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[每日一题] 11gOCP 1z0-052 :2013-09-23 Oracle11g 内存参数设置

[每日一题] 11gOCP 1z0-052 :2013-09-23 Oracle11g 内存参数设置
 

 
正确答案:CD(题库给出的答案是AD,大家要相信自己,有些答案是错的!一切以实战为依据)
 
一、我们先来看Oracle 11g内存架构图,来自OCP教材:
 
 
二、内存参数的一些关系:
memory_max_target、 memory_target、sga_max_size、sga_target、pga_aggregate_target
  1、   sga_target=0 ,pga_aggregate_target=0 -〉完全自动管理,SGA=memory_target*60%   PGA=memory_target*40%
  2、   sga_target=600(最小值) ,pga_aggregate_target=200(最小值) -〉memory_target=sga_target+pga_aggregate_target
   3、  sga_target=600,pga_aggregate_target=0  -〉pga_aggregate_target=memory_target-sga_target
   4、  sga_target=0,pga_aggregate_target=200  -〉sga_target=memory_target-pga_aggregate_target
 
了解了内存的基本知识后,我们一起来解题:
答案A,不正确
 
 
根据题意,我们来实验一把:
1、设置参数
[html]
sys@OCM> alter system set memory_max_target=0 scope=spfile;  
  
System altered.  
  
sys@OCM> alter system set memory_target=804M;  
  
System altered.  
  
sys@OCM> alter system set pga_aggregate_target=90M;  
  
System altered.  
  
sys@OCM> alter system set sga_target=270M;  
  
System altered.  
 
2、重启数据库,报错如下
[html]
sys@OCM> startup force;  
ORA-00837: Specified value of MEMORY_TARGET greater than MEMORY_MAX_TARGET  
sys@OCM> show parameter mem  
ORA-01034: ORACLE not available  
Process ID: 0  
Session ID: 148 Serial number: 493  
 
3、  从spfile创建出一个pfile
[html]
sys@OCM> create pfile='/tmp/pfile.ora' from spfile;  
ERROR:  
OCI-21710: argument is expecting a valid memory address of an object  
  
  
  
File created.  
 
 
4、  查pfile中memory_max_target的值,结果看到:
[html]
[root@mydb tmp]# more /temp/pfile.ora  
ocm.__db_cache_size=343932928  
ocm.__java_pool_size=4194304  
ocm.__large_pool_size=4194304  
ocm.__oracle_base='/u01/app/oracle'#ORACLE_BASE set from environment  
ocm.__pga_aggregate_target=159383552  
ocm.__sga_target=683671552  
ocm.__shared_io_pool_size=0  
ocm.__shared_pool_size=314572800  
ocm.__streams_pool_size=4194304  
*.audit_file_dest='/u01/app/oracle/admin/ocm/adump'  
*.audit_trail='db'  
*.compatible='11.2.0.0.0'  
*.control_files='/u01/app/oracle/oradata/ocm/control01.ctl','/u01/app/oracle/oradata/ocm/control02.ctl'  
*.db_block_size=8192  
*.db_domain=''  
*.db_name='ocm'  
*.diagnostic_dest='/u01/app/oracle'  
*.dispatchers='(PROTOCOL=TCP) (SERVICE=ocmXDB)'  
*.log_archive_dest_1='location=/arch'  
*.memory_max_target=0  
*.memory_target=842006528  
*.open_cursors=300  
*.pga_aggregate_target=94371840  
*.processes=150  
*.remote_login_passwordfile='EXCLUSIVE'  
*.sga_target=285212672  
*.undo_tablespace='UNDOTBS1'  
 
  从上面的参数可以看出memory_max_target=0,还没有自动变为804M,所以不正确。实际上memory_max_target是控制memory_target的值不能超过它。
答案B,不正确,我们从上面的参数可以看出:pga_aggregate_target=94371840和sga_target=285212672,而并非为0
 
答案C,正确,从下面的参数可以看出.memory_max_target=0,除非手功改变
 
答案D,正确,上面的参数可以看出:pga_aggregate_target=94371840和sga_target=285212672
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