Instance Memory Structure

Instance Memory Structure

The size of these structures affects the performance of the Oracle database server and is controlled by initialization parameters. These initialization parameters can be categorized as memory parameters. When a database is created with DBCA, the memory parameters are automatically set to optimal values based on your specification of the database workload. However, as your database usage expands, you might find it necessary to alter the settings of the memory parameters. Oracle provides alerts and advisors to identify memory sizing problems and to help you determine appropriate values for memory parameters. Oracle’s memory structure consists of two memory areas known as:

• System Global Area (SGA): Allocated at instance startup, and is a fundamental component of an Oracle Instance

• Program Global Area (PGA): Allocated when the server process is started