In Oracle what is system global area and how is it organized?
The SGA is a collection of shared memory fields which along with the Oracle processes constitute an Oracle instance. All SGA components allocate and deallocate space within units of granules. Granule size is determined through total SGA size. On most platforms, the size of a granule is 4 MB if the total size of SGA is less than 1 GB, and granule size is 16MB for larger SGAs. A few platform dependencies arise. For instance, on 32-bit Windows, the granule size is 8M for SGAs larger than 1GB