A prototype of a schema-based XPath satisfiability tester

Abstract

The satisfiability test of queries can be used in query optimization for avoiding submission and computation of unsatisfiable queries. Thus, applying the satisfiability test before executing a query can save evaluation time and transportation costs in distributed scenarios. Therefore, we propose a schema-based approach to the satisfiability test of XPath queries, which checks whether or not an XPath query conforms to the constraints in a given schema. If an XPath query does not conform to the constraints given in the schema, the evaluation of the query will return an empty result for every XML document. Thus, the XPath query is unsatisfiable. We present a complexity analysis of our approach, which proves that our approach is efficient at typical cases. We present an experimental analysis of our developed prototype, which shows the optimization potential of avoiding the evaluation of unsatisfiable queries. © Springer-Verlag Berlin Heidelberg 2006.