pt-mext实现的功能比较简单,就是将mysqladmin输出的多次迭代的相同status变量值放到同一行输出。
参数很少,除了–help和–version外,只有一个–relative参数
short form: -r
Subtract each column from the previous column.
支持两种用法:
1. 直接对输出进行聚合
pt-mext -r — mysqladmin ext -i1 -c3
注意:上述命令中会有三次迭代,但只会输出第一次的结果,第二次和第一次相差的结果。
其中,
-i, –sleep=# Execute commands repeatedly with a sleep between.
-c, –count=# Number of iterations to make. This works with -i (–sleep) only.
extended-status Gives an extended status message from the server
[root@localhost ~]# pt-mext -r -- mysqladmin ext -i1 -c3
Aborted_clients
Aborted_connects
Binlog_cache_disk_use
Binlog_cache_use
Binlog_stmt_cache_disk_use
Binlog_stmt_cache_use
Bytes_received
Bytes_sent
......
上述命令如果不加-r参数的话,则原样输出。
# pt-mext — mysqladmin ext -i1 -c3
Aborted_clients
Aborted_connects
Binlog_cache_disk_use
Binlog_cache_use
Binlog_stmt_cache_disk_use
Binlog_stmt_cache_use
Bytes_received
Bytes_sent
.....
2. 对文本文件进行聚合
pt-mext -r — cat mysqladmin-output.txt
注意:无论是否带-r参数,最后一次的迭代结果都不会纳入输出的范围。
关于它的原理,可参考官方文档的说明
pt-mext executes the COMMAND you specify, and reads through the result one line at a time. It places each line into a
temporary file. When it finds a blank line, it assumes that a new sample of SHOW GLOBAL STATUS is starting, and
it creates a new temporary file. At the end of this process, it has a number of temporary files. It joins the temporary
files together side-by-side and prints the result. If --relative option is given, it first subtracts each sample from
the one after it before printing results.
即每次迭代的结果都会放入到一个临时文件中,然后对这些临时文件进行join。
其实,该脚本的作用不限于mysqladmin的status变量值
如下所示:
# cat 4.txt
one
two one
two
three one
two
# pt-mext — cat 4.txt
one
two