Manually Evolve and Accept SQL PLAN BASELINES in Oracle 12c

这里将介绍如何使用命令行来evolve sql plan baselines。为了evolve一个特定的sql执行计划执行以下操作:
1.创建一个evolve任务
2.设置evolve任务参数
3.执行evolve任务
4.实现任务中给出的建议
5.显示任务执行的结果

下面将举例来说明,假设满足以下条件
.数据库没有启用自动evolve任务
.对下面的查询创建一个SQL Plan Baseline

SELECT /* q2_group_by */ prod_name, sum(quantity_sold)
FROM products p, sales s
WHERE p.prod_id = s.prod_id
AND p.prod_category_id =204
GROUP BY prod_name;

.想要创建两个索引来提高查询语句的性能,如果使用索引的性能比SQL Plan Baseline中的当前执行计划的性能好那么就evolve该执行计划

为了evolve一个特定的执行计划需要执行以下操作
1.执行初始化设置操作
清空共享池与缓冲区缓存

SQL> ALTER SYSTEM FLUSH SHARED_POOL;

System altered.

SQL> ALTER SYSTEM FLUSH BUFFER_CACHE;

System altered.

启用自动捕获SQL Plan Baselines

SQL> ALTER SYSTEM SET OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES=true;

System altered.

SQL> show parameter sql_plan

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
optimizer_capture_sql_plan_baselines boolean     TRUE
optimizer_use_sql_plan_baselines     boolean     TRUE

以sh用户登录到数据库,然后设置SQLPLUS的显示参数

[oracle@jytest1 ~]$ sqlplus sh/sh@jypdb

SQL*Plus: Release 12.2.0.1.0 Production on Thu Feb 14 23:30:09 2019

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Last Successful login time: Thu Feb 14 2019 23:01:23 +08:00

Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production


SQL> SET PAGES 10000 LINES 140
SQL> SET SERVEROUTPUT ON
SQL> COL SQL_TEXT FORMAT A20
SQL> COL SQL_HANDLE FORMAT A20
SQL> COL PLAN_NAME FORMAT A30
SQL> COL ORIGIN FORMAT A12
SQL> SET LONGC 60535
SQL> SET LONG 60535
SQL> SET ECHO ON

2.执行SQL语句,因此可以自动捕获它
执行下面的SQL语句

SQL> SELECT /* q1_group_by */ prod_name, sum(quantity_sold)
  2  FROM products p, sales s
  3  WHERE p.prod_id = s.prod_id
  4  AND p.prod_category_id =203
  5  GROUP BY prod_name;

PROD_NAME                                          SUM(QUANTITY_SOLD)
-------------------------------------------------- ------------------
Envoy External 6X CD-ROM                                        11526
Model SM26273 Black Ink Cartridge                               15910
PCMCIA modem/fax 28800 baud                                     19278
Multimedia speakers- 3" cones                                   10969
Internal 8X CD-ROM                                              11197
Deluxe Mouse                                                    11609
Model CD13272 Tricolor Ink Cartridge                            12321
Model NM500X High Yield Toner Cartridge                          6466
18" Flat Panel Graphics Monitor                                  4415
External 8X CD-ROM                                              13886
SIMM- 8MB PCMCIAII card                                         17544
PCMCIA modem/fax 19200 baud                                     20467
Envoy External 8X CD-ROM                                        14850
Envoy External Keyboard                                          2857
External 6X CD-ROM                                              11732
Model A3827H Black Image Cartridge                              17314
Internal 6X CD-ROM                                               8533
17" LCD w/built-in HDTV Tuner                                    4874
SIMM- 16MB PCMCIAII card                                        14191
Multimedia speakers- 5" cones                                   10419
Standard Mouse                                                   8714

21 rows selected.

