object_id与data_object_id的关系

object_id 是逻辑对象ID

data_object_id 是物理对象ID

SQL> create table test as select rownum rn from dba_objects;

Table created.

SQL> select object_id,data_object_id from dba_objects where object_name='TEST' AITPUB个人空间$p.SW@u5]N!L3IN
ND WNER='SYS';

 OBJECT_ID DATA_OBJECT_IDITPUB个人空间mz/T(S$W
---------- --------------ITPUB个人空间.i5x @rV Gw
      6680           6680

SQL> select header_file,header_block,blocks from dba_segments where segment_name
(MJL/D7Vp O;r0='TEST' and WNER='SYS';

HEADER_FILE HEADER_BLOCK     BLOCKS
C|g@_1fDrBM)T&u0----------- ------------ ----------
#|(i4p;GKpK0          1        42921         16

SQL> alter table test move;

Table altered.

SQL> select object_id,data_object_id from dba_objects where object_name='TEST' AITPUB个人空间c"Xc3q-h~
ND WNER='SYS';

 OBJECT_ID DATA_OBJECT_ID
k(VQdBo.eH0---------- --------------ITPUB个人空间yY\5krOWoN%x
      6680           6681

表经过move后，物理ID发生变化

SQL> select header_file,header_block,blocks from dba_segments where segment_nameITPUB个人空间iJQV3\Ejzh]5T
='TEST' and WNER='SYS';

HEADER_FILE HEADER_BLOCK     BLOCKSITPUB个人空间.W5zR)g
W4kt
----------- ------------ ----------ITPUB个人空间 hc8P``&o;y{^;m
          1        43105         16

SQL> truncate table test;

Table truncated.

SQL> select header_file,header_block,blocks from dba_segments where segment_name
i?;I0aQ5j];?#V@/w)b0='TEST' and WNER='SYS';

HEADER_FILE HEADER_BLOCK     BLOCKSITPUB个人空间!I{$Q'FRjD
----------- ------------ ----------
&_s!D2^A%`;E0          1        43105          8

SQL> select object_id,data_object_id from dba_objects where object_name='TEST' A
'v,rZ.H l!`y0ND WNER='SYS';

 OBJECT_ID DATA_OBJECT_IDITPUB个人空间.L3Vo7_!z$K
---------- --------------ITPUB个人空间0kb7K7{5p6Qer
      6680           6682

表经过truncate 后 物理ID也发生变化

SQL> alter table test add(n number);

Table altered.

SQL> select object_id,data_object_id from dba_objects where object_name='TEST' A
ikr7W;D _Q&F\Z|0ND WNER='SYS';

 OBJECT_ID DATA_OBJECT_IDITPUB个人空间5X@3G5TH7XE*MVBy
---------- --------------
TfO[/a\0      6680           6682

给表增加一个列，也没发生变化

所以总上所简述

只有当segment发生变化时data_object_id才发生变化

有时候我们根据rowid 算时得到的data_object_id会误以为就是object_id,因为要是没有发生segment变化时

两者值是相等的