Oracle固定执行计划的方法----SQL Profie（三）

继续学习SQL Profile，SQL Profile的基本知识参考文章《Oracle固定执行计划的方法----SQL Profie（一）》、《Oracle固定执行计划的方法----SQL Profie（二）》

一、使用 COE_XFR_SQL_PROFILE 脚本构建SQL Profile------自动化利器

从 MOS（My Oracle Support）可以下载到 SQLT (SQLTXPLAIN) 工具包。其中包含的 coe_xfr_sql_profile.sql 脚本可以自动从 shared pool 或 AWR 中提取指定 SQL ID 的 Outline Data 并生成创建 SQL Profile 的脚本。

主要作用：如果一个SQL语句包含多条执行计划，且经常出现执行速度变化的情况，可以通过该脚本，选择一个预期的执行计划（当前内存中、AWR历史资料库中保存的执行计划），生成SQL Profile，来稳定该语句的执行计划！

备注：类似的脚本还有很多，例如create_sql_profile、create_sql_profile_awr，这里不一一介绍

1、下载与准备

从 MOS 下载 sqlt.zip 文件（文档 ID: 215187.1）。
解压后，在目录中找到 coe_xfr_sql_profile.sql 脚本。

2、执行脚本

首先在 shared pool 中执行目标 SQL：

sql 复制代码

SELECT /*+ sql_profile_test3 */ t1.*, t2.owner
FROM t1, t2
WHERE t1.object_name LIKE '%T1%'
  AND t1.object_id = t2.object_id;
  
--注意需要查询 plan_hash_value 这一列
set linesize 200 pagesize 999
col sql_text format a40
SELECT sql_text, sql_id, hash_value, child_number,plan_hash_value
  FROM v$sql 
 WHERE sql_text LIKE '%sql_profile_test3%' 
   AND sql_text NOT LIKE '%v$sql%';

SQL_TEXT                                 SQL_ID        HASH_VALUE CHILD_NUMBER PLAN_HASH_VALUE
---------------------------------------- ------------- ---------- ------------ ---------------
SELECT /*+ sql_profile_test3 */ t1.*, t2 cdy6d6t5quzfd 1265466829            0      2959412835
.owner FROM t1, t2 WHERE t1.object_name
LIKE '%T1%'   AND t1.object_id = t2.obje
ct_id

执行 coe_xfr_sql_profile.sql 脚本：

sql 复制代码

@coe_xfr_sql_profile.sql

SQL> @coe_xfr_sql_profile.sql

Parameter 1:
SQL_ID (required)

Enter value for 1: cdy6d6t5quzfd   ---输入sql_id


PLAN_HASH_VALUE AVG_ET_SECS
--------------- -----------
     2959412835        .033

Parameter 2:
PLAN_HASH_VALUE (required)

Enter value for 2: 2959412835     --输入语句想要生成sql profile的plan_hash_value

Values passed to coe_xfr_sql_profile:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SQL_ID         : "cdy6d6t5quzfd"
PLAN_HASH_VALUE: "2959412835"

SQL>BEGIN
  2    IF :sql_text IS NULL THEN
  3      RAISE_APPLICATION_ERROR(-20100, 'SQL_TEXT for SQL_ID &&sql_id. was not found in memory (gv$sqltext_with_newlines) or AWR (dba_hist_sqltext).');
  4    END IF;
  5  END;
  6  /
SQL>SET TERM OFF;
SQL>BEGIN
  2    IF :other_xml IS NULL THEN
  3      RAISE_APPLICATION_ERROR(-20101, 'PLAN for SQL_ID &&sql_id. and PHV &&plan_hash_value. was not found in memory (gv$sql_plan) or AWR (dba_hist_sql_plan).');
  4    END IF;
  5  END;
  6  /
SQL>SET TERM OFF;

Execute coe_xfr_sql_profile_cdy6d6t5quzfd_2959412835.sql    --生成一个脚本文件，运行该脚本，就可以创建sql profile
on TARGET system in order to create a custom SQL Profile
with plan 2959412835 linked to adjusted sql_text.


COE_XFR_SQL_PROFILE completed.

