A difference-based version model for OODBMS

Data versioning is important for many applications such as CASE, CAD and CAM. New design objects in these applications are usually created from existing ones because they share a large degree of similarity. In this paper we propose a difference-based version model for object-oriented database systems. The large object stores only the difference data from its parent version. To show the feasibility of this version model, a prototype is implemented and a performance study on the version storage and access time is made. We observe from this study that, when the difference between two versions is less than 10%, the system has the best storage efficiency and incurs the least overhead in access time. Our implementation experience also shows that the proposed version model can be implemented as an independent module to plug in a data storage system easily.