Expert Oracle Database Architecture: 9i and 10g Programming Techniques and Solutions

CHAPTER 4Memory 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, and is not accessible from other processes/threads.
• User Global Area (UGA): This is memory associated with your session. It will be found either in the SGA or the PGA depending on whether you are connected to the database using shared server (then it will be in the SGA), or dedicated server (it will be in the PGA, in the process memory).

Note In earlier releases of Oracle, shared server was referred to as Multi-Threaded ...