脚本会生成另一个脚本 coe_xfr_sql_profile_cdy6d6t5quzfd_2959412835.sql。

3、执行生成的脚本

运行生成的脚本即可创建 SQL Profile：

sql 复制代码

@coe_xfr_sql_profile_cdy6d6t5quzfd_2959412835.sql

SQL>@coe_xfr_sql_profile_cdy6d6t5quzfd_2959412835.sql
......
SQL>REM
SQL>DECLARE
  2  sql_txt CLOB;
  3  h       SYS.SQLPROF_ATTR;
  4  PROCEDURE wa (p_line IN VARCHAR2) IS
  5  BEGIN
  6  DBMS_LOB.WRITEAPPEND(sql_txt, LENGTH(p_line), p_line);
  7  END wa;
  8  BEGIN
  9  DBMS_LOB.CREATETEMPORARY(sql_txt, TRUE);
 10  DBMS_LOB.OPEN(sql_txt, DBMS_LOB.LOB_READWRITE);
 11  -- SQL Text pieces below do not have to be of same length.
 12  -- So if you edit SQL Text (i.e. removing temporary Hints),
 13  -- there is no need to edit or re-align unmodified pieces.
 14  wa(q'[SELECT /*+ sql_profile_test3 */ t1.*, t2.owner
 15  FROM t1, t2
 16  WHERE]');
 17  wa(q'[ t1.object_name LIKE '%T1%'
 18    AND t1.object_id = t2.object_id]');
 19  DBMS_LOB.CLOSE(sql_txt);
 20  h := SYS.SQLPROF_ATTR(
 21  q'[BEGIN_OUTLINE_DATA]',
 22  q'[IGNORE_OPTIM_EMBEDDED_HINTS]',
 23  q'[OPTIMIZER_FEATURES_ENABLE('11.2.0.4')]',
 24  q'[DB_VERSION('11.2.0.4')]',
 25  q'[ALL_ROWS]',
 26  q'[OUTLINE_LEAF(@"SEL$1")]',
 27  q'[FULL(@"SEL$1" "T2"@"SEL$1")]',
 28  q'[FULL(@"SEL$1" "T1"@"SEL$1")]',
 29  q'[LEADING(@"SEL$1" "T2"@"SEL$1" "T1"@"SEL$1")]',
 30  q'[USE_HASH(@"SEL$1" "T1"@"SEL$1")]',
 31  q'[END_OUTLINE_DATA]');
 32  :signature := DBMS_SQLTUNE.SQLTEXT_TO_SIGNATURE(sql_txt);
 33  :signaturef := DBMS_SQLTUNE.SQLTEXT_TO_SIGNATURE(sql_txt, TRUE);
 34  DBMS_SQLTUNE.IMPORT_SQL_PROFILE (
 35  sql_text    => sql_txt,
 36  profile     => h,
 37  name        => 'coe_cdy6d6t5quzfd_2959412835',
 38  description => 'coe cdy6d6t5quzfd 2959412835 '||:signature||' '||:signaturef||'',
 39  category    => 'DEFAULT',
 40  validate    => TRUE,
 41  replace     => TRUE,
 42  force_match => FALSE /* TRUE:FORCE (match even when different literals in SQL). FALSE:EXACT (similar to CURSOR_SHARING) */ );
 43  DBMS_LOB.FREETEMPORARY(sql_txt);
 44  END;
 45  /
PL/SQL procedure successfully completed.
SQL>WHENEVER SQLERROR CONTINUE
SQL>SET ECHO OFF;
            SIGNATURE
---------------------
 10081132228680031145
           SIGNATUREF
---------------------
  7070267937381023371
... manual custom SQL Profile has been created
COE_XFR_SQL_PROFILE_cdy6d6t5quzfd_2959412835 completed

