性能优化 Oracle如何固定执行计划 SQL PROFILE概要文件分析
1. 引子
Oracle系统为了合理分配和使用系统的资源提出了概要文件的概念。所谓概要文件，就是一份描述如何使用系统的资源(主要是CPU资源)的配置文件。将概要文件赋予某个数据库用户，在用户连接并访问数据库服务器时，系统就按照概要文件给他分配资源。
包括:
1、管理数据库系统资源。
利用Profile来分配资源限额，必须把初始化参数resource_limit设置为true默认是TRUE的。
2、管理数据库口令及验证方式。
默认给用户分配的是DEFAULT概要文件，将该文件赋予了每个创建的用户。但该文件对资源没有任何限制，因此管理员常常需要根据自己数据库系统的环境自行建立概要文件。
2. 概要文件限制
概要文件主要可以对数据库系统如下指标进行限制。
1）用户的最大并发会话数（SESSION_PER_USER)
2）每个会话的CPU时钟限制（CPU_PER_SESSION）
3）每次调用的CPU时钟限制，调用包含解析、执行命令和获取数据等等。（CPU_PER_CALL）
4）最长连接时间。一个会话的连接时间超过指定时间之后，Oracle会自动的断开连接（CONNECT_TIME）
5）最长空闲时间。如果一个会话处于空闲状态超过指定时间，Oracle会自动断开连接（IDLE_TIME）
6）每个会话可以读取的最大数据块数量（LOGICAL_READS_PER_SESSION）
7）每次调用可以读取的最大数据块数量（LOGICAL_READS_PER_CALL）
8）SGA私有区域的最大容量（PRIVATE_SGA）
概要文件对口令的定义和限制如下：
1）登录失败的最大尝试次数（FAILED_LOGIN_ATTEMPTS）
2）口令的最长有效期(PASSWORD_LIFE_TIME)
3）口令在可以重用之前必须修改的次数(PASSWORD_REUSE_MAX)
4）口令在可以重用之前必须经过的天数(PASSWORD_REUSE_TIME)
5）超过登录失败的最大允许尝试次数后，账户被锁定的天数
6）指定用于判断口令复杂度的函数名
在指定概要文件之后，DBA可以手工的将概要文件赋予每个用户。但是概要文件不是立即生效，而是要将初始化参数文件中的参数RESOURCE_LIMIT设置为TRUE之后，概要文件才会生效。
3. SQL PROFILE
SQL PROFILE在ORACLE10g中引入，主要目的侧重于SQL优化，弥补了存储概要的缺点.
DBA可以使用SQL调整顾问(STA)或SQL访问顾问(SAA)来识别可以得到更好性能的SQL语句，
这些语句可以保存在SQL调整集、一个AWR快照或保存在当前的库缓存中，一旦识别出调整候选者， 这些顾问程序就开始分析捕获到的语句以期获得更好的性能，然后生成专用的语句扩展(就叫做SQL配置文件)并重写SQL语句以在执行期间获取更佳的性能。
与存储概要类似，一个SQL配置文件提供了使用更好的执行计划的能力(如果这个执行计
划是可用的)，SQL配置文件也可以象存储概要一样分阶段执行，或限制到对特定会话才能执行该SQL配置文件，但是大多数重要的改进超过了存储概要.
SQLProfile对于一下类型语句有效：
SELECT语句；
UPDATE语句；
INSERT语句（仅当使用SELECT子句时有效）；
DELETE语句；
CREATE语句（仅当使用SELECT子句时有效）；
MERGE语句（仅当作UPDATE和INSERT操作时有效）。
另外，使用SQL Profile还必须有CREATE ANY SQL PROFILE、DROP ANY SQL PROFILE和ALTER ANY SQL PROFILE等系统权限。
4. 测试一
创建表
tpcc@TOADDB> create table t1 as selectobject_id,object_name from dba_objects where rownum<=50000;
Table created.
tpcc@TOADDB> create table t2 as select * fromdba_objects;
Table created.
