In the database management systems developed by the Oracle Corporation, the System Global Area (SGA) forms the part of the system memory (RAM) shared by all the processes belonging to a single Oracle database instance.
In general, the SGA consists of the following: From Oracle Database version 10g, Automatic Memory Management (AMM) allows simplified and dynamic configuration of the SGA.
[2] In the Oracle DBMS, the Oracle server allocates the system global area (SGA) in granule units at the time of instance startup.
The granule size depends on the database version and sometimes on the operating system.
It is possible to retrieve information about the current granule size at any time by querying the dynamic view V$SGAINFO.