关于oracle 10g中参数optimizer_mode的测试
感到很疑惑:真的是这样么,10g中的rule和choose是无效的选项?
但我测试时,也能设置choose啊,而且执行计划和all_Rows确实不一样啊!
问了一下网上的朋友,又作了些测试如下,结果也在下面:
C:Documents and SettingsAdministrator>sqlplus system/manager
SQL*Plus: Release 10.2.0.1.0 - Production on 星期五 3月 19 14:06:01 2010
Copyright (c) 1982, 2005, Oracle. All rights reserved.
连接到:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> show parameter optimizer_mode
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
optimizer_mode string ALL_ROWS
SQL> alter session set optimizer_mode=rule;
会话已更改。
SQL> show parameter optimizer_mode
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
optimizer_mode string RULE
SQL> set autotrace on
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
执行计划
----------------------------------------------------------
Plan hash value: 1078166315
--------------------------------------
| Id | Operation | Name |
--------------------------------------
| 0 | SELECT STATEMENT | |
|* 1 | FIXED TABLE FULL| X$VERSION |
--------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("INST_ID"=USERENV('INSTANCE'))
Note
-----
- rule based optimizer used (consider using cbo) --Oracle给出的提示
统计信息
----------------------------------------------------------
8 recursive calls
0 db block gets
2 consistent gets
0 physical reads
0 redo size
680 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
5 rows processed
SQL> alter session set optimizer_mode=chooose;
ERROR:
ORA-00096: 值 CHOOOSE 对参数 optimizer_mode 无效, 它必须来自 first_rows_1000,
first_rows_100, first_rows_10, first_rows_1, first_rows, all_rows, choose, rule之间
-->一次错误输入,得到了参数的选项值
SQL> alter session set optimizer_mode=choose;
会话已更改。
SQL> show parameter optimizer_mode
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
optimizer_mode string CHOOSE
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
执行计划
----------------------------------------------------------
Plan hash value: 1078166315
--------------------------------------
| Id | Operation | Name |
--------------------------------------
| 0 | SELECT STATEMENT | |
|* 1 | FIXED TABLE FULL| X$VERSION |
--------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("INST_ID"=USERENV('INSTANCE'))
Note
-----
- rule based optimizer used (consider using cbo) --Oracle给出的提示
统计信息
---------------------------
Tag:
Oracle
Oracle基础
TTTBLOG
dbms_privilege_capture使用案例
2021-01-11
<濒湖脉学白话解>复印说明
2004-02-02
[转]Linux 下NEWS server(INN)架设全过
2010-05-21
OutLook Express关闭时提示压缩解决方法
2009-07-02
数据库系统性能优化(应用程序优化)
2009-08-19
转一篇朋友的诗歌:六月的遐思
2009-06-21
北京地铁将延伸进河北1100公里
2010-11-12
野外生存知识:各类绳结的打法及用途
2011-11-04
关于oracle数据库性能监控指标
2023-01-06
学习笔记:oracle数据字典详解
2010-03-15
各地2009高考零分作文
2009-07-18
真是没有人性,该死的警察……
2010-06-03
Redhat Linux安装拼音五笔中文输入法
2010-04-28
我和女儿大胆的北京一日游~~
2009-08-03
[转]解决夫妻矛盾的最佳五步骤
2010-06-22
在博客上加GFC模块,未果~~
2009-07-30
Delphi错误“RichEdit Line inserti
2009-08-14
09年最经典的动画--打,打个大西瓜(经典国产)
2009-10-24
今天,在资料上看到如下内容:
相关内容
评论
热门推荐
最新主题