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Components and Granules in the SGA

翻译 Oracle 作者:wanghanjun 时间:2015-12-31 11:12:49 0 删除 编辑

The SGA comprises several memory components, which are pools of memory used to satisfy a particular class of memory allocation requests. Examples of memory components include the shared pool (used to allocate memory for SQL and PL/SQL execution), the java pool (used for java objects and other java execution memory), and the buffer cache (used for caching disk blocks). All SGA components allocate and deallocate space in units of granules. Oracle Database tracks SGA memory use in internal numbers of granules for each SGA component.
SGA由几个不同的内存组件构成,它是一个内存吃用于满足特殊级别的内存分配请求.例如共享池,用于SQL和PL/SQL的运行,java pool,用于java对象和其他java执行.以及缓存池,用于缓存磁盘数据.所有的SGA的分配和回收都已granules为一个单元.Oracle追踪SGA的使用也是以granules来进行的                                                                  

The memory for dynamic components in the SGA is allocated in the unit of granules. The granule size is determined by the amount of SGA memory requested when the instance starts. Specifically, the granule size is based on the value of the SGA_MAX_SIZE initialization parameter. Table 6-1 shows the granule size for different amounts of SGA memory.
SGA的动态组件也是以granules来进行调配的.granule的大小由SGA的内存大小来决定,尤其是SGA_MAX_SIZE,下图给出granlu的尺寸大小

Table 6-1 Granule Size



Some platform dependencies may arise. Consult your operating system specific documentation for more details.
有一些平台由于关联关系会和这个不同.请咨询OS管理员                                                         

You can query the V$SGAINFO view to see the granule size that is being used by an instance. The same granule size is used for all components in the SGA.

If you specify a size for a component that is not a multiple of granule size, Oracle Database rounds the specified size up to the nearest multiple. For example, if the granule size is 4 MB and you specify DB_CACHE_SIZE as 10 MB, the database actually allocates 12 MB.
你可以通过V$SGAINFO来确定当前的granule的大小.不同的组件使用相同的granule.如果你指定的其中一个组件的大小不能并不是granule的倍数,那么Oracle会将这个值近似成granule的倍数                                                                                                                                                              

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