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|
drop table if exists t0, t1, t2, t3, t4;
create table t0
(
key1 int not null,
INDEX i1(key1)
);
alter table t0 add key2 int not null, add index i2(key2);
alter table t0 add key3 int not null, add index i3(key3);
alter table t0 add key4 int not null, add index i4(key4);
alter table t0 add key5 int not null, add index i5(key5);
alter table t0 add key6 int not null, add index i6(key6);
alter table t0 add key7 int not null, add index i7(key7);
alter table t0 add key8 int not null, add index i8(key8);
update t0 set key2=key1,key3=key1,key4=key1,key5=key1,key6=key1,key7=key1,key8=1024-key1;
analyze table t0;
Table Op Msg_type Msg_text
test.t0 analyze status OK
explain select * from t0 where key1 < 3 or key1 > 1020;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 range i1 i1 4 NULL 78 Using where
explain
select * from t0 where key1 < 3 or key2 > 1020;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 45 Using sort_union(i1,i2); Using where
select * from t0 where key1 < 3 or key2 > 1020;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
2 2 2 2 2 2 2 1022
1021 1021 1021 1021 1021 1021 1021 3
1022 1022 1022 1022 1022 1022 1022 2
1023 1023 1023 1023 1023 1023 1023 1
1024 1024 1024 1024 1024 1024 1024 0
explain select * from t0 where key1 < 3 or key2 <4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 7 Using sort_union(i1,i2); Using where
explain
select * from t0 where (key1 > 30 and key1<35) or (key2 >32 and key2 < 40);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 11 Using sort_union(i1,i2); Using where
select * from t0 where (key1 > 30 and key1<35) or (key2 >32 and key2 < 40);
key1 key2 key3 key4 key5 key6 key7 key8
31 31 31 31 31 31 31 993
32 32 32 32 32 32 32 992
33 33 33 33 33 33 33 991
34 34 34 34 34 34 34 990
35 35 35 35 35 35 35 989
36 36 36 36 36 36 36 988
37 37 37 37 37 37 37 987
38 38 38 38 38 38 38 986
39 39 39 39 39 39 39 985
explain select * from t0 ignore index (i2) where key1 < 3 or key2 <4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1 NULL NULL NULL 1024 Using where
explain select * from t0 where (key1 < 3 or key2 <4) and key3 = 50;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ref i1,i2,i3 i3 4 const 1 Using where
explain select * from t0 use index (i1,i2) where (key1 < 3 or key2 <4) and key3 = 50;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 7 Using sort_union(i1,i2); Using where
explain select * from t0 where (key1 > 1 or key2 > 2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2 NULL NULL NULL 1024 Using where
explain select * from t0 force index (i1,i2) where (key1 > 1 or key2 > 2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 1024 Using sort_union(i1,i2); Using where
explain
select * from t0 where key1<3 or key2<3 or (key1>5 and key1<8) or
(key1>10 and key1<12) or (key2>100 and key2<110);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 17 Using sort_union(i1,i2); Using where
explain select * from t0 where key2 = 45 or key1 <=> null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 range i1,i2 i2 4 NULL 1 Using where
explain select * from t0 where key2 = 45 or key1 is not null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2 NULL NULL NULL 1024 Using where
explain select * from t0 where key2 = 45 or key1 is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ref i2 i2 4 const 1
explain select * from t0 where key2=10 or key3=3 or key4 <=> null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i2,i3,i4 i2,i3 4,4 NULL 2 Using union(i2,i3); Using where
explain select * from t0 where key2=10 or key3=3 or key4 is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i2,i3 i2,i3 4,4 NULL 2 Using union(i2,i3); Using where
explain select key1 from t0 where (key1 <=> null) or (key2 < 5) or
(key3=10) or (key4 <=> null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i4 i2,i3 4,4 NULL 6 Using sort_union(i2,i3); Using where
