join_buffer_size = @@join_buffer_size;
set join_buffer_size= 8000;
Warnings:
Warning 1292 Truncated incorrect join_buffer_size value: '8000'
create table t1 (a int, filler1 binary(200), filler2 binary(200));
insert into t1 select a, 'filler123456', 'filler123456' from t0;
insert into t1 select a+10, 'filler123456', 'filler123456' from t0;
create table t2 as select * from t1;
insert into t1 select a+20, 'filler123456', 'filler123456' from t0;
insert into t1 values (2, 'duplicate ok', 'duplicate ok');
insert into t1 values (18, 'duplicate ok', 'duplicate ok');
insert into t2 values (3, 'duplicate ok', 'duplicate ok');
insert into t2 values (19, 'duplicate ok', 'duplicate ok');
explain select
a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z
from t1 ot where a in (select a from t2 it);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY it ALL NULL NULL NULL NULL 22 Start temporary
1 PRIMARY ot ALL NULL NULL NULL NULL 32 Using where; End temporary; Using join buffer
select
a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z
from t1 ot where a in (select a from t2 it);
a mid(filler1, 1,10) Z
0 filler1234 1
1 filler1234 1
2 filler1234 1
3 filler1234 1
4 filler1234 1
5 filler1234 1
6 filler1234 1
7 filler1234 1
8 filler1234 1
9 filler1234 1
10 filler1234 1
11 filler1234 1
12 filler1234 1
13 filler1234 1
14 filler1234 1
15 filler1234 1
16 filler1234 1
17 filler1234 1
18 filler1234 1
19 filler1234 1
2 duplicate 1
18 duplicate 1
explain select
a, mid(filler1, 1,10), length(filler1)=length(filler2)
from t2 ot where a in (select a from t1 it);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY ot ALL NULL NULL NULL NULL 22 Start temporary
1 PRIMARY it ALL NULL NULL NULL NULL 32 Using where; End temporary; Using join buffer
select
a, mid(filler1, 1,10), length(filler1)=length(filler2)
from t2 ot where a in (select a from t1 it);
a mid(filler1, 1,10) length(filler1)=length(filler2)
0 filler1234 1
1 filler1234 1
2 filler1234 1
3 filler1234 1
4 filler1234 1
5 filler1234 1
6 filler1234 1
7 filler1234 1
8 filler1234 1
9 filler1234 1
10 filler1234 1
11 filler1234 1
12 filler1234 1
13 filler1234 1
14 filler1234 1
15 filler1234 1
16 filler1234 1
17 filler1234 1
18 filler1234 1
3 duplicate 1
19 filler1234 1
19 duplicate 1
insert into t1 select a+20, 'filler123456', 'filler123456' from t0;
insert into t1 select a+20, 'filler123456', 'filler123456' from t0;
explain select
a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z
from t1 ot where a in (select a from t2 it);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY it ALL NULL NULL NULL NULL 22 Start temporary
1 PRIMARY ot ALL NULL NULL NULL NULL 52 Using where; End temporary; Using join buffer
select
a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z
from t1 ot where a in (select a from t2 it);
a mid(filler1, 1,10) Z
0 filler1234 1
1 filler1234 1
2 filler1234 1
3 filler1234 1
4 filler1234 1
5 filler1234 1
6 filler1234 1
7 filler1234 1
8 filler1234 1
