Tri Query: Modifying XQuery for RDF and Relational Data

The ability to convert between different data formats is important in large and heterogeneous information systems. Although XML was established as an universal standard for data exchange, XML-related languages like XQuery lack the ability to access data in other formats; in particular, relational data and RDF. In this paper, we describe TriQuery - an extension of the XQuery language which adds records (tuples) and RDF-specific operators. Using the statically optimizable record types, relational data as well as the results from RDF sub-queries can be integrated more efficiently than with their traditional encoding using XML elements and attributes.