mysqldumpslow是mysql自带的用来分析慢查询的工具
经常使用几个命令
-s ORDER what to sort by (al, at, ar, c, l, r, t), ‘at’ is default
-t NUM just show the top n queries
-g PATTERN grep: only consider stmts that include this string
-r Reverse the sort order
-s，是order的顺序，主要有
c,t,l,r和ac,at,al,ar，分别是按照query次数，查询时间，lock的时间和返回的记录
