对MySQL慢查询日志进行分析的基本教程

0、首先查看当前是否开启慢查询：

（1）快速办法，运行sql语句

show VARIABLES like "%slow%" 

（2）直接去my.conf中查看。

my.conf中的配置(放在[mysqld]下的下方加入)

[mysqld]

log-slow-queries = /usr/local/mysql/var/slowquery.log
long_query_time = 1 #单位是秒
log-queries-not-using-indexes

使用sql语句来修改：不能按照my.conf中的项来修改的。修改通过"show VARIABLES like "%slow%" "

语句列出来的变量，运行如下sql：

set global log_slow_queries = ON;
set global slow_query_log = ON;
set global long_query_time=0.1; #设置大于0.1s的sql语句记录下来

慢查询日志文件的信息格式：

# Time: 130905 14:15:59   时间是2013年9月5日 14:15:59(前面部分容易看错哦,乍看以为是时间戳)
# User@Host: root[root] @ [183.239.28.174] 请求mysql服务器的客户端ip
# Query_time: 0.735883 Lock_time: 0.000078 Rows_sent: 262 Rows_examined: 262 这里表示执行用时多少秒，0.735883秒，1秒等于1000毫秒

SET timestamp=1378361759; 这目前我还不知道干嘛用的

show tables from `test_db`; 这个就是关键信息，指明了当时执行的是这条语句

1、MySQL 慢查询日志分析

pt-query-digest分析慢查询日志

pt-query-digest –report slow.log

报告最近半个小时的慢查询：

pt-query-digest –report –since 1800s slow.log

报告一个时间段的慢查询：

pt-query-digest –report –since ‘2013-02-10 21:48:59′ –until ‘2013-02-16 02:33:50′ slow.log

报告只含select语句的慢查询:

pt-query-digest –filter ‘$event->{fingerprint} =~ m/^select/i' slow.log

报告针对某个用户的慢查询:

pt-query-digest –filter ‘($event->{user} || “”) =~ m/^root/i' slow.log

报告所有的全表扫描或full join的慢查询:

pt-query-digest –filter ‘(($event->{Full_scan} || “”) eq “yes”) || (($event->{Full_join} || “”) eq “yes”)' slow.log

2、将慢查询日志的分析结果可视化

Query-Digest-UI

其实，这是一个非常简单和直接的工具，浏览和统计Mysql慢查询，基于AJAX的Web界面。

配置Query-Digest-UI：

下载：

wget https://nodeload.github.com/kormoc/Query-Digest-UI/zip/master
 unzip Query-Digest-UI-master.zip

查询分析结果可视化步骤如下:

（1）创建相关数据库表

-- install.sql
-- Create the database needed for the Query-Digest-UI
DROP DATABASE IF EXISTS slow_query_log;
CREATE DATABASE slow_query_log;
USE slow_query_log;
 
