mysql slow 分析工具

慢查询有什么用？   
      它能记录下所有执行超过long_query_time时间的SQL语句，帮你找到执行慢的SQL，方便我们对这些SQL进行优化。   

测试用 MySQL 版本。   
Server version: 5.6.10-log Source distribution   

未做任何慢日志设置时。   

mysql> show variables like "%query%";     
+------------------------------+--------------------------------------+ 
| Variable_name                | Value                                | 
+------------------------------+--------------------------------------+ 
| binlog_rows_query_log_events | OFF                                  |  
| ft_query_expansion_limit     | 20                                   |  
| have_query_cache             | YES                                  |  
| long_query_time              | 10.000000                            |  
| query_alloc_block_size       | 8192                                 |  
| query_cache_limit            | 1048576                              |  
| query_cache_min_res_unit     | 4096                                 |  
| query_cache_size             | 1048576                              |  
| query_cache_type             | OFF                                  |  
| query_cache_wlock_invalidate | OFF                                  |  
| query_prealloc_size          | 8192                                 |  
| slow_query_log               | OFF                                  |  
| slow_query_log_file          | /usr/local/mysql/data/Betty-slow.log |  
+------------------------------+--------------------------------------+ 
13 rows in set (0.01 sec) 

mysql>

修改配置文件，开启 slow log 。  

[root@Betty data]# vi /etc/my.cnf            

# For advice on how to change settings please see 
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html 
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the 
# *** default location during install, and will be replaced if you 
# *** upgrade to a newer version of MySQL. 

[mysqld] 

# Remove leading # and set to the amount of RAM for the most important data 
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. 
# innodb_buffer_pool_size = 128M 

# Remove leading # to turn on a very important data integrity option: logging 
# changes to the binary log between backups. 
log_bin=mysql-bin 

slow_query_log=on 
slow_query_log_file=mysql-slow 
long_query_time=2 

# These are commonly set, remove the # and set as required. 
# basedir = ..... 
# datadir = ..... 
# port = ..... 
# server_id = ..... 
# socket = ..... 

# Remove leading # to set options mainly useful for reporting servers. 
# The server defaults are faster for transactions and fast SELECTs. 
# Adjust sizes as needed, experiment to find the optimal values. 
# join_buffer_size = 128M 
# sort_buffer_size = 2M 
# read_rnd_buffer_size = 2M  

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES 

[mysql] 
socket = /tmp/mysql.sock

重启 MySQL 。  

[root@Betty data]# /etc/init.d/mysql restart 
Shutting down MySQL..                                      [  OK  ] 
Starting MySQL.                                            [  OK  ] 
[root@Betty data]#

查看 slow log 。  

[root@Betty data]# ll mysql-slow  
-rw-rw---- 1 mysql mysql 719 Sep  6 12:43 mysql-slow

重新查看系统变量值。  

mysql>  
mysql> show variables like "%query%"; 
+------------------------------+------------+ 
| Variable_name                | Value      | 
+------------------------------+------------+ 
| binlog_rows_query_log_events | OFF        |  
| ft_query_expansion_limit     | 20         |  
| have_query_cache             | YES        |  
| long_query_time              | 2.000000   |  
| query_alloc_block_size       | 8192       |  
| query_cache_limit            | 1048576    |  
| query_cache_min_res_unit     | 4096       |  
| query_cache_size             | 1048576    |  
| query_cache_type             | OFF        |  
| query_cache_wlock_invalidate | OFF        |  
| query_prealloc_size          | 8192       |  
| slow_query_log               | ON         |  
| slow_query_log_file          | mysql-slow |  
+------------------------------+------------+ 
13 rows in set (0.00 sec) 

mysql>

查看新生成的 slow log 的内容。  

[root@Betty data]# cat mysql-slow  
/usr/local/mysql/bin/mysqld, Version: 5.6.10-log (Source distribution). started with: 
Tcp port: 0  Unix socket: (null) 
Time                 Id Command    Argument 
[root@Betty data]#