查询数据字典确认在SQL Plan Baseline中不存在执行计划,因为只有重复执行的SQL语句才会被捕获

SQL> SELECT SQL_HANDLE, SQL_TEXT, PLAN_NAME, ORIGIN, ENABLED,
  2  ACCEPTED, FIXED, AUTOPURGE
  3  FROM DBA_SQL_PLAN_BASELINES
  4  WHERE SQL_TEXT LIKE '%q1_group%';

no rows selected

再次执行SQL语句

SQL> SELECT /* q1_group_by */ prod_name, sum(quantity_sold)
  2  FROM products p, sales s
  3  WHERE p.prod_id = s.prod_id
  4  AND p.prod_category_id =203
  5  GROUP BY prod_name;

PROD_NAME                                          SUM(QUANTITY_SOLD)
-------------------------------------------------- ------------------
Envoy External 6X CD-ROM                                        11526
Model SM26273 Black Ink Cartridge                               15910
PCMCIA modem/fax 28800 baud                                     19278
Multimedia speakers- 3" cones                                   10969
Internal 8X CD-ROM                                              11197
Deluxe Mouse                                                    11609
Model CD13272 Tricolor Ink Cartridge                            12321
Model NM500X High Yield Toner Cartridge                          6466
18" Flat Panel Graphics Monitor                                  4415
External 8X CD-ROM                                              13886
SIMM- 8MB PCMCIAII card                                         17544
PCMCIA modem/fax 19200 baud                                     20467
Envoy External 8X CD-ROM                                        14850
Envoy External Keyboard                                          2857
External 6X CD-ROM                                              11732
Model A3827H Black Image Cartridge                              17314
Internal 6X CD-ROM                                               8533
17" LCD w/built-in HDTV Tuner                                    4874
SIMM- 16MB PCMCIAII card                                        14191
Multimedia speakers- 5" cones                                   10419
Standard Mouse                                                   8714

21 rows selected.

3.查询数据字典来确保执行计划已经被加载到SQL Plan Baseline中了,下面的查询显示执行计划已经被接受,这意味着执行计划已经存储在SQL Plan Baselines中了。origin列显示为AUTO-CAPTURE,这意味着执行计划是被自动捕获的

SQL> SELECT SQL_HANDLE, SQL_TEXT, PLAN_NAME,
  2  ORIGIN, ENABLED, ACCEPTED, FIXED
  3  FROM DBA_SQL_PLAN_BASELINES
  4  WHERE SQL_TEXT LIKE '%q1_group%';

SQL_HANDLE           SQL_TEXT             PLAN_NAME                      ORIGIN       ENA ACC FIX
-------------------- -------------------- ------------------------------ ------------ --- --- ---
SQL_07f16c76ff893342 SELECT /* q1_group_b SQL_PLAN_0gwbcfvzskcu242949306 AUTO-CAPTURE YES YES NO
                     y */ prod_name, sum(
                     quantity_sold)
                     FROM products p, sal
                     es s
                     WHERE p.prod_id = s.
                     prod_id
                     AND p.prod_category_
                     id =203
                     GROUP BY prod_name

4.下面对SQL语句进行解析并验证优化器是否会使用SQL Plan Baseline中的执行计划

SQL> EXPLAIN PLAN FOR
  2  SELECT /* q1_group_by */ prod_name, sum(quantity_sold)
  3  FROM products p, sales s
  4  WHERE p.prod_id = s.prod_id
  5  AND p.prod_category_id =203
  6  GROUP BY prod_name;

Explained.

SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(null, null, 'basic +note'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 3535171836

------------------------------------------
| Id  | Operation             | Name     |
------------------------------------------
|   0 | SELECT STATEMENT      |          |
|   1 |  HASH GROUP BY        |          |
|   2 |   HASH JOIN           |          |
|   3 |    TABLE ACCESS FULL  | PRODUCTS |
|   4 |    PARTITION RANGE ALL|          |
|   5 |     TABLE ACCESS FULL | SALES    |
------------------------------------------

Note
-----
   - SQL plan baseline "SQL_PLAN_0gwbcfvzskcu242949306" used for this statement

16 rows selected.

从执行计划的Note部分可以看到SQL Plan Baseline已经应用到这个SQL语句了

5.创建两个索引用来提高上面SQL语句的性能

SQL> CREATE INDEX ind_prod_cat_name ON products(prod_category_id, prod_name, prod_id);

Index created.

SQL> CREATE INDEX ind_sales_prod_qty_sold ON sales(prod_id, quantity_sold);

Index created.

