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在MySQL数据库中，可以通过配置profiling参数来启用SQL剖析。该参数开启后，后续执行的SQL语句都将记录其资源开销，诸如IO，上下文切换，CPU，Memory等，根据这些开销分析当前SQL瓶颈从而进行优化与调整。
MySQL版本
mysql> show variables like 'version';
+---------------+--------+
| Variable_name | Value |
+---------------+--------+
| version | 5.7.22 |
+---------------+--------+
1 row in set (0.00 sec)
profile参数
mysql> show variables like '%profil%';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| have_profiling | YES |
| profiling | ON |
| profiling_history_size | 15 |
+------------------------+-------+
3 rows in set (0.01 sec)
have_profiling
have_profiling 是System Var 全局参数，不支持动态修改。如果该参数为YES，表示支持profiling功能，如果为NO表示不支持profiling功能。如果支持profiling功能，profiling参数可以用来控制该功能是否启用。(have_profiling参数在5.6.8中将被弃用，并且可能在以后的版本中可能被删除)
profiling
profiling 是System Var 全局参数，支持动态修改。如果设置为0或者OFF(该参数默认值即为OFF)，sql的profiling功能被禁用。如果设置为1或者ON，这之后执行语句会被profiling(除了show profiles, show profile)。
profiling_history_size
profiling_history_size是Cmd-Line,Option File,System Var 全局参数，支持动态修改。该参数控制保存的被profiling的sql数量,默认值为15。如果该值设为0则禁用profiling功能。
profile帮助
mysql> help profile;
Name: 'SHOW PROFILE'
Description:
Syntax:
SHOW PROFILE [type [, type] ... ]
[FOR QUERY n]
[LIMIT row_count [OFFSET offset]]
type:
ALL
| BLOCK IO
| CONTEXT SWITCHES
| CPU
| IPC
| MEMORY
| PAGE FAULTS
| SOURCE
| SWAPS
The SHOW PROFILE and SHOW PROFILES statements display profiling information that indicates resource
usage for statements executed during the course of the current session.
*Note*:
These statements are deprecated and will be removed in a future MySQL release. Use the Performance
Schema instead; see http://dev.mysql.com/doc/refman/5.7/en/performance-schema-query-profiling.html.
Profiling is controlled by the profiling session variable, which has a default value of 0 (OFF).
Profiling is enabled by setting profiling to 1 or ON:
mysql> SET profiling = 1;
SHOW PROFILES displays a list of the most recent statements sent to the server.
The size of the list is controlled by the profiling_history_size session variable, which has a default value of 15.
The maximum value is 100. Setting the value to 0 has the practical effect of disabling profiling.
All statements are profiled except SHOW PROFILE and SHOW PROFILES, so you will find neither of those statements in the profile list.
Malformed statements are profiled. For example, SHOW PROFILING is an illegal statement,
and a syntax error occurs if you try to execute it, but it will show up in the profiling list.
SHOW PROFILE displays detailed information about a single statement. Without the FOR QUERY n clause,
the output pertains to the most recently executed statement. If FOR QUERY n is included, SHOW PROFILE displays information for statement n.
The values of n correspond to the Query_ID values displayed by SHOW PROFILES.
The LIMIT row_count clause may be given to limit the output to row_count rows.
If LIMIT is given, OFFSET offset may be added to begin the output offset rows into the full set of rows.
By default, SHOW PROFILE displays Status and Duration columns.
The Status values are like the State values displayed by SHOW PROCESSLIST,
although there might be some minor differences in interpretion for the two statements for some status values
(see http://dev.mysql.com/doc/refman/5.7/en/thread-information.html).
Optional type values may be specified to display specific additional
types of information:
o ALL displays all information
o BLOCK IO displays counts for block input and output operations
o CONTEXT SWITCHES displays counts for voluntary and involuntary
context switches
o CPU displays user and system CPU usage times
o IPC displays counts for messages sent and received
o MEMORY is not currently implemented
o PAGE FAULTS displays counts for major and minor page faults
o SOURCE displays the names of functions from the source code, together with the name and line number of the file in which the function occurs
o SWAPS displays swap counts
Profiling is enabled per session. When a session ends, its profiling information is lost.
