Tree Graph Views: On Efficient Evaluation of XQuery in an XML Mediator

XQuery is the emerging standard for querying XML data sources. XLive is a light XML/XQuery mediator developed at University of Versailles whose engine processes an XML algebra derived from the relational one extended to process in dataflow XML trees. The query optimizer translates a subset of XQuery in this algebra. To extend the optimizer's coverage of XQuery and better optimize query plans, we propose a representation of queries as graphs of trees, more precisely as tree pattern graphs interconnected by hyperlinks. Our structure called Tree Graph View (TGV) is an extension of the Generalized Tree Pattern graph proposed in [5] as a concise and practical representation of an XQuery request. It is designed to be a more intuitive model of queries and to allow direct optimization before generating the physical execution plan. TGV lends itself to simple algorithms to generate efficient algebraic execution plans. Moreover, it is effective for view translation and query simplification,...

• Type: Conference
• Year: 2004
• Where: BDA
• Authors: Tuyet-Tram Dang-Ngoc, Georges Gardarin, Nicolas Travers
• Keywords: BDA 2004, BDA 2007, Execution Plan, Tree Pattern Graph, XQuery