User Global Area

The UGA is session memory, which is memory allocated for session variables, such as logon information, and other information required by a database session. Essentially, the UGA stores the session state.

Within the Program Global Area, the UGA is a part of the RAM heap in the PGA that controls user sessions space for sorting and hash joins Within the MTS (shared servers), the UGA is in the SGA large pool.

UGA memory is assoicated with your session, it can be found in the PGA or SGA depending on whether you are connected to the database via shared server

Shared Server – the UGA will be in the SGA
Dedicated Server – the UGA will be in the PGA