Concurrency Control for Knowledge Bases

As the demand for ever larger knowledge bases grows knowledge base management techniques assume paramount importance In this paper we show that large multi user knowledge bases need concurrency control We discuss known techniques from database concurrency control and explain their inad equacies in the context of knowledge bases We o er a concurrency control algorithm called the Dynamic Directed Graph DDG policy that addresses the speci c needs of knowledge bases The DDG policy exploits the rich structure of a knowledge base to support the interleaved concurrent execu tion of several user requests thereby improv ing overall system performance We give a proof of correctness of the proposed concur rency control algorithm and an analysis of its properties We demonstrate that these re sults from concurrency control interact in in teresting ways with knowledge base features and highlight the importance of performance oriented tradeo s in the design of knowledge based systems