使用SQL Profile及SQL Tuning Advisor固定运行计划

SQL Profile就是为某一SQL语句提供除了系统统计信息、对象（表和索引等）统计信息之外的其它信息，比方执行环境、额外的更准确的统计信息，以帮助优化器为SQL语句选择更适合的执行计划。

SQL Profiles可以说是Outlines的进化。Outlines可以实现的功能SQL Profiles也全然可以实现，而SQL Profiles具有Outlines不具备的优化，最重要的有二点：

    SQL Profiles更easy生成、更改和控制。

SQL Profiles在对SQL语句的支持上做得更好。也就是适用范围更广。

使用SQL Profiles两个目的：

    锁定或者说是稳定运行计划。

在不能改动应用中的SQL的情况下使SQL语句按指定的执行计划执行。

參考老熊的博客。链接：http://www.laoxiong.net/sql-profiles-partii.html    http://www.laoxiong.net/sql-profiles-part.html   http://blog.sina.com.cn/s/blog_5037eacb01011mgu.htm

1.实验环境构造语句：

create table bys.t1 as select * from dba_objects;

create index bys.t1_idx on t1(object_id);

exec dbms_stats.gather_table_stats('bys','t1',cascade=>true,degree=>4);

set autotrace trace;

select a.*,b.owner from t1 a,t1 b where a.object_name like '%T1%' and a.object_id=b.object_id;

select /*+ use_nl(a b) index(t2) */ a.*,b.owner from t1 a,t1 b where a.object_name like '%T1%' and a.object_id=b.object_id;

set autotrace off;

explain plan for select /*+ use_nl(a b) index(t2) */ a.*,b.owner from t1 a,t1 b where a.object_name like '%T1%' and a.object_id=b.object_id;

col sql_text for a100

SELECT SQL_ID,SQL_TEXT FROM V$SQL WHERE SQL_TEXT LIKE '%a.*,b.owner from t1 a,t1 b%';

####2t5xqt4d1dsaw

10g開始，v$sql_plan中就包含了SQL语句OUTLINE数据，也就是稳定运行计划的Hints。例如以下：

set pagesize 1000

SQL> select * from table(dbms_xplan.display_cursor('2t5xqt4d1dsaw',null,'outline'));

PLAN_TABLE_OUTPUT

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

SQL_ID  2t5xqt4d1dsaw, child number 0

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

select /*+ use_nl(a b) index(t2) */ a.*,b.owner from t1 a,t1 b where

a.object_name like '%T1%' and a.object_id=b.object_id

Plan hash value: 190596302

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

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

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

|   0 | SELECT STATEMENT            |        |       |       |   979 (100)|          |

|   1 |  TABLE ACCESS BY INDEX ROWID| T1     |     1 |     9 |     2   (0)| 00:00:01 |

|   2 |   NESTED LOOPS              |        |   471 | 43803 |   979   (1)| 00:00:12 |

|*  3 |    TABLE ACCESS FULL        | T1     |   471 | 39564 |    36   (0)| 00:00:01 |

|*  4 |    INDEX RANGE SCAN         | T1_IDX |     1 |       |     1   (0)| 00:00:01 |

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



Outline Data              ----------这一部分： /*+     */ 之间的就是所需的数据了

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

  /*+

      BEGIN_OUTLINE_DATA

      IGNORE_OPTIM_EMBEDDED_HINTS

      OPTIMIZER_FEATURES_ENABLE('10.2.0.1')

      ALL_ROWS

      OUTLINE_LEAF(@"SEL$1")

      FULL(@"SEL$1" "A"@"SEL$1")

      INDEX(@"SEL$1" "B"@"SEL$1" ("T1"."OBJECT_ID"))

      LEADING(@"SEL$1" "A"@"SEL$1" "B"@"SEL$1")

      USE_NL(@"SEL$1" "B"@"SEL$1")

      END_OUTLINE_DATA

  */



PLAN_TABLE_OUTPUT

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

Predicate Information (identified by operation id):

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

   3 - filter("A"."OBJECT_NAME" LIKE '%T1%')

   4 - access("A"."OBJECT_ID"="B"."OBJECT_ID")

###############################################################################

2.開始创建并应用SQL Profile

使用未加HINT的SQL语句，并指定SQL_PROFILE名字：SQLPROFILE_T1

注意事项：两个引號---如('10.2.0.1')要写成(''10.2.0.1'')--'%T1%'写成''%T1%''

