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set @save_userstat=@@global.userstat; 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 4 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 7 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=@save_userstat;