explain select key1 from t0 where (key1 <=> null) or (key1 < 5) or
(key3=10) or (key4 <=> null);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i3,i4 i1,i3 4,4 NULL 6 Using sort_union(i1,i3); Using where
explain select * from t0 where
(key1 < 3 or key2 < 3) and (key3 < 4 or key4 < 4) and (key5 < 5 or key6 < 5);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i4,i5,i6 i1,i2 4,4 NULL 6 Using sort_union(i1,i2); Using where
explain
select * from t0 where (key1 < 3 or key2 < 6) and (key1 < 7 or key3 < 4);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3 i1,i2 4,4 NULL 9 Using sort_union(i1,i2); Using where
select * from t0 where (key1 < 3 or key2 < 6) and (key1 < 7 or key3 < 4);
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
2 2 2 2 2 2 2 1022
3 3 3 3 3 3 3 1021
4 4 4 4 4 4 4 1020
5 5 5 5 5 5 5 1019
explain select * from t0 where
(key1 < 3 or key2 < 3) and (key3 < 4 or key4 < 4) and (key5 < 2 or key6 < 2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i4,i5,i6 i1,i2 4,4 NULL 6 Using sort_union(i1,i2); Using where
explain select * from t0 where
(key1 < 3 or key2 < 3) and (key3 < 100);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 range i1,i2,i3 i3 4 NULL 95 Using where
explain select * from t0 where
(key1 < 3 or key2 < 3) and (key3 < 1000);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2,i3 NULL NULL NULL 1024 Using where
explain select * from t0 where
((key1 < 4 or key2 < 4) and (key2 <5 or key3 < 4))
or
key2 > 5;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2,i3 NULL NULL NULL 1024 Using where
explain select * from t0 where
((key1 < 4 or key2 < 4) and (key2 <5 or key3 < 4))
or
key1 < 7;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3 i1,i2 4,4 NULL 10 Using sort_union(i1,i2); Using where
select * from t0 where
((key1 < 4 or key2 < 4) and (key2 <5 or key3 < 4))
or
key1 < 7;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
2 2 2 2 2 2 2 1022
3 3 3 3 3 3 3 1021
4 4 4 4 4 4 4 1020
5 5 5 5 5 5 5 1019
6 6 6 6 6 6 6 1018
explain select * from t0 where
((key1 < 4 or key2 < 4) and (key3 <5 or key5 < 4))
or
((key5 < 5 or key6 < 6) and (key7 <7 or key8 < 4));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6,i7,i8 i1,i2,i5,i6 4,4,4,4 NULL 19 Using sort_union(i1,i2,i5,i6); Using where
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key7 <7 or key8 < 4) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6,i7,i8 i3,i5,i7,i8 4,4,4,4 NULL 20 Using sort_union(i3,i5,i7,i8); Using where
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 <7 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6 i3,i5 4,4 NULL 11 Using sort_union(i3,i5); Using where
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
(((key3 <7 and key7 < 6) or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6,i7 i3,i5 4,4 NULL 11 Using sort_union(i3,i5); Using where
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2,i3,i5,i6 NULL NULL NULL 1024 Using where
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6 i3,i5 0,4 NULL 1024 Using sort_union(i3,i5); Using where
select * from t0 where key1 < 5 or key8 < 4 order by key1;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
2 2 2 2 2 2 2 1022
3 3 3 3 3 3 3 1021
4 4 4 4 4 4 4 1020
1021 1021 1021 1021 1021 1021 1021 3
1022 1022 1022 1022 1022 1022 1022 2
1023 1023 1023 1023 1023 1023 1023 1
1024 1024 1024 1024 1024 1024 1024 0
explain
select * from t0 where key1 < 5 or key8 < 4 order by key1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i8 i1,i8 4,4 NULL 9 Using sort_union(i1,i8); Using where; Using filesort
create table t2 like t0;
insert into t2 select * from t0;
alter table t2 add index i1_3(key1, key3);
alter table t2 add index i2_3(key2, key3);
alter table t2 drop index i1;
alter table t2 drop index i2;
alter table t2 add index i321(key3, key2, key1);
explain select key3 from t2 where key1 = 100 or key2 = 100;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index_merge i1_3,i2_3 i1_3,i2_3 4,4 NULL 2 Using sort_union(i1_3,i2_3); Using where