SQL语句结尾的;不要写上,绑定变量值是'1'时，要输入''1''

 declare

 v_hints sys.sqlprof_attr;

 begin

 v_hints:=sys.sqlprof_attr(

      'BEGIN_OUTLINE_DATA',

      'IGNORE_OPTIM_EMBEDDED_HINTS',

      'OPTIMIZER_FEATURES_ENABLE(''10.2.0.1'')',

      'ALL_ROWS',

      'OUTLINE_LEAF(@"SEL$1")',

      'FULL(@"SEL$1" "A"@"SEL$1")',

      'INDEX(@"SEL$1" "B"@"SEL$1" ("T1"."OBJECT_ID"))',

      'LEADING(@"SEL$1" "A"@"SEL$1" "B"@"SEL$1")',

      'USE_NL(@"SEL$1" "B"@"SEL$1")',

      'END_OUTLINE_DATA');

dbms_sqltune.import_sql_profile(

'select a.*,b.owner from t1 a,t1 b where a.object_name like ''%T1%'' and a.object_id=b.object_id',

v_hints,'SQLPROFILE_T1',                

force_match=>true,replace=>true);

end;

/

删除语句：

exec dbms_sqltune.drop_sql_profile(name =>'SQLPROFILE_T1' );

######

3.验证SQL语句是否使用上一步创建的SQL_PROFILE：

SQL> set autotrace trace;

SQL> select a.*,b.owner from t1 a,t1 b where a.object_name like '%T1%' and a.object_id=b.object_id;

23 rows selected.

Execution Plan

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

Plan hash value: 190596302

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

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

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

|   0 | SELECT STATEMENT            |        |   471 | 43803 |   979   (1)| 00:00:12 |

|   1 |  TABLE ACCESS BY INDEX ROWID| T1     |     1 |     9 |     2   (0)| 00:00:01 |

|   2 |   NESTED LOOPS              |        |   471 | 43803 |   979   (1)| 00:00:12 |

|*  3 |    TABLE ACCESS FULL        | T1     |   471 | 39564 |    36   (0)| 00:00:01 |

|*  4 |    INDEX RANGE SCAN         | T1_IDX |     1 |       |     1   (0)| 00:00:01 |

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

Predicate Information (identified by operation id):

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

   3 - filter("A"."OBJECT_NAME" LIKE '%T1%')

   4 - access("A"."OBJECT_ID"="B"."OBJECT_ID")

Note

-----

   - SQL profile "SQLPROFILE_T1" used for this statement



Statistics

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

          1  recursive calls

          0  db block gets

        163  consistent gets

          0  physical reads

          0  redo size

       2609  bytes sent via SQL*Net to client

        392  bytes received via SQL*Net from client

          3  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

         23  rows processed          0  sorts (disk)

#####################################################################

使用Oracle的SQL Tuning Advisor固定运行计划--SQL_ID

----通过sql_id的方式  sql_id => 'a2h6pzvqncfvg',--想调优的sql_id

show serveroutput

set serveroutput on;



DECLARE  

    a_tuning_task VARCHAR2(30);  

  BEGIN  

    a_tuning_task := dbms_sqltune.create_tuning_task(sql_id => 'a2h6pzvqncfvg',task_name => 'tuning_test');    

    dbms_sqltune.execute_tuning_task(a_tuning_task);   

  END;  

  /

set long 1000

SELECT dbms_sqltune.report_tuning_task('tuning_test') FROM dual;

 

这里的输出中的sql_id是从v$sql查出。相应的是没有加hint的SQL。

假设SQL Tuning Advisor找到了理想的运行计划。下一步就是：Accept SQL Profile，接受这个SQL Profile。



## execute dbms_sqltune.accept_sql_profile(task_name =>'tuning_test' ,replace => TRUE,force_match=>true);

 完毕后验证语句：

set autotrace trace;

select a.*,b.owner from t1 a,t1 b where a.object_name like '%T1%' and a.object_id=b.object_id;

set autotrace off;

删除SQL语句：

exec dbms_sqltune.drop_tuning_task('tuning_test');  

 假设未找到理想的运行计划，则參考下一个方法。

##################################################################

使用Oracle的SQL Tuning Advisor固定运行计划--使用SQL_TEXT，參考下面：

DECLARE

 my_task_name VARCHAR2 (30);

 my_sqltext CLOB;

 BEGIN

 my_sqltext := 'select * from test where OBJECT_ID=15';  --想调优的sql

 my_task_name := dbms_sqltune.create_tuning_task (sql_text=> my_sqltext,

 --bind_list =>  'UNDO$',

 --user_name => 'SONG',

 --scope => 'COMPREHENSIVE',

 --time_limit => 60,

 task_name => 'sql_tuning_test'

 --description => 'Tuning Task'

 );

 END;

 /

 

 exec dbms_sqltune.execute_tuning_task('sql_tuning_test');   --运行调优的任务

  SELECT STATUS FROM USER_ADVISOR_TASKS WHERE task_name = 'sql_tuning_test'; --查看调优作业的状态

 SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('sql_tuning_test') FROM DUAL;--查看调优的建议

 exec dbms_sqltune.drop_tuning_task('sql_tuning_test');--删除任务