MySQL性能瓶頸分析工具（profiling）

時間 2019-11-11

標籤 mysql 性能瓶頸分析工具 profiling 欄目 MySQL 简体版

原文原文鏈接

1、介紹
一、分析SQL執行帶來的開銷是優化SQL的重要手段。
二、在MySQL數據庫中，能夠經過配置profiling參數來啓用SQL剖析。
三、該參數能夠在全局和session級別來設置。
四、對於全局級別則做用於整個MySQL實例，而session級別緊影響當前session。
五、該參數開啓後，後續執行的SQL語句都將記錄其資源開銷，諸如IO，上下文切換，CPU，Memory等等。根據這些開銷進一步分析當前SQL瓶頸從而進行優化與調整。
2、有關profile的描述
show variables like 'version';

show variables like '%profil%';
mysql

mysql> show variables like '%profil%';  
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| have_profiling         | YES   |          --只讀變量，用於控制是否由系統變量開啓或禁用profiling
| profiling              | OFF   |               --開啓SQL語句剖析功能
| profiling_history_size | 15    |          --設置保留profiling的數目，缺省爲15，範圍爲0至100，爲0時將禁
+------------------------+-------+
3 rows in set (0.00 sec)

--獲取profile的幫助
root@localhost[sakila]> help profile;
Name: 'SHOW PROFILE'
Description:
Syntax:
SHOW PROFILE [type [, type] ... ]
[FOR QUERY n]
[LIMIT row_count [OFFSET offset]] sql

二、開啓porfiling

--啓用session級別的profiling  
root@localhost[sakila]> set profiling=1;  
Query OK, 0 rows affected, 1 warning (0.00 sec)  

--驗證修改後的結果  
root@localhost[sakila]> show variables like '%profil%';  
+------------------------+-------+  
| Variable_name          | Value |  
+------------------------+-------+  
| have_profiling         | YES   |  
| profiling              | ON    |  
| profiling_history_size | 15    |  
+------------------------+-------+  

--發佈SQL查詢  
root@localhost[sakila]> select count(*) from customer;  
+----------+  
| count(*) |  
+----------+  
|      599 |  
+----------+  

--查看當前session全部已產生的profile  
root@localhost[sakila]> show profiles;  
+----------+------------+--------------------------------+  
| Query_ID | Duration   | Query                          |  
+----------+------------+--------------------------------+  
|        1 | 0.00253600 | show variables like '%profil%' |  
|        2 | 0.00138150 | select count(*) from customer  |  
+----------+------------+--------------------------------+  
2 rows in set, 1 warning (0.01 sec)  

--咱們看到有2個warning，以前一個，如今一個  
root@localhost[sakila]> show warnings;    --下面的結果代表SHOW PROFILES未來會被Performance Schema替換掉  
+---------+------+--------------------------------------------------------------------------------------------------------------+  
| Level   | Code | Message                                                                                                      |  
+---------+------+--------------------------------------------------------------------------------------------------------------+  
| Warning | 1287 | 'SHOW PROFILES' is deprecated and will be removed in a future release. Please use Performance Schema instead |  
+---------+------+--------------------------------------------------------------------------------------------------------------+

三、獲取SQL語句的開銷信息session

--能夠直接使用show profile來查看上一條SQL語句的開銷信息  
--注，show profile之類的語句不會被profiling，即自身不會產生Profiling  
--咱們下面的這個show profile查看的是show warnings產生的相應開銷  
root@localhost[sakila]> show profile;    
+----------------+----------+  
| Status         | Duration |  
+----------------+----------+  
| starting       | 0.000141 |  
| query end      | 0.000058 |  
| closing tables | 0.000014 |  
| freeing items  | 0.001802 |  
| cleaning up    | 0.000272 |  
+----------------+----------+  

--以下面的查詢show warnings被添加到profiles  
root@localhost[sakila]> show profiles;  
+----------+------------+--------------------------------+  
| Query_ID | Duration   | Query                          |  
+----------+------------+--------------------------------+  
|        1 | 0.00253600 | show variables like '%profil%' |  
|        2 | 0.00138150 | select count(*) from customer  |  
|        3 | 0.00228600 | show warnings                  |  
+----------+------------+--------------------------------+  

