一,show profiles 之類的語句來查看
1,查一下profile是不是打開了,默認是不打開的。
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)
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
我查看一下profiles裏面沒有東西,所以公司的電腦裏面profile是沒有打開的,我查看了一下MySQL變量,果然是OFF的。
2,開啓profile,然後測試
開啓profile
mysql> set profiling=1;
Query OK, 0 rows affected (0.00 sec)
- 1
- 2
- 1
- 2
測試如下:
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)
- 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
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 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
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
二,timestampdiff來查看測試時間
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)
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
這種方法有一點要注意,就是三條sql語句要儘量連一起執行,不然誤差太大,根本不準
set @d=now();
select * from comment;
select timestampdiff(second,@d,now());
- 1
- 2
- 3
- 1
- 2
- 3
如果是用命令行來執行的話,有一點要注意,就是在select timestampdiff(second,@d,now());後面,一定要多copy一個空行,不然最後一個sql要你自己按回車執行,這樣就不準了。
其實我覺得吧,真正要我們關心的是那些查詢慢的sql,因爲真正影響速度的是他們,關於慢查詢的東西,有空寫一下。
http://www.jb51.net/article/45185.htm
參數各種含義:http://www.jb51.net/article/29820.htm