Optimizing query answering under ontological constraints
Giorgio Orsi, Andréas Pieris · Proceedings of the VLDB Endowment · 2011
Ontological queries are evaluated against a database combined with ontological constraints. Answering such queries is a challenging new problem for database research. For many ontological modelling languages, query answering can be solved via query rewriting: given a conjunctive query and an ontology, the query can be transformed into a first-order query, called the perfect rewriting , that takes into account the semantic consequences of the ontology. Then, for every extensional database D , the answer to the query is obtained by evaluating the rewritten query against D. In this paper we present a new algorithm that computes the perfect rewriting of a conjunctive query w.r.t. a linear Datalog ± ontology. Also, we provide an experimental comparison of our algorithm with existing rewriting techniques.