9 filler1234 1
10 filler1234 1
11 filler1234 1
12 filler1234 1
13 filler1234 1
14 filler1234 1
15 filler1234 1
16 filler1234 1
17 filler1234 1
18 filler1234 1
19 filler1234 1
2 duplicate 1
18 duplicate 1
explain select
a, mid(filler1, 1,10), length(filler1)=length(filler2)
from t2 ot where a in (select a from t1 it);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY ot ALL NULL NULL NULL NULL 22 Start temporary
1 PRIMARY it ALL NULL NULL NULL NULL 52 Using where; End temporary; Using join buffer
select
a, mid(filler1, 1,10), length(filler1)=length(filler2)
from t2 ot where a in (select a from t1 it);
a mid(filler1, 1,10) length(filler1)=length(filler2)
0 filler1234 1
1 filler1234 1
2 filler1234 1
3 filler1234 1
4 filler1234 1
5 filler1234 1
6 filler1234 1
7 filler1234 1
8 filler1234 1
9 filler1234 1
10 filler1234 1
11 filler1234 1
12 filler1234 1
13 filler1234 1
14 filler1234 1
15 filler1234 1
16 filler1234 1
17 filler1234 1
18 filler1234 1
3 duplicate 1
19 filler1234 1
19 duplicate 1
drop table t1, t2;
create table t1 (a int, b int, key(a));
create table t2 (a int, b int, key(a));
create table t3 (a int, b int, key(a));
insert into t1 select a,a from t0;
insert into t2 select a,a from t0;
insert into t3 select a,a from t0;
t2 and t3 must be use 'ref', not 'ALL':
explain select *
from t0 where a in
(select t2.a+t3.a from t1 left join (t2 join t3) on t2.a=t1.a and t3.a=t1.a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t0 ALL NULL NULL NULL NULL 10 Start temporary
1 PRIMARY t1 index NULL a 5 NULL 10 Using index; Using join buffer
1 PRIMARY t2 ref a a 5 test.t1.a 1 Using index
1 PRIMARY t3 ref a a 5 test.t1.a 1 Using where; Using index; End temporary
drop table t0, t1,t2,t3;
CREATE TABLE t1 (
ID int(11) NOT NULL auto_increment,
Name char(35) NOT NULL default '',
Country char(3) NOT NULL default '',
Population int(11) NOT NULL default '0',
PRIMARY KEY (ID),
INDEX (Population),
INDEX (Country)
);
CREATE TABLE t2 (
Code char(3) NOT NULL default '',
Name char(52) NOT NULL default '',
SurfaceArea float(10,2) NOT NULL default '0.00',
Population int(11) NOT NULL default '0',
Capital int(11) default NULL,
PRIMARY KEY (Code),
UNIQUE INDEX (Name),
INDEX (Population)
);
CREATE TABLE t3 (
Country char(3) NOT NULL default '',
Language char(30) NOT NULL default '',
Percentage float(3,1) NOT NULL default '0.0',
PRIMARY KEY (Country, Language),
INDEX (Percentage)
);
EXPLAIN
SELECT Name FROM t2
WHERE t2.Code IN (SELECT Country FROM t1 WHERE Population > 5000000)
AND
t2.Code IN (SELECT Country FROM t3
WHERE Language='English' AND Percentage > 10 AND
t2.Population > 100000);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL Population,Country NULL NULL NULL 30 Using where; Start temporary
1 PRIMARY t3 eq_ref PRIMARY,Percentage PRIMARY 33 test.t1.Country,const 1 Using index condition; Using where
1 PRIMARY t2 eq_ref PRIMARY,Population PRIMARY 3 test.t3.Country 1 Using index condition; Using where; End temporary
DROP TABLE t1,t2,t3;
