Oracle SQL Profile固定執行計劃的方法

SQL> select * from v$version;

 

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

PL/SQL Release 11.2.0.4.0 - Production

CORE 11.2.0.4.0 Production

TNS for Linux: Version 11.2.0.4.0 - Production

NLSRTL Version 11.2.0.4.0 - Production

 

SQL> create table table_gl as select * from dba_objects;

 

Table created

 

SQL> create index idx_gl on table_gl(object_id);

 

Index created

手動蒐集統計資訊，以免執行計劃不準確

 

SQL> EXEC DBMS_STATS.gather_table_stats(user,'table_gl',CASCADE=>TRUE);

 

PL/SQL procedure successfully completed

然後執行SET AUTO TRACE EXP

檢視出執行計劃，發現走的索引查詢

SQL> EXPLAIN PLAN FOR SELECT OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100;

 

Explained

 

SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY); 

 

PLAN_TABLE_OUTPUT

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

Plan hash value: 358855602

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

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

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

|   0 | SELECT STATEMENT            |          |     1 |    30 |     2   (0)| 00

|   1 |  TABLE ACCESS BY INDEX ROWID| TABLE_GL |     1 |    30 |     2   (0)| 00

|*  2 |   INDEX RANGE SCAN          | IDX_GL   |     1 |       |     1   (0)| 00

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

Predicate Information (identified by operation id):

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

   2 - access("OBJECT_ID"=100)

 

14 rows selected

使用hint引數強制該表走全表掃描

SQL> EXPLAIN PLAN FOR SELECT /*+ FULL(table_gl)*/OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100;

 

Explained

 

SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);

 

PLAN_TABLE_OUTPUT

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

Plan hash value: 3610250390

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

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

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

|   0 | SELECT STATEMENT  |          |     1 |    30 |   294   (1)| 00:00:04 |

|*  1 |  TABLE ACCESS FULL| TABLE_GL |     1 |    30 |   294   (1)| 00:00:04 |

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

Predicate Information (identified by operation id):

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

   1 - filter("OBJECT_ID"=100)

 

13 rows selected

把以下SQL拿到其他視窗執行

SELECT /*+ FULL(table_gl)*/OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100;

然後檢視該SQL的SQL_ID

SQL> SELECT SQL_ID,SQL_TEXT FROM V$SQL WHERE SQL_TEXT LIKE '%/*+ FULL(table_gl)*/%';

 

SQL_ID        SQL_TEXT

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

c073nzyv9h0s3  EXPLAIN PLAN FOR SELECT /*+ FULL(table_gl)*/OBJECT_NAME FROM table_gl WHERE OBJ

2qvpsar7w0k85  SELECT SQL_ID,SQL_TEXT FROM V$SQL WHERE SQL_TEXT LIKE '%/*+ FULL(table_gl)*/%'

chwqmxqgyqqpg SELECT /*+ FULL(table_gl)*/OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100

獲得對應Outline

SQL> select * from table(dbms_xplan.display_cursor('chwqmxqgyqqpg',null,'outline'));

 

PLAN_TABLE_OUTPUT

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

SQL_ID  chwqmxqgyqqpg, child number 0

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

SELECT /*+ FULL(table_gl)*/OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100

Plan hash value: 3610250390

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

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

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

|   0 | SELECT STATEMENT  |          |       |       |   294 (100)|          |

|*  1 |  TABLE ACCESS FULL| TABLE_GL |     1 |    30 |   294   (1)| 00:00:04 |

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

Outline Data

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

  /*+

      BEGIN_OUTLINE_DATA

      IGNORE_OPTIM_EMBEDDED_HINTS

      OPTIMIZER_FEATURES_ENABLE('11.2.0.4')

 

PLAN_TABLE_OUTPUT

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

      DB_VERSION('11.2.0.4')

      ALL_ROWS

      OUTLINE_LEAF(@"SEL$1")

      FULL(@"SEL$1" "TABLE_GL"@"SEL$1")

      END_OUTLINE_DATA

  */

Predicate Information (identified by operation id):

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

   1 - filter("OBJECT_ID"=100)

 

32 rows selected

可以另找視窗執行，建立sql profile

declare

 v_hints sys.sqlprof_attr;

 begin

 v_hints:=sys.sqlprof_attr(

      'BEGIN_OUTLINE_DATA',

      'IGNORE_OPTIM_EMBEDDED_HINTS',

      'OPTIMIZER_FEATURES_ENABLE(''11.2.0.4'')',

      'DB_VERSION(''11.2.0.4'')',

      'ALL_ROWS',

      'OUTLINE_LEAF(@"SEL$1")',

      'FULL(@"SEL$1" "TABLE_GL"@"SEL$1")',   --這個是由於hint產生,其實我們需要的就是這個

      'END_OUTLINE_DATA');

dbms_sqltune.import_sql_profile(

'SELECT OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100',

v_hints,'SQLPROFILE_gl',                 --sql profile 名稱

force_match=>true,replace=>true);

end;

/

驗證sql profile結果，發現即使不加hint引數，執行計劃也是全表掃描

SQL> EXPLAIN PLAN FOR SELECT OBJECT_NAME FROM table_gl WHERE OBJECT_ID=100;

 

Explained

 

SQL> 

SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);

 

PLAN_TABLE_OUTPUT

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

Plan hash value: 3610250390

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

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

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

|   0 | SELECT STATEMENT  |          |     1 |    30 |   294   (1)| 00:00:04 |

|*  1 |  TABLE ACCESS FULL| TABLE_GL |     1 |    30 |   294   (1)| 00:00:04 |

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

Predicate Information (identified by operation id):

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

   1 - filter("OBJECT_ID"=100)

Note

-----

   - SQL profile "SQLPROFILE_gl" used for this statement

 

17 rows selected