11g中物件細粒度管理一例

 

11g中oracle提供了細粒度的物件管理。如：檢視所依賴的表若發生結構變化，在10g及以前版本中會導致檢視失效，而在11g中，若結構變化未影響檢視，則檢視仍然有效。

在11g中：

SQL> drop table t;

Table dropped

SQL> create table t as select * from emp;

Table created

SQL> create view v_t as select ename,deptno from t;

View created

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

SQL> alter table t add a varchar2(2);

Table altered

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

 

在10g中：

SQL> drop table t;

Table dropped

SQL> create table t as select * from emp;

Table created

SQL> create view v_t as select ename,deptno from t;

View created

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

SQL> alter table t add a varchar2(2);

Table altered

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
INVALID

 

若檢視是select * from table得到的，即使將檢視對應的表增加列，檢視也不會失效。

SQL> create view v_t2 as select * from t;

View created

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

SQL> alter table t add b varchar2(2);

Table altered

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

刪除一列，檢視依然無動於衷：

SQL> alter table t drop column a;

Table altered

SQL> select status from dba_objects where object_name='V_T';

STATUS
-------
VALID

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