set @old_concurrent_insert= @@global.concurrent_insert;
set @@global.concurrent_insert= 0;
SET @old_log_output = @@global.log_output;
SET GLOBAL LOG_OUTPUT = 'FILE';
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
TABLE_LOCKS_WAITED	0
# Switched to connection: con1
set sql_log_bin=0;
set @old_general_log = @@global.general_log;
set global general_log = 'OFF';
drop table if exists t1;
create table t1(n int) engine=myisam;
insert into t1 values(1);
select 1;
1
1
# Switched to connection: con2
lock tables t1 read;
unlock tables;
lock tables t1 read;
# Switched to connection: con1
update t1 set n = 3;
# Switched to connection: con2
unlock tables;
# Switched to connection: con1
show status like 'Table_locks_waited';
Variable_name	Value
Table_locks_waited	1
drop table t1;
set global general_log = @old_general_log;
# Switched to connection: default
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
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
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
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
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
SET GLOBAL thread_cache_size=@save_thread_cache_size;
CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (1), (2);
SELECT a FROM t1 LIMIT 1;
a
1
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	2.402418
EXPLAIN SELECT a FROM t1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	2.402418
SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
a
1
2
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	0.000000
EXPLAIN SELECT a FROM t1 UNION SELECT a FROM t1 ORDER BY a;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
2	UNION	t1	ALL	NULL	NULL	NULL	NULL	2	
NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	Using filesort
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	0.000000
SELECT a IN (SELECT a FROM t1) FROM t1 LIMIT 1;
a IN (SELECT a FROM t1)
1
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	0.000000
SELECT (SELECT a FROM t1 LIMIT 1) x FROM t1 LIMIT 1;
x
1
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	0.000000
SELECT * FROM t1 a, t1 b LIMIT 1;
a	a
1	1
SHOW SESSION STATUS LIKE 'Last_query_cost';
Variable_name	Value
Last_query_cost	5.205836
DROP TABLE t1;
show status like 'com_show_status';
Variable_name	Value
Com_show_status	3
show status like 'hand%write%';
Variable_name	Value
Handler_tmp_write	0
Handler_write	0
show status like '%tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	0
Handler_tmp_update	0
Handler_tmp_write	0
Rows_tmp_read	5
show status like 'hand%write%';
Variable_name	Value
Handler_tmp_write	0
Handler_write	0
show status like '%tmp%';
Variable_name	Value
Created_tmp_disk_tables	0
Created_tmp_files	0
Created_tmp_tables	0
Handler_tmp_update	0
Handler_tmp_write	0
Rows_tmp_read	13
show status like 'com_show_status';
Variable_name	Value
Com_show_status	8
rnd_diff	tmp_table_diff
28	8
flush status;
show status like 'Com%function';
Variable_name	Value
Com_alter_function	0
Com_create_function	0
Com_drop_function	0
create function f1 (x INTEGER) returns integer
begin
declare ret integer;
set ret = x * 10;
return ret;
end //
drop function f1;
show status like 'Com%function';
Variable_name	Value
Com_alter_function	0
Com_create_function	1
Com_drop_function	1
create database db37908;
create table db37908.t1(f1 int);
insert into db37908.t1 values(1);
create user mysqltest_1@localhost;
grant usage,execute on test.* to mysqltest_1@localhost;
create procedure proc37908() begin select 1; end |
create function func37908() returns int sql security invoker
return (select * from db37908.t1 limit 1)|
select * from db37908.t1;
ERROR 42000: SELECT command denied to user 'mysqltest_1'@'localhost' for table 't1'
show status where variable_name ='uptime' and 2 in (select * from db37908.t1);
ERROR 42000: SELECT command denied to user 'mysqltest_1'@'localhost' for table 't1'
show procedure status where name ='proc37908' and 1 in (select f1 from db37908.t1);
ERROR 42000: SELECT command denied to user 'mysqltest_1'@'localhost' for table 't1'
show function status where name ='func37908' and 1 in (select func37908());
ERROR 42000: SELECT command denied to user 'mysqltest_1'@'localhost' for table 't1'
drop database db37908;
drop procedure proc37908;
drop function func37908;
REVOKE ALL PRIVILEGES, GRANT OPTION FROM mysqltest_1@localhost;
DROP USER mysqltest_1@localhost;
DROP PROCEDURE IF EXISTS p1;
DROP FUNCTION IF EXISTS f1;
CREATE FUNCTION f1() RETURNS INTEGER
BEGIN
DECLARE foo INTEGER;
DECLARE bar INTEGER;
SET foo=1;
SET bar=2;
RETURN foo;
END $$
CREATE PROCEDURE p1()
BEGIN
SELECT 1;
END $$
SELECT f1();
f1()
1
CALL p1();
1
1
SELECT 9;
9
9
DROP PROCEDURE p1;
DROP FUNCTION f1;
flush status;
create table t1 (a int not null auto_increment primary key, g int, b blob);
insert into t1 (g,b) values (1,'a'), (2, 'b'), (3, 'b'), (1, 'c');
select * from t1;
a	g	b
1	1	a
2	2	b
3	3	b
4	1	c
select b, count(*) from t1 group by b;
b	count(*)
a	1
b	2
c	1
select g, count(*) from t1 group by g;
g	count(*)
1	2
2	1
3	1
show status like 'Row%';
Variable_name	Value
Rows_read	12
Rows_sent	10
Rows_tmp_read	14
show status like 'Handler%';
Variable_name	Value
Handler_commit	0
Handler_delete	0
Handler_discover	0
Handler_external_lock	0
Handler_icp_attempts	0
Handler_icp_match	0
Handler_mrr_init	0
Handler_mrr_key_refills	0
Handler_mrr_rowid_refills	0
Handler_prepare	0
Handler_read_first	0
Handler_read_key	4
Handler_read_last	0
Handler_read_next	0
Handler_read_prev	0
Handler_read_retry	0
Handler_read_rnd	7
Handler_read_rnd_deleted	0
Handler_read_rnd_next	23
Handler_rollback	0
Handler_savepoint	0
Handler_savepoint_rollback	0
Handler_tmp_update	2
Handler_tmp_write	7
Handler_update	0
Handler_write	4
show status like '%tmp%';
Variable_name	Value
Created_tmp_disk_tables	1
Created_tmp_files	0
Created_tmp_tables	2
Handler_tmp_update	2
Handler_tmp_write	7
Rows_tmp_read	43
drop table t1;
CREATE TABLE t1 (i int(11) DEFAULT NULL, KEY i (i) ) ENGINE=MyISAM;
insert into t1 values (1),(2),(3),(4),(5);
flush status;
select * from t1 where i=5 union select * from t1 where i=5;
i
5
show status like "handler%";
Variable_name	Value
Handler_commit	0
Handler_delete	0
Handler_discover	0
Handler_external_lock	0
Handler_icp_attempts	0
Handler_icp_match	0
Handler_mrr_init	0
Handler_mrr_key_refills	0
Handler_mrr_rowid_refills	0
Handler_prepare	0
Handler_read_first	0
Handler_read_key	2
Handler_read_last	0
Handler_read_next	2
Handler_read_prev	0
Handler_read_retry	0
Handler_read_rnd	0
Handler_read_rnd_deleted	1
Handler_read_rnd_next	2
Handler_rollback	0
Handler_savepoint	0
Handler_savepoint_rollback	0
Handler_tmp_update	0
Handler_tmp_write	2
Handler_update	0
Handler_write	0
drop table t1;
set @@global.concurrent_insert= @old_concurrent_insert;
SET GLOBAL log_output = @old_log_output;