set unused column和视图，约束，同义词和索引的关系

当使用alter table set unused column语法之后，会对其相关联的视图，约束，同义词和索引有什么作用么？

答案是：

视图和同义词会失效，其中同义词再次引用即可重新编译，但是视图重新编译会报错；

约束和索引会被自动删除。

实验：

SQL> create table test as select * from dba_objects;

Table created.

SQL> create view testview as select * from test;

View created.

SQL> alter table test add constraint testc check(object_id<999999);

Table altered.

SQL> create index testidx on test(object_id);

Index created.

SQL> create synonym testsyn for test;

Synonym created.

SQL> select CONSTRAINT_NAME,status from user_constraints

2 where CONSTRAINT_NAME in ('TESTC');

CONSTRAINT_NAME STATUS

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

TESTC ENABLED

SQL> select OBJECT_NAME,status from user_objects

2 where OBJECT_NAME in ('TESTVIEW','TESTIDX','TESTSYN');

OBJECT_NAME STATUS

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

TESTIDX VALID

TESTSYN VALID

TESTVIEW VALID

SQL> alter table test set unused (object_id);

Table altered.

SQL> select CONSTRAINT_NAME,status from user_constraints

2 where CONSTRAINT_NAME in ('TESTC');

no rows selected

SQL> select OBJECT_NAME,status from user_objects

2 where OBJECT_NAME in ('TESTVIEW','TESTIDX','TESTSYN');

OBJECT_NAME STATUS

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

TESTSYN INVALID

TESTVIEW INVALID

SQL> select count(*) from TESTSYN;

COUNT(*)

----------

10069

SQL> select count(*) from TESTVIEW;

select count(*) from TESTVIEW

*

ERROR at line 1:

ORA-04063: view "HAO.TESTVIEW" has errors