测试 slow log 。

mysql>  
mysql> select 1; 
+---+ 
| 1 | 
+---+ 
| 1 |  
+---+ 
1 row in set (0.00 sec) 

mysql>  
mysql> select sleep(1); 
+----------+ 
| sleep(1) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (1.00 sec) 

mysql>  
mysql>  
mysql> select sleep(3);  
+----------+ 
| sleep(3) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (3.00 sec) 

mysql>  
mysql> select sleep(4);  
+----------+ 
| sleep(4) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (4.01 sec) 

mysql>  
mysql>  
mysql> select sleep(5);  
+----------+ 
| sleep(5) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (5.00 sec) 

mysql> select sleep(2);  
+----------+ 
| sleep(2) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (2.01 sec) 

mysql>  
mysql> select sleep(1);  
+----------+ 
| sleep(1) | 
+----------+ 
|        0 |  
+----------+ 
1 row in set (1.00 sec) 

mysql> select 2;        
+---+ 
| 2 | 
+---+ 
| 2 |  
+---+ 
1 row in set (0.00 sec) 

mysql>

查看此时 slow log 的内容。  

[root@Betty data]# cat mysql-slow  
/usr/local/mysql/bin/mysqld, Version: 5.6.10-log (Source distribution). started with: 
Tcp port: 0  Unix socket: (null) 
Time                 Id Command    Argument 
# Time: 130906 12:52:51 
# User@Host: root[root] @ localhost []  Id:     1 
# Query_time: 3.002864  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0 
SET timestamp=1378443171; 
select sleep(3); 
# Time: 130906 12:53:01 
# User@Host: root[root] @ localhost []  Id:     1 
# Query_time: 4.001943  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0 
SET timestamp=1378443181; 
select sleep(4); 
# Time: 130906 12:53:09 
# User@Host: root[root] @ localhost []  Id:     1 
# Query_time: 5.002093  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0 
SET timestamp=1378443189; 
select sleep(5); 
# Time: 130906 12:53:15 
# User@Host: root[root] @ localhost []  Id:     1 
# Query_time: 2.002984  Lock_time: 0.000000 Rows_sent: 1  Rows_examined: 0 
SET timestamp=1378443195; 
select sleep(2); 
[root@Betty data]#

实验：  

a. 使用 mysql 自带慢查询日志分析工具 mysqldumpslow 。  

[root@Betty data]# mysqldumpslow mysql-slow  

Reading mysql slow query log from mysql-slow 
Count: 4  Time=3.50s (14s)  Lock=0.00s (0s)  Rows=1.0 (4), root[root]@localhost 
  select sleep(N) 

[root@Betty data]#

b. 使用 hackmysql.com 推出的一款日志分析工具 mysqlsla 。  

[root@Betty data]# mysqlsla -lt slow mysql-slow  
Report for slow logs: mysql-slow 
4 queries total, 1 unique 
Sorted by 't_sum' 
Grand Totals: Time 14 s, Lock 0 s, Rows sent 4, Rows Examined 0 

______________________________________________________________________ 001 ___ 
Count         : 4  (100.00%) 
Time          : 14.009884 s total, 3.502471 s avg, 2.002984 s to 5.002093 s max  (100.00%) 
Lock Time (s) : 0 total, 0 avg, 0 to 0 max  (0.00%) 
Rows sent     : 1 avg, 1 to 1 max  (100.00%) 
Rows examined : 0 avg, 0 to 0 max  (0.00%) 
Database      :  
Users         :  
        root@localhost  : 100.00% (4) of query, 100.00% (4) of all users 

Query abstract: 
SET timestamp=N; SELECT sleep(N); 

Query sample: 
SET timestamp=1378443171; 
select sleep(3); 
[root@Betty data]#

c. 使用德国人写的 mysql_explain_slow_log 。（不知道为什么未统计出信息）  

[root@Betty WGET_DIR]# ./mysql_explain_slow_log --user=root --password= --socket=/tmp/mysql.sock < /usr/local/mysql/data/mysql-slow      
mysql_explain_slow_log 
====================== 

Index usage ------------------------------------ 

Queries causing table scans ------------------- 

Sum: 0 table scans 

Summary --------------------------------------- 

Select:         0 queries 
Update:         0 queries 
Load:   0 queries 

Logfile:        26 lines 
Started:        Fri Sep  6 15:59:13 2013 
Finished:       Fri Sep  6 15:59:13 2013 
[root@Betty WGET_DIR]#

d.    google code 上的一个分析工具 mysql_filter_slow_log （最后更新日期为2007年），提供了 python 和 php 两种可执行的脚本。   

[root@Betty WGET_DIR]# python mysql_filter_slow_log.py /usr/local/mysql/data/mysql-slow --no-duplicates --sort-execution-count --top=10
# Execution count: 1 time on 2013-09-06 16:07:23.
# Column       : avg | max | sum
# Query time   :   5 |   5 |   5
# Lock time    :   0 |   0 |   0
# Rows examined:   0 |   0 |   0
# Rows sent    :   1 |   1 |   1
# User@Host: root[root] @ localhost []  Id:     1

SET timestamp=1378454843;select sleep(5);

