Chapter 4. Memory Structures

In this chapter, we'll look at Oracle's three major memory structures:

  • System Global Area (SGA): This is a large, shared memory segment that virtually all Oracle processes will access at one point or another.

  • Process Global Area (PGA): This is memory that is private to a single process or thread; it is not accessible from other processes/threads.

  • User Global Area (UGA): This is memory associated with your session. It is located either in the SGA or the PGA, depending whether you are connected to the database using a shared server (it will be in the SGA), or a dedicated server (it will be in the PGA).

Note

In earlier releases of Oracle, shared server was referred to as Multi-Threaded Server or MTS. In this book, we will ...

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