Posted in MySQL onApril 05, 2021
简介
mysql提供可以用来分析当前会话中语句执行的资源消耗情况，可以用于SQL的调优的测量。
官网：https://dev.mysql.com/doc/refman/8.0/en/show-profile.html
默认情况下，参数处于关闭状态，并保存最近15次的运行结果。
分析步骤
- 是否支持，看看当前的mysql版本是否支持
mysql> Show variables like 'profiling';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| profiling | OFF |
+---------------+-------+
1 row in set (0.04 sec)
# 默认是关闭，使用前需要开启
- 开启功能，默认是关闭，使用前需要开启
mysql> set profiling=1;
Query OK, 0 rows affected (0.00 sec)
mysql> Show variables like 'profiling';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| profiling | ON |
+---------------+-------+
1 row in set (0.05 sec)
- 运行SQL
mysql> select * from emp group by id%20 order by 2;
+----+-------+--------+----------+-----+------------+---------+--------+--------+
| id | empno | ename | job | mgr | hiredate | sal | comm | deptno |
+----+-------+--------+----------+-----+------------+---------+--------+--------+
| 1 | 1002 | Oobqzz | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 100 |
| 2 | 1003 | ESDoGs | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 3 | 1004 | qZXPfi | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 104 |
| 4 | 1005 | ZxrpzB | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 101 |
| 5 | 1006 | tpqNQQ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 106 |
| 6 | 1007 | JCHGkg | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 100 |
| 7 | 1008 | QVjinQ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 102 |
| 8 | 1009 | cqwnXX | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 109 |
| 9 | 1010 | YVLQWn | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 104 |
| 10 | 1011 | uKopHs | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 11 | 1012 | mEknMS | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 101 |
| 12 | 1013 | XyzdPR | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 107 |
| 13 | 1014 | kRBijz | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 14 | 1015 | RGFiZA | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 105 |
| 15 | 1016 | bEVOht | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 104 |
| 16 | 1017 | qdwVnE | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 101 |
| 17 | 1018 | YvhAdQ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 18 | 1019 | asPVhZ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 105 |
| 19 | 1020 | KTpTzR | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 106 |
| 20 | 1021 | SnOcYH | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 103 |
+----+-------+--------+----------+-----+------------+---------+--------+--------+
20 rows in set (2.12 sec)
mysql> select * from emp group by id%10 limit 150000;
+----+-------+--------+----------+-----+------------+---------+--------+--------+
| id | empno | ename | job | mgr | hiredate | sal | comm | deptno |
+----+-------+--------+----------+-----+------------+---------+--------+--------+
| 10 | 1011 | uKopHs | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 1 | 1002 | Oobqzz | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 100 |
| 2 | 1003 | ESDoGs | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 108 |
| 3 | 1004 | qZXPfi | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 104 |
| 4 | 1005 | ZxrpzB | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 101 |
| 5 | 1006 | tpqNQQ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 106 |
| 6 | 1007 | JCHGkg | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 100 |
| 7 | 1008 | QVjinQ | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 102 |
| 8 | 1009 | cqwnXX | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 109 |
| 9 | 1010 | YVLQWn | salesman | 1 | 2021-04-04 | 2000.00 | 400.00 | 104 |
+----+-------+--------+----------+-----+------------+---------+--------+--------+
10 rows in set (1.91 sec)
- 查看结果
mysql> show profiles;
+----------+------------+-----------------------------------------------+
| Query_ID | Duration | Query |
+----------+------------+-----------------------------------------------+
| 1 | 0.00059150 | Show variables like 'profiling' |
| 2 | 1.82311475 | select * from emp group by id%10 limit 150000 |
| 3 | 1.92254050 | select * from emp group by id%20 order by 5 |
| 4 | 1.91409800 | select * from emp group by id%20 order by 2 |
| 5 | 1.81238075 | select * from emp group by id%10 limit 150000 |
+----------+------------+-----------------------------------------------+
5 rows in set (0.14 sec)
- 诊断SQL
show profile cpu,block io for query n (n为上一步前面的问题SQL数字号码);
mysql> show profile cpu,block io for query 4;
+----------------------+----------+----------+------------+--------------+---------------+