--獲取指定查詢的開銷  
root@localhost[sakila]> show profile for query 2;  
+----------------------+----------+  
| Status               | Duration |  
+----------------------+----------+  
| starting             | 0.000148 |  
| checking permissions | 0.000014 |  
| Opening tables       | 0.000047 |  
| init                 | 0.000023 |  
| System lock          | 0.000035 |  
| optimizing           | 0.000012 |  
| statistics           | 0.000019 |  
| preparing            | 0.000014 |  
| executing            | 0.000006 |  
| Sending data         | 0.000990 |  
| end                  | 0.000010 |  
| query end            | 0.000011 |  
| closing tables       | 0.000010 |  
| freeing items        | 0.000016 |  
| cleaning up          | 0.000029 |  
+----------------------+----------+  

--查看特定部分的開銷，以下爲CPU部分的開銷  
root@localhost[sakila]> show profile cpu for query 2 ;  
+----------------------+----------+----------+------------+  
| Status               | Duration | CPU_user | CPU_system |  
+----------------------+----------+----------+------------+  
| starting             | 0.000148 | 0.000000 |   0.000000 |  
| checking permissions | 0.000014 | 0.000000 |   0.000000 |  
| Opening tables       | 0.000047 | 0.000000 |   0.000000 |  
| init                 | 0.000023 | 0.000000 |   0.000000 |  
| System lock          | 0.000035 | 0.000000 |   0.000000 |  
| optimizing           | 0.000012 | 0.000000 |   0.000000 |  
| statistics           | 0.000019 | 0.000000 |   0.000000 |  
| preparing            | 0.000014 | 0.000000 |   0.000000 |  
| executing            | 0.000006 | 0.000000 |   0.000000 |  
| Sending data         | 0.000990 | 0.001000 |   0.000000 |  
| end                  | 0.000010 | 0.000000 |   0.000000 |  
| query end            | 0.000011 | 0.000000 |   0.000000 |  
| closing tables       | 0.000010 | 0.000000 |   0.000000 |  
| freeing items        | 0.000016 | 0.000000 |   0.000000 |  
| cleaning up          | 0.000029 | 0.000000 |   0.000000 |  
+----------------------+----------+----------+------------+  

--以下爲MEMORY部分的開銷  
root@localhost[sakila]> show profile memory for query 2 ;  
+----------------------+----------+  
| Status               | Duration |  
+----------------------+----------+  
| starting             | 0.000148 |  
| checking permissions | 0.000014 |  
| Opening tables       | 0.000047 |  
| init                 | 0.000023 |  
| System lock          | 0.000035 |  
| optimizing           | 0.000012 |  
| statistics           | 0.000019 |  
| preparing            | 0.000014 |  
| executing            | 0.000006 |  
| Sending data         | 0.000990 |  
| end                  | 0.000010 |  
| query end            | 0.000011 |  
| closing tables       | 0.000010 |  
| freeing items        | 0.000016 |  
| cleaning up          | 0.000029 |  
+----------------------+----------+  

--同時查看不一樣資源開銷  
root@localhost[sakila]> show profile block io,cpu for query 2;  
+----------------------+----------+----------+------------+--------------+---------------+  
| Status               | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |  
+----------------------+----------+----------+------------+--------------+---------------+  
| starting             | 0.000148 | 0.000000 |   0.000000 |            0 |             0 |  
| checking permissions | 0.000014 | 0.000000 |   0.000000 |            0 |             0 |  
| Opening tables       | 0.000047 | 0.000000 |   0.000000 |            0 |             0 |  
| init                 | 0.000023 | 0.000000 |   0.000000 |            0 |             0 |  
| System lock          | 0.000035 | 0.000000 |   0.000000 |            0 |             0 |  
| optimizing           | 0.000012 | 0.000000 |   0.000000 |            0 |             0 |  
| statistics           | 0.000019 | 0.000000 |   0.000000 |            0 |             0 |  
| preparing            | 0.000014 | 0.000000 |   0.000000 |            0 |             0 |  
| executing            | 0.000006 | 0.000000 |   0.000000 |            0 |             0 |  
| Sending data         | 0.000990 | 0.001000 |   0.000000 |            0 |             0 |  
| end                  | 0.000010 | 0.000000 |   0.000000 |            0 |             0 |  
| query end            | 0.000011 | 0.000000 |   0.000000 |            0 |             0 |  
| closing tables       | 0.000010 | 0.000000 |   0.000000 |            0 |             0 |  
| freeing items        | 0.000016 | 0.000000 |   0.000000 |            0 |             0 |  
| cleaning up          | 0.000029 | 0.000000 |   0.000000 |            0 |             0 |  
+----------------------+----------+----------+------------+--------------+---------------+  

