51.In a system, large online transaction processing (OLTP) jobs run during the daytime that require

51.In a system, large online transaction processing (OLTP) jobs run during the daytime that require a

large database buffer cache. In the night, the system supports batch jobs that require a higher value to be

set for the large pool. You must simultaneously configure the memory components to accommodate the

peak requirement.

What would you do to automate this configuration for the memory components with change in mode of

working?

A.Set the SGA_TARGET initialization parameter to zero.

B.Set the PRE_PAGE_SGA initialization parameter to TRUE.

C.Set the MEMORY_MAX_TARGET initialization parameter to zero.

D.Set the SGA_TARGET initialization parameter to a nonzero value.

答案：D

解析：这道题的意思是白天需要大的buffer cache，晚上需要大的large pool，需要设置什么

这个其实是asmm的功能给

ASMM(automatic shared memory management) 自动共享内存管理
1.除了sga_target,sga_max_size,lock_sga,pre_page_sga需要静态调整外，其他都可以动态调整
2.启用方法是需要将sga_target 设置为非0，同时将statistics_level设置为typical或者all

   3.如果使用了自动共享内存管理，下面这些缓存区就不需要在进行设置了,他们会自动设置为0

          i.db_cache_size

          ii.shared_pool_size

          iii.large_pool_size

          iv.java_pool_size

          v.streams_pool

    4.尽管使用了assm，还是可以设置缓存区大小的，设置后表示的是该缓存区的下限值，即orale任何时候

    该缓存区都应该不小于这个值，至少预留这么大的空间

具体设置步骤

   1.运行如下语句进行查询应该设置的sga_target

     SELECT (

    (SELECT SUM(value) FROM V$SGA) -

    (SELECT CURRENT_SIZE FROM V$SGA_DYNAMIC_FREE_MEMORY)

    ) "SGA_TARGET"
FROM DUAL; 
2.设置sga的值
  ALTER SYSTEM SET SGA_TARGET=value [SCOPE={SPFILE|MEMORY|BOTH}]
3.将上面那5个缓存参数设置为0(如果设置为其他值表示的是最小值)

--因此选择D