What is the PGA memory
An additional memory structure called PGA (Global Area Program) is created for each logged in user.
PGA stores user session specific control information such as private areas for cursor processing, bind variables, session information, sort area ...
Each server process has its own private PGA memory which is exclusively reserved for it.
When the user process disconnects (end of session), the associated server process ends and the PGA memory is freed.
N.B: In a shared server configuration:
a server process handles requests from multiple user processes.
a global amount of PGA memory can be allocated to the Oracle instance through the PGA_AGGREGATE_TARGET initialization parameter.
Depending on the technical architecture of the application, the user process exists, either on the user's PC (in the case of a client / server application) or on the application server of the intermediate level (middle-tier) in the case of an n-tier application.
To learn more about the components and basic concepts of the Oracle architecture, take look at our Expert DBA Team Club blog and more advance topics are available at this source.
