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Scalable XQuery Type Matching

Publication Details


Scalable XQuery Type Matching


Jens Teubner


Proceedings 11th Int'l Conference on Extending Database Technology (EDBT)


paper (PDF), presentation slides (PDF)


XML Schema awareness has been an integral part of the XQuery language since its early design stages. Matching XML data against XML types is the main operation that backs up XQuery type expressions, such as typeswitch, instance of, or certain XPath operators. This interaction is particularly vital in data-centric XQuery applications, where data come with detailed type information from an XML Schema document.

So far there has been little work on the optimization of those operations. This work presents an efficient implementation of the runtime aspects of XML Schema support. We propose type ranks as a novel and uniform way to implement all facets of type matching in the W3C XQuery Recommendation. As a concise encoding of the type hierarchy defined by an XML Schema document, type ranks minimize the cost of checking the runtime type of XQuery singleton items. By aggregating type ranks, we leverage the grouping capabilities of modern DBMS implementations to efficiently execute type matching on XQuery sequences. In addition, we improve the complexity bounds incurring with typeswitch expressions over existing approaches. Experiments on an off-the-shelf database system demonstrate the potential of our approach.

Publication Log

December 2007

camera-ready for EDBT 2007

September 2007

submission to EDBT 2008 (accepted)

Sub content


Prof. Dr. Jens Teubner
Tel.: 0231 755-6481