Program Global Area

A Program Global Area (PGA) is a memory area used by a single Oracle Database server process. When you connect to an Oracle database instance, you create a session that uses a server process for communication between the client and database instance. Each server process has its own PGA.

The PGA is used to process SQL statements and to hold logon and other session information. A large part of the PGA is dedicated to SQL work areas, which are working memory areas for sorts and other SQL operations.

The amount of PGA memory used and the contents of the PGA depend on whether the instance is running in dedicated server or shared server mode.

The total memory used by all individual PGAs is known as the total instance PGA memory, and the collection of individual PGAs is referred to as the total instance PGA, or just instance PGA. With Database Control, you set the size of the instance PGA, not individual PGAs.