Mysql 慢查询之showprofile

show profiles:返回服务器上最近执行的语句资源的使用情况。

一、使用准备

Show profiles是5.0.37之后添加的，要想使用此功能，要确保版本在5.0.37之后。

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.5.36    |
+-----------+

profile 功能默认是关闭的通过以下命令查看，开启

mysql> select @@profiling;
+-------------+
| @@profiling |
+-------------+
|           0 |
+-------------+

mysql> show variables like '%profiling%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| have_profiling         | YES   |
| profiling              | OFF   |
| profiling_history_size | 15    |
+------------------------+-------+

mysql> set global profiling = 1;
mysql> set global profiling_history_size = 10;

其中 profiling_history_size为保存多少条最近记录。

重开会话后显示生效。

二、具体语法

查看记录中的语句

mysql> show profiles;
+----------+------------+---------------------------------------------+
| Query_ID | Duration   | Query                                       |
+----------+------------+---------------------------------------------+
|        1 | 0.00015600 | select @@version_comment limit 1            |
|        2 | 0.00056675 | show variables like '%profiling%'           |
|        3 | 0.00007050 | select * from b limit 10000                 |
|        4 | 0.00014075 | SELECT DATABASE()                           |
|        5 | 0.00592575 | select * from b limit 10000                 |
|        6 | 0.06692075 | select * from b group by id%10 limit 10000  |
|        7 | 0.06478225 | select * from b group by id%10 limit 100000 |
+----------+------------+---------------------------------------------+

查看表中具体记录的详细执行信息

show profile [参数[,参数...]] for query [上面的Query_ID]

mysql> show profile cpu,block io for query 7;
+----------------------+----------+----------+------------+--------------+---------------+
| Status               | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+----------------------+----------+----------+------------+--------------+---------------+
| starting             | 0.000060 | 0.000000 |   0.000000 |         NULL |          NULL |
| checking permissions | 0.000004 | 0.000000 |   0.000000 |         NULL |          NULL |
| Opening tables       | 0.000026 | 0.000000 |   0.000000 |         NULL |          NULL |
| System lock          | 0.000006 | 0.000000 |   0.000000 |         NULL |          NULL |
| init                 | 0.000013 | 0.000000 |   0.000000 |         NULL |          NULL |
| optimizing           | 0.000003 | 0.000000 |   0.000000 |         NULL |          NULL |
| statistics           | 0.000014 | 0.000000 |   0.000000 |         NULL |          NULL |
| preparing            | 0.000005 | 0.000000 |   0.000000 |         NULL |          NULL |
| Creating tmp table   | 0.000288 | 0.000000 |   0.000000 |         NULL |          NULL |
| executing            | 0.000003 | 0.000000 |   0.000000 |         NULL |          NULL |
| Copying to tmp table | 0.064244 | 0.062500 |   0.000000 |         NULL |          NULL |
| Sorting result       | 0.000021 | 0.000000 |   0.000000 |         NULL |          NULL |
| Sending data         | 0.000011 | 0.000000 |   0.000000 |         NULL |          NULL |
| end                  | 0.000002 | 0.000000 |   0.000000 |         NULL |          NULL |
| removing tmp table   | 0.000006 | 0.000000 |   0.000000 |         NULL |          NULL |
| end                  | 0.000002 | 0.000000 |   0.000000 |         NULL |          NULL |
| query end            | 0.000002 | 0.000000 |   0.000000 |         NULL |          NULL |
| closing tables       | 0.000004 | 0.000000 |   0.000000 |         NULL |          NULL |
| freeing items        | 0.000046 | 0.000000 |   0.000000 |         NULL |          NULL |
| logging slow query   | 0.000023 | 0.000000 |   0.000000 |         NULL |          NULL |
| cleaning up          | 0.000001 | 0.000000 |   0.000000 |         NULL |          NULL |
+----------------------+----------+----------+------------+--------------+---------------+

可选参数：

ALL 显示所有信息
BLOCK IO 块设备IO输入输出次数
CONTEXT SWITCHES 上下文切换的相关开销
CPU 用户和系统的CPU使用情况
IPC 发送和接收消息的相关消耗
MEMEORY 内存相关消耗
PAGE FAULTS 主要和次要页面故障的开销
SOURCE source_function，source_file 等相关开销
SWAPS 交换次数开销

表中遇到Status 需要注意执行时间

converting HEAP to MySIAM 数据过大MyISAM内存装不下，向磁盘上搬运
Creating tmp table 临时表创建
Copying to tmp table on disk 复制临时表到磁盘
locked 锁。阻塞

秒客网

Mysql 慢查询之showprofile

一、使用准备

二、具体语法

相关文章