/*+ FULL(TABLE)*/
表明对表选择全局扫描的方法.
SELECT /*+FULL(A)*/ EMP_NO,EMP_NAM FROM BSEMPMS A WHERE EMP_NO='SCOTT';
2、/*+ INDEX(TABLE INDEX_NAME) */
表明对表选择索引的扫描方法.
SELECT /*+INDEX(BSEMPMS SEX_INDEX) */ * FROM BSEMPMS WHERE SEX='M';
5、/*+ INDEX_ASC(TABLE INDEX_NAME)*/
表明对表选择索引升序的扫描方法.
SELECT /*+INDEX_ASC(BSEMPMS PK_BSEMPMS) */ * FROM BSEMPMS WHERE DPT_NO='SCOTT';
6、/*+ INDEX_COMBINE*/
为指定表选择位图访问路经,如果INDEX_COMBINE中没有提供作为参数的索引,将选择出位图索引的布尔组合方式.
SELECT /*+INDEX_COMBINE(BSEMPMS SAL_BMI HIREDATE_BMI) */ * FROM BSEMPMS
WHERE SAL<5000000 AND HIREDATE
7、/*+ INDEX_JOIN(TABLE INDEX_NAME1 INDEX_NAME2) */
当谓词中引用的列都有索引的时候，可以通过指定采用索引关联的方式，来访问数据
select /*+ index_join(t t_ind t_bm) */ id from t where id=100 and object_name='EMPLOYEES'
8、/*+ INDEX_DESC(TABLE INDEX_NAME)*/
表明对表选择索引降序的扫描方法.
SELECT /*+INDEX_DESC(BSEMPMS PK_BSEMPMS) */ * FROM BSEMPMS WHERE DPT_NO='SCOTT';
9、/*+ INDEX_FFS(TABLE INDEX_NAME) */
对指定的表执行快速全索引扫描,而不是全表扫描的办法.
SELECT /* + INDEX_FFS(BSEMPMS IN_EMPNAM)*/ * FROM BSEMPMS WHERE DPT_NO='TEC305';
10、/*+ INDEX_SS(T T_IND) */
从9i开始，oracle引入了这种索引访问方式。当在一个联合索引中，某些谓词条件并不在联合索引的第一列时，可以通过Index Skip Scan来访问索引获得数据。当联合索引第一列的唯一值个数很少时，使用这种方式比全表扫描效率高。
SQL> create table t as select 1 id,object_name from dba_objects;
Table created.
SQL> insert into t select 2,object_name from dba_objects;
50366 rows created.
SQL> insert into t select 3,object_name from dba_objects;
50366 rows created.
SQL> insert into t select 4,object_name from dba_objects;
50366 rows created.
SQL> commit;
Commit complete.
SQL> create index t_ind on t(id,object_name);
Index created.
SQL> exec dbms_stats.gather_table_stats('HR','T',cascade=>true);
PL/SQL procedure successfully completed.
执行全表扫描
SQL> select /*+ full(t) */ * from t where object_name='EMPLOYEES';
6 rows selected.
Execution Plan
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 5 | 135 | 215 (3)| 00:00:03 |
|* 1 | TABLE ACCESS FULL| T | 5 | 135 | 215 (3)| 00:00:03 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("OBJECT_NAME"='EMPLOYEES')
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
942 consistent gets
0 physical reads
0 redo size
538 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
6 rows processed
不采用hint
SQL> select * from t where object_name='EMPLOYEES';
6 rows selected.
Execution Plan
----------------------------------------------------------
Plan hash value: 2869677071
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 5 | 135 | 5 (0)| 00:00:01 |
|* 1 | INDEX SKIP SCAN | T_IND | 5 | 135 | 5 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
-----------------------------------------------