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Query Processing in Data Integration Systems
- Studied the issue of query rewriting using the mappings established for the integration of XML and RDF data. Proposed query rewriting algorithms for both the rewriting from XML queries to RDF queries and that from RDF queries to XML queries. We looked at query languages such as XQuery, RQL, and RDQL, and focused on a particular class of queries, that is, conjunctive queries.
- Schematic (structural) heterogeneity is a primary handicap in query processing (including answer integration) in XML data integration. Proposed a method to encode and decode XML structural information in our query rewriting algorithms, so as to assure the correctness of the query rewriting and of the integration of heterogeneous query answers.
- Discussed several fundamental theoretical issues of P2P query processing, including query containment, query answering, and query rewriting.