# Execution count: 1 time on 2013-09-06 16:07:15.
# Column       : avg | max | sum
# Query time   :   4 |   4 |   4
# Lock time    :   0 |   0 |   0
# Rows examined:   0 |   0 |   0
# Rows sent    :   1 |   1 |   1
# User@Host: root[root] @ localhost []  Id:     1

SET timestamp=1378454835;select sleep(4);

# Execution count: 1 time on 2013-09-06 16:07:01.
# Column       : avg | max | sum
# Query time   :   3 |   3 |   3
# Lock time    :   0 |   0 |   0
# Rows examined:   0 |   0 |   0
# Rows sent    :   1 |   1 |   1
# User@Host: root[root] @ localhost []  Id:     1

SET timestamp=1378454821;select sleep(3);

# Execution count: 1 time on 2013-09-06 16:07:28.
# Column       : avg | max | sum
# Query time   :   2 |   2 |   2
# Lock time    :   0 |   0 |   0
# Rows examined:   0 |   0 |   0
# Rows sent    :   1 |   1 |   1
# User@Host: root[root] @ localhost []  Id:     1

SET timestamp=1378454848;select sleep(2);

[root@Betty WGET_DIR]#

e. 使用 percona-toolkit 中的 pt-query-digest （在《高性能MySQL》中多次提出，值得使用的工具）。   

[root@Betty data]# pt-query-digest --user=root  mysql-slow              

# 120ms user time, 10ms system time, 20.21M rss, 68.70M vsz
# Current date: Mon Sep  9 13:21:38 2013
# Hostname: Betty
# Files: mysql-slow
# Overall: 4 total, 1 unique, 0.15 QPS, 0.52x concurrency ________________
# Time range: 2013-09-06 16:07:01 to 16:07:28
# Attribute          total     min     max     avg     95%  stddev  median
# ============     ======= ======= ======= ======= ======= ======= =======
# Exec time            14s      2s      5s      4s      5s      1s      4s
# Lock time              0       0       0       0       0       0       0
# Rows sent              4       1       1       1       1       0       1
# Rows examine           0       0       0       0       0       0       0
# Query size            60      15      15      15      15       0      15

# Profile
# Rank Query ID           Response time  Calls R/Call V/M   Item
# ==== ================== ============== ===== ====== ===== ======
#    1 0xF9A57DD5A41825CA 14.0097 100.0%     4 3.5024  0.36 SELECT

# Query 1: 0.15 QPS, 0.52x concurrency, ID 0xF9A57DD5A41825CA at byte 548
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.36
# Time range: 2013-09-06 16:07:01 to 16:07:28
# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count        100       4
# Exec time    100     14s      2s      5s      4s      5s      1s      4s
# Lock time      0       0       0       0       0       0       0       0
# Rows sent    100       4       1       1       1       1       0       1
# Rows examine   0       0       0       0       0       0       0       0
# Query size   100      60      15      15      15      15       0      15
# String:
# Hosts        localhost
# Users        root
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms
#  10ms
# 100ms
#    1s  ################################################################
#  10s+
# EXPLAIN /*!50100 PARTITIONS*/
select sleep(5)G
[root@Betty data]#

慢查询配置项   

# I.e. you could add the following lines under the [mysqld] section of your my.ini or my.cnf configuration file:

# Log all queries taking more than 3 seconds
long_query_time=3  # minimum: 1, default: 10

# MySQL >= 5.1.21 (or patched): 3 seconds = 3000000 microseconds
# long_query_time=3.000000  # minimum: 0.000001 (1 microsecond)

# Activate the Slow Query Log
slow_query_log  # >= 5.1.29
# log-slow-queries  # deprecated since 5.1.29

# Write to a custom file name (>= 5.1.29)
# slow_query_log_file=file_name  # default: /data_dir/host_name-slow.log

# Log all queries without indexes
# log-queries-not-using-indexes

# Log only queries which examine at least N rows (>= 5.1.21)
# min_examined_row_limit=1000  # default: 0

# Log slow OPTIMIZE TABLE, ANALYZE TABLE, and ALTER TABLE statements
# log-slow-admin-statements

# Log slow queries executed by replication slaves (>= 5.1.21)
# log-slow-slave-statements

# MySQL 5.1.6 through 5.1.20 had a default value of log-output=TABLE, so you should force
# Attention: logging to TABLE only includes whole seconds information
log-output=FILE


## Admin query for online activation is possible since MySQL 5.1 (without server restart)
## SET @@global.slow_query_log=1
## SET @@global.long_query_time=1


