使用mysqldumpslow分析mysql慢日志

简介

mysqldumpslow 是mysql自带的分析满查询日志的工具

操作

首先开启mysql的满查询日志,mysql的满查询日志可以放在mysql的表中也可以放在文件中,下面是具体的参数

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# 开启慢查询
slow_query_log = on
# 慢查询输出到表和文件中
log_output = TABLE,FILE
# 如果查询时间超过2s就定义为是慢查询
long_query_time = 2
# 慢查询文件的路径,如果不是指定绝对路径,比如就和我下面一样写,默认就在mysql的data文件夹中比如/var/lib/mysql
slow_query_log_file = slow.log

之后重启mysql

等一段时间有慢日志之后就可以使用mysqldumpslow分析了

其实mysqldumpslow的参数也很简单

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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 (aa, ae, al, ar, at, a, c, e, l, r, t), 'at' is default
aa: average rows affected
ae: aggregated rows examined
al: average lock time
ar: average rows sent
at: average query time
a: rows affected
c: count
e: rows examined
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

介绍两个常见用法

查询最慢的前3条

mysqldumpslow -s at -t 3 ./slow.log

查询次数最多的前3条

mysqldumpslow -s ac -t 3 slow.log

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