-- Create the global query review table
CREATE TABLE `global_query_review` (
 `checksum` bigint(20) unsigned NOT NULL,
 `fingerprint` text NOT NULL,
 `sample` longtext NOT NULL,
 `first_seen` datetime DEFAULT NULL,
 `last_seen` datetime DEFAULT NULL,
 `reviewed_by` varchar(20) DEFAULT NULL,
 `reviewed_on` datetime DEFAULT NULL,
 `comments` text,
 `reviewed_status` varchar(24) DEFAULT NULL,
 PRIMARY KEY (`checksum`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
-- Create the historical query review table
CREATE TABLE `global_query_review_history` (
 `hostname_max` varchar(64) NOT NULL,
 `db_max` varchar(64) DEFAULT NULL,
 `checksum` bigint(20) unsigned NOT NULL,
 `sample` longtext NOT NULL,
 `ts_min` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
 `ts_max` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
 `ts_cnt` float DEFAULT NULL,
 `Query_time_sum` float DEFAULT NULL,
 `Query_time_min` float DEFAULT NULL,
 `Query_time_max` float DEFAULT NULL,
 `Query_time_pct_95` float DEFAULT NULL,
 `Query_time_stddev` float DEFAULT NULL,
 `Query_time_median` float DEFAULT NULL,
 `Lock_time_sum` float DEFAULT NULL,
 `Lock_time_min` float DEFAULT NULL,
 `Lock_time_max` float DEFAULT NULL,
 `Lock_time_pct_95` float DEFAULT NULL,
 `Lock_time_stddev` float DEFAULT NULL,
 `Lock_time_median` float DEFAULT NULL,
 `Rows_sent_sum` float DEFAULT NULL,
 `Rows_sent_min` float DEFAULT NULL,
 `Rows_sent_max` float DEFAULT NULL,
 `Rows_sent_pct_95` float DEFAULT NULL,
 `Rows_sent_stddev` float DEFAULT NULL,
 `Rows_sent_median` float DEFAULT NULL,
 `Rows_examined_sum` float DEFAULT NULL,
 `Rows_examined_min` float DEFAULT NULL,
 `Rows_examined_max` float DEFAULT NULL,
 `Rows_examined_pct_95` float DEFAULT NULL,
 `Rows_examined_stddev` float DEFAULT NULL,
 `Rows_examined_median` float DEFAULT NULL,
 `Rows_affected_sum` float DEFAULT NULL,
 `Rows_affected_min` float DEFAULT NULL,
 `Rows_affected_max` float DEFAULT NULL,
 `Rows_affected_pct_95` float DEFAULT NULL,
 `Rows_affected_stddev` float DEFAULT NULL,
 `Rows_affected_median` float DEFAULT NULL,
 `Rows_read_sum` float DEFAULT NULL,
 `Rows_read_min` float DEFAULT NULL,
 `Rows_read_max` float DEFAULT NULL,
 `Rows_read_pct_95` float DEFAULT NULL,
 `Rows_read_stddev` float DEFAULT NULL,
 `Rows_read_median` float DEFAULT NULL,
 `Merge_passes_sum` float DEFAULT NULL,
 `Merge_passes_min` float DEFAULT NULL,
 `Merge_passes_max` float DEFAULT NULL,
 `Merge_passes_pct_95` float DEFAULT NULL,
 `Merge_passes_stddev` float DEFAULT NULL,
 `Merge_passes_median` float DEFAULT NULL,
 `InnoDB_IO_r_ops_min` float DEFAULT NULL,
 `InnoDB_IO_r_ops_max` float DEFAULT NULL,
 `InnoDB_IO_r_ops_pct_95` float DEFAULT NULL,
 `InnoDB_IO_r_bytes_pct_95` float DEFAULT NULL,
 `InnoDB_IO_r_bytes_stddev` float DEFAULT NULL,
 `InnoDB_IO_r_bytes_median` float DEFAULT NULL,
 `InnoDB_IO_r_wait_min` float DEFAULT NULL,
 `InnoDB_IO_r_wait_max` float DEFAULT NULL,
 `InnoDB_IO_r_wait_pct_95` float DEFAULT NULL,
 `InnoDB_IO_r_ops_stddev` float DEFAULT NULL,
 `InnoDB_IO_r_ops_median` float DEFAULT NULL,
 `InnoDB_IO_r_bytes_min` float DEFAULT NULL,
 `InnoDB_IO_r_bytes_max` float DEFAULT NULL,
 `InnoDB_IO_r_wait_stddev` float DEFAULT NULL,
 `InnoDB_IO_r_wait_median` float DEFAULT NULL,
 `InnoDB_rec_lock_wait_min` float DEFAULT NULL,
 `InnoDB_rec_lock_wait_max` float DEFAULT NULL,
 `InnoDB_rec_lock_wait_pct_95` float DEFAULT NULL,
 `InnoDB_rec_lock_wait_stddev` float DEFAULT NULL,
 `InnoDB_rec_lock_wait_median` float DEFAULT NULL,
 `InnoDB_queue_wait_min` float DEFAULT NULL,
 `InnoDB_queue_wait_max` float DEFAULT NULL,
 `InnoDB_queue_wait_pct_95` float DEFAULT NULL,
 `InnoDB_queue_wait_stddev` float DEFAULT NULL,
 `InnoDB_queue_wait_median` float DEFAULT NULL,
 `InnoDB_pages_distinct_min` float DEFAULT NULL,
 `InnoDB_pages_distinct_max` float DEFAULT NULL,
 `InnoDB_pages_distinct_pct_95` float DEFAULT NULL,
 `InnoDB_pages_distinct_stddev` float DEFAULT NULL,
 `InnoDB_pages_distinct_median` float DEFAULT NULL,
 `QC_Hit_cnt` float DEFAULT NULL,
 `QC_Hit_sum` float DEFAULT NULL,
 `Full_scan_cnt` float DEFAULT NULL,
 `Full_scan_sum` float DEFAULT NULL,
 `Full_join_cnt` float DEFAULT NULL,
 `Full_join_sum` float DEFAULT NULL,
 `Tmp_table_cnt` float DEFAULT NULL,
 `Tmp_table_sum` float DEFAULT NULL,
 `Filesort_cnt` float DEFAULT NULL,
 `Filesort_sum` float DEFAULT NULL,
 `Tmp_table_on_disk_cnt` float DEFAULT NULL,
 `Tmp_table_on_disk_sum` float DEFAULT NULL,
 `Filesort_on_disk_cnt` float DEFAULT NULL,
 `Filesort_on_disk_sum` float DEFAULT NULL,
 `Bytes_sum` float DEFAULT NULL,
 `Bytes_min` float DEFAULT NULL,
 `Bytes_max` float DEFAULT NULL,
 `Bytes_pct_95` float DEFAULT NULL,
 `Bytes_stddev` float DEFAULT NULL,
 `Bytes_median` float DEFAULT NULL,
 UNIQUE KEY `hostname_max` (`hostname_max`,`checksum`,`ts_min`,`ts_max`),
 KEY `ts_min` (`ts_min`),
 KEY `checksum` (`checksum`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