创建索引：
tpcc@TOADDB> create index t2_idx on t2(object_id);
Index created.
收集统计信息：
tpcc@TOADDB> execdbms_stats.gather_table_stats(user,’t1′,cascade=>true,method_opt=>’forall columns size 1′);
PL/SQL procedure successfully completed.
tpcc@TOADDB> execdbms_stats.gather_table_stats(user,’t1′,cascade=>true,method_opt=>’forall columns size 1′);
PL/SQL procedure successfully completed.
执行无HINT的SQL
tpcc@TOADDB> set autotrace on
tpcc@TOADDB> select t1.*,t2.owner from t1,t2 wheret1.object_name like ‘%T1%’ and t1.object_id=t2.object_id;
42 rows selected.
Execution Plan
———————————————————-
Plan hash value: 1838229974
—————————————————————————
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
—————————————————————————
| 0| SELECT STATEMENT | | 2500 | 97K| 498 (1)| 00:00:01 |
|* 1| HASH JOIN | | 2500 | 97K| 498 (1)| 00:00:01 |
|* 2| TABLE ACCESS FULL| T1 | 2500 | 72500 | 68 (0)| 00:00:01 |
| 3| TABLE ACCESS FULL| T2 | 92021 | 988K| 430 (1)| 00:00:01 |
—————————————————————————
Predicate Information (identified byoperation id):
—————————————————
1-access(“T1″.”OBJECT_ID”=”T2″.”OBJECT_ID”)
2- filter(“T1″.”OBJECT_NAME” LIKE ‘%T1%’ AND”T1″.”OBJECT_NAME” IS
NOT NULL)
Statistics
———————————————————-
1 recursive calls
0 dbblock gets
1789 consistent gets
0 physical reads
0 redosize
2350 bytes sent via SQL*Net toclient
573 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
42 rowsprocessed
执行带Hint的SQL
SQL>select /*+ use_nl(t1 t2) index(t2)*/ t1.*,t2.owner from t1,t2 where t1.object_name like ‘%T1%’ and t1.object_id=t2.object_id;
42 rows selected.
Execution Plan
———————————————————-
Plan hash value: 1022743391
—————————————————————————————
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|Time |
—————————————————————————————
| 0| SELECT STATEMENT | | 2500 | 97K| 5069 (1)|00:00:01 |
| 1| NESTED LOOPS | | 2500| 97K| 5069 (1)| 00:00:01 |
| 2| NESTED LOOPS | | 2500 | 97K| 5069 (1)| 00:00:01 |
|* 3| TABLE ACCESS FULL | T1 | 2500 | 72500 | 68 (0)|00:00:01 |
|* 4| INDEX RANGE SCAN |T2_IDX | 1 | | 1 (0)| 00:00:01 |
| 5| TABLE ACCESS BY INDEX ROWID| T2 | 1 | 11 | 2 (0)|00:00:01 |
—————————————————————————————
Predicate Information (identified byoperation id):
—————————————————
3- filter(“T1″.”OBJECT_NAME” LIKE ‘%T1%’ AND”T1″.”OBJECT_NAME” IS NOT
NULL)
4-access(“T1″.”OBJECT_ID”=”T2″.”OBJECT_ID”)
Statistics
———————————————————-
1 recursive calls
0 dbblock gets
304 consistent gets
24 physical reads
0 redosize
2350 bytes sent via SQL*Net toclient
573 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
42 rowsprocessed
使用SQL PROFILE
查找执行SQL的SQL_ID
tpcc@TOADDB> select sql_id,sql_text from v$sqlwhere sql_text like ‘%t1.object_name%’;
SQL_ID
————-
SQL_TEXT
—————————————————————————————————-
4zbqykx89yc8v
select t1.*,t2.owner from t1,t2 wheret1.object_name like ‘%T1%’ and t1.object_id=t2.object_id
18bphz37dajq9
select /*+ use_nl(t1 t2) index(t2) */t1.*,t2.owner from t1,t2 where t1.object_name like ‘%T1%’ and
t1.object_id=t2.object_id
运行存储过程如下：
var tuning_task varchar2(100);
DECLARE
l_sql_id v$session.prev_sql_id%TYPE;
l_tuning_task VARCHAR2(30);
BEGIN
l_sql_id:=’4zbqykx89yc8v’;
l_tuning_task := dbms_sqltune.create_tuning_task(sql_id =>l_sql_id);
:tuning_task:=l_tuning_task;
dbms_sqltune.execute_tuning_task(l_tuning_task);
dbms_output.put_line(l_tuning_task);
END;
/
TASK_114
PL/SQL procedure successfully completed.
