Exploiting Semantic of Typed Objects Under an Optimistic Control in the Transactional Deferred Update Model: A Promising Approach

摘要

The transactional deferred update (DU) model is typically used in client/server DBMS. When typed objects are used, greater concurrency is possible by exploiting properties such as commutativity of typed operations. To extract concurrency from objects, for the DU model, theoretical studies based on dependency graph model emphasized different types of dependencies between operations. Dependencies allow to specify possible concurrency between operations even if they do not "for-ward" commute. In this paper we exploit these dependencies in a new optimistic concurrency control scheme based on timestamps intervals. The protocol achieves the highest concurrency when the semantic of typed operations is exploited. The scheme uses a backward control to achieve serializability, and a forward control to detect earlier non serializable situations. This study shows that, unlike previous semantic objects-based protocols, the new protocol is very adapted to client/server architectures.