使用OUTLINE调整执行计划

使用OUTLINE调整执行计划

1.测试SQL：

VAR PVNUMBER;
EXEC:PV:=1456;
selectcount(1) from t where object_id= :PV;

ExecutionPlan
----------------------------------------------------------
   0     SELECT STATEMENT Optimizer=CHOOSE
   1   0   SORT (AGGREGATE)
   2   1     INDEX (RANGE SCAN) OF'IDX_OBJECT_ID' (NON-UNIQUE)

Statistics
----------------------------------------------------------
          0 recursive calls
          0 db block gets
          3 consistent gets
          0 physical reads
          0 redo size
        517 bytes sent via SQL*Net to client
        655 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
          1 rows processed

2.创建要交换执行计划的OUTLN

创建两个outln：10g创建outln方法，可以参考：
HOWTO: Create a Stored Outline Based Upon an Existing Cursor [ID 445126.1]
 
一个用户需要使用OUTLN,需要有如下权限：
create session,create table,create procedure,create any outline,以及alter session
 
SQL>conn / as sysdba
Connected.
grantcreate any outline to scott;
grantalter session to scott;
grantexecute on dbms_outln to scott;
grantexecute on dbms_outln_edit to scott;

SQL>select name from dba_outlines;
no rowsselected
SCOTT用户创建outln：
 
create orreplace outline OL1
forcategory demo on
selectcount(1) from t where object_id= :PV;
 
create orreplace outline OL2
forcategory demo on
select/*+full(t)*/ count(1) from t where object_id= :PV;
Outlinecreated.
 
SQL>create private outline OLFROM from OL1;
createprivate outline OLFROM from OL1
*
ERROR atline 1:
ORA-18009:one or more outline system tables do not exist
 
# 调用如下过程，在scott用户下创建private outln使用的表
SQL>execute dbms_outln_edit.create_edit_tables;

PL/SQLprocedure successfully completed.
 
SQL>create private outline OLFROM from OL1;
Outlinecreated.
 
SQL>create private outline OLTO FROM OL2;
Outlinecreated.

3.调整outline使用的执行计划

SQL> update ol$ set hintcount=(select hintcount from ol$ where ol_name='OLTO') where ol_name='OLFROM';

1 row updated.

SQL> delete from ol$ where ol_name='OLTO';

1 row deleted.

SQL> update ol$ set ol_name='OLTO' where ol_name='OLFROM';

1 row updated.

SQL> commit;

Commit complete.
 
SQL> execute dbms_outln_edit.refresh_private_outline('OLTO');
 

4.测试private OUTLN

SQL> altersession set use_private_outlines=true;
SQL>alter session set use_stored_outlines=demo;
Sessionaltered.
 
SQL>select count(1) from t where object_id= :PV;
ExecutionPlan
----------------------------------------------------------
   0     SELECT STATEMENT Optimizer=CHOOSE (Cost=1120 Card=1 Bytes=13
          )

   1   0   SORT (AGGREGATE)
   2   1     TABLE ACCESS (FULL) OF 'T'(Cost=1120 Card=9495 Bytes=12
          3435)

Statistics
----------------------------------------------------------
          0 recursive calls
          0 db block gets
      11636 consistent gets
       9795 physical reads
          0 redo size
        519 bytes sent via SQL*Net to client
        655 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
1   rowsprocessed

5.发布private outline

create orreplace outline OL1 from private OLTO for category demo;

6.测试public outline

SQL>alter session set use_stored_outlines=demo;
SQL>select count(1) from t where object_id= :PV;
 
ExecutionPlan
----------------------------------------------------------
   0     SELECT STATEMENT Optimizer=CHOOSE (Cost=1120 Card=1 Bytes=13
          )
   1   0   SORT (AGGREGATE)
   2   1     TABLE ACCESS (FULL) OF 'T'(Cost=1120 Card=9495 Bytes=12
          3435)
Statistics
----------------------------------------------------------
          6 recursive calls
          4 db block gets
     11637  consistent gets
       9595 physical reads
        628 redo size
        519 bytes sent via SQL*Net to client
        655 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
          1 rows processed

SQL>alter session set use_stored_outlines=;

Session altered.
SQL>select count(1) from t where object_id= :PV;
 
ExecutionPlan
----------------------------------------------------------
   0     SELECT STATEMENT Optimizer=CHOOSE
   1   0   SORT (AGGREGATE)
   2   1     INDEX (RANGE SCAN) OF'IDX_OBJECT_ID' (NON-UNIQUE)

Statistics
----------------------------------------------------------
          0 recursive calls
          0 db block gets
          3 consistent gets
          0 physical reads
          0 redo size
        519 bytes sent via SQL*Net to client
        655 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
1   rowsprocessed

7.系统级发布

altersystem set use_stored_outlines=demo;

参考metalink：
Howto Edit a Stored Outline to Use the Plan from Another Stored Outline [ID730062.1]