查看task的名字
tpcc@TOADDB> print tuning_task;
TUNING_TASK
—————————————————————————————————-
TASK_114
查看执行报告
set long 99999
col comments format a200
SELECT dbms_sqltune.report_tuning_task(:tuning_task)COMMENTS FROM dual;
COMMENTS
—————————————————————————————————-
GENERAL INFORMATION SECTION
——————————————————————————-
Tuning Task Name : TASK_114
Tuning Task Owner : TPCC
Workload Type : Single SQL Statement
Scope : COMPREHENSIVE
Time Limit(seconds): 1800
Completion Status : COMPLETED
Started at : 03/06/2016 05:27:21
Completed at : 03/06/2016 05:27:24
——————————————————————————-
Schema Name: TPCC
SQL ID : 4zbqykx89yc8v
SQL Text : select t1.*,t2.owner from t1,t2 where t1.object_name like ‘%T1%’
and t1.object_id=t2.object_id
——————————————————————————-
FINDINGS SECTION (1 finding)
——————————————————————————-
1- SQL Profile Finding (see explain planssection below)
——————————————————–
Apotentially better execution plan was found for this statement.
Recommendation (estimated benefit: 83.08%)
——————————————
-Consider accepting the recommended SQL profile.
executedbms_sqltune.accept_sql_profile(task_name => ‘TASK_114′,
task_owner =>’TPCC’, replace => TRUE);
Validation results
——————
TheSQL profile was tested by executing both its plan and the original plan
andmeasuring their respective execution statistics. A plan may have been
only partially executed if the other could be run to completion in lesstime.
Original Plan With SQL Profile % Improved
————- —————- ———-
Completion Status: COMPLETE COMPLETE
Elapsed Time (s): .012865 .004556 64.58 %
CPUTime (s): .0124 .0045 63.7%
User I/O Time (s): 0 0
Buffer Gets: 1787 302 83.1%
Physical Read Requests: 0 0
Physical Write Requests: 0 0
Physical Read Bytes: 0 0
Physical Write Bytes: 0 0
Rows Processed: 42 42
Fetches: 42 42
Executions: 1 1
Notes
—–
1.Statistics for the original plan were averaged over 10 executions.
2.Statistics for the SQL profile plan were averaged over 10 executions.