URL: http://dev.mysql.com/doc/refman/5.7/en/show-profile.html
Examples:
mysql> SELECT @@profiling;
+-------------+
| @@profiling |
+-------------+
| 0 |
+-------------+
1 row in set (0.00 sec)
mysql> SET profiling = 1;
Query OK, 0 rows affected (0.00 sec)
mysql> DROP TABLE IF EXISTS t1;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> CREATE TABLE T1 (id INT);
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW PROFILES;
+----------+----------+--------------------------+
| Query_ID | Duration | Query |
+----------+----------+--------------------------+
| 0 | 0.000088 | SET PROFILING = 1 |
| 1 | 0.000136 | DROP TABLE IF EXISTS t1 |
| 2 | 0.011947 | CREATE TABLE t1 (id INT) |
+----------+----------+--------------------------+
3 rows in set (0.00 sec)
mysql> SHOW PROFILE;
+----------------------+----------+
| Status | Duration |
+----------------------+----------+
| checking permissions | 0.000040 |
| creating table | 0.000056 |
| After create | 0.011363 |
| query end | 0.000375 |
| freeing items | 0.000089 |
| logging slow query | 0.000019 |
| cleaning up | 0.000005 |
+----------------------+----------+
7 rows in set (0.00 sec)
mysql> SHOW PROFILE FOR QUERY 1;
+--------------------+----------+
| Status | Duration |
+--------------------+----------+
| query end | 0.000107 |
| freeing items | 0.000008 |
| logging slow query | 0.000015 |
| cleaning up | 0.000006 |
+--------------------+----------+
4 rows in set (0.00 sec)
mysql> SHOW PROFILE CPU FOR QUERY 2;
+----------------------+----------+----------+------------+
| Status | Duration | CPU_user | CPU_system |
+----------------------+----------+----------+------------+
| checking permissions | 0.000040 | 0.000038 | 0.000002 |
| creating table | 0.000056 | 0.000028 | 0.000028 |
| After create | 0.011363 | 0.000217 | 0.001571 |
| query end | 0.000375 | 0.000013 | 0.000028 |
| freeing items | 0.000089 | 0.000010 | 0.000014 |
| logging slow query | 0.000019 | 0.000009 | 0.000010 |
| cleaning up | 0.000005 | 0.000003 | 0.000002 |
+----------------------+----------+----------+------------+
7 rows in set (0.00 sec)
profile示例
mysql> set profiling=1;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> select count(1) from store;
+----------+
| count(1) |
+----------+
| 193 |
+----------+
1 row in set (0.06 sec)
mysql> show profiles;
+----------+------------+----------------------------+
| Query_ID | Duration | Query |
+----------+------------+----------------------------+
| 1 | 0.05912400 | select count(1) from store |
+----------+------------+----------------------------+
1 row in set, 1 warning (0.00 sec)
mysql> select count(1) from store_bak;
+----------+
| count(1) |
+----------+
| 3162113 |
+----------+
1 row in set (5.81 sec)
mysql> show profiles;
+----------+------------+--------------------------------+
| Query_ID | Duration | Query |
+----------+------------+--------------------------------+
| 1 | 0.05912400 | select count(1) from store |
| 2 | 5.82553775 | select count(1) from store_bak |
+----------+------------+--------------------------------+
2 rows in set, 1 warning (0.00 sec)
查看资源的消耗情况，如io，cpu
mysql> show profile cpu,block io for query 2;
+----------------------+----------+----------+------------+--------------+---------------+
| Status | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+----------------------+----------+----------+------------+--------------+---------------+
| starting | 0.000095 | 0.000000 | 0.000000 | 0 | 0 |
| checking permissions | 0.000011 | 0.000000 | 0.000000 | 0 | 0 |
| Opening tables | 0.017916 | 0.001000 | 0.000000 | 32 | 0 |
| init | 0.000028 | 0.000000 | 0.000000 | 0 | 0 |
| System lock | 0.000018 | 0.000000 | 0.000000 | 0 | 0 |
| optimizing | 0.000010 | 0.000000 | 0.000000 | 0 | 0 |
| statistics | 0.000021 | 0.000000 | 0.000000 | 0 | 0 |
| preparing | 0.000020 | 0.000000 | 0.000000 | 0 | 0 |
| executing | 0.000005 | 0.000000 | 0.000000 | 0 | 0 |
| Sending data | 5.794340 | 5.794119 | 0.000000 | 0 | 0 |
| end | 0.000025 | 0.000000 | 0.000000 | 0 | 0 |
| query end | 0.000014 | 0.000000 | 0.000000 | 0 | 0 |
| closing tables | 0.000026 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000045 | 0.000000 | 0.000000 | 0 | 0 |
| logging slow query | 0.012937 | 0.001000 | 0.000000 | 264 | 8 |
| cleaning up | 0.000028 | 0.000000 | 0.000000 | 0 | 0 |
+----------------------+----------+----------+------------+--------------+---------------+
16 rows in set, 13 warnings (0.00 sec)
通过INFORMATION_SCHEMA.PROFILING表来查询语句消耗情况
mysql> select min(seq) seq,state,count(*) num_ops,
-> round(sum(duration),5) sum_dur, round(avg(duration),5) avg_dur,
-> round(sum(cpu_user),5) sum_cpu, round(avg(cpu_user),5) avg_cpu
-> from information_schema.profiling
-> where query_id = 21
-> group by state
-> order by seq;
+------+--------------------+----------+----------+---------+---------+---------+
| seq | state | num_ops | sum_dur | avg_dur | sum_cpu | avg_cpu |
+------+--------------------+---------+----------+---------+---------+---------+
| 2375 | Sending data | 47 | 20.98920 | 0.44658 | 0.00000 | 0.00000 |
| 2376 | executing | 46 | 0.00126 | 0.00003 | 0.00000 | 0.00000 |
| 2468 | updating | 1 | 0.00003 | 0.00003 | 0.00000 | 0.00000 |
| 2469 | end | 1 | 0.00002 | 0.00002 | 0.00000 | 0.00000 |
| 2470 | query end | 1 | 0.00094 | 0.00094 | 0.00000 | 0.00000 |
| 2471 | closing tables | 1 | 0.00005 | 0.00005 | 0.00000 | 0.00000 |
| 2472 | freeing items | 1 | 0.00010 | 0.00010 | 0.00000 | 0.00000 |
| 2473 | logging slow query | 1 | 0.00012 | 0.00012 | 0.00000 | 0.00000 |
| 2474 | cleaning up | 1 | 0.00012 | 0.00012 | 0.00000 | 0.00000 |
+------+--------------------+---------+----------+---------+---------+---------+
9 rows in set (0.00 sec)