The PGA is a memory region containing data and control information for a single process (server or background). One PGA is allocated for each server process; the PGA is exclusive to that server process and is read and written only by Oracle code acting on behalf of that process. A PGA is allocated by Oracle when a user connects to an Oracle database and a session is created.

This article explains how to know if PGA size is set properly through analysis with different performance views. Those views are:

• v$pgastat
• v$sql_workarea
• v$sql_workarea_histogram
• v$sesstat, v$sysstat, and v$statname

Please find complete article at attachment.