explain select key3 from t2 where key1 <100 or key2 < 100;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index i1_3,i2_3 i321 12 NULL 1024 Using where; Using index
explain select key7 from t2 where key1 <100 or key2 < 100;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL i1_3,i2_3 NULL NULL NULL 1024 Using where
create table t4 (
key1a int not null,
key1b int not null,
key2 int not null,
key2_1 int not null,
key2_2 int not null,
key3 int not null,
index i1a (key1a, key1b),
index i1b (key1b, key1a),
index i2_1(key2, key2_1),
index i2_2(key2, key2_1)
);
insert into t4 select key1,key1,key1 div 10, key1 % 10, key1 % 10, key1 from t0;
select * from t4 where key1a = 3 or key1b = 4;
key1a key1b key2 key2_1 key2_2 key3
3 3 0 3 3 3
4 4 0 4 4 4
explain select * from t4 where key1a = 3 or key1b = 4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t4 index_merge i1a,i1b i1a,i1b 4,4 NULL 2 Using sort_union(i1a,i1b); Using where
explain select * from t4 where key2 = 1 and (key2_1 = 1 or key3 = 5);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t4 ref i2_1,i2_2 i2_1 4 const 10 Using where
explain select * from t4 where key2 = 1 and (key2_1 = 1 or key2_2 = 5);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t4 ref i2_1,i2_2 i2_1 4 const 10 Using where
explain select * from t4 where key2_1 = 1 or key2_2 = 5;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t4 ALL NULL NULL NULL NULL 1024 Using where
create table t1 like t0;
insert into t1 select * from t0;
explain select * from t0 left join t1 on (t0.key1=t1.key1)
where t0.key1=3 or t0.key2=4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 2 Using union(i1,i2); Using where
1 SIMPLE t1 ref i1 i1 4 test.t0.key1 1
select * from t0 left join t1 on (t0.key1=t1.key1)
where t0.key1=3 or t0.key2=4;
key1 key2 key3 key4 key5 key6 key7 key8 key1 key2 key3 key4 key5 key6 key7 key8
3 3 3 3 3 3 3 1021 3 3 3 3 3 3 3 1021
4 4 4 4 4 4 4 1020 4 4 4 4 4 4 4 1020
explain
select * from t0,t1 where (t0.key1=t1.key1) and ( t0.key1=3 or t0.key2=4);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 2 Using union(i1,i2); Using where
1 SIMPLE t1 ref i1 i1 4 test.t0.key1 1
explain
select * from t0,t1 where (t0.key1=t1.key1) and
(t0.key1=3 or t0.key2=4) and t1.key1<200;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2 NULL NULL NULL 1024 Using where
1 SIMPLE t1 ref i1 i1 4 test.t0.key1 1
explain
select * from t0,t1 where (t0.key1=t1.key1) and
(t0.key1=3 or t0.key2<4) and t1.key1=2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ref i1,i2 i1 4 const 1 Using where
1 SIMPLE t1 ref i1 i1 4 const 1
explain select * from t0,t1 where t0.key1 = 5 and
(t1.key1 = t0.key1 or t1.key8 = t0.key1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ref i1 i1 4 const 1
1 SIMPLE t1 index_merge i1,i8 i1,i8 4,4 NULL 2 Using union(i1,i8); Using where
explain select * from t0,t1 where t0.key1 < 3 and
(t1.key1 = t0.key1 or t1.key8 = t0.key1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 range i1 i1 4 NULL 3 Using where
1 SIMPLE t1 ALL i1,i8 NULL NULL NULL 1024 Range checked for each record (index map: 0x81)
explain select * from t1 where key1=3 or key2=4
union select * from t1 where key1<4 or key3=5;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index_merge i1,i2 i1,i2 4,4 NULL 2 Using union(i1,i2); Using where
2 UNION t1 index_merge i1,i3 i1,i3 4,4 NULL 5 Using sort_union(i1,i3); Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
explain select * from (select * from t1 where key1 = 3 or key2 =3) as Z where key8 >5;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> system NULL NULL NULL NULL 1
2 DERIVED t1 index_merge i1,i2 i1,i2 4,4 NULL 2 Using union(i1,i2); Using where; Using index
create table t3 like t0;
insert into t3 select * from t0;
alter table t3 add key9 int not null, add index i9(key9);
alter table t3 add keyA int not null, add index iA(keyA);
