pager 命令
https://www.percona.com/blog/2013/01/21/fun-with-the-mysql-pager-command/
Last time I wrote about a few tips that can make you more efficient when using the command line on Unix. Today I want to focus more on pager.
The most common usage of pager is to set it to a Unix pager such as less. It can be very useful to view the result of a command spanning over many lines (for instance SHOW ENGINE INNODB STATUS
):
mysql> pager less;
PAGER set to 'less'
mysql> show engine innodb status\G *************************** . row ***************************
Type: InnoDB
Name:
Status:
=====================================
-- :: 2ab7b4f90940 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: srv_active, srv_shutdown, srv_idle
srv_master_thread log flush and writes:
----------
SEMAPHORES
----------
----------
MUTEX INFO
----------
Locked mutex: addr 0x1829940 thread file /usr/src/mysql-5.6./storage/innobase/handler/ha_innodb.cc line
Locked mutex: addr 0x18298c0 thread file /usr/src/mysql-5.6./storage/innobase/srv/srv0srv.cc line
Total number of mutexes
-------------
:
Now you are inside less
and you can easily navigate through the result set (use q to quit, space to scroll down, etc).
Reminder: if you want to leave your custom pager, this is easy, just run pager
:
mysql> pager
Default pager wasn't set, using stdout.
2.\n
:
mysql> \n
PAGER set to stdout
But the pager command is not restricted to such basic usage! You can pass the output of queries to most Unix programs that are able to work on text. We have discussed the topic, but here are a few more examples.
Discarding the result set
Sometimes you don’t care about the result set, you only want to see timing information. This can be true if you are trying different execution plans for a query by changing indexes. Discarding the result is possible with pager:
mysql> pager cat > /root/.txt
mysql> pager cat > /dev/null
PAGER set to 'cat > /dev/null'
mysql> show engine innodb status\G
row in set (0.03 sec)
Now it’s much easier to see all the timing information on one screen.
Comparing result sets
Let’s say you are rewriting a query and you want to check if the result set is the same before and after rewrite. Unfortunately, it has a lot of rows:
mysql> select * from COLLATIONS ;
+--------------------------+--------------------+-----+------------+-------------+---------+
| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN |
+--------------------------+--------------------+-----+------------+-------------+---------+
| big5_chinese_ci | big5 | | Yes | Yes | |
| big5_bin | big5 | | | Yes | |
| dec8_swedish_ci | dec8 | | Yes | Yes | |
| dec8_bin | dec8 | | | Yes | |
| cp850_general_ci | cp850 | | Yes | Yes | |
| cp850_bin | cp850 | | | Yes | |
| hp8_english_ci | hp8 | | Yes | Yes | |
| hp8_bin | hp8 | | | Yes | |
| koi8r_general_ci | koi8r | | Yes | Yes | |
| koi8r_bin | koi8r | | | Yes | |
| latin1_german1_ci | latin1 | | | Yes | |
| latin1_swedish_ci | latin1 | | Yes | Yes | |
| latin1_danish_ci | latin1 | | | Yes | |
