[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

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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

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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

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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：

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[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