truncate导致data_object_id改变

oracle中一般情况下表的OBJECT_ID与DATA_OBJECT_ID是一致的。

但在truncate后表达DATA_OBJECT_ID会发生改变。利用这一特性可以判断表是否发生过truncate操作。

注：(DATABASE LINK,FUNCTION,PROCEDURE,SEQUENCE,VIEW)没有DATA_OBJECT_ID。

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0

Connected as report

SQL> SELECT t.table_name, t.last_analyzed, t.num_rows
  2    FROM USER_TABLES t
  3   WHERE t.table_name = 'T2';

TABLE_NAME LAST_ANALYZED       NUM_ROWS
---------- --------------------------          ----------
T2         2011-04-04 16:56:17                    3

--T2的 OBJECT_ID  与DATA_OBJECT_ID相同

SQL> SELECT object_name, object_type, object_id, data_object_id
  2    FROM USER_OBJECTS
  3   WHERE object_name = 'T2';

OBJECT_NAM OBJECT_TYPE          OBJECT_ID  DATA_OBJECT_ID
---------- -------------------                ----------         -----------------------
T2           TABLE                              75567                             75567

SQL> truncate table T2;
Table truncated

SQL>  analyze table t2 compute statistics;
Table analyzed

-- 对表T2进行truncate后OBJECT_ID未发生改变，而DATA_OBJECT_ID由 75567 变为 76592

SQL> SELECT object_name, object_type, object_id, data_object_id
  2    FROM USER_OBJECTS
  3   WHERE object_name = 'T2';
OBJECT_NAM OBJECT_TYPE          OBJECT_ID       DATA_OBJECT_ID
----------         -------------------        ----------           --------------
T2                  TABLE                         75567             76592

SQL>

from: