A semantic approach to query rewriting for integrated XML data

Query rewriting is a fundamental task in query optimization and data integration. With the advent of the web, there has been renewed interest in data integration, where data is dispersed among many sources and an integrated view over these sources is provided. Queries on the integrated view are rewritten to query the underlying source repositories. In this paper, we develop a novel algorithm for rewriting queries that considers the XML hierarchy,structure and the semantic relationship between the source schemas and the integrated schema. Our approach is based on the semantically rich Object-Relationship-Attribute model for SemiStructured data (ORA-SS), and guarantees that the rewritten queries give the expected results, even where the integrated view is complex.