| latin1_german2_ci | latin1 | | | Yes | |
| latin1_bin | latin1 | | | Yes | |
| latin1_general_ci | latin1 | | | Yes | |
| latin1_general_cs | latin1 | | | Yes | |
| latin1_spanish_ci | latin1 | | | Yes | |
| latin2_czech_cs | latin2 | | | Yes | |
| latin2_general_ci | latin2 | | Yes | Yes | |
| latin2_hungarian_ci | latin2 | | | Yes | |
| latin2_croatian_ci | latin2 | | | Yes | |
| latin2_bin | latin2 | | | Yes | |
| swe7_swedish_ci | swe7 | | Yes | Yes | |
| swe7_bin | swe7 | | | Yes | |
| ascii_general_ci | ascii | | Yes | Yes | |
| ascii_bin | ascii | | | Yes | |
| ujis_japanese_ci | ujis | | Yes | Yes | |
| ujis_bin | ujis | | | Yes | |
| sjis_japanese_ci | sjis | | Yes | Yes | |
| sjis_bin | sjis | | | Yes | |
| hebrew_general_ci | hebrew | | Yes | Yes | |
| hebrew_bin | hebrew | | | Yes | |
| tis620_thai_ci | tis620 | | Yes | Yes | |
| tis620_bin | tis620 | | | Yes | |
| euckr_korean_ci | euckr | | Yes | Yes | |
| euckr_bin | euckr | | | Yes | |
| koi8u_general_ci | koi8u | | Yes | Yes | |
| koi8u_bin | koi8u | | | Yes | |
| gb2312_chinese_ci | gb2312 | | Yes | Yes | |
| gb2312_bin | gb2312 | | | Yes | |
| greek_general_ci | greek | | Yes | Yes | |
| greek_bin | greek | | | Yes | |
| cp1250_general_ci | cp1250 | | Yes | Yes | |
| cp1250_czech_cs | cp1250 | | | Yes | |
| cp1250_croatian_ci | cp1250 | | | Yes | |
| cp1250_bin | cp1250 | | | Yes | |
| cp1250_polish_ci | cp1250 | | | Yes | |
| gbk_chinese_ci | gbk | | Yes | Yes | |
| gbk_bin | gbk | | | Yes | |
| latin5_turkish_ci | latin5 | | Yes | Yes | |
| latin5_bin | latin5 | | | Yes | |
| armscii8_general_ci | armscii8 | | Yes | Yes | |
| armscii8_bin | armscii8 | | | Yes | |
| utf8_general_ci | utf8 | | Yes | Yes | |
| utf8_bin | utf8 | | | Yes | |
| utf8_unicode_ci | utf8 | | | Yes | |
| utf8_icelandic_ci | utf8 | | | Yes | |
| utf8_latvian_ci | utf8 | | | Yes | |
| utf8_romanian_ci | utf8 | | | Yes | |
| utf8_slovenian_ci | utf8 | | | Yes | |
| utf8_polish_ci | utf8 | | | Yes | |
| utf8_estonian_ci | utf8 | | | Yes | |
| utf8_spanish_ci | utf8 | | | Yes | |
| utf8_swedish_ci | utf8 | | | Yes | |
| utf8_turkish_ci | utf8 | | | Yes | |
| utf8_czech_ci | utf8 | | | Yes | |
| utf8_danish_ci | utf8 | | | Yes | |
| utf8_lithuanian_ci | utf8 | | | Yes | |
| utf8_slovak_ci | utf8 | | | Yes | |
| utf8_spanish2_ci | utf8 | | | Yes | |
| utf8_roman_ci | utf8 | | | Yes | |
| utf8_persian_ci | utf8 | | | Yes | |
| utf8_esperanto_ci | utf8 | | | Yes | |
| utf8_hungarian_ci | utf8 | | | Yes | |
| utf8_sinhala_ci | utf8 | | | Yes | |
| utf8_german2_ci | utf8 | | | Yes | |
| utf8_croatian_ci | utf8 | | | Yes | |
| utf8_unicode_520_ci | utf8 | | | Yes | |
| utf8_vietnamese_ci | utf8 | | | Yes | |
| utf8_general_mysql500_ci | utf8 | | | Yes | |
| ucs2_general_ci | ucs2 | | Yes | Yes | |
| ucs2_bin | ucs2 | | | Yes | |
| ucs2_unicode_ci | ucs2 | | | Yes | |
| ucs2_icelandic_ci | ucs2 | | | Yes | |
| ucs2_latvian_ci | ucs2 | | | Yes | |
| ucs2_romanian_ci | ucs2 | | | Yes | |
