通道参数实际上更像是全局区，只不过在模板调用栈中可以改变它的值。

Tunnel parameters are actually more like a global pool, except you can change a value as you go further in your stack of template invocations.

youdao

这是因为Oracle使用了大量的虚拟内存，特别是对于其系统全局区(SGA)。

This is because Oracle USES a lot of virtual memory, particularly with respect to its System Global Area (SGA).

youdao

数据库也会为服务器进程分配私有的内存空间，这块空间叫做PGA(程序全局区)，那里存放着私有的进程和会话信息。

It will also allocate a private memory area called PGA, where it stores what is private to the process and to the session.

youdao