mysql查看索引大小和重建索引

查看索引大小：

use information_schema;
select 
  concat(round(sum(index_LENGTH)/(1024*1024),2),'MB') as 'Index Size(MB)',
  index_LENGTH as 'Index Size(Bytes)' 
from tables 
where table_schema='my_db' and table_name='table_name';

重建索引(MyISAM下面语句有效;innodb下面语句无效，需要先删除索引，然后重建)：

use my_db;
REPAIR TABLE table_name QUICK;