Oracle Core: Essential Internals for DBAs and Developers

Summary

The data cache can be split into multiple buffer pools, either by block size or (with the keep and recycle pools) by usage. Many sites, though, stick to a single buffer pool using the default block size offered by the Database Configuration Assistant (DBCA) for their platform—and this is generally the most sensible strategy.

The data cache is also split into granules of a fixed size—4MB, 8MB, or 16MB, depending on platform version and the size of the SGA. The granular approach makes it possible to reallocate memory dynamically between the data cache and other key parts of the SGA. Each buffer pool is made up of many discrete granules, and each individual granule is owned by a single buffer pool. A granule that belongs to the data cache ...