| ucs2_slovenian_ci | ucs2 | | | Yes | |
| ucs2_polish_ci | ucs2 | | | Yes | |
| ucs2_estonian_ci | ucs2 | | | Yes | |
| ucs2_spanish_ci | ucs2 | | | Yes | |
| ucs2_swedish_ci | ucs2 | | | Yes | |
| ucs2_turkish_ci | ucs2 | | | Yes | |
| ucs2_czech_ci | ucs2 | | | Yes | |
| ucs2_danish_ci | ucs2 | | | Yes | |
| ucs2_lithuanian_ci | ucs2 | | | Yes | |
| ucs2_slovak_ci | ucs2 | | | Yes | |
| ucs2_spanish2_ci | ucs2 | | | Yes | |
| ucs2_roman_ci | ucs2 | | | Yes | |
| ucs2_persian_ci | ucs2 | | | Yes | |
| ucs2_esperanto_ci | ucs2 | | | Yes | |
| ucs2_hungarian_ci | ucs2 | | | Yes | |
| ucs2_sinhala_ci | ucs2 | | | Yes | |
| ucs2_german2_ci | ucs2 | | | Yes | |
| ucs2_croatian_ci | ucs2 | | | Yes | |
| ucs2_unicode_520_ci | ucs2 | | | Yes | |
| ucs2_vietnamese_ci | ucs2 | | | Yes | |
| ucs2_general_mysql500_ci | ucs2 | | | Yes | |
| cp866_general_ci | cp866 | | Yes | Yes | |
| cp866_bin | cp866 | | | Yes | |
| keybcs2_general_ci | keybcs2 | | Yes | Yes | |
| keybcs2_bin | keybcs2 | | | Yes | |
| macce_general_ci | macce | | Yes | Yes | |
| macce_bin | macce | | | Yes | |
| macroman_general_ci | macroman | | Yes | Yes | |
| macroman_bin | macroman | | | Yes | |
| cp852_general_ci | cp852 | | Yes | Yes | |
| cp852_bin | cp852 | | | Yes | |
| latin7_estonian_cs | latin7 | | | Yes | |
| latin7_general_ci | latin7 | | Yes | Yes | |
| latin7_general_cs | latin7 | | | Yes | |
| latin7_bin | latin7 | | | Yes | |
| utf8mb4_general_ci | utf8mb4 | | Yes | Yes | |
| utf8mb4_bin | utf8mb4 | | | Yes | |
| utf8mb4_unicode_ci | utf8mb4 | | | Yes | |
| utf8mb4_icelandic_ci | utf8mb4 | | | Yes | |
| utf8mb4_latvian_ci | utf8mb4 | | | Yes | |
| utf8mb4_romanian_ci | utf8mb4 | | | Yes | |
| utf8mb4_slovenian_ci | utf8mb4 | | | Yes | |
| utf8mb4_polish_ci | utf8mb4 | | | Yes | |
| utf8mb4_estonian_ci | utf8mb4 | | | Yes | |
| utf8mb4_spanish_ci | utf8mb4 | | | Yes | |
| utf8mb4_swedish_ci | utf8mb4 | | | Yes | |
| utf8mb4_turkish_ci | utf8mb4 | | | Yes | |
| utf8mb4_czech_ci | utf8mb4 | | | Yes | |
| utf8mb4_danish_ci | utf8mb4 | | | Yes | |
| utf8mb4_lithuanian_ci | utf8mb4 | | | Yes | |
| utf8mb4_slovak_ci | utf8mb4 | | | Yes | |
| utf8mb4_spanish2_ci | utf8mb4 | | | Yes | |
| utf8mb4_roman_ci | utf8mb4 | | | Yes | |
| utf8mb4_persian_ci | utf8mb4 | | | Yes | |
| utf8mb4_esperanto_ci | utf8mb4 | | | Yes | |
| utf8mb4_hungarian_ci | utf8mb4 | | | Yes | |
| utf8mb4_sinhala_ci | utf8mb4 | | | Yes | |
| utf8mb4_german2_ci | utf8mb4 | | | Yes | |
| utf8mb4_croatian_ci | utf8mb4 | | | Yes | |
| utf8mb4_unicode_520_ci | utf8mb4 | | | Yes | |
| utf8mb4_vietnamese_ci | utf8mb4 | | | Yes | |
| cp1251_bulgarian_ci | cp1251 | | | Yes | |
| cp1251_ukrainian_ci | cp1251 | | | Yes | |
| cp1251_bin | cp1251 | | | Yes | |
| cp1251_general_ci | cp1251 | | Yes | Yes | |
| cp1251_general_cs | cp1251 | | | Yes | |
| utf16_general_ci | utf16 | | Yes | Yes | |
| utf16_bin | utf16 | | | Yes | |
| utf16_unicode_ci | utf16 | | | Yes | |
| utf16_icelandic_ci | utf16 | | | Yes | |
