面试官：MySQL怎么查看表占用空间大小

前言

在mysql中有一个默认的数据表information_schema，information_schema这张数据表保存了MySQL服务器所有数据库的信息。如数据库名，数据库的表，表栏的数据类型与访问权限等。

再简单点，这台MySQL服务器上，到底有哪些数据库、各个数据库有哪些表，每张表的字段类型是什么，各个数据库要什么权限才能访问，等等信息都保存在information_schema表里面，所以请勿删改此表。整理了一份328页MySQLPDF文档

代码

1，切换数据库

use information_schema;

2，查看数据库使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ ;

3，查看表使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ and table_name=’Table_Name’;

网上找的一个，亲测可用:

• 先进去MySQL自带管理库：information_schema

• 然后查询 data_length,index_length

• 你自己的数据库名：dbname

• 你自己的表名：tablename

  mysql> use information_schema;Database changedmysql> select data_length,index_length-> from tables where-> table_schema=\'dbname\'-> and table_name = \'tablename\';+-------------+--------------+| data_length | index_length |+-------------+--------------+| 166379520 | 235782144 |+-------------+--------------+row in set (0.02 sec)

  mysql> select concat(round(sum(data_length/1024/1024),2),\'MB\') as data_length_MB,-> concat(round(sum(index_length/1024/1024),2),\'MB\') as index_length_MB-> from tables where-> table_schema=\'dbname\'-> and table_name = \'tablename\';+----------------+-----------------+| data_length_MB | index_length_MB |+----------------+-----------------+| 158.67MB | 224.86MB |+----------------+-----------------+row in set (0.03 sec)

  1.查看所有数据库容量大小

selecttable_schema as \'数据库\',sum(table_rows) as \'记录数\',sum(truncate(data_length/1024/1024, 2)) as \'数据容量(MB)\',sum(truncate(index_length/1024/1024, 2)) as \'索引容量(MB)\'from information_schema.tablesgroup by table_schemaorder by sum(data_length) desc, sum(index_length) desc;

2.查看所有数据库各表容量大小

selecttable_schema as \'数据库\',table_name as \'表名\',table_rows as \'记录数\',truncate(data_length/1024/1024, 2) as \'数据容量(MB)\',truncate(index_length/1024/1024, 2) as \'索引容量(MB)\'from information_schema.tablesorder by data_length desc, index_length desc;

3.查看指定数据库容量大小

例：查看mysql库容量大小

selecttable_schema as \'数据库\',sum(table_rows) as \'记录数\',sum(truncate(data_length/1024/1024, 2)) as \'数据容量(MB)\',sum(truncate(index_length/1024/1024, 2)) as \'索引容量(MB)\'from information_schema.tableswhere table_schema=\'mysql\';

4.查看指定数据库各表容量大小

例：查看mysql库各表容量大小

selecttable_schema as \'数据库\',table_name as \'表名\',table_rows as \'记录数\',truncate(data_length/1024/1024, 2) as \'数据容量(MB)\',truncate(index_length/1024/1024, 2) as \'索引容量(MB)\'from information_schema.tableswhere table_schema=\'mysql\'order by data_length desc, index_length desc;select concat(round(sum(data_length/1024/1024),2),\'MB\') as data_length_MB, concat(round(sum(index_length/1024/1024),2),\'MB\') as index_length_MBfrom tableswhere table_schema=\'passport\' and table_name=\'tb_user_info\';

— 569.98MB 141.98MB

select concat(round(sum(data_length/1024/1024),2),\'MB\') as data_length_MB, concat(round(sum(index_length/1024/1024),2),\'MB\') as index_length_MBfrom tableswhere table_schema=\'passport_v2\' and table_name=\'tb_user_info\';

— 2128.94MB 285.00MB 整理了一份328页MySQLPDF文档