|
------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("EMPNO"=200)
2- Using SQL Profile
--------------------
Plan hash value: 2008370210
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 39 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| T2 | 1 | 39 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_T2 | 1 | | 1 (0)| 00:00:01 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("EMPNO"=200)
-------------------------------------------------------------------------------
我们可以看到他提供的建议，执行sql_profile，我们根据他的建议执行这个profile
execute dbms_sqltune.accept_sql_profile(task_name => 'test01',task_owner=> 'SCOTT',replace => TRUE);
然后我们再来执行下原来的带hint的语句
select /*+ full(t2) */ * from t2 where empno=200;
13:39:32 scott@orcl> select /*+ full(t2) */ * from t2 where empno=200;
Elapsed: 00:00:00.01
Execution Plan
----------------------------------------------------------
Plan hash value: 2008370210
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 39 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| T2 | 1 | 39 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_T2 | 1 | | 1 (0)| 00:00:01 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("EMPNO"=200)
Note
-----
- SQL profile "SYS_SQLPROF_014a6b5a4a4a0000" used for this statement
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
1092 bytes sent via SQL*Net to client
520 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
可以看到使用了sql_profile 从而走了正确的执行计划
现在我们再来看看其他的情况，我们原来的表上没有索引，看看tune advisor能提供什么样的建议
13:42:44 scott@orcl> select * from t4 where empno=200;
Elapsed: 00:00:00.04
Execution Plan
----------------------------------------------------------
Plan hash value: 2560505625
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 100 | 15 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T4 | 1 | 100 | 15 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("EMPNO"=200)
Note
-----
- dynamic sampling used for this statement (level=2)
|