MYSQL数据库查看mysql语句运行时间的2种方法

《MYSQL数据库查看mysql语句运行时间的2种方法》要点：
本文介绍了MYSQL数据库查看mysql语句运行时间的2种方法，希望对您有用。如果有疑问，可以联系我们。

网站运行很慢的时候,我就特别起知道为什么这么慢,所以我查啊查,数据库绝对是很重要的一部分,里面运行的sql是绝对不能放过的.平时做项目的时候,我也会注意sql语句的书写,写出一些高效的sql来,所以我会经常测试自己写的sql语句.我把我知道的二个方法,总结一下发出来.MYSQL数据库

一,show profiles 之类的语句来查看MYSQL数据库

1,查一下profile是不是打开了,默认是不打开的.MYSQL数据库

mysql> show profiles; 
Empty set (0.02 sec) 
mysql> show variables like "%pro%"; 
+---------------------------+-------+ 
| Variable_name | Value | 
+---------------------------+-------+ 
| profiling | OFF | 
| profiling_history_size | 15 | 
| protocol_version | 10 | 
| slave_compressed_protocol | OFF | 
+---------------------------+-------+ 
4 rows in set (0.00 sec)

我查看一下profiles里面没有东西,所以公司的电脑里面profile是没有打开的,我查看了一下mysql变量,果然是OFF的.MYSQL数据库

2,开启profile,然后测试MYSQL数据库

开启profileMYSQL数据库

mysql> set profiling=1; 
Query OK, 0 rows affected (0.00 sec)

测试如下：MYSQL数据库

mysql> show tables; 
+----------------+ 
| Tables_in_test | 
+----------------+ 
| aa | 
| bb | 
| comment | 
| string_test | 
| user | 
+----------------+ 
5 rows in set (0.00 sec) 
mysql> select * from aa; 
+----+------+------------+------+ 
| id | name | nname | sex | 
+----+------+------------+------+ 
| 2 | tank | bbbb,4bbbb | NULL | 
| 3 | zhang| 3,c,u | NULL | 
+----+------+------------+------+ 
2 rows in set (0.00 sec) 
mysql> update aa set name='d'; 
Query OK, 2 rows affected (0.00 sec) 
Rows matched: 2 Changed: 2 Warnings: 0 
mysql> delete from bb; 
Query OK, 2 rows affected (0.00 sec) 
mysql> show profiles; 
+----------+------------+------------------------+ 
| Query_ID | Duration | Query | 
+----------+------------+------------------------+ 
| 1 | 0.00054775 | show tables | 
| 2 | 0.00022400 | select * from aa | 
| 3 | 0.00026275 | update aa set name='d' | 
| 4 | 0.00043000 | delete from bb | 
+----------+------------+------------------------+ 
4 rows in set (0.00 sec) 
mysql> show profile; 
+----------------------+-----------+ 
| Status | Duration | 
+----------------------+-----------+ 
| (initialization) | 0.0000247 | 
| checking permissions | 0.0000077 | 
| Opening tables | 0.0000099 | 
| System lock | 0.000004 | 
| Table lock | 0.000005 | 
| init | 0.0003057 | 
| query end | 0.0000062 | 
| freeing items | 0.000057 | 
| closing tables | 0.000008 | 
| logging slow query | 0.0000015 | 
+----------------------+-----------+ 
10 rows in set (0.00 sec) 
mysql> show profile for query 1; 
+----------------------+-----------+ 
| Status | Duration | 
+----------------------+-----------+ 
| (initialization) | 0.000028 | 
| checking permissions | 0.000007 | 
| Opening tables | 0.0000939 | 
| System lock | 0.0000017 | 
| Table lock | 0.0000055 | 
| init | 0.000009 | 
| optimizing | 0.0000027 | 
| statistics | 0.0000085 | 
| preparing | 0.0000065 | 
| executing | 0.000004 | 
| checking permissions | 0.000258 | 
| Sending data | 0.000049 | 
| end | 0.0000037 | 
| query end | 0.0000027 | 
| freeing items | 0.0000307 | 
| closing tables | 0.0000032 | 
| removing tmp table | 0.0000275 | 
| closing tables | 0.0000037 | 
| logging slow query | 0.000002 | 
+----------------------+-----------+ 
19 rows in set (0.00 sec) 
mysql> show profile for query 3; 
+----------------------+-----------+ 
| Status | Duration | 
+----------------------+-----------+ 
| (initialization) | 0.0000475 | 
| checking permissions | 0.0000077 | 
| Opening tables | 0.000026 | 
| System lock | 0.0000042 | 
| Table lock | 0.0000045 | 
| init | 0.0000205 | 
| Updating | 0.0000787 | 
| end | 0.0000567 | 
| query end | 0.000004 | 
| freeing items | 0.0000067 | 
| closing tables | 0.000004 | 
| logging slow query | 0.000002 | 
+----------------------+-----------+ 
12 rows in set (0.00 sec)

二,timestampdiff来查看测试时间MYSQL数据库

mysql> set @d=now(); 
Query OK, 0 rows affected (0.00 sec) 
mysql> select * from comment; 
+------+-----+------+------------+---------------------+ 
| c_id | mid | name | content | datetime | 
+------+-----+------+------------+---------------------+ 
| 1 | 1 | ?? | 2222222211 | 2010-05-12 00:00:00 | 
| 2 | 1 | ?? | ????(??) | 2010-05-13 00:00:00 | 
| 3 | 2 | tank | ?????? | 0000-00-00 00:00:00 | 
+------+-----+------+------------+---------------------+ 
3 rows in set (0.00 sec) 
mysql> select timestampdiff(second,@d,now()); 
+--------------------------------+ 
| timestampdiff(second,@d,now()) | 
+--------------------------------+ 
| 0 | 
+--------------------------------+ 
1 row in set (0.00 sec) 

这种方法有一点要注意,就是三条sql语句要尽量连一起执行,不然误差太大,根本不准MYSQL数据库

set @d=now(); 
select * from comment; 
select timestampdiff(second,@d,now()); 

如果是用命令行来执行的话,有一点要注意,就是在select timestampdiff(second,@d,now());后面,一定要多copy一个空行,不然最后一个sql要你自己按回车执行,这样就不准了.MYSQL数据库

其实我觉得吧,真正要我们关心的是那些查询慢的sql,因为真正影响速度的是他们,关于慢查询的东西,有空写一下.MYSQL数据库

转载请注明本页网址：
http://www.vephp.com/jiaocheng/2419.html