Semantic Optimization of XQuery by Rewriting

Queries on XML data are increasingly widespread in use and scope of application. However, optimization strategies are not yet as developed as they are for traditional DBMSs. Current strategies mostly involve logical or physical query plan optimization. We propose a novel optimization for XQuery using semantic information from the XML schema, where we rewrite a query into an equivalent query with fewer XPath expressions based on schema information. Our experimental results indicate that this optimization can result in substantial performance gains.