Oracle SQL Tuning Advisor 测试

如果面对一个需要优化的SQL语句，没有很好的想法，可以先试试Oracle的SQL Tuning Advisor。

SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for 64-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
--创建测试表
SQL> create table test_sql_tuning(id_ number);

Table created.

SQL> declare
  2  begin
  3    for i in 1..100000 loop
  4      insert into test_sql_tuning values(i)
  5    end loop;
  6    commit;
  7  end;
  8  /

PL/SQL procedure successfully completed.

SQL> set autotrace on exp
SQL> select * from test_sql_tuning t where t.id_=333;

       ID_
----------
       333

Execution Plan
----------------------------------------------------------
Plan hash value: 3855182387

-------------------------------------------------------------------------------------
| Id  | Operation         | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |                 |     3 |    39 |    69   (2)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| TEST_SQL_TUNING |     3 |    39 |    69   (2)| 00:00:01 |
-------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("T"."ID_"=333)

Note
-----
   - dynamic sampling used for this statement (level=2)

SQL> declare
  2  my_task_name varchar2(50);
  3  begin
  4    my_task_name := dbms_sqltune.create_tuning_task(
  5    SQL_ID => 'g72kdvcacxvtf',
  6    scope => 'COMPREHENSIVE',
  7    task_name => 'ZEN_TEST_SQLTUNE');
  8    DBMS_SQLTUNE.execute_tuning_task(my_task_name);
  9  end;
 10  /

PL/SQL procedure successfully completed.

SQL> select dbms_sqltune.report_tuning_task('ZEN_TEST_SQLTUNE') from dual;

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
GENERAL INFORMATION SECTION
-------------------------------------------------------------------------------
Tuning Task Name   : ZEN_TEST_SQLTUNE
Tuning Task Owner  : HR
Workload Type      : Single SQL Statement
Scope              : COMPREHENSIVE
Time Limit(seconds): 1800
Completion Status  : COMPLETED
Started at         : 07/02/2017 16:31:20
Completed at       : 07/02/2017 16:31:20

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Schema Name: HR
SQL ID     : cnvs1fb15pqb4
SQL Text   : select * from test_sql_tuning t where t.id_=333

-------------------------------------------------------------------------------
FINDINGS SECTION (2 findings)
-------------------------------------------------------------------------------

1- Statistics Finding
---------------------

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
  Table "HR"."TEST_SQL_TUNING" was not analyzed.

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

  Rationale

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
  ---------
    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: 98.55%)
  ------------------------------------------

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
  - Consider running the Access Advisor to improve the physical schema design
    or creating the recommended index.
    create index HR.IDX$$_06650001 on HR.TEST_SQL_TUNING("ID_");

  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('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------

-------------------------------------------------------------------------------
EXPLAIN PLANS SECTION
-------------------------------------------------------------------------------

1- Original
-----------
Plan hash value: 3855182387

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

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
-------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |                 |     3 |    39 |    69   (2)| 00:00:01 |

|*  1 |  TABLE ACCESS FULL| TEST_SQL_TUNING |     3 |    39 |    69   (2)| 00:00:01 |
-------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("T"."ID_"=333)

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------
2- Using New Indices
--------------------
Plan hash value: 1603088386

-----------------------------------------------------------------------------------
| Id  | Operation        | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------
|   0 | SELECT STATEMENT |                |     1 |    13 |     1   (0)| 00:00:01 |
|*  1 |  INDEX RANGE SCAN| IDX$$_06650001 |     1 |    13 |     1   (0)| 00:00:01
|
-----------------------------------------------------------------------------------

DBMS_SQLTUNE.REPORT_TUNING_TASK('ZEN_TEST_SQLTUNE')
--------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - access("T"."ID_"=333)

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

1 row selected.

Execution Plan
----------------------------------------------------------
Plan hash value: 1388734953

-----------------------------------------------------------------
| Id  | Operation        | Name | Rows  | Cost (%CPU)| Time     |
-----------------------------------------------------------------
|   0 | SELECT STATEMENT |      |     1 |     2   (0)| 00:00:01 |
|   1 |  FAST DUAL       |      |     1 |     2   (0)| 00:00:01 |
-----------------------------------------------------------------

SQL>

上面的report总共分为3个部分，
分别是SQL调优的基本信息、SQL调优的建议findings、以及SQL对应的执行计划部分
在基本信息部分包含了SQL调优的任务名称，状态，执行，完成时间，对应的SQL完整语句等
在finding部分则给出本次调优所得到的成果，如本次是提示缺少统计信息，可以及创建索引。
在执行计划部分则给出了当前SQL语句的执行计划以及谓词信息