6.再次执行SQL语句,因为启用了自动捕获功能,所以新的执行计划会被加载到SQL Plan Baseline中

SQL> SELECT /* q1_group_by */ prod_name, sum(quantity_sold)
  2  FROM products p, sales s
  3  WHERE p.prod_id = s.prod_id
  4  AND p.prod_category_id =203
  5  GROUP BY prod_name;

PROD_NAME                                          SUM(QUANTITY_SOLD)
-------------------------------------------------- ------------------
Envoy External 6X CD-ROM                                        11526
Model SM26273 Black Ink Cartridge                               15910
PCMCIA modem/fax 28800 baud                                     19278
Multimedia speakers- 3" cones                                   10969
Internal 8X CD-ROM                                              11197
Deluxe Mouse                                                    11609
Model CD13272 Tricolor Ink Cartridge                            12321
Model NM500X High Yield Toner Cartridge                          6466
18" Flat Panel Graphics Monitor                                  4415
External 8X CD-ROM                                              13886
SIMM- 8MB PCMCIAII card                                         17544
PCMCIA modem/fax 19200 baud                                     20467
Envoy External 8X CD-ROM                                        14850
Envoy External Keyboard                                          2857
External 6X CD-ROM                                              11732
Model A3827H Black Image Cartridge                              17314
Internal 6X CD-ROM                                               8533
17" LCD w/built-in HDTV Tuner                                    4874
SIMM- 16MB PCMCIAII card                                        14191
Multimedia speakers- 5" cones                                   10419
Standard Mouse                                                   8714

21 rows selected.

7.查询数据字典来确保新的执行计划被加载到SQL Plan Baseline中了

SQL> SELECT SQL_HANDLE, SQL_TEXT, PLAN_NAME, ORIGIN, ENABLED, ACCEPTED
  2  FROM DBA_SQL_PLAN_BASELINES
  3  WHERE SQL_HANDLE IN ('SQL_07f16c76ff893342')
  4  ORDER BY SQL_HANDLE, ACCEPTED;

SQL_HANDLE           SQL_TEXT             PLAN_NAME                      ORIGIN       ENA ACC
-------------------- -------------------- ------------------------------ ------------ --- ---
SQL_07f16c76ff893342 SELECT /* q1_group_b SQL_PLAN_0gwbcfvzskcu20135fd6c AUTO-CAPTURE YES NO
                     y */ prod_name, sum(
                     quantity_sold)
                     FROM products p, sal
                     es s
                     WHERE p.prod_id = s.
                     prod_id
                     AND p.prod_category_
                     id =203
                     GROUP BY prod_name

SQL_07f16c76ff893342 SELECT /* q1_group_b SQL_PLAN_0gwbcfvzskcu242949306 AUTO-CAPTURE YES YES
                     y */ prod_name, sum(
                     quantity_sold)
                     FROM products p, sal
                     es s
                     WHERE p.prod_id = s.
                     prod_id
                     AND p.prod_category_
                     id =203
                     GROUP BY prod_name

上面的查询结果显示新的执行计划是为被接受的。

8.再次解析SQL语句并验证优化器是不是使用原始没有索引的执行计划

SQL> EXPLAIN PLAN FOR
  2  SELECT /* q1_group_by */ prod_name, sum(quantity_sold)
  3  FROM products p, sales s
  4  WHERE p.prod_id = s.prod_id
  5  AND p.prod_category_id =203
  6  GROUP BY prod_name;

Explained.

SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(null, null, 'basic +note'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 3535171836

------------------------------------------
| Id  | Operation             | Name     |
------------------------------------------
|   0 | SELECT STATEMENT      |          |
|   1 |  HASH GROUP BY        |          |
|   2 |   HASH JOIN           |          |
|   3 |    TABLE ACCESS FULL  | PRODUCTS |
|   4 |    PARTITION RANGE ALL|          |
|   5 |     TABLE ACCESS FULL | SALES    |
------------------------------------------

Note
-----
   - SQL plan baseline "SQL_PLAN_0gwbcfvzskcu242949306" used for this statement

16 rows selected.