（2）创建数据库账号

$ mysql -uroot -p -h 192.168.1.190 < install.sql
$ mysql -uroot -p -h 192.168.1.190 -e "grant ALL ON slow_query_log.* to 'slowlog'@'%' IDENTIFIED BY '123456';"

（3）配置Query-Digest-UI

修改数据库连接配置

cd Query-Digest-UI
cp config.php.example config.php
vi config.php
$reviewhost = array(
// Replace hostname and database in this setting
// use host=hostname;port=portnum if not the default port
 'dsn'   => 'mysql:host=192.168.1.190;port=3306;dbname=slow_query_log',
 'user'   => 'slowlog',
 'password'  => '123456',
// See http://www.percona.com/doc/percona-toolkit/2.1/pt-query-digest.html#cmdoption-pt-query-digest--review
 'review_table' => 'global_query_review',
// This table is optional. You don't need it, but you lose detailed stats
// Set to a blank string to disable
// See http://www.percona.com/doc/percona-toolkit/2.1/pt-query-digest.html#cmdoption-pt-query-digest--review-history
 'history_table' => 'global_query_review_history',
);

（4）使用pt-query-digest分析日志并将分析结果导入数据库

pt-query-digest --user=slowlog 
--password=123456 
--review h=192.168.1.190,D=slow_query_log,t=global_query_review 
--review-history h=192.168.1.190,D=slow_query_log,t=global_query_review_history
--no-report --limit=0% 
--filter=" $event->{Bytes} = length($event->{arg}) and $event->{hostname}="$HOSTNAME"" 
/usr/local/mysql/data/slow.log