| utf16_latvian_ci | utf16 | | | Yes | |
| utf16_romanian_ci | utf16 | | | Yes | |
| utf16_slovenian_ci | utf16 | | | Yes | |
| utf16_polish_ci | utf16 | | | Yes | |
| utf16_estonian_ci | utf16 | | | Yes | |
| utf16_spanish_ci | utf16 | | | Yes | |
| utf16_swedish_ci | utf16 | | | Yes | |
| utf16_turkish_ci | utf16 | | | Yes | |
| utf16_czech_ci | utf16 | | | Yes | |
| utf16_danish_ci | utf16 | | | Yes | |
| utf16_lithuanian_ci | utf16 | | | Yes | |
| utf16_slovak_ci | utf16 | | | Yes | |
| utf16_spanish2_ci | utf16 | | | Yes | |
| utf16_roman_ci | utf16 | | | Yes | |
| utf16_persian_ci | utf16 | | | Yes | |
| utf16_esperanto_ci | utf16 | | | Yes | |
| utf16_hungarian_ci | utf16 | | | Yes | |
| utf16_sinhala_ci | utf16 | | | Yes | |
| utf16_german2_ci | utf16 | | | Yes | |
| utf16_croatian_ci | utf16 | | | Yes | |
| utf16_unicode_520_ci | utf16 | | | Yes | |
| utf16_vietnamese_ci | utf16 | | | Yes | |
| utf16le_general_ci | utf16le | | Yes | Yes | |
| utf16le_bin | utf16le | | | Yes | |
| cp1256_general_ci | cp1256 | | Yes | Yes | |
| cp1256_bin | cp1256 | | | Yes | |
| cp1257_lithuanian_ci | cp1257 | | | Yes | |
| cp1257_bin | cp1257 | | | Yes | |
| cp1257_general_ci | cp1257 | | Yes | Yes | |
| utf32_general_ci | utf32 | | Yes | Yes | |
| utf32_bin | utf32 | | | Yes | |
| utf32_unicode_ci | utf32 | | | Yes | |
| utf32_icelandic_ci | utf32 | | | Yes | |
| utf32_latvian_ci | utf32 | | | Yes | |
| utf32_romanian_ci | utf32 | | | Yes | |
| utf32_slovenian_ci | utf32 | | | Yes | |
| utf32_polish_ci | utf32 | | | Yes | |
| utf32_estonian_ci | utf32 | | | Yes | |
| utf32_spanish_ci | utf32 | | | Yes | |
| utf32_swedish_ci | utf32 | | | Yes | |
| utf32_turkish_ci | utf32 | | | Yes | |
| utf32_czech_ci | utf32 | | | Yes | |
| utf32_danish_ci | utf32 | | | Yes | |
| utf32_lithuanian_ci | utf32 | | | Yes | |
| utf32_slovak_ci | utf32 | | | Yes | |
| utf32_spanish2_ci | utf32 | | | Yes | |
| utf32_roman_ci | utf32 | | | Yes | |
| utf32_persian_ci | utf32 | | | Yes | |
| utf32_esperanto_ci | utf32 | | | Yes | |
| utf32_hungarian_ci | utf32 | | | Yes | |
| utf32_sinhala_ci | utf32 | | | Yes | |
| utf32_german2_ci | utf32 | | | Yes | |
| utf32_croatian_ci | utf32 | | | Yes | |
| utf32_unicode_520_ci | utf32 | | | Yes | |
| utf32_vietnamese_ci | utf32 | | | Yes | |
| binary | binary | | Yes | Yes | |
| geostd8_general_ci | geostd8 | | Yes | Yes | |
| geostd8_bin | geostd8 | | | Yes | |
| cp932_japanese_ci | cp932 | | Yes | Yes | |
| cp932_bin | cp932 | | | Yes | |
| eucjpms_japanese_ci | eucjpms | | Yes | Yes | |
| eucjpms_bin | eucjpms | | | Yes | |
+--------------------------+--------------------+-----+------------+-------------+---------+
rows in set (0.02 sec)
Instead of manually comparing each row, you can calculate a checksum and only compare the checksum:
mysql> pager md5sum;
PAGER set to 'md5sum'
mysql> select * from COLLATIONS;
6650d5d87f2abe18b6ead3588b133087 -
rows in set (0.02 sec)
mysql> pager md5sum
PAGER set to 'md5sum' # Original query
mysql> SELECT ...