--下面的SQL語句用於查詢query_id爲2的SQL開銷，且按最大耗用時間倒序排列  
root@localhost[sakila]> set @query_id=2;  

root@localhost[sakila]> SELECT STATE, SUM(DURATION) AS Total_R,  
    ->   ROUND(  
    ->        100 * SUM(DURATION) /  
    ->           (SELECT SUM(DURATION)  
    ->            FROM INFORMATION_SCHEMA.PROFILING  
    ->            WHERE QUERY_ID = @query_id  
    ->        ), 2) AS Pct_R,  
    ->     COUNT(*) AS Calls,  
    ->     SUM(DURATION) / COUNT(*) AS "R/Call"  
    ->  FROM INFORMATION_SCHEMA.PROFILING  
    ->  WHERE QUERY_ID = @query_id  
    ->  GROUP BY STATE  
    ->  ORDER BY Total_R DESC;  
+----------------------+----------+-------+-------+--------------+  
| STATE                | Total_R  | Pct_R | Calls | R/Call       |  
+----------------------+----------+-------+-------+--------------+  
| Sending data         | 0.000990 | 71.53 |     1 | 0.0009900000 |--最大耗用時間部分爲發送數據  
| starting             | 0.000148 | 10.69 |     1 | 0.0001480000 |  
| Opening tables       | 0.000047 |  3.40 |     1 | 0.0000470000 |  
| System lock          | 0.000035 |  2.53 |     1 | 0.0000350000 |  
| cleaning up          | 0.000029 |  2.10 |     1 | 0.0000290000 |  
| init                 | 0.000023 |  1.66 |     1 | 0.0000230000 |  
| statistics           | 0.000019 |  1.37 |     1 | 0.0000190000 |  
| freeing items        | 0.000016 |  1.16 |     1 | 0.0000160000 |  
| preparing            | 0.000014 |  1.01 |     1 | 0.0000140000 |  
| checking permissions | 0.000014 |  1.01 |     1 | 0.0000140000 |  
| optimizing           | 0.000012 |  0.87 |     1 | 0.0000120000 |  
| query end            | 0.000011 |  0.79 |     1 | 0.0000110000 |  
| end                  | 0.000010 |  0.72 |     1 | 0.0000100000 |  
| closing tables       | 0.000010 |  0.72 |     1 | 0.0000100000 |  
| executing            | 0.000006 |  0.43 |     1 | 0.0000060000 |  
+----------------------+----------+-------+-------+--------------+  

--開啓profiling後，咱們能夠經過show profile等方式查看，其實質是這些開銷信息被記錄到information_schema.profiling表  
--以下面的查詢，部分信息省略  
profiling  
root@localhost[information_schema]> select * from profiling limit 3,3\G;  
*************************** 1. row ***************************  
           QUERY_ID: 1  
                SEQ: 5  
              STATE: init  
           DURATION: 0.000020  
           CPU_USER: 0.000000  
         CPU_SYSTEM: 0.000000  
  CONTEXT_VOLUNTARY: 0  
CONTEXT_INVOLUNTARY: 0  
       BLOCK_OPS_IN: 0  
      BLOCK_OPS_OUT: 0  
      MESSAGES_SENT: 0  
  MESSAGES_RECEIVED: 0  
  PAGE_FAULTS_MAJOR: 0  
  PAGE_FAULTS_MINOR: 0  
              SWAPS: 0  
    SOURCE_FUNCTION: mysql_prepare_select  
        SOURCE_FILE: sql_select.cc  
        SOURCE_LINE: 1050  

--中止profile,能夠設置profiling參數，或者在session退出以後,profiling會被自動關閉  
root@localhost[sakila]> set profiling=off;  
Query OK, 0 rows affected, 1 warning (0.00 sec)

本文摘抄自MySQL性能分析工具profile使用教程ide