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Path-partitioned encoding supports wildcard-awareness twig queries

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Journal of Shanghai University (English Edition)

Abstract

Finding all occurrences of a twig query in an XML database is a core operation for efficient evaluation of XML queries. It is important to effectively handle twig queries with wildcards. In this paper, a novel path-partitioned encoding scheme is proposed for XML documents to capture paths of all elements, and a twig query is modeled as an XPattern extended from tree pattern. After definition, simplification, normalization, verification and initialization of the XPattern, both work sets and a join plan are generated. According to these measures, an effective algorithm to answer for a twig query, called DMTwig, is designed without unnecessary elements and invalid structural joins. The algorithm can adaptively deal with twig queries with branch ([]), child edge (/), descendant edge (//), and wildcard (*) synthetically. We show that path-partitioned encoding scheme and XPattern guarantee the I/O and CPU optimality for twig queries. Experiments on representative data set indicate that the proposed solution performs significantly.

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Authors and Affiliations

  1. School of Computer, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China

    Xiao-shuang Xu  (徐小双) & Yu-cai Feng  (冯玉才)

  2. School of Computer, Huanggang Normal University, Huanggang, 438000, Hubei, P. R. China

    Xiao-shuang Xu  (徐小双) & Feng Wang  (王 锋)

  3. Technic Pre-research Department, Dameng Database Company Limited, Wuhan, 430074, P. R. China

    Yu-cai Feng  (冯玉才)

Authors
  1. Xiao-shuang Xu  (徐小双)
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  2. Yu-cai Feng  (冯玉才)
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  3. Feng Wang  (王 锋)
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Corresponding author

Correspondence to Xiao-shuang Xu  (徐小双).

Additional information

Project supported by the National High-Tech Research and Development Plan of China (Grant No.2005AA4Z3030)

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Xu, Xs., Feng, Yc. & Wang, F. Path-partitioned encoding supports wildcard-awareness twig queries. J. Shanghai Univ.(Engl. Ed.) 13, 363–374 (2009). https://doi.org/10.1007/s11741-009-0506-1

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  • DOI: https://doi.org/10.1007/s11741-009-0506-1

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