查看用户的数据占用的空间大小

在导入导出时，我们需要估计某用户的数据占用的空间大小，使用如下sql语句可以解决这个问题

SQL> select sum(bytes)/1024/1024 as sizeM from user_segments;

     SIZEM                                                                     
----------                                                                     
     .8125                                                                     

SQL> conn system/yang as sysdba
已连接。
SQL> select owner,sum(bytes)/1024/1024 sizeM
  2  FROM DBA_SEGMENTS
  3  WHERE OWNER IN ('SYSTEM','SCOTT')
  4  GROUP BY OWNER ORDER BY 2 DESC;

OWNER                               SIZEM                                      
------------------------------ ----------                                      
SYSTEM                            24.1875                                      
SCOTT                               .8125