A Persistent Store for Large Shared Knowledge Bases

Abstract

We propose a knowledge base management system (KBMS) with the following goals: 1) to allow a knowledge engineer to update a knowledge base and have these updates persist on secondary storage, 2) to allow multiple knowledge engineers to have shared access to a knowledge base and modify the knowledge base concurrently, and 3) to maintain consistency of the shared knowledge base as it evolves. At the heart of the KBMS is the version store which is a persistent storage structure which maintains multiple versions of a knowledge base. Retrieve and update operations have been defined on the version store to efficiently access and modify any version. Objects in the version store are clustered so as to support efficient access of an entire version or some subparts of it. To store the effects of an update requires space proportional to the size of the update and which is independent of the size of the knowledge base. That is, beyond our concerns with overall efficiency, the additional cost of maintaining multiple versions is within a small constant factor of maintaining a single version. © 1991 IEEE