34.14. Pattern: Cache Management

It is desirable to maintain materialized objects in a local cache to improve performance (materialization is relatively slow) and support transaction management operations such as a commit.

The Cache Management pattern [BW96] proposes making the Database Mappers responsible for maintaining its cache. If a different mapper is used for each class of persistent object, each mapper can maintain its own cache.

When objects are materialized, they are placed in the cache, with their OID as the key. Subsequent requests to the mapper for an object will cause the mapper to first search the cache, thus avoiding unnecessary materialization.