4、验证 SQL Profile 中的 Hints

sql 复制代码

SELECT name, category, signature, type, status, force_matching 
FROM dba_sql_profiles;
NAME                           CATEGORY        SIGNATURE TYPE    STATUS   FOR
------------------------------ -------------- ---------- ------- -------- ---
MANUAL_PROFILE_T1_T2           DEFAULT        3.9607E+18 MANUAL  ENABLED  YES
coe_cdy6d6t5quzfd_2959412835   DEFAULT        1.0081E+19 MANUAL  ENABLED  NO

set linesize 200 pagesize 9999
set long 100000
SELECT COMP_DATA
FROM dba_sql_profiles a, sys.sqlobj$data b
WHERE a.signature = b.signature
  AND a.name = 'coe_cdy6d6t5quzfd_2959412835';

COMP_DATA
--------------------------------------------------------------------------------
<outline_data><hint><![CDATA[BEGIN_OUTLINE_DATA]]></hint><hint><![CDATA[IGNORE_O
PTIM_EMBEDDED_HINTS]]></hint><hint><![CDATA[OPTIMIZER_FEATURES_ENABLE('11.2.0.4'
)]]></hint><hint><![CDATA[DB_VERSION('11.2.0.4')]]></hint><hint><![CDATA[ALL_ROW
S]]></hint><hint><![CDATA[OUTLINE_LEAF(@"SEL$1")]]></hint><hint><![CDATA[FULL(@"
SEL$1" "T2"@"SEL$1")]]></hint><hint><![CDATA[FULL(@"SEL$1" "T1"@"SEL$1")]]></hin
t><hint><![CDATA[LEADING(@"SEL$1" "T2"@"SEL$1" "T1"@"SEL$1")]]></hint><hint><![C
DATA[USE_HASH(@"SEL$1" "T1"@"SEL$1")]]></hint><hint><![CDATA[END_OUTLINE_DATA]]>
</hint></outline_data>

5、脚本的注意事项

脚本会从 shared pool 和 AWR 中获取 SQL 执行的各个执行计划的统计信息。
需要输入你认为正确的、需要稳定的执行计划的 hash value。
生成的 SQL Profile 名称格式为：coe + sql_id + plan_hash_value。
force_match 默认为 FALSE，可以手工修改生成的脚本将其改为 TRUE。
也可以按需要修改生成脚本的其他内容。

二、高级技巧：在不修改 SQL 的情况下改变执行计划

在实际生产环境中，常常遇到这样的情况：SQL 语句的执行计划有问题，或者 SQL 使用了错误的 Hints（例如 /*+ RULE */），但应用代码不能修改或短期内无法修改。

有三种解决办法：

调整统计信息------不推荐，因为复杂、不稳定（统计信息可能被重新收集），且影响面广。
使用 Outline------方法复杂。
使用 SQL Profile------推荐方案。

1、解决思路："乾坤大挪移"

使用 SQL Profile 改变 SQL 执行计划的核心思路是：

取得原始 SQL 的文本（如有可能还包括 SQL_ID）
通过 COE_XFR_SQL_PROFILE脚本生成构建sql profile的脚本。
构造一个与原始 SQL 在逻辑上、结构上完全相同的 SQL。
执行构造的 SQL，通过 COE_XFR_SQL_PROFILE脚本生成新的构建sql profile的脚本。
修改第二步生成的COE脚本内容修改（修改OUTLINE部分），使用第四步的COE脚本内容中的（OUTLINE DATA）。

2、案例演示

第一步：原始 SQL（待调整的执行计划）

sql 复制代码

SELECT /*+ old_sql full(t1) full(t2) use_hash(t1 t2) */ t1.*, t2.owner
FROM t1, t2
WHERE t1.object_name LIKE '%T1%'
  AND t1.object_id = t2.object_id;
  
  
set linesize 200 pagesize 999
col sql_text format a40
SELECT sql_text, sql_id, hash_value, child_number,plan_hash_value
  FROM v$sql 
 WHERE sql_text LIKE '%old_sql%' 
   AND sql_text NOT LIKE '%v$sql%';
   

SQL_TEXT                                 SQL_ID        HASH_VALUE CHILD_NUMBER PLAN_HASH_VALUE
---------------------------------------- ------------- ---------- ------------ ---------------
SELECT /*+ old_sql full(t1) full(t2) use g7ndz4jp2j3uh 1781043024            0      2959412835
_hash(t1 t2) */ t1.*, t2.owner FROM t1,
t2 WHERE t1.object_name LIKE '%T1%'   AN
D t1.object_id = t2.object_id

