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分类: Oracle

2014-04-01 17:18:40


SQL调优工具包DBMS_SQLTUNE的使用方法

oracle 提供了优化建议功能包DBMS_SQLTUNE,该包可以帮助我们分析SQL,并提供优化建议。

原有执行计划
alter session set statistics_level=all;
set serveroutput off
select * from test.emp where ename='SCOTT' and DEPTNO=20;
SELECT * FROM table(dbms_xplan.display_cursor(NULL,NULL,'runstats_last'));

PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
SQL_ID  8k1gbrapm7zpd, child number 0
-------------------------------------
select * from test.emp where ename='SCOTT' and DEPTNO=20

Plan hash value: 3956160932

------------------------------------------------------------------------------------
| Id  | Operation         | Name | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |      1 |        |      1 |00:00:00.01 |       4 |
|*  1 |  TABLE ACCESS FULL| EMP  |      1 |      1 |      1 |00:00:00.01 |       4 |
-------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------
   1 - filter(("ENAME"='SCOTT' AND "DEPTNO"=20))


下面就用DBMS_SQLTUNE优化该SQL
--1.赋予用户ADVISOR权限
grant ADVISOR  to test;

--2.创建sql tuning任务
conn test/test

DECLARE
 my_task_name VARCHAR2(30);
 my_sqltext   CLOB;
BEGIN
 my_sqltext := 'select * from emp where ename= :name and DEPTNO= :deptno';
 my_task_name := DBMS_SQLTUNE.CREATE_TUNING_TASK(
         sql_text    => my_sqltext,
bind_list   => sql_binds(anydata.convertvarchar2(10),anydata.convertnumber(2)),
         user_name   => 'TEST',
         scope       => 'COMPREHENSIVE',
         time_limit  => 60,
         task_name   => 'test_sql_tuning',
         description => 'Task to tune a query on emp');
END;
/

参数说明:
bind_list:多个绑定变量以','逗号分隔。参数值一定要根据绑定变量对应的列的类型书写.
如:emp.ename类型是VARCHAR2(10),那么就要写成
 bind_list    =>sql_binds(anydata.convertvarchar2(10)),

time_limit:执行的最长时间,默认是60。

scope:
LIMITED,用大概1秒时间去优化SQL语句,但是并不进行SQL Profiling分析。
COMPREHENSIVE,进行全面分析,包含SQL Profiling分析;比LIMITED用时更长。

/*2014-4-8日增加 begin*/
**也可以用sql_id创建sql tunning任务,比用sql_text方便很多
FUNCTION CREATE_TUNING_TASK RETURNS VARCHAR2
 Argument Name                  Type                    In/Out Default?
 ------------------------------ ----------------------- ------ --------
 SQL_ID                         VARCHAR2                IN
 PLAN_HASH_VALUE                NUMBER                  IN     DEFAULT
 SCOPE                          VARCHAR2                IN     DEFAULT
 TIME_LIMIT                     NUMBER                  IN     DEFAULT
 TASK_NAME                      VARCHAR2                IN     DEFAULT
 DESCRIPTION                    VARCHAR2                IN     DEFAULT

DECLARE
 my_task_name VARCHAR2(30);
BEGIN
  my_task_name := DBMS_SQLTUNE.CREATE_TUNING_TASK(
         SQL_ID      => 'ddw7j6yfnw0vz',
         scope       => 'COMPREHENSIVE',
         time_limit  => 60,
         task_name   => 'tunning_task_ddw7j6yfnw0vz',
         description => 'Task to tune a query on  ddw7j6yfnw0vz');
END;
/

/*2014-4-8日增加 end*/

--3.查看任务名 SELECT TASK_NAME 
FROM   DBA_ADVISOR_LOG 
WHERE  OWNER = 'TEST';
TASK_NAME
------------------------------
test_sql_tuning

--4.执行sql tuning任务
BEGIN
  DBMS_SQLTUNE.EXECUTE_TUNING_TASK( task_name => 'test_sql_tuning' );
END;
/

--5.查看sql tunning任务状态
SELECT status 
FROM   USER_ADVISOR_TASKS 
WHERE  task_name = 'test_sql_tuning';
STATUS
-----------
COMPLETED

--6.展示sql tunning结果
SET LONG 10000
SET LONGCHUNKSIZE 1000
SET LINESIZE 100
SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('test_sql_tuning')
FROM   DUAL;