上面的Note部分指示优化器使用了原始的没有索引的执行计划

9.以管理员用户登录数据库,然后创建一个evolve任务它包含未被接受执行计划相关的所有SQL语句

[oracle@jytest1 ~]$ sqlplus sys/xxzx7817600@jypdb as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Thu Feb 14 23:48:51 2019

Copyright (c) 1982, 2016, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL> VARIABLE cnt NUMBER
SQL> VARIABLE tk_name VARCHAR2(50)
SQL> VARIABLE exe_name VARCHAR2(50)
SQL> VARIABLE evol_out CLOB
SQL> EXECUTE :tk_name := DBMS_SPM.CREATE_EVOLVE_TASK(sql_handle => 'SQL_07f16c76ff893342',plan_name => 'SQL_PLAN_0gwbcfvzskcu20135fd6c');

PL/SQL procedure successfully completed.

SQL> SELECT :tk_name FROM DUAL;

:TK_NAME
--------------------------------------------------------------------------------------------------------------------------------
TASK_11



10.执行evolve任务
SQL>EXECUTE :exe_name :=DBMS_SPM.EXECUTE_EVOLVE_TASK(task_name=>:tk_name);
PL/SQL procedure successfully completed.

SQL>SELECT :exe_name FROM DUAL;
:EXE_NAME
---------------------------------------------------------------------------
EXEC_1

11.查看报告

EXECUTE :evol_out := DBMS_SPM.REPORT_EVOLVE_TASK( task_name=>:tk_name,
execution_name=>:exe_name );
SELECT :evol_out FROM DUAL;
GENERAL INFORMATION SECTION
--------------------------------------------------------------------------
Task Information:
---------------------------------------------
Task Name : TASK_11
Task Owner : SYS
Execution Name : EXEC_1
Execution Type       : SPM EVOLVE
Scope                : COMPREHENSIVE
Status               : COMPLETED
Started              : 02/15/2019 17:49:32
Finished             : 02/15/2019 17:49:35
Last Updated         : 02/15/2019 17:49:35
Global Time Limit    : 2147483646
Per-Plan Time Limit  : UNUSED
Number of Errors     : 0
---------------------------------------------------------------------------
SUMMARY SECTION
---------------------------------------------------------------------------
Number of plans processed : 1
Number of findings : 1
Number of recommendations : 1
Number of errors : 0
---------------------------------------------------------------------------
DETAILS SECTION
---------------------------------------------------------------------------
Object ID : 2
Test Plan Name : SQL_PLAN_0gwbcfvzskcu20135fd6c
Base Plan Name : SQL_PLAN_0gwbcfvzskcu242949306
SQL Handle : SQL_07f16c76ff893342
Parsing Schema : SH
Test Plan Creator : SH
SQL Text : SELECT /*q1_group_by*/ prod_name,
sum(quantity_sold)
FROM products p, sales s
WHERE p.prod_id=s.prod_id AND p.prod_category_id=203
GROUP BY prod_name
Execution Statistics:
-----------------------------
Base Plan Test Plan
---------------------------- ------------------------
Elapsed Time (s): .044336 .012649
CPU Time (s): .044003 .012445
Buffer Gets: 360 99
Optimizer Cost: 924 891
Disk Reads: 341 82
Direct Writes: 0 0
Rows Processed: 4 2
Executions: 5 9
FINDINGS SECTION
---------------------------------------------------------------------------
Findings (1):
-----------------------------
1. The plan was verified in 2.18 seconds. It passed the benefit criterion
because its verified performance was 2.01 times better than that of the
baseline plan.
Recommendation:
-----------------------------
Consider accepting the plan. Execute
dbms_spm.accept_sql_plan_baseline(task_name => 'TASK_11', object_id => 2,
task_owner => 'SYS');
EXPLAIN PLANS SECTION
---------------------------------------------------------------------------
Baseline Plan
-----------------------------
Plan Id : 1
Plan Hash Value : 1117033222
---------------------------------------------------------------------------
| Id| Operation               | Name     | Rows | Bytes   |Cost | Time    |
---------------------------------------------------------------------------
| 0 | SELECT STATEMENT        |          |   21 |     861 | 924 | 00:00:12|
| 1 |   HASH GROUP BY         |          |   21 |     861 | 924 | 00:00:12|
| *2|    HASH JOIN            |          |267996|10987836 | 742 | 00:00:09|
| *3|     TABLE ACCESS FULL   | PRODUCTS |   21 |     714 |   2 | 00:00:01|
| 4 |     PARTITION RANGE ALL |          |918843| 6431901 | 662 | 00:00:08|
| 5 |      TABLE ACCESS FULL  | SALES    |918843| 6431901 | 662 | 00:00:08|
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
------------------------------------------
* 2 - access("P"."PROD_ID"="S"."PROD_ID")
* 3 - filter("P"."PROD_CATEGORY_ID"=203)
Test Plan
-----------------------------
Plan Id : 2
Plan Hash Value : 20315500
---------------------------------------------------------------------------
|Id| Operation           | Name             | Rows | Bytes  | Cost| Time   |
---------------------------------------------------------------------------
| 0|SELECT STATEMENT     |                  |    21|     861|  891|00:00:11|
| 1| SORT GROUP BY NOSORT|                  |    21|     861|  891|00:00:11|
| 2|  NESTED LOOPS       |                  |267996|10987836|  891|00:00:11|
|*3|   INDEX RANGE SCAN  |IND_PROD_CAT_NAME |    21|     714|    1|00:00:01|
|*4|   INDEX RANGE SCAN  |IND_SALES_PROD_QTY| 12762|   89334|   42|00:00:01|
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
------------------------------------------
* 3 - access("P"."PROD_CATEGORY_ID"=203)
* 4 - access("P"."PROD_ID"="S"."PROD_ID")

