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flush status;
show status like 'Table_lock%';
Variable_name Value
Table_locks_immediate 0
Table_locks_waited 0
select * from information_schema.session_status where variable_name like 'Table_lock%';
VARIABLE_NAME VARIABLE_VALUE
TABLE_LOCKS_IMMEDIATE 0.0000000
TABLE_LOCKS_WAITED 0.0000000
SET SQL_LOG_BIN=0;
drop table if exists t1;
create table t1(n int) engine=myisam;
insert into t1 values(1);
lock tables t1 read;
unlock tables;
lock tables t1 read;
update t1 set n = 3;
unlock tables;
show status like 'Table_lock%';
Variable_name Value
Table_locks_immediate 3
Table_locks_waited 1
select * from information_schema.session_status where variable_name like 'Table_lock%';
VARIABLE_NAME VARIABLE_VALUE
TABLE_LOCKS_IMMEDIATE 3.0000000
TABLE_LOCKS_WAITED 1.0000000
drop table t1;
select 1;
1
1
show status like 'last_query_cost';
Variable_name Value
Last_query_cost 0.000000
create table t1 (a int);
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
select * from t1 where a=6;
a
6
6
6
6
6
show status like 'last_query_cost';
Variable_name Value
Last_query_cost 12.084449
show status like 'last_query_cost';
Variable_name Value
Last_query_cost 12.084449
select 1;
1
1
show status like 'last_query_cost';
Variable_name Value
Last_query_cost 0.000000
drop table t1;
FLUSH STATUS;
SHOW STATUS LIKE 'max_used_connections';
Variable_name Value
Max_used_connections 1
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
VARIABLE_NAME VARIABLE_VALUE
MAX_USED_CONNECTIONS 1.0000000
SET @save_thread_cache_size=@@thread_cache_size;
SET GLOBAL thread_cache_size=3;
SHOW STATUS LIKE 'max_used_connections';
Variable_name Value
Max_used_connections 3
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
VARIABLE_NAME VARIABLE_VALUE
MAX_USED_CONNECTIONS 3.0000000
FLUSH STATUS;
SHOW STATUS LIKE 'max_used_connections';
Variable_name Value
Max_used_connections 2
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
VARIABLE_NAME VARIABLE_VALUE
MAX_USED_CONNECTIONS 2.0000000
SHOW STATUS LIKE 'max_used_connections';
Variable_name Value
Max_used_connections 3
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
VARIABLE_NAME VARIABLE_VALUE
MAX_USED_CONNECTIONS 3.0000000
SHOW STATUS LIKE 'max_used_connections';
Variable_name Value
Max_used_connections 4
SELECT * FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME LIKE 'max_used_connections';
VARIABLE_NAME VARIABLE_VALUE
MAX_USED_CONNECTIONS 4.0000000
SET GLOBAL thread_cache_size=@save_thread_cache_size;
show status like 'com_show_status';
Variable_name Value
Com_show_status 3
show status like 'hand%write%';
Variable_name Value
Handler_write 0
show status like '%tmp%';
Variable_name Value
Created_tmp_disk_tables 0
Created_tmp_files 0
Created_tmp_tables 0
show status like 'hand%write%';
Variable_name Value
Handler_write 0
show status like '%tmp%';
Variable_name Value
Created_tmp_disk_tables 0
Created_tmp_files 0
Created_tmp_tables 0
show status like 'com_show_status';
Variable_name Value
Com_show_status 8
rnd_diff tmp_table_diff
20 8
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