执行计划：

复制代码

select * from table(dbms_xplan.display_cursor('g7ndz4jp2j3uh','',''));

Plan hash value: 2959412835
-----------------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |       |       |       |  5854 (100)|          |
|*  1 |  HASH JOIN         |      |  2500K|    97M|  1968K|  5854   (7)| 00:01:11 |
|   2 |   TABLE ACCESS FULL| T2   | 87356 |   938K|       |   344   (1)| 00:00:05 |
|*  3 |   TABLE ACCESS FULL| T1   |  2500K|    71M|       |   437  (84)| 00:00:06 |
-----------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------
   1 - access("T1"."OBJECT_ID"="T2"."OBJECT_ID")
   3 - filter(("T1"."OBJECT_NAME" LIKE '%T1%' AND "T1"."OBJECT_NAME" IS NOT NULL))

原始 SQL 中使用了 FULL(t1)、FULL(t2) 和 USE_HASH(t1 t2) 这些 Hints，强制使用全表扫描 + 哈希连接。执行后 SQL_ID 为 g7ndz4jp2j3uh。

第二步：通过 COE_XFR_SQL_PROFILE脚本生成构建sql profile的脚本

复制代码

SQL>@coe_xfr_sql_profile.sql
Parameter 1:
SQL_ID (required)
Enter value for 1: g7ndz4jp2j3uh

PLAN_HASH_VALUE AVG_ET_SECS
--------------- -----------
     2959412835        .057

Parameter 2:
PLAN_HASH_VALUE (required)

Enter value for 2: 2959412835

Values passed to coe_xfr_sql_profile:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SQL_ID         : "g7ndz4jp2j3uh"
PLAN_HASH_VALUE: "2959412835"

......

Execute coe_xfr_sql_profile_g7ndz4jp2j3uh_2959412835.sql
on TARGET system in order to create a custom SQL Profile
with plan 2959412835 linked to adjusted sql_text.
COE_XFR_SQL_PROFILE completed.

第三步：构造目标 SQL（我们希望的执行计划）

构造一条在逻辑上和结构上与原始 SQL 完全相同的 SQL，但使用我们希望的执行计划：

sql 复制代码

SELECT /*+ new_sql index(t2) use_nl(t1 t2) */ t1.*, t2.owner
FROM t1, t2
WHERE t1.object_name LIKE '%T1%'
  AND t1.object_id = t2.object_id;

set linesize 200 pagesize 999
col sql_text format a40
SELECT sql_text, sql_id, hash_value, child_number,plan_hash_value
  FROM v$sql 
 WHERE sql_text LIKE '%new_sql%' 
   AND sql_text NOT LIKE '%v$sql%';


SQL_TEXT                                 SQL_ID        HASH_VALUE CHILD_NUMBER PLAN_HASH_VALUE
---------------------------------------- ------------- ---------- ------------ ---------------
SELECT /*+ new_sql index(t2) use_nl(t1 t 0sz1znbny6v0m 3923995667            0      1386590592
2) */ t1.*, t2.owner FROM t1, t2 WHERE t
1.object_name LIKE '%T1%'   AND t1.objec
t_id = t2.object_id

执行计划：

复制代码

select * from table(dbms_xplan.display_cursor('0sz1znbny6v0m','',''));
Plan hash value: 1386590592
---------------------------------------------------------------------------------------
| Id  | Operation                    | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |        |       |       |  5001K(100)|          |
|   1 |  NESTED LOOPS                |        |  2500K|    97M|  5001K  (1)| 16:40:18 |
|   2 |   NESTED LOOPS               |        |  2500K|    97M|  5001K  (1)| 16:40:18 |
|*  3 |    TABLE ACCESS FULL         | T1     |  2500K|    71M|   437  (84)| 00:00:06 |
|*  4 |    INDEX RANGE SCAN          | IND_T2 |     1 |       |     1   (0)| 00:00:01 |
|   5 |   TABLE ACCESS BY INDEX ROWID| T2     |     1 |    11 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------------------