报告显示使用两个索引的执行计划比原始执行计划性能更好

12.实现evolve任务所给出的建议

SQL>EXECUTE :cnt := DBMS_SPM.IMPLEMENT_EVOLVE_TASK( task_name=>:tk_name,execution_name=>:exe_name );
PL/SQL procedure successfully completed.

13.查询数据字典来确保新的执行计划已经是接受状态

SQL> SELECT SQL_HANDLE, SQL_TEXT, PLAN_NAME, ORIGIN, ENABLED, ACCEPTED
  2  FROM DBA_SQL_PLAN_BASELINES
  3  WHERE SQL_HANDLE IN ('SQL_07f16c76ff893342')
  4  ORDER BY SQL_HANDLE, ACCEPTED;

SQL_HANDLE           SQL_TEXT             PLAN_NAME                      ORIGIN               ENA ACC
-------------------- -------------------- ------------------------------ -------------------- --- ---
SQL_07f16c76ff893342 SELECT /* q1_group_b SQL_PLAN_0gwbcfvzskcu242949306 AUTO-CAPTURE         YES YES
                     y */ prod_name, sum(
                     quantity_sold)
                     FROM products p, sal
                     es s
                     WHERE p.prod_id = s.
                     prod_id
                     AND p.prod_category_
                     id =203
                     GROUP BY prod_name


SQL_HANDLE           SQL_TEXT             PLAN_NAME                      ORIGIN               ENA ACC
-------------------- -------------------- ------------------------------ -------------------- --- ---
SQL_07f16c76ff893342 SELECT /* q1_group_b SQL_PLAN_0gwbcfvzskcu2ae9b4305 AUTO-CAPTURE         YES YES
                     y */ prod_name, sum(
                     quantity_sold)
                     FROM products p, sal
                     es s
                     WHERE p.prod_id = s.
                     prod_id
                     AND p.prod_category_
                     id =203
                     GROUP BY prod_name

14.执行清除操作

SQL> VARIABLE cnt NUMBER
SQL> EXEC :cnt := DBMS_SPM.DROP_SQL_PLAN_BASELINE('SQL_07f16c76ff893342');

PL/SQL procedure successfully completed.


SQL> DELETE FROM SQLLOG$;

13 rows deleted.

SQL> commit;

Commit complete.


SQL> DROP INDEX IND_SALES_PROD_QTY_SOLD;
Index dropped.



SQL> DROP INDEX IND_PROD_CAT_NAME;

Index dropped.

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