## Show current variables related to the Slow Query Log
## SHOW GLOBAL VARIABLES WHERE Variable_name REGEXP 'admin|min_examined|log_output|log_queries|log_slave|long|slow_quer'

========= 我是分割线 =========    

下面给出网上一篇流传已久的博客文章，供参考（做了部分修正）。
参考：《 五款常用mysql slow log分析工具的比较 》，原文写于2008年。       

mysql slow log 分析工具的比较       

mysql 中的 slow log 是用来记录执行时间较长(超过 long_query_time 秒)的 sql 的一种日志工具。       

启用 slow log       
在 my.cnf 中设置

[mysqld]
slow_query_log=on
slow_query_log_file=mysql-slow

重启 MySQL 服务。

五款常用工具       

1. mysqldumpslow
2. mysqlsla
3. myprofi
4. mysql-explain-slow-log
5. mysql-log-filter

mysqldumpslow
      mysql官方提供的慢查询日志分析工具。输出图表如下：       
       
主要功能包括统计不同慢 sql 的       

• 出现次数(Count)
• 执行耗费的平均时间和累计总耗费时间(Time)
• 等待锁耗费的时间(Lock)
• 发送给客户端的行总数(Rows)
• 扫描的行总数(Rows)
• 用户以及sql语句本身(抽象了一下格式，比如 limit 1, 20 用 limit N,N 表示)

mysqlsla
      hackmysql.com 推出的一款日志分析工具(该网站还维护了 mysqlreport，mysqlidxchk 等比较实用的mysql 工具)。       
       
      整体来说，功能非常强大。输出的数据报表非常有利于分析慢查询的原因，包括执行频率、数据量、查询消耗等。       

格式说明如下：       

• 总查询次数 (queries total)，去重后的 sql 数量 (unique)
• 输出报表的内容排序(sorted by)
• 最重大的慢 sql 统计信息，包括平均执行时间、等待锁时间、结果行的总数、扫描的行总数。

• Count -- sql 的执行次数及占总的 slow log 数量的百分比。
• Time -- 执行时间，包括总时间、平均时间、最小、最大时间、时间占到总慢 sql 时间的百分比。
• 95% of Time -- 去除最快和最慢的 sql，覆盖率占 95% 的 sql 的执行时间。
• Lock Time -- 等待锁的时间。
• 95% of Lock -- 95% 的慢 sql 等待锁时间。
• Rows sent -- 结果行统计数量，包括平均、最小、最大数量。
• Rows examined -- 扫描的行数量。
• Database -- 属于哪个数据库。
• Users -- 哪个用户、IP、占到所有用户执行的 sql 百分比。
• Query abstract -- 抽象后的 sql 语句。
• Query sample -- sql 语句。

除了以上的输出，官方还提供了很多定制化参数，是一款不可多得的好工具。       


mysql-explain-slow-log
      德国人写的一个 perl 脚本。       
http://www.willamowius.de/mysql-tools.html       
http://www.bt285.cn/content.php?id=1196863       
       

       
功能上有点瑕疵。不仅把所有的 slow log 打印到屏幕上，而且统计也只有数量而已，不推荐使用。

mysql-log-filter
      google code 上找到的一个分析工具，提供了 python 和 php 两种可执行的脚本。       
http://code.google.com/p/mysql-log-filter/ 
           功能上比官方的 mysqldumpslow 多了查询时间的统计信息(平均、最大、累计)，其他功能都与 mysqldumpslow 类似。       
      特色功能除了统计信息外，还针对输出内容做了排版和格式化，保证整体输出的简洁。喜欢简洁报表的朋友，推荐使用一下。

myprofi
      纯 php 写的一个开源分析工具.项目在 sourceforge 上。       
http://myprofi.sourceforge.net/   ==>  已变为 http://sourceforge.net/projects/myprofi/ 
 
      功能上，列出了总的慢查询次数和类型、去重后的 sql 语句、执行次数及其占总的 slow log 数量的百分比。     
      从整体输出样式来看，比 mysql-log-filter 还要简洁，省去了很多不必要的内容。对于只想看 sql 语句及执行次数的用户来说，比较推荐。       

总结：   

工具/功能	一般统计信息	高级统计信息	脚本	优势
mysqldumpslow	支持	不支持	perl	mysql官方自带
mysqlsla	支持	支持	perl	功能强大,数据报表齐全,定制化能力强
mysql-explain-slow-log	支持	不支持	perl	无
mysql-log-filter	支持	部分支持	python or php	不失功能的前提下,保持输出简洁
myprofi	支持	不支持	php	非常精简

原文博客：https://my.oschina.net/moooofly/blog/160201