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

   3 - filter(("T1"."OBJECT_NAME" LIKE '%T1%' AND "T1"."OBJECT_NAME" IS NOT NULL))
   4 - access("T1"."OBJECT_ID"="T2"."OBJECT_ID")

第四步：通过 COE_XFR_SQL_PROFILE脚本，提取构造 SQL 的SQL Profile

使用 coe_xfr_sql_profile.sql 脚本提取构造 SQL 的 Outline Data：

sql 复制代码

@coe_xfr_sql_profile.sql
-- 输入构造 SQL 的 SQL_ID（0sz1znbny6v0m）和 PLAN_HASH_VALUE（1386590592）
-- /*+ new_sql index(t2) use_nl(t1 t2) */SQL 的 Outline Data

SQL>@coe_xfr_sql_profile.sql
Parameter 1:
SQL_ID (required)
Enter value for 1: 0sz1znbny6v0m
PLAN_HASH_VALUE AVG_ET_SECS
--------------- -----------
     1386590592        .033
Parameter 2:
PLAN_HASH_VALUE (required)

Enter value for 2: 1386590592

Values passed to coe_xfr_sql_profile:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SQL_ID         : "0sz1znbny6v0m"
PLAN_HASH_VALUE: "1386590592"

......
SQL>SET TERM OFF;
Execute coe_xfr_sql_profile_0sz1znbny6v0m_1386590592.sql
on TARGET system in order to create a custom SQL Profile
with plan 1386590592 linked to adjusted sql_text.

COE_XFR_SQL_PROFILE completed.

生成的脚本 coe_xfr_sql_profile_0sz1znbny6v0m_1386590592.sql 中包含 Outline Data：

sql 复制代码

h := SYS.SQLPROF_ATTR(
q'[BEGIN_OUTLINE_DATA]',
q'[IGNORE_OPTIM_EMBEDDED_HINTS]',
q'[OPTIMIZER_FEATURES_ENABLE('11.2.0.4')]',
q'[DB_VERSION('11.2.0.4')]',
q'[ALL_ROWS]',
q'[OUTLINE_LEAF(@"SEL$1")]',
q'[FULL(@"SEL$1" "T1"@"SEL$1")]',
q'[INDEX(@"SEL$1" "T2"@"SEL$1" ("T2"."OBJECT_ID"))]',
q'[LEADING(@"SEL$1" "T1"@"SEL$1" "T2"@"SEL$1")]',
q'[USE_NL(@"SEL$1" "T2"@"SEL$1")]',
q'[NLJ_BATCHING(@"SEL$1" "T2"@"SEL$1")]',
q'[END_OUTLINE_DATA]');

第五步：修改第二步的脚本内容

针对原始 SQL（SQL_ID = g7ndz4jp2j3uh，PLAN_HASH_VALUE = 2959412835）使用 coe_xfr_sql_profile.sql 生成脚本。

然后手工修改 生成的脚本 coe_xfr_sql_profile_g7ndz4jp2j3uh_2959412835.sql：

将 h := SYS.SQLPROF_ATTR(...) 那段替换成第四步得到的 Outline Data。

复制代码

q'[BEGIN_OUTLINE_DATA]',
q'[IGNORE_OPTIM_EMBEDDED_HINTS]',
q'[OPTIMIZER_FEATURES_ENABLE('11.2.0.4')]',
q'[DB_VERSION('11.2.0.4')]',
q'[ALL_ROWS]',
q'[OUTLINE_LEAF(@"SEL$1")]',
q'[FULL(@"SEL$1" "T2"@"SEL$1")]',
q'[FULL(@"SEL$1" "T1"@"SEL$1")]',
q'[LEADING(@"SEL$1" "T2"@"SEL$1" "T1"@"SEL$1")]',
q'[USE_HASH(@"SEL$1" "T1"@"SEL$1")]',
q'[END_OUTLINE_DATA]');
改为
q'[BEGIN_OUTLINE_DATA]',
q'[IGNORE_OPTIM_EMBEDDED_HINTS]',
q'[OPTIMIZER_FEATURES_ENABLE('11.2.0.4')]',
q'[DB_VERSION('11.2.0.4')]',
q'[ALL_ROWS]',
q'[OUTLINE_LEAF(@"SEL$1")]',
q'[FULL(@"SEL$1" "T1"@"SEL$1")]',
q'[INDEX(@"SEL$1" "T2"@"SEL$1" ("T2"."OBJECT_ID"))]',
q'[LEADING(@"SEL$1" "T1"@"SEL$1" "T2"@"SEL$1")]',
q'[USE_NL(@"SEL$1" "T2"@"SEL$1")]',
q'[NLJ_BATCHING(@"SEL$1" "T2"@"SEL$1")]',
q'[END_OUTLINE_DATA]');

