Dynamic SGA Granules
With dynamic SGA, the unit of allocation is called a granule. Components, such as the
buffer cache, the shared pool, the java pool, and the large pool, allocate and free
SGA space in units of granules. Oracle tracks SGA memory use in integral numbers
of granules, by SGA component. All information about a granule is stored in a
corresponding granule entry. Oracle maintains the state of each granule in the
granule entry and the granule type.
Granule size is determined by total SGA size. On most platforms, the size of a
granule is 4 MB if the total SGA size is less than 128 MB, and it is 16 MB for larger
SGAs. Theremay be some platformdependency, for example, on 32-bit Windows
NT, the granule size is 8 MB for SGAs larger than 128 MB.
The granule size that is currently being used for SGA can be viewed in the view
V$SGA_DYNAMIC_COMPONENTS. The same granule size is used for all dynamic
components in the SGA. |