——————————————————————————-
EXPLAIN PLANS SECTION
——————————————————————————-
1- Original With Adjusted Cost
——————————
Plan hash value: 1838229974
—————————————————————————
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
—————————————————————————
| 0| SELECT STATEMENT | | 42 | 1680 | 498 (1)| 00:00:01 |
|* 1| HASH JOIN | | 42 | 1680 | 498 (1)| 00:00:01 |
|* 2| TABLE ACCESS FULL| T1 | 42 | 1218 | 68 (0)| 00:00:01 |
| 3| TABLE ACCESS FULL| T2 | 92021 | 988K| 430 (1)| 00:00:01 |
—————————————————————————
Predicate Information (identified byoperation id):
—————————————————
1-access(“T1″.”OBJECT_ID”=”T2″.”OBJECT_ID”)
2- filter(“T1″.”OBJECT_NAME” LIKE ‘%T1%’ AND”T1″.”OBJECT_NAME” IS
NOT NULL)
2- Using SQL Profile
——————–
Plan hash value: 1022743391
—————————————————————————————
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|Time |
—————————————————————————————
| 0| SELECT STATEMENT | | 42 | 1680 | 152 (0)|00:00:01 |
| 1| NESTED LOOPS | | 42 | 1680 | 152 (0)| 00:00:01 |
| 2| NESTED LOOPS | | 42 | 1680 | 152 (0)| 00:00:01 |
|* 3| TABLE ACCESS FULL | T1 | 42 | 1218 | 68 (0)| 00:00:01 |
|* 4| INDEX RANGE SCAN |T2_IDX | 1 | | 1 (0)| 00:00:01 |
| 5| TABLE ACCESS BY INDEX ROWID| T2 | 1 | 11 | 2 (0)|00:00:01 |
—————————————————————————————
Predicate Information (identified byoperation id):
—————————————————
3- filter(“T1″.”OBJECT_NAME” LIKE ‘%T1%’ AND”T1″.”OBJECT_NAME” IS NOT
NULL)
4-access(“T1″.”OBJECT_ID”=”T2″.”OBJECT_ID”)
——————————————————————————-
接受分析建议
报告中给出了执行方法，如上红色部分
接受报告的建议，验证一下如下：
tpcc@TOADDB> execute dbms_sqltune.accept_sql_profile(task_name=> ‘TASK_114’,task_owner => ‘TPCC’, replace => TRUE);
PL/SQL procedure successfully completed.
执行测试
再执行原先命令如下：
tpcc@TOADDB> select t1.*,t2.owner from t1,t2 wheret1.object_name like ‘%T1%’ and t1.object_id=t2.object_id;
42 rows selected.
Execution Plan
———————————————————-
Plan hash value: 1022743391
—————————————————————————————
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|Time |
—————————————————————————————
| 0| SELECT STATEMENT | | 42 | 1680 | 152 (0)|00:00:01 |
| 1| NESTED LOOPS | | 42| 1680 | 152 (0)|00:00:01 |
| 2| NESTED LOOPS | | 42 | 1680 | 152 (0)| 00:00:01 |
|* 3| TABLE ACCESS FULL | T1 | 42 | 1218 | 68 (0)| 00:00:01 |
|* 4| INDEX RANGE SCAN |T2_IDX | 1 | | 1 (0)| 00:00:01 |
| 5| TABLE ACCESS BY INDEX ROWID| T2 | 1 | 11 | 2 (0)|00:00:01 |
—————————————————————————————
Predicate Information (identified byoperation 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”SYS_SQLPROF_01534b8309b90000″ used for this statement
– this is an adaptive plan
Statistics
———————————————————-
35 recursive calls
0 dbblock gets
317 consistent gets
1 physical reads
0 redosize
2350 bytes sent via SQL*Net toclient
573 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
42 rowsprocessed
启用了PROFILE，PS：如果执行中多加几个空格，并不会影响PROFILE的生效的。
5. 维护操作
禁用命令
如下：
begin
dbms_sqltune.alter_sql_profile(
name => ‘SYS_SQLPROF_01534b8309b90000’,
attribute_name => ‘status’,
value => ‘disabled’);
end;
/
启用命令
如下：
begin
dbms_sqltune.alter_sql_profile(
name => ‘SYS_SQLPROF_01534b8309b90000’,
attribute_name => ‘status’,
value => ‘enabled’);
end;
/
查看使用的PROFILE
如下：
SQL>SELECT task_name,status FROMUSER_ADVISOR_TASKS ;
删除PROFILE
BEGIN
DBMS_SQLTUNE.DROP_SQL_PROFILE(name => ‘SYS_SQLPROF_01534b8309b90000’);
END;
总结
以上所述是小编给大家介绍的Oracle固定执行计划之SQL PROFILE概要文件 ，大家如有疑问可以留言，或者联系站长。感谢亲们支持！！！
