4、格式化慢查询日志

结构化慢查询日志就是把慢查询日志中的重要信息按照便于阅读以及按照特定的排序方式来提取SQL。

这种方式有点类似于Oracle中有个tkprof来格式化oracle的trace文件。

对于前面的慢查询日志我们使用MySQLdumpslow来提取如下：

SUSE11b:~ # mysqldumpslow -s at,al /var/lib/mysql/suse11b-slow.log

Reading mysql slow query log from /var/lib/mysql/suse11b-slow.log

Count: 4  Time=16.87s (67s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost

insert into tb_slow select * from tb_slow

Count: 1  Time=0.20s (0s)  Lock=0.00s (0s)  Rows=1.0 (1), root[root]@localhost

select count(*) from tb_slow

Count: 1  Time=1.57s (1s)  Lock=0.00s (0s)  Rows=83.0 (83), root[root]@localhost

select table_schema,table_name,count(*) from tb_slow

group by table_schema,table_name order by N,N

#以下是按照最大耗用时间排最后，只显示2条的方式格式化日志文件

suse11b:~ # mysqldumpslow -r -t 2 /var/lib/mysql/suse11b-slow.log

Reading mysql slow query log from /var/lib/mysql/suse11b-slow.log

Count: 1  Time=1.57s (1s)  Lock=0.00s (0s)  Rows=83.0 (83), root[root]@localhost

select table_schema,table_name,count(*) from tb_slow

group by table_schema,table_name order by N,N

Count: 4  Time=16.87s (67s)  Lock=0.00s (0s)  Rows=0.0 (0), root[root]@localhost

insert into tb_slow select * from tb_slow

#获取mysqldumpslow的帮助信息

suse11b:~ # 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        #query的次数

l: lock time

r: rows sent    #返回的记录数

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