32a1894d773c9b85172969c659175d2d -
row in set (0.40 sec) # Rewritten query - wrong
mysql> SELECT ...
fdb94521558684afedc8148ca724f578 -
row in set (0.16 sec)
Hmmm, checksums don’t match, something is wrong. Let’s retry:
# Rewritten query - correct
mysql> SELECT ...
32a1894d773c9b85172969c659175d2d -
row in set (0.17 sec)
Checksums are identical, the rewritten query is much likely to produce the same result as the original one.
Cleaning up SHOW PROCESSLIST
If you have lots of connections on your MySQL, it’s very difficult to read the output of SHOW PROCESSLIST
. For instance, if you have several hundreds of connections and you want to know how many connections are sleeping, manually counting the rows from the output of SHOW PROCESSLIST
is probably not the best solution. With pager, it is straightforward:
mysql> show processlist;
+----+------+-----------+--------------------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+--------------------+---------+------+-------+------------------+
| | root | localhost | information_schema | Query | | init | show processlist |
| | root | localhost | test | Sleep | | | NULL |
+----+------+-----------+--------------------+---------+------+-------+------------------+
rows in set (0.00 sec) mysql> pager grep Sleep |wc -l
PAGER set to 'grep Sleep |wc -l' mysql> show processlist; rows in set (0.00 sec)
Slightly more complicated now: you want to know the number of connections for each status:
mysql> pager awk -F '|' '{print $6}' | sort | uniq -c | sort -r
PAGER set to 'awk -F '|' '{print $}' | sort | uniq -c | sort -r'
mysql> show processlist; Sleep
Query
Command
rows in set (0.00 sec)
Astute readers will have noticed that these questions could have been solved by querying INFORMATION_SCHEMA. For instance, counting the number of sleeping connections can be done with:
mysql> SELECT COUNT(*) FROM INFORMATION_SCHEMA.PROCESSLIST WHERE COMMAND='Sleep';
+----------+
| COUNT(*) |
+----------+
| 1 |
+----------+
1 row in set (0.17 sec)
and counting the number of connection for each status can be done with:
mysql> SELECT COMMAND,COUNT(*) TOTAL FROM INFORMATION_SCHEMA.PROCESSLIST GROUP BY COMMAND ORDER BY TOTAL DESC;
+---------+-------+
| COMMAND | TOTAL |
+---------+-------+
| Query | |
| Sleep | |
+---------+-------+
rows in set (0.01 sec)
True, but:
- It’s nice to know several ways to get the same result
- Some of you may feel more comfortable with writing SQL queries, while others will prefer command line tools
pager 命令的更多相关文章
- mysql中pager命令妙用
pager命令的妙用在mysql,可以大大提高工作效率. 一 当处理大量数据时,不想显示查询的结果,而只需知道查询话费的时间. mysql> select * from t3; +----- ...
- 介绍一些有趣的MySQL pager命令
一.分页结果集 在Linux系统中中,我们经常也会使用一些分页查看命令,例如less.more等.同样,MySQL客户端也提供了类似的命令,用来帮助我们对查询结果集进行分页.比如,SHOW ENGIN ...
- mysql pager用法&命令行命令
下面讲的命令,有部分只能在linux上才有.像pager命令windows上就没有了. 分屏:在Linux上,而且不是xwindow时,使用mysql命令行时,输出太多的东西,看不到就很悲剧了.在sh ...
- mysql的一些特殊命令
mysql命令行工具的编辑技巧 从mysql performace blog 中学到的: 1. pager 例子 mysql> pager more PAGER set to 'more' my ...
