4、格式化慢查詢日志

結構化慢查詢日志就是把慢查詢日志中的重要信息按照便于閱讀以及按照特定的排序方式來提取SQL。

這種方式有點類似于Oracle中有個tkprof來格式化oracle的trace文件。

對于前面的慢查詢日志我們使用MySQLdumpslow來提取如下：

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時間排最后，只顯示2條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

#獲取mysqldumpslow的幫助信息

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的次數

l: lock time

r: rows sent? ? #返回的記錄數

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

總結

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