Physical independence in object databases

In the current implementations of Object Database Systems, the physical database organization is usually hard-coded in the system, i.e., the strategy (or memorizing the data objects is fixed and usually reflects the logical object definitions. Instead, the possibility of choosing the most suitable physical organization for an object database would be essential. In this paper, a canonical object data model and a storage object data model are presented. In the first, the objects are organized in classes; in the second, physical objects with similar structures are grouped in collections. Mechanisms for mapping data structures from the logical level to the physical level are discussed, and a comprehensive example is given.