oracle spm使用1

oracle11g new feature SPM

有助于保持sql的语句特性，仅仅同意运行性能提高的运行计划。

它不同于stored outlines， spm在于稳定sql性能，而store outlines在于冻结sql运行计划





事列

1.启用optimizer_cature_sql_plan_baselines 捕获sql语句

SQL> alter session set optimizer_capture_sql_plan_baselines = true;

Session altered.

SQL> select * from objs where object_id = 2;

no rows selected

SQL> select * from objs where object_id = 2;

no rows selected

SQL> alter session set optimizer_capture_sql_plan_baselines = false;

Session altered.

2.查询dba_sql_plan_baselines，确定sql的spm状态

SQL> select plan_name, sql_handle, enabled, accepted, fixed,

  2             module, sql_text

  3  from dba_sql_plan_baselines;

PLAN_NAME                      SQL_HANDLE           ENABLED   ACCEPTED  FIXED     MODULE               SQL_TEXT

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

SQL_PLAN_4pzq3z6xcqkpwd0984253 SQL_4afec3f9bacb4abc YES       YES       NO        SQL*Plus             select * from objs where object_id = 2

3.添加索引改变环境再执行sql

SQL> alter session set optimizer_capture_sql_plan_baselines = true;

Session altered.

SQL> select * from objs where object_id = 2;

no rows selected

SQL> select * from objs where object_id = 2;

no rows selected

SQL> alter session set optimizer_capture_sql_plan_baselines = false;

Session altered.

4.查询dba_sql_plan_baselines

SQL> select plan_name, sql_handle, enabled, accepted, fixed, module, sql_text from dba_sql_plan_baselines;

PLAN_NAME                      SQL_HANDLE           ENABLED   ACCEPTED  FIXED     MODULE               SQL_TEXT

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

SQL_PLAN_4pzq3z6xcqkpwbe4c314c SQL_4afec3f9bacb4abc YES       NO        NO        SQL*Plus             select * from objs where object_id = 2

SQL_PLAN_4pzq3z6xcqkpwd0984253 SQL_4afec3f9bacb4abc YES       YES       NO        SQL*Plus             select * from objs where object_id = 2

SQL>

5.測试

SQL>

SQL> set autotrace on

SQL> select * from objs where object_id = 2;

no rows selected

Execution Plan

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

Plan hash value: 954894094





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

| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |

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

|   0 | SELECT STATEMENT  |      |     1 |    98 |   247   (1)| 00:00:03 |

|*  1 |  TABLE ACCESS FULL| OBJS |     1 |    98 |   247   (1)| 00:00:03 |

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





Predicate Information (identified by operation id):

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





   1 - filter("OBJECT_ID"=2)





Note

-----

   - SQL plan baseline "SQL_PLAN_4pzq3z6xcqkpwd0984253" used for this statement









Statistics

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

        255  recursive calls

          0  db block gets

       1044  consistent gets

        879  physical reads

          0  redo size

       1343  bytes sent via SQL*Net to client

        513  bytes received via SQL*Net from client

          1  SQL*Net roundtrips to/from client

         28  sorts (memory)

          0  sorts (disk)

          0  rows processed





SQL> alter session set optimizer_use_sql_plan_baselines = false;

Session altered.

SQL> select * from objs where object_id = 2;

no rows selected

Execution Plan

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

Plan hash value: 613004408





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

| Id  | Operation                   | Name            | Rows  | Bytes | Cost (%CPU)| Time     |

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

|   0 | SELECT STATEMENT            |                 |     1 |    98 |     2   (0)| 00:00:01 |

|   1 |  TABLE ACCESS BY INDEX ROWID| OBJS            |     1 |    98 |     2   (0)| 00:00:01 |

|*  2 |   INDEX RANGE SCAN          | IDX_OBJSID_OBJS |     1 |       |     1   (0)| 00:00:01 |

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





Predicate Information (identified by operation id):

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





   2 - access("OBJECT_ID"=2)









Statistics

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

          1  recursive calls

          0  db block gets

          2  consistent gets

          4  physical reads

          0  redo size

       1343  bytes sent via SQL*Net to client

        513  bytes received via SQL*Net from client

          1  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

          0  rows processed

能够看到当启动optimizer_user_sql_plan_baselines时走索引应该是最优的却没有使用

plan_name accecpt 为 no 影响了走索引计划