A selective enumeration based heuristic for rule allocation

A Distributed Deductive Database System consists of many autonomous deductive database systems connected by a computer network to facilitate sharing of both database and rules. The design of a distributed deductive database system diiers from the design of conventional non-distributed deductive database systems. The former requires design of distribution of both the database and rulebase, where as the latter requires design of data distribution. This paper addresses the problem of allocating rules in a distributed deductive database system , where rulebase (a collection of rules) and database are shared across autonomous sites. The problem is relevant and challenging in applications involving large rulebases. We have identiied communication cost as the primary consideration in allocation of rules. The optimal allocation of rules over a set of sites is an NP-complete problem. It has prohibitive execution time for large rule-bases. In this paper, We propose an eecient heuristic algorithm for nonreplicated rule allocation and study its performance visa -vis the enumerative algorithm for optimal allocation. A heuristic for replicated allocation of rules is also presented which starts from the nonreplicated allocation.