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2005
Springer

Optimizing cursor movement in holistic twig joins

11 years 6 months ago
Optimizing cursor movement in holistic twig joins
Holistic twig join algorithms represent the state of the art for evaluating path expressions in XML queries. Using inverted indexes on XML elements, holistic twig joins move a set of index cursors in a coordinated way to quickly find structural matches. Because each cursor move can trigger I/O, the performance of a holistic twig join is largely determined by how many cursor moves it makes, yet, surprisingly, existing join algorithms have not been optimized along these lines. In this paper, we describe TwigOptimal, a new holistic twig join algorithm with optimal cursor movement. We sketch the proof of TwigOptimal’s optimality, and describe how TwigOptimal can use information in the return clause of XQuery to boost its performance. Finally, experimental results are presented, showing TwigOptimal’s superiority over existing holistic twig join algorithms. Categories and Subject Descriptors: H.3[Information Systems]: Information Storage and Retrieval; E.1[Data]: Data Structures Genera...
Marcus Fontoura, Vanja Josifovski, Eugene J. Sheki
Added 26 Jun 2010
Updated 26 Jun 2010
Type Conference
Year 2005
Where CIKM
Authors Marcus Fontoura, Vanja Josifovski, Eugene J. Shekita, Beverly Yang
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