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SET SESSION STORAGE_ENGINE = InnoDB;
drop table if exists t1, t2, t3,t4;
create table t1 (
pk1 int not NULL,
key1 int(11),
key2 int(11),
PRIMARY KEY (pk1),
KEY key1 (key1),
KEY key2 (key2)
);
insert into t1 values (-5, 1, 1),
(-100, 1, 1),
(3, 1, 1),
(0, 1, 1),
(10, 1, 1);
explain select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge key1,key2 key1,key2 5,5 NULL 5 Using sort_union(key1,key2); Using where
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 key1 key2
-100 1 1
-5 1 1
0 1 1
3 1 1
10 1 1
drop table t1;
create table t1 (
pk1 int unsigned not NULL,
key1 int(11),
key2 int(11),
PRIMARY KEY (pk1),
KEY key1 (key1),
KEY key2 (key2)
);
insert into t1 values (0, 1, 1),
(0xFFFFFFFF, 1, 1),
(0xFFFFFFFE, 1, 1),
(1, 1, 1),
(2, 1, 1);
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 key1 key2
0 1 1
1 1 1
2 1 1
4294967294 1 1
4294967295 1 1
drop table t1;
create table t1 (
pk1 char(4) not NULL,
key1 int(11),
key2 int(11),
PRIMARY KEY (pk1),
KEY key1 (key1),
KEY key2 (key2)
) collate latin2_general_ci;
insert into t1 values ('a1', 1, 1),
('b2', 1, 1),
('A3', 1, 1),
('B4', 1, 1);
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 key1 key2
a1 1 1
A3 1 1
b2 1 1
B4 1 1
drop table t1;
create table t1 (
pk1 int not NULL,
pk2 char(4) not NULL collate latin1_german1_ci,
pk3 char(4) not NULL collate latin1_bin,
key1 int(11),
key2 int(11),
PRIMARY KEY (pk1,pk2,pk3),
KEY key1 (key1),
KEY key2 (key2)
);
insert into t1 values
(1, 'u', 'u', 1, 1),
(1, 'u', char(0xEC), 1, 1),
(1, 'u', 'x', 1, 1);
insert ignore into t1 select pk1, char(0xEC), pk3, key1, key2 from t1;
insert ignore into t1 select pk1, 'x', pk3, key1, key2 from t1 where pk2='u';
insert ignore into t1 select 2, pk2, pk3, key1, key2 from t1;
select * from t1;
pk1 pk2 pk3 key1 key2
1 ì u 1 1
1 ì x 1 1
1 ì ì 1 1
1 u u 1 1
1 u x 1 1
1 u ì 1 1
1 x u 1 1
1 x x 1 1
1 x ì 1 1
2 ì u 1 1
2 ì x 1 1
2 ì ì 1 1
2 u u 1 1
2 u x 1 1
2 u ì 1 1
2 x u 1 1
2 x x 1 1
2 x ì 1 1
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 pk2 pk3 key1 key2
1 ì u 1 1
1 ì x 1 1
1 ì ì 1 1
1 u u 1 1
1 u x 1 1
1 u ì 1 1
1 x u 1 1
1 x x 1 1
1 x ì 1 1
2 ì u 1 1
2 ì x 1 1
2 ì ì 1 1
2 u u 1 1
2 u x 1 1
2 u ì 1 1
2 x u 1 1
2 x x 1 1
2 x ì 1 1
alter table t1 drop primary key;
select * from t1;
pk1 pk2 pk3 key1 key2
1 ì u 1 1
1 ì x 1 1
1 ì ì 1 1
1 u u 1 1
1 u x 1 1
1 u ì 1 1
1 x u 1 1
1 x x 1 1
1 x ì 1 1
2 ì u 1 1
2 ì x 1 1
2 ì ì 1 1
2 u u 1 1
2 u x 1 1
2 u ì 1 1
2 x u 1 1
2 x x 1 1
2 x ì 1 1
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 pk2 pk3 key1 key2
1 ì u 1 1
1 ì x 1 1
1 ì ì 1 1
1 u u 1 1
1 u x 1 1
1 u ì 1 1
1 x u 1 1
1 x x 1 1
1 x ì 1 1
2 ì u 1 1
2 ì x 1 1
2 ì ì 1 1
2 u u 1 1
2 u x 1 1
2 u ì 1 1
2 x u 1 1
2 x x 1 1
2 x ì 1 1
drop table t1;
create table t1 (
pk1 varchar(8) NOT NULL default '',
pk2 varchar(4) NOT NULL default '',
key1 int(11),
key2 int(11),
primary key(pk1, pk2),
KEY key1 (key1),
KEY key2 (key2)
);
insert into t1 values ('','empt',2,2),
('a','a--a',2,2),
('bb','b--b',2,2),
('ccc','c--c',2,2),
('dddd','d--d',2,2);
select * from t1 force index(key1, key2) where key1 < 3 or key2 < 3;
pk1 pk2 key1 key2
empt 2 2
a a--a 2 2
bb b--b 2 2
ccc c--c 2 2
dddd d--d 2 2
drop table t1;
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