使用SQL Profile及SQL Tuning Advisor固定执行计划

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）统计信息之外的其他信息，比如运行环境、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能够实现的功能SQL Profiles也完全能够实现，而SQL Profiles具有Outlines不具备的优化，最重要的有二点：
    SQL Profiles更容易生成、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：
    锁定或者说是稳定执行计划。
    在不能修改应用中的SQL的情况下使SQL语句按指定的执行计划运行。
参考老熊的博客，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$SQL WHERE SQL_TEXT LIKE ‘%a.*,b.owner from t1 a,t1 b%‘;
####2t5xqt4d1dsaw
10g开始，v$sql_plan中就包括了SQL语句OUTLINE数据，也就是稳定执行计划的Hints。如下：
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.开始创建并应用SQL Profile

使用未加HINT的SQL语句，并指定SQL_PROFILE名字：SQLPROFILE_T1
注意事项：两个引号---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固定执行计划--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，对应的是没有加hint的SQL。
如果SQL Tuning Advisor找到了理想的执行计划，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);
 完成后验证语句：
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‘);  
 如果未找到理想的执行计划，则参考下一个方法。
##################################################################

使用Oracle的SQL Tuning Advisor固定执行计划--使用SQL_TEXT，参考以下：

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‘);   --执行调优的任务
  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

使用SQL Profile及SQL Tuning Advisor固定执行计划,古老的榕树,5-wow.com