1.
alter session set skip_unusable_indexes=true;
[url]http://www.seeitco.com/doc/Html/DataBasc/105625986.html[/url]
2. 请问如何恢复unusable的索引
[url]http://www.itpub.net/395459[/url],1.html 
2.1
SQL> create table test as select * from all_objects;
 
Table created.
 
SQL> create index t_owner_ind on test(owner);
 
Index created.
 
SQL> alter index t_owner_ind unusable;
 
Index altered.
 
SQL> drop index t_owner_ind;
 
Index dropped.
 
SQL>
2.2
SQL> create table test as select * from sys.dba_objects;
 
Table created.
 
SQL> alter table test add constraint unique_id unique(object_id);
 
Table altered.
 
SQL> select index_name from user_indexes where lowercase(table_name)='test';
select index_name from user_indexes where lowercase(table_name)='test'
*
ERROR at line 1:
ORA-00904: "LOWERCASE": invalid identifier
 
 
SQL> select index_name from user_indexes where lower(table_name)='test';
 
INDEX_NAME
------------------------------
UNIQUE_ID
 
SQL> select segment_name from user_segments;
 
SEGMENT_NAME
--------------------------------------------------------------------------------
UNIQUE_ID
TEST_CON
TEST
SALGRADE
BONUS
PK_EMP
EMP
PK_DEPT
DEPT
 
9 rows selected.
 
SQL> alter table test drop constraint unique_id;
 
Table altered.
 
SQL> select index_name from user_indexes where lower(table_name)='test';
 
no rows selected
 
SQL> select segment_name from user_segments;
 
SEGMENT_NAME
--------------------------------------------------------------------------------
TEST_CON
TEST
SALGRADE
BONUS
PK_EMP
EMP
PK_DEPT
DEPT
 
8 rows selected.
 
SQL>
 
不存在unique_id segment．

3. skip_unusable_indexes使用的几点补充- -

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4. ORA-01502 state unusable错误成因和解决方法(二)
[url]http://www.cndw.com/tech/data/2006051167352.asp[/url]
5. SKIP_UNUSABLE_INDEXES 的使用与索引实效解决方法
[url]http://blog.chinaunix.net/u/7121/showart_270366.html[/url]