Query optimization of disjunctive databases with constraints through binding propagation

In this paper we present a technique for the optimization of bound queries over disjunctive deductive databases with constraints, i.e. rules defining properties which have to be satisfied by all instances over database schema. The technique we propose, allows the binding propagation into disjunctive queries with a set of constraints; thus, reducing the size of the data relevant to answer the query it, consequently, minimizes both the complexity of computing a single model and the whole number of models to be considered. The main contribution of this work consists in the extension of previous techniques by considering Datalog programs with both disjunctive heads and constraints. In particular, by considering weak constraints the technique is also suitable for dealing with optimization problems. Several experiments have confirmed the value of the technique.