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
野外生存知识:各类绳结的打法及用途
2011-11-04
OutLook Express关闭时提示压缩解决方法
2009-07-02
以后上大学不用发愁了,高考或许取消~~高兴啊
2009-06-24
[转]解决夫妻矛盾的最佳五步骤
2010-06-22
[转]教你照相时该怎么摆Pose
2010-06-01
经典的车型,越看越喜欢……
2009-11-20
平平谈谈才是真
2009-05-12
英报:“中国文明”将覆盖全世界
2009-06-30
微软的面试题及答案 (试题篇)
2009-07-17
不想看南京南京
2009-05-25
使用google免费移动产品:免费的天气预报
2009-09-18
我的流水帐
2003-03-20
七十三、八十四,阎王不叫自己去。
2009-12-23
Delphi错误“RichEdit Line inserti
2009-08-14
DevCon 命令与批处理自动禁用启用网卡
2010-01-22
发现猫腻小说的一个惊天秘密
2010-01-09
Oracle硬解析(hard prase)和软解析(soft
2009-11-25
[待录]买车过程
2010-08-19
[存档]42种方法全面提升宝宝的智能
2011-03-21
oracle9i,oracle10g如何切换使用spfile
2010-03-24
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