- Mysql 客户端查询结果如何保存到本地而不是服务端?
应用场景:知道某台DB服务器的IP和账户,登录上去查询了10W条记录,需要把这些记录拉到本地做分析 方法1,远程连接到DB服务器执行OUTFILE命令,文件存储在DB机器上,只有mysql账户的情况下 ...
- MySQL 实用技巧
概述: MySQL有许多实用的技巧,利用这些技巧能提高工作的效率,减少一些不必要的麻烦.以下是几个我在MySQL日常维护从常用的技巧. 一.prompt 命令 功能:设置mysql客户端提示符 说明: ...
- 【Linux】使用update-alternatives命令进行版本的切换
引言 在Redhat中也有此功能,用于切换不同版本. 在Debian系统中,我们可能会同时安装有很多功能类似的程序和可选配置,可能会出现同一软件的多个版本并存的场景.比如像是一些编程语言工具,一些系统 ...
- 十个节省时间的MySQL命令
十个节省时间的MySQL命令 2011-02-23 16:07 黄永兵 译 IT168 字号:T | T 编者在工作中积累起来了一些MySQL命令行客户端技巧,这些技巧或多或少会帮助您节省大量的时间. ...
- [Android ] linux命令英文缩写的含义(方便记忆)
du -sh */ reference to : http://blog.chinaunix.net/uid-27164517-id-3299073.html linux常用命令的英文单词缩写 命令缩 ...
随机推荐
- ASP.NET常用技巧方法代码断
1. 打开新的窗口并传送参数:传送参数:response.write("<script>window.open('*.aspx?id="+this.DropDownLi ...
- 最小化安装CentOS7 + xfce4 +PHP + nginx +mariadb 开发环境
虚拟机自定义最小化安装,新增用户做为管理员,打开自动获取网络,桥接模式.所有的操作只有命令,不做解释,看不明白的可以自行搜索相关的资料. # 开头的行是注释行,# 开头的空行,我自己装机时做了快照.未 ...
- MapReduce TopK统计加排序
Hadoop技术内幕中指出Top K算法有两步,一是统计词频,二是找出词频最高的前K个词.在网上找了很多MapReduce的Top K案例,这些案例都只有排序功能,所以自己写了个案例. 这个案例分两个 ...
- 附加题-stack的理解
这次的附加题推荐的博客是http://www.ruanyifeng.com/blog/2013/11/stack.html阮一峰的,感觉讲的深入浅出,比较适合对计算机刚刚接触的人: 下面谈谈感想: 这 ...
- Light oj 1234 - Harmonic Number
题目链接:http://lightoj.com/volume_showproblem.php?problem=1234 给你一个数n,让你求 这个要是直接算的话肯定TLE,要是用1e8的数组预处理存储 ...
- POJ 3666 Making the Grade (DP)
题意:输入N, 然后输入N个数,求最小的改动这些数使之成非严格递增即可,要是非严格递减,反过来再求一下就可以了. 析:并不会做,知道是DP,但就是不会,菜....d[i][j]表示前 i 个数中,最大 ...
- jquery validation ajax 验证
<link href="${base}/res/basic/css/jquery/validationEngine/validationEngine.jquery.css" ...
- 【Java】IO流简单分辨
转载请注明原文地址:http://www.cnblogs.com/ygj0930/p/5827509.html Java的IO流体系十分庞大,并且体系层次稍复杂,很容易记混或记错.在此,我把平时经常用 ...
- 求一列的和,awk和perl哪个快?
下午和群里的朋友争论了一下,有关awk和perl处理文本的速度,自己一直比较推崇perl,对awk知之甚少,结果就想当然的觉得perl快,结果一番争吵后,觉得还是实验一下靠谱,(其实是想证明一下per ...
- 在VB中使用Linq To SQLite注意事项
昨天使Linq To SQLite 支持VB,今天在VB中写了几条Linq语句,发现了几个问题: 1.在Linq To SQLite中的Linq语句查询后并不是得到的匿名数据类,而是将Linq转换为S ...