前言

对于开发或者运维人员来说，Mysql数据库每张表的数量肯定是要了解下，有助于我们清理无用数据或者了解哪张表比较占用空间。
另外多次统计表的行数，还能发现Mysql表的增量情况，能够预测表未来会有多大的量。
废话不多说，直接带大家写一个简单的Shell小脚本

循环获取数据库名

直接上Shell代码，show databases获取所有的库名。结果有一个我们不想要的，就是Database，这个grep -v掉，轻松获取所有数据库

[root@shijiangeit ~]# mysql -h 127.0.0.1 -uxxx -pxxx -e "show databases;" 2>/dev/null
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| shijiange          |
| test               |
| wordpress          |
+--------------------+

[root@shijiangeit ~]# mysql -h 127.0.0.1 -uxxx -pxxx -e "show databases;" 2>/dev/null |grep -v Database
information_schema
mysql
performance_schema
shijiange
test
wordpress

循环获取所有表

有了库信息，获取所有表就简单了，直接上Shell代码。show tables获取所有表名，其中Tables_in不需要，grep -v掉。

[root@shijiangeit ~]# for onedb in $(mysql -h 127.0.0.1 -uxxx -pxxx -e "show databases;" 2>/dev/null |grep -v Database);do
>   echo $onedb
>   mysql -h 127.0.0.1 -uxxx -pxxx $onedb -e "show tables" 2>/dev/null
> done
information_schema
+---------------------------------------+
| Tables_in_information_schema          |
+---------------------------------------+
| CHARACTER_SETS                        |
| COLLATIONS                            |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS                               |
| COLUMN_PRIVILEGES                     |
| ENGINES                               |
| EVENTS                                |
| FILES                                 |
| GLOBAL_STATUS                         |
| GLOBAL_VARIABLES                      |
| KEY_COLUMN_USAGE                      |

循环统计每张表的行数

取出库名加表名，一个select count(1)统计表的行数，循环统计，直接上Shell代码。

[root@shijiangeit ~]# for onedb in $(mysql -h 127.0.0.1 -uxxx -pxxx -e "show databases;" 2>/dev/null |grep -v Database);do
>   for onetab in $(mysql -h 127.0.0.1 -uxxx -pxxx $onedb -e "show tables" 2>/dev/null |grep -v 'Tables_in_');do
>     onetablength=$(mysql -h 127.0.0.1 -uxxx -pxxx $onedb -e "select count(1) from $onetab" 2>/dev/null |grep -v 'count')
>     echo -e "$onedb.$onetab\t$onetablength"
>   done
> done
information_schema.CHARACTER_SETS   40
information_schema.COLLATIONS   219
information_schema.COLLATION_CHARACTER_SET_APPLICABILITY    219
information_schema.COLUMNS  1789
information_schema.COLUMN_PRIVILEGES    0
shijiange.logincount    4
shijiange.member    0
shijiange.user  2097153
test.detect_servers 0
wordpress.wp_commentmeta    0
wordpress.wp_comments   0
wordpress.wp_links  0
wordpress.wp_options    156

变量化，脚本直接用

需要统计哪个Mysql，前面三个变量一改，立马就能统计所有表的大小了。

mysqlhost=127.0.0.1
mysqluser=xxx
mysqlpassword=xxx

for onedb in $(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword -e "show databases;" 2>/dev/null |grep -v Database);do
  for onetab in $(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword $onedb -e "show tables" 2>/dev/null |grep -v 'Tables_in_');do
    onetablength=$(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword $onedb -e "select count(1) from $onetab" 2>/dev/null |grep -v 'count')
    echo -e "$onedb.$onetab\t$onetablength"
  done
done

想看哪张表的行数最多？

之前的脚本加个 |sort -nrk 2|less 搞定，超实用的小脚本就这样完成了

[root@shijiangeit ~]# for onedb in $(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword -e "show databases;" 2>/dev/null |grep -v Database);do
>   for onetab in $(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword $onedb -e "show tables" 2>/dev/null |grep -v 'Tables_in_');do
>     onetablength=$(mysql -h $mysqlhost -u$mysqluser -p$mysqlpassword $onedb -e "select count(1) from $onetab" 2>/dev/null |grep -v 'count')
>     echo -e "$onedb.$onetab\t$onetablength"
>   done
> done | sort -nrk 2
shijiange.user  2097153
information_schema.INNODB_BUFFER_PAGE   8191
performance_schema.events_waits_summary_by_thread_by_event_name 5320
information_schema.INNODB_BUFFER_PAGE_LRU   3453