Query-Customized Rewriting and Deployment of DB-to-XML Mappings

Given the current trend towards application interoperability and XML-based data integration, there is an increasing need for XML interfaces to relational database management systems. In this paper we consider the problem of rewriting a DB-to-XML mapping, into several modified mappings in order to support clients that require various portions of the mapping-defined data. Mapping rewriting has the effect of reducing the amount of shipped data and, potentially, query processing time at the client. We ship sufficient data to correctly answer the client queries. Various techniques to further limit the amount of shipped data are examined. We have conducted experiments to validate the usefulness of our shipped data reduction techniques in the context of the TPC-W benchmark. The experiments confirm that in reasonable applications, data reduction is indeed significant (60-90%).