Scalable XQuery type matching

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...

• Type: Conference
• Year: 2008
• Where: EDBT
• Authors: Jens Teubner
• Keywords: Database, EDBT 2008, Type Ranks, XML Schema Document, XQuery Type Expressions