将 force_match 从 FALSE 改为 TRUE。

第六步：执行修改后的脚本

sql 复制代码

@@coe_xfr_sql_profile_g7ndz4jp2j3uh_2959412835.sql
PL/SQL 过程已成功完成。
            SIGNATURE
---------------------
 15211772502623681692
           SIGNATUREF
---------------------
  1099879712749910124
... manual custom SQL Profile has been created
COE_XFR_SQL_PROFILE_g7ndz4jp2j3uh_2959412835 completed

第七步：验证效果

执行原始 SQL：

sql 复制代码

SELECT /*+ old_sql full(t1) full(t2) use_hash(t1 t2) */ t1.*, t2.owner
 FROM t1, t2
 WHERE t1.object_name LIKE '%T1%'
 AND t1.object_id = t2.object_id;

set linesize 200 pagesize 999
col sql_text format a40
SELECT sql_text, sql_id, hash_value, child_number,plan_hash_value
  2    FROM v$sql 
  3   WHERE sql_text LIKE '%old_sql%' 
  4     AND sql_text NOT LIKE '%v$sql%';
SQL_TEXT                                 SQL_ID        HASH_VALUE CHILD_NUMBER PLAN_HASH_VALUE
---------------------------------------- ------------- ---------- ------------ ---------------
SELECT /*+ old_sql full(t1) full(t2) use g7ndz4jp2j3uh 1781043024            0      1386590592
_hash(t1 t2) */ t1.*, t2.owner FROM t1,
t2 WHERE t1.object_name LIKE '%T1%'   AN
D t1.object_id = t2.object_id

执行计划：

复制代码

SQL>select * from table(dbms_xplan.display_cursor('g7ndz4jp2j3uh','',''));
PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------------------------
SQL_ID  g7ndz4jp2j3uh, child number 0
-------------------------------------
SELECT /*+ old_sql full(t1) full(t2) use_hash(t1 t2) */ t1.*, t2.owner
FROM t1, t2 WHERE t1.object_name LIKE '%T1%'   AND t1.object_id =
t2.object_id
Plan hash value: 1386590592
---------------------------------------------------------------------------------------
| Id  | Operation                    | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |        |       |       |  5001K(100)|          |
|   1 |  NESTED LOOPS                |        |  2500K|    97M|  5001K  (1)| 16:40:18 |
|   2 |   NESTED LOOPS               |        |  2500K|    97M|  5001K  (1)| 16:40:18 |
|*  3 |    TABLE ACCESS FULL         | T1     |  2500K|    71M|   437  (84)| 00:00:06 |
|*  4 |    INDEX RANGE SCAN          | IND_T2 |     1 |       |     1   (0)| 00:00:01 |
|   5 |   TABLE ACCESS BY INDEX ROWID| T2     |     1 |    11 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   3 - filter(("T1"."OBJECT_NAME" LIKE '%T1%' AND "T1"."OBJECT_NAME" IS NOT   NULL))
   4 - access("T1"."OBJECT_ID"="T2"."OBJECT_ID")
Note
-----
   - SQL profile coe_g7ndz4jp2j3uh_2959412835 used for this statement

成功！ SQL Profile 起作用了，执行计划从全表扫描 + 哈希连接变成了嵌套循环连接 + 索引范围扫描。