今天看到一ocp的题有点疑问，就做了个小实验，碰到了ORA-02097、ORA-00837两个错误；
题如下：
Q484. You set the following parameters in the parameter fileand restarted the database:
MEMORY_MAX_TARGET=0
MEMORY_TARGET=500M
PGA_AGGREGATE_TARGET=90M
SGA_TARGET=270M
Which two statements are true regarding these parameters afterthe database instance is restarted? (Choose two.)
A. The MEMORY_MAX_TARGET parameter is automatically set to500 MB.
B. The value of the MEMORY_MAX_TARGET parameter remains zerotill it is changed manually.
C. The PGA_AGGREGATE_TARGET and SGA_TARGET parameters areautomatically set to zero.
D. The lower bounds of PGA_AGGREGATE_TARGET and SGA_TARGETparameters are set to 90 MB and 270 MB, respectively.
Answer: A,D
我以为应该B正确而不是A；经过实验，答案却是没问题；
实验过程
Microsoft Windows XP [版本 5.1.2600]
(C) 版权所有 1985-2001 Microsoft Corp.
C:Documents and SettingsAdministrator>
SQL*Plus: Release 11.2.0.1.0 Production on 星期六 8月 3 09:54:47 2013
Copyright (c) 1982, 2010, Oracle. All rights reserved.
连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
hi_shared_memory_address integer 0
memory_max_target big integer 0
memory_target big integer 0
shared_memory_address integer 0
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 194M
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 800M
sga_target big integer 700M
出现错误的地方：
SQL> scope=both
alter system set memory_target=900M scope=both
*
第 1 行出现错误:
无法修改参数, 因为指定的值无效
指定的值 MEMORY_TARGET 大于 MEMORY_MAX_TARGET
既然不能对现有的值做调整，那就改用重启后生效的策略
SQL> scope=spfile
系统已更改。
看来，这样是可以的，在重启前建议先创建一个pfile,以免启动不起来时能够手工调整
SQL>
文件已创建。
SQL>
数据库已经关闭。
已经卸载数据库。
ORACLE 例程已经关闭。
SQL> startup
ORACLE 例程已经启动。
Total System Global Area 836976640 bytes
Fixed Size 1377812 bytes
Variable Size 683674092 bytes
Database Buffers 146800640 bytes
Redo Buffers 5124096 bytes
数据库装载完毕。
数据库已经打开。
看来是修改成功了，接下来看看出现了什么情况
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
hi_shared_memory_address integer 0
memory_max_target big integer 900M
memory_target big integer 900M
shared_memory_address integer 0
memory_max_target 已经被自动调整到900M
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 194M
SQL>
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 800M
sga_target big integer 700M
pga_aggregate_target 和 sga_target 保持不变