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
GENERAL INFORMATION SECTION
-------------------------------------------------------------------------------
Tuning Task Name   : test_sql_tuning
Tuning Task Owner  : TEST
Workload Type      : Single SQL Statement
Scope              : COMPREHENSIVE
Time Limit(seconds): 60
Completion Status  : COMPLETED
Started at         : 04/01/2014 16:45:16
Completed at       : 04/01/2014 16:45:17

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Schema Name: TEST
SQL ID     : 95fv6dbj64d0f
SQL Text   : select * from emp where ename= :name and DEPTNO= :deptno

-------------------------------------------------------------------------------
FINDINGS SECTION (2 findings)
-------------------------------------------------------------------------------
1- Statistics Finding
---------------------

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
  Table "TEST"."EMP" was not analyzed.

  Recommendation
  --------------
  - Consider collecting optimizer statistics for this table.
    execute dbms_stats.gather_table_stats(ownname => 'TEST', tabname =>
            'EMP', estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE,
            method_opt => 'FOR ALL COLUMNS SIZE AUTO');

  Rationale
  ---------

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
    The optimizer requires up-to-date statistics for the table in order to
    select a good execution plan.

2- Index Finding (see explain plans section below)
--------------------------------------------------
  The execution plan of this statement can be improved by creating one or more
  indices.

  Recommendation (estimated benefit: 66.67%)
  ------------------------------------------
  - Consider running the Access Advisor to improve the physical schema design


DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
    or creating the recommended index.
    create index TEST.IDX$$_00D80001 on TEST.EMP("ENAME","DEPTNO");

  Rationale
  ---------
    Creating the recommended indices significantly improves the execution plan
    of this statement. However, it might be preferable to run "Access Advisor"
    using a representative SQL workload as opposed to a single statement. This
    will allow to get comprehensive index recommendations which takes into
    account index maintenance overhead and additional space consumption.

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------
EXPLAIN PLANS SECTION
-------------------------------------------------------------------------------

1- Original
-----------
Plan hash value: 3956160932

--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     1 |    87 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| EMP  |     1 |    87 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------
   1 - filter("ENAME"=:NAME AND "DEPTNO"=:DEPTNO)

2- Using New Indices
--------------------

DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
Plan hash value: 2106247215
----------------------------------------------------------------------------------------------
| Id  | Operation                   | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                |     1 |    87 |     1   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP            |     1 |    87 |     1   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | IDX$$_00D80001 |     1 |       |     1   (0)| 00:00:01 |
----------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
DBMS_SQLTUNE.REPORT_TUNING_TASK('TEST_SQL_TUNING')
----------------------------------------------------------------------------------------------------
---------------------------------------------------
   2 - access("ENAME"=:NAME AND "DEPTNO"=:DEPTNO)

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


建议报告总结:
<1>收集EMP表的统计信息
execute dbms_stats.gather_table_stats(ownname => 'TEST', tabname =>'EMP', estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE,method_opt => 'FOR ALL COLUMNS SIZE AUTO');

<2>创建索引
create index TEST.IDX$$_00D80001 on TEST.EMP("ENAME","DEPTNO");


优化后执行计划
--------------------------------------------------------------------------------------------------------
| Id  | Operation                   | Name           | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
--------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                |      1 |        |      1 |00:00:00.01 |       3 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP            |      1 |      1 |      1 |00:00:00.01 |       3 |
|*  2 |   INDEX RANGE SCAN          | IDX$$_00D80001 |      1 |      1 |      1 |00:00:00.01 |       2 |
--------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   2 - access("ENAME"='SCOTT' AND "DEPTNO"=20)


--7.完成后删除sql tunning任务
EXEC DBMS_SQLTUNE.DROP_TUNING_TASK('test_sql_tuning');

--8.其他
--sql tunning任务创建后,也可以修改参数
BEGIN
  DBMS_SQLTUNE.SET_TUNING_TASK_PARAMETER(
    task_name => 'test_sql_tuning',
    parameter => 'TIME_LIMIT', value => 300);
END;
/

--查看SQL Tuning Advisor的进展(task执行很久)
col opname for a20
col ADVISOR_NAME for a20
SELECT SID,SERIAL#,USERNAME,OPNAME,ADVISOR_NAME,TARGET_DESC,START_TIME SOFAR, TOTALWORK 
FROM   V$ADVISOR_PROGRESS 
WHERE  USERNAME = 'TEST';


以上根据oracle doc整理
http://docs.oracle.com/cd/E11882_01/server.112/e41573/sql_tune.htm#PFGRF94856
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