CREATE TABLE t1 (
Code char(3) NOT NULL DEFAULT '',
Name char(52) NOT NULL DEFAULT '',
Continent enum('Asia','Europe','North America','Africa','Oceania','Antarctica','South America') NOT NULL DEFAULT 'Asia',
Region char(26) NOT NULL DEFAULT '',
SurfaceArea float(10,2) NOT NULL DEFAULT '0.00',
IndepYear smallint(6) DEFAULT NULL,
Population int(11) NOT NULL DEFAULT '0',
LifeExpectancy float(3,1) DEFAULT NULL,
GNP float(10,2) DEFAULT NULL,
GNPOld float(10,2) DEFAULT NULL,
LocalName char(45) NOT NULL DEFAULT '',
GovernmentForm char(45) NOT NULL DEFAULT '',
HeadOfState char(60) DEFAULT NULL,
Capital int(11) DEFAULT NULL,
Code2 char(2) NOT NULL DEFAULT '',
PRIMARY KEY (Code)
);
CREATE TABLE t2 (
ID int(11) NOT NULL AUTO_INCREMENT,
Name char(35) NOT NULL DEFAULT '',
CountryCode char(3) NOT NULL DEFAULT '',
District char(20) NOT NULL DEFAULT '',
Population int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (ID),
KEY CountryCode (CountryCode)
);
Fill the table with test data
This must not use LooseScan:
EXPLAIN SELECT Name FROM t1
WHERE t1.Code IN (
SELECT t2.CountryCode FROM t2 WHERE Population > 5000000);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL CountryCode NULL NULL NULL 545 Using where; Start temporary
1 PRIMARY t1 eq_ref PRIMARY PRIMARY 3 test.t2.CountryCode 1 End temporary
SELECT Name FROM t1
WHERE t1.Code IN (
SELECT t2.CountryCode FROM t2 WHERE Population > 5000000);
Name
Austria
Canada
China
Czech Republic
drop table t1, t2;
CREATE TABLE t1(a INT);
CREATE TABLE t2(c INT);
CREATE PROCEDURE p1(v1 int)
BEGIN
SELECT 1 FROM t1 WHERE a = v1 AND a IN (SELECT c FROM t2);
END
//
CREATE PROCEDURE p2(v1 int)
BEGIN
SELECT 1 FROM t1 WHERE a IN (SELECT c FROM t2);
END
//
CREATE PROCEDURE p3(v1 int)
BEGIN
SELECT 1
FROM
t1 t01,t1 t02,t1 t03,t1 t04,t1 t05,t1 t06,t1 t07,t1 t08,
t1 t09,t1 t10,t1 t11,t1 t12,t1 t13,t1 t14,t1 t15,t1 t16,
t1 t17,t1 t18,t1 t19,t1 t20,t1 t21,t1 t22,t1 t23,t1 t24,
t1 t25,t1 t26,t1 t27,t1 t28,t1 t29,t1 t30,t1 t31,t1 t32,
t1 t33,t1 t34,t1 t35,t1 t36,t1 t37,t1 t38,t1 t39,t1 t40,
t1 t41,t1 t42,t1 t43,t1 t44,t1 t45,t1 t46,t1 t47,t1 t48,
t1 t49,t1 t50,t1 t51,t1 t52,t1 t53,t1 t54,t1 t55,t1 t56,
t1 t57,t1 t58,t1 t59,t1 t60
WHERE t01.a IN (SELECT c FROM t2);
END
//
CREATE PROCEDURE p4(v1 int)
BEGIN
SELECT 1
FROM
t1 t01,t1 t02,t1 t03,t1 t04,t1 t05,t1 t06,t1 t07,t1 t08,
t1 t09,t1 t10,t1 t11,t1 t12,t1 t13,t1 t14,t1 t15,t1 t16,
t1 t17,t1 t18,t1 t19,t1 t20,t1 t21,t1 t22,t1 t23,t1 t24,
t1 t25,t1 t26,t1 t27,t1 t28,t1 t29,t1 t30,t1 t31,t1 t32,
t1 t33,t1 t34,t1 t35,t1 t36,t1 t37,t1 t38,t1 t39,t1 t40,
t1 t41,t1 t42,t1 t43,t1 t44,t1 t45,t1 t46,t1 t47,t1 t48,
t1 t49,t1 t50,t1 t51,t1 t52,t1 t53,t1 t54,t1 t55,t1 t56,
t1 t57,t1 t58,t1 t59,t1 t60
WHERE t01.a = v1 AND t01.a IN (SELECT c FROM t2);
END
//
CALL p1(1);
1
CALL p2(1);
1
CALL p3(1);
1
CALL p4(1);
1
DROP TABLE t1, t2;
DROP PROCEDURE p1;
DROP PROCEDURE p2;
DROP PROCEDURE p3;
DROP PROCEDURE p4;
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