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
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
set global userstat=1;
create table just_a_test(id int,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30));
insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
alter table just_a_test add primary key (id);
alter table just_a_test add key IND_just_a_test_first_name_last_name(first_name,last_name);
alter table just_a_test add key IND_just_a_test_state(state);
select count(*) from just_a_test where first_name='fc' and last_name='lc';
count(*)
1
select count(*) from just_a_test where state = 'California';
count(*)
2
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
test just_a_test IND_just_a_test_first_name_last_name 1
test just_a_test IND_just_a_test_state 2
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
test just_a_test 18 5 5
alter table just_a_test drop key IND_just_a_test_first_name_last_name;
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
test just_a_test IND_just_a_test_state 2
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
test just_a_test 23 5 5
alter table just_a_test drop column state;
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
test just_a_test 28 5 5
drop table just_a_test;
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
create table just_a_test(id int not null primary key,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30),key(first_name,last_name),key(state));
insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
select count(*) from just_a_test where first_name='fc' and last_name='lc';
count(*)
1
select count(*) from just_a_test where state = 'California';
count(*)
2
select count(*) from just_a_test where id between 2 and 4;
count(*)
3
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
test just_a_test PRIMARY 5
test just_a_test first_name 1
test just_a_test state 2
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
test just_a_test 8 5 15
drop table just_a_test;
select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME INDEX_NAME ROWS_READ
select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
TABLE_SCHEMA TABLE_NAME ROWS_READ ROWS_CHANGED ROWS_CHANGED_X_INDEXES
set global userstat=0;
|
