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Overview of the Program Global Area (PGA)

翻译 Oracle 作者:wanghanjun 时间:2015-12-31 16:56:42 0 删除 编辑

The PGA is memory specific to an operating process or thread that is not shared by other processes or threads on the system. Because the PGA is process-specific, it is never allocated in the SGA.
PGA是一个进程或者县城的独占内存区域.因为PGA是与指定进程有关系的  ,所以它不会在SGA出现.                                                                                                     

The PGA is a memory heap that contains session-dependent variables required by a dedicated or shared server process. The server process allocates memory structures that it requires in the PGA.

An analogy for a PGA is a temporary countertop workspace used by a file clerk. In this analogy, the file clerk is the server process doing work on behalf of the customer (client process). The clerk clears a section of the countertop, uses the workspace to store details about the customer request and to sort the folders requested by the customer, and then gives up the space when the work is done.
有一个PGA的比喻, PGA好比是一个档案管理员的临时台面,档案管理员是一个服务器进程,代表客户在做事情.这个档案管理员收拾好台面的一部分,用存放于客户请求相关的所有内容,然后收回这个区域当工作完成以后.

Figure 14-3 shows an instance PGA (collection of all PGAs) for an instance that is not configured for shared servers. You can use an initialization parameter to set a target maximum size of the instance PGA (see "Summary of Memory Management Methods"). Individual PGAs can grow as needed up to this target size.

Figure 14-3 Instance PGA
De.ion of

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