University of Ljubljana
Ontology-Based Data Access (OBDA) is regarded as a key ingredient for the new generation of information systems. In the OBDA paradigm, an ontology defines a high-level global schema and provides a vocabulary for user queries, thus isolating the user from the details of the data source structure. The authors present technologies that underpin the OBDA system Ontop and take full advantage of storing data in relational databases. They discuss the theoretical foundations of Ontop, including the tree-witness query rewriting, T -mappings and optimizations based on database integrity constraints and SQL features.