MySQL优化方案之开启慢查询日志

mysql> show databases;

mysql> use test;   //指定一个数据库

mysql> show variables like 'slow_query%';
+---------------------------+----------------------------------+
| Variable_name   | Value     |
+-----------------+-----------+
| slow_query_log | ON |
+-----------------+-----------+
| slow_query_log_file | YH-20161209QIZC-slow.log |
+-----------------+-----------+
mysql> show variables like 'long_query_time';
+-----------------+-----------+
| Variable_name   | Value     |
+-----------------+-----------+
| long_query_time | 10.000000 |
+-----------------+-----------+

//默认查询超过10秒才记录

mysql> set global slow_query_log='ON'; 

mysql> set global slow_query_log_file='/usr/local/mysql/data/slow.log'; //linux
mysql> set global slow_query_log_file='D:\\mysq\data\slow.log';         //windows

mysql> set global long_query_time=1;

[mysqld]
slow_query_log = ON
slow_query_log_file = /usr/local/mysql/data/slow.log     //linux
long_query_time = 1

service mysqld restart

[root@DB-Server ~]# mysqldumpslow --help

Usage: mysqldumpslow [ OPTS... ] [ LOGS... ]

 

Parse and summarize the MySQL slow query log. Options are

 

  --verbose    verbose

  --debug      debug

  --help       write this text to standard output

 

  -v           verbose

  -d           debug

  -s ORDER     what to sort by (al, at, ar, c, l, r, t), 'at' is default

                al: average lock time

                ar: average rows sent

                at: average query time

                 c: count

                 l: lock time

                 r: rows sent

                 t: query time  

  -r           reverse the sort order (largest last instead of first)

  -t NUM       just show the top n queries

  -a           don't abstract all numbers to N and strings to 'S'

  -n NUM       abstract numbers with at least n digits within names

  -g PATTERN   grep: only consider stmts that include this string

  -h HOSTNAME  hostname of db server for *-slow.log filename (can be wildcard),

               default is '*', i.e. match all

  -i NAME      name of server instance (if using mysql.server startup script)

  -l           don't subtract lock time from total time