查询表占用的空间大小

1.查询分配给一个表的空间大小

使用视图user_segments查询:

SQL> select segment_name,sum(bytes/1024) kb from user_segments where segment_name=upper('emp') group by segment_name;

SEGMENT_NAME

--------------------------------------------------------------------------------

        KB

----------

EMP

        64

使用视图user_extents查询：

SQL> select segment_name,sum(bytes/1024) kb from user_extents where segment_name=upper('emp') group by segment_name;

SEGMENT_NAME

--------------------------------------------------------------------------------

        KB

----------

EMP

        64

2.查询表实际使用的空间：

SQL> analyze table emp compute statistics;

Table analyzed.

SQL> select num_rows*avg_row_len from user_tables where table_name='EMP';

NUM_ROWS*AVG_ROW_LEN

--------------------

                 585

SQL> select segment_name,sum(bytes)/1024 KB from user_segments

  2  where segment_name='EMP' group by segment_name;

SEGMENT_NAME

--------------------------------------------------------------------------------

        KB

----------

EMP

        64