alter table t3 add keyB int not null, add index iB(keyB);
alter table t3 add keyC int not null, add index iC(keyC);
update t3 set key9=key1,keyA=key1,keyB=key1,keyC=key1;
explain select * from t3 where
key1=1 or key2=2 or key3=3 or key4=4 or
key5=5 or key6=6 or key7=7 or key8=8 or
key9=9 or keyA=10 or keyB=11 or keyC=12;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index_merge i1,i2,i3,i4,i5,i6,i7,i8,i9,iA,iB,iC i1,i2,i3,i4,i5,i6,i7,i8,i9,iA,iB,iC 4,4,4,4,4,4,4,4,4,4,4,4 NULL 12 Using union(i1,i2,i3,i4,i5,i6,i7,i8,i9,iA,iB,iC); Using where
select * from t3 where
key1=1 or key2=2 or key3=3 or key4=4 or
key5=5 or key6=6 or key7=7 or key8=8 or
key9=9 or keyA=10 or keyB=11 or keyC=12;
key1 key2 key3 key4 key5 key6 key7 key8 key9 keyA keyB keyC
1 1 1 1 1 1 1 1023 1 1 1 1
2 2 2 2 2 2 2 1022 2 2 2 2
3 3 3 3 3 3 3 1021 3 3 3 3
4 4 4 4 4 4 4 1020 4 4 4 4
5 5 5 5 5 5 5 1019 5 5 5 5
6 6 6 6 6 6 6 1018 6 6 6 6
7 7 7 7 7 7 7 1017 7 7 7 7
9 9 9 9 9 9 9 1015 9 9 9 9
10 10 10 10 10 10 10 1014 10 10 10 10
11 11 11 11 11 11 11 1013 11 11 11 11
12 12 12 12 12 12 12 1012 12 12 12 12
1016 1016 1016 1016 1016 1016 1016 8 1016 1016 1016 1016
explain select * from t0 where key1 < 3 or key2 < 4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2 i1,i2 4,4 NULL 7 Using sort_union(i1,i2); Using where
select * from t0 where key1 < 3 or key2 < 4;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
2 2 2 2 2 2 2 1022
3 3 3 3 3 3 3 1021
update t0 set key8=123 where key1 < 3 or key2 < 4;
select * from t0 where key1 < 3 or key2 < 4;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 123
2 2 2 2 2 2 2 123
3 3 3 3 3 3 3 123
delete from t0 where key1 < 3 or key2 < 4;
select * from t0 where key1 < 3 or key2 < 4;
key1 key2 key3 key4 key5 key6 key7 key8
select count(*) from t0;
count(*)
1021
drop table t4;
create table t4 (a int);
insert into t4 values (1),(4),(3);
set @save_join_buffer_size=@@join_buffer_size;
set join_buffer_size= 4000;
explain select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
where (A.key1 < 500000 or A.key2 < 3)
and (B.key1 < 500000 or B.key2 < 3);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE A index_merge i1,i2 i1,i2 4,4 NULL 1013 Using sort_union(i1,i2); Using where
1 SIMPLE B index_merge i1,i2 i1,i2 4,4 NULL 1013 Using sort_union(i1,i2); Using where
select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
where (A.key1 < 500000 or A.key2 < 3)
and (B.key1 < 500000 or B.key2 < 3);
max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
10240
update t0 set key1=1;
explain select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
where (A.key1 = 1 or A.key2 = 1)
and (B.key1 = 1 or B.key2 = 1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE A index_merge i1,i2 i1,i2 4,4 NULL 1020 Using union(i1,i2); Using where
1 SIMPLE B index_merge i1,i2 i1,i2 4,4 NULL 1020 Using union(i1,i2); Using where
select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
where (A.key1 = 1 or A.key2 = 1)
and (B.key1 = 1 or B.key2 = 1);
max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
8194
alter table t0 add filler1 char(200), add filler2 char(200), add filler3 char(200);
update t0 set key2=1, key3=1, key4=1, key5=1,key6=1,key7=1 where key7 < 500;
explain select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A, t0 as B
where (A.key1 = 1 and A.key2 = 1 and A.key3 = 1 and A.key4=1 and A.key5=1 and A.key6=1 and A.key7 = 1 or A.key8=1)
and (B.key1 = 1 and B.key2 = 1 and B.key3 = 1 and B.key4=1 and B.key5=1 and B.key6=1 and B.key7 = 1 or B.key8=1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE A index_merge i1,i2,i3,i4,i5,i6,i7?,i8 i2,i3,i4,i5,i6,i7?,i8 X NULL # Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where
1 SIMPLE B index_merge i1,i2,i3,i4,i5,i6,i7?,i8 i2,i3,i4,i5,i6,i7?,i8 X NULL # Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where
select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
from t0 as A, t0 as B