| Status | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+----------------------+----------+----------+------------+--------------+---------------+
| starting | 0.000037 | 0.000000 | 0.000000 | NULL | NULL |
| checking permissions | 0.000005 | 0.000000 | 0.000000 | NULL | NULL |
| Opening tables | 0.000016 | 0.000000 | 0.000000 | NULL | NULL |
| System lock | 0.000008 | 0.000000 | 0.000000 | NULL | NULL |
| init | 0.000018 | 0.000000 | 0.000000 | NULL | NULL |
| optimizing | 0.000003 | 0.000000 | 0.000000 | NULL | NULL |
| statistics | 0.000017 | 0.000000 | 0.000000 | NULL | NULL |
| preparing | 0.000006 | 0.000000 | 0.000000 | NULL | NULL |
| Creating tmp table | 0.000308 | 0.000000 | 0.000000 | NULL | NULL |
| executing | 0.000003 | 0.000000 | 0.000000 | NULL | NULL |
| Copying to tmp table | 1.913459 | 1.921875 | 0.000000 | NULL | NULL |
| Sorting result | 0.000025 | 0.000000 | 0.000000 | NULL | NULL |
| Sending data | 0.000044 | 0.000000 | 0.000000 | NULL | NULL |
| end | 0.000004 | 0.000000 | 0.000000 | NULL | NULL |
| removing tmp table | 0.000007 | 0.000000 | 0.000000 | NULL | NULL |
| end | 0.000002 | 0.000000 | 0.000000 | NULL | NULL |
| query end | 0.000003 | 0.000000 | 0.000000 | NULL | NULL |
| closing tables | 0.000010 | 0.000000 | 0.000000 | NULL | NULL |
| freeing items | 0.000124 | 0.000000 | 0.000000 | NULL | NULL |
| logging slow query | 0.000002 | 0.000000 | 0.000000 | NULL | NULL |
| cleaning up | 0.000001 | 0.000000 | 0.000000 | NULL | NULL |
+----------------------+----------+----------+------------+--------------+---------------+
21 rows in set (0.19 sec)
参数：
| 类型 | 含义 |
|---|---|
| ALL | 显示所有的开销信息 |
| BLOCK IO | 显示块IO相关开销 |
| CONTEXT SWITCHES | 上下文切换相关开销 |
| CPU | 显示CPU相关开销信息 |
| IPC | 显示发送和接收相关开销信息 |
| MEMORY | 显示内存相关开销信息 |
| PAGE FAULTS | 显示页面错误相关开销信息 |
| SOURCE | 显示和Source_function，Source_file，Source_line相关的开销信息 |
| SWAPS | 显示交换次数相关开销的信息 |
展示个最全的：
mysql> show profile all for query 4;
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------+---------------+-------------+
| Status | Duration | CPU_user | CPU_system | Context_voluntary | Context_involuntary | Block_ops_in | Block_ops_out | Messages_sent | Messages_received | Page_faults_major | Page_faults_minor | Swaps | Source_function | Source_file | Source_line |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------+---------------+-------------+
| starting | 0.000037 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
| checking permissions | 0.000005 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 4833 |
| Opening tables | 0.000016 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_base.cc | 4888 |
| System lock | 0.000008 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | lock.cc | 299 |
| init | 0.000018 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 2594 |
| optimizing | 0.000003 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 865 |
| statistics | 0.000017 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 1071 |
| preparing | 0.000006 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 1093 |
| Creating tmp table | 0.000308 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 1616 |
| executing | 0.000003 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 1851 |
| Copying to tmp table | 1.913459 | 1.921875 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 1998 |
| Sorting result | 0.000025 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 2282 |
| Sending data | 0.000044 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 2395 |
| end | 0.000004 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 2630 |
| removing tmp table | 0.000007 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 11304 |
| end | 0.000002 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_select.cc | 11329 |
| query end | 0.000003 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 4512 |
| closing tables | 0.000010 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 4564 |
| freeing items | 0.000124 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 5840 |
| logging slow query | 0.000002 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 1512 |
| cleaning up | 0.000001 | 0.000000 | 0.000000 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | <unknown> | sql_parse.cc | 1468 |
+----------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+---------------+-------------------+-------------------+-------------------+-------+-----------------+---------------+-------------+
21 rows in set (0.23 sec)
- 特别需要注意的结论
- converting HEAP to MyISAM 查询结果太大，内存都不够用了往磁盘上搬了。
- Creating tmp table 创建临时表，拷贝数据到临时表，用完再删除。
- Copying to tmp table on disk 把内存中临时表复制到磁盘，很危险！
- locked 锁了都
Mysql Show Profile
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