1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
SET DEFAULT_STORAGE_ENGINE = 'tokudb';
DROP TABLE IF EXISTS foo;
set session unique_checks=off;
create table foo (a int, b int, c int, primary key (a), key(b));
insert into foo values (1,10,100),(2,20,200),(3,30,300),(4,40,400),(5,50,500),(6,60,600);
explain select * from foo;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE foo ALL NULL NULL NULL NULL 6 NULL
select * from foo;
a b c
1 10 100
2 20 200
3 30 300
4 40 400
5 50 500
6 60 600
explain select b from foo;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE foo index NULL b 5 NULL 6 Using index
select b from foo;
b
10
20
30
40
50
60
replace into foo values (1,1,1);
explain select * from foo;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE foo ALL NULL NULL NULL NULL 6 NULL
select * from foo;
a b c
1 1 1
2 20 200
3 30 300
4 40 400
5 50 500
6 60 600
explain select b from foo;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE foo index NULL b 5 NULL 6 Using index
select b from foo;
b
1
20
30
40
50
60
set session unique_checks=on;
DROP TABLE foo;
|