where (A.key1 = 1 and A.key2 = 1 and A.key3 = 1 and A.key4=1 and A.key5=1 and A.key6=1 and A.key7 = 1 or A.key8=1)
and (B.key1 = 1 and B.key2 = 1 and B.key3 = 1 and B.key4=1 and B.key5=1 and B.key6=1 and B.key7 = 1 or B.key8=1);
max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
8186
set join_buffer_size= @save_join_buffer_size;
drop table t0, t1, t2, t3, t4;
CREATE TABLE t1 (
cola char(3) not null, colb char(3) not null, filler char(200),
key(cola), key(colb)
);
INSERT INTO t1 VALUES ('foo','bar', 'ZZ'),('fuz','baz', 'ZZ');
OPTIMIZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 optimize status OK
select count(*) from t1;
count(*)
8704
explain select * from t1 WHERE cola = 'foo' AND colb = 'bar';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge cola,colb cola,colb 3,3 NULL 24 Using intersect(cola,colb); Using where
explain select * from t1 force index(cola,colb) WHERE cola = 'foo' AND colb = 'bar';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge cola,colb cola,colb 3,3 NULL 24 Using intersect(cola,colb); Using where
drop table t1;
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,
filler1 char(200), filler2 char(200),
key(a),key(b)
);
insert into t1 select @v:= A.a, @v, 't1', 'filler2' from t0 A, t0 B, t0 C;
create table t2 like t1;
create table t3 (
a int, b int,
filler1 char(200), filler2 char(200),
key(a),key(b)
) engine=merge union=(t1,t2);
explain select * from t1 where a=1 and b=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge a,b a,b 5,5 NULL # Using intersect(a,b); Using where
explain select * from t3 where a=1 and b=1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index_merge a,b a,b 5,5 NULL # Using intersect(a,b); Using where
drop table t3;
drop table t0, t1, t2;
CREATE TABLE t1(a INT);
INSERT INTO t1 VALUES(1);
CREATE TABLE t2(a INT, b INT, dummy CHAR(16) DEFAULT '', KEY(a), KEY(b));
INSERT INTO t2(a,b) VALUES
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),(0,0),
(1,2);
LOCK TABLES t1 WRITE, t2 WRITE;
INSERT INTO t2(a,b) VALUES(1,2);
SELECT t2.a FROM t1,t2 WHERE t2.b=2 AND t2.a=1;
a
1
1
UNLOCK TABLES;
DROP TABLE t1, t2;
CREATE TABLE `t1` (
`a` int(11) DEFAULT NULL,
`filler` char(200) DEFAULT NULL,
`b` int(11) DEFAULT NULL,
KEY `a` (`a`),
KEY `b` (`b`)
) ENGINE=MEMORY DEFAULT CHARSET=latin1;
insert into t1 values
(0, 'filler', 0), (1, 'filler', 1), (2, 'filler', 2), (3, 'filler', 3),
(4, 'filler', 4), (5, 'filler', 5), (6, 'filler', 6), (7, 'filler', 7),
(8, 'filler', 8), (9, 'filler', 9), (0, 'filler', 0), (1, 'filler', 1),
(2, 'filler', 2), (3, 'filler', 3), (4, 'filler', 4), (5, 'filler', 5),
(6, 'filler', 6), (7, 'filler', 7), (8, 'filler', 8), (9, 'filler', 9),
(10, 'filler', 10), (11, 'filler', 11), (12, 'filler', 12), (13, 'filler', 13),
(14, 'filler', 14), (15, 'filler', 15), (16, 'filler', 16), (17, 'filler', 17),
(18, 'filler', 18), (19, 'filler', 19), (4, '5 ', 0), (5, '4 ', 0),
(4, '4 ', 0), (4, 'qq ', 5), (5, 'qq ', 4), (4, 'zz ', 4);
create table t2(
`a` int(11) DEFAULT NULL,
`filler` char(200) DEFAULT NULL,
`b` int(11) DEFAULT NULL,
KEY USING BTREE (`a`),
KEY USING BTREE (`b`)
) ENGINE=MEMORY DEFAULT CHARSET=latin1;
insert into t2 select * from t1;
must use sort-union rather than union:
explain select * from t1 where a=4 or b=4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index_merge a,b a,b 5,5 NULL # Using sort_union(a,b); Using where
select * from t1 where a=4 or b=4;
a filler b
4 4 0
4 5 0
4 filler 4
4 filler 4
4 qq 5
4 zz 4
5 qq 4
select * from t1 ignore index(a,b) where a=4 or b=4;
a filler b
4 4 0
4 5 0
4 filler 4
4 filler 4
4 qq 5
4 zz 4
5 qq 4
must use union, not sort-union:
explain select * from t2 where a=4 or b=4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index_merge a,b a,b 5,5 NULL # Using union(a,b); Using where
select * from t2 where a=4 or b=4;
a filler b
4 4 0
4 5 0
4 filler 4
4 filler 4
4 qq 5
4 zz 4
5 qq 4
drop table t1, t2;
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