Enabling XPath Optional Axes Cardinality Estimation Using Path Synopses

  • Yury Soldak
  • Maxim Lukichev
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5207)

Abstract

The effective support for XML query languages is becoming increasingly important with the emergence of new applications that access large volumes of XML data. The efficient query execution, especially in the distributed case, requires estimating of the path expression cardinalities. In this paper, we propose two novel techniques for the cardinality estimation of the simple path expressions with optional axes (following/preceding): the document order grouping (DG) and the neighborhood grouping (NG). Both techniques summarize the structure of source XML data in compact graph structures (path synopses) and use these summaries for cardinality estimation. We experimentally evaluated accuracy of the techniques, size of the summaries and studied performance of the prototypes. The wide range of source data was used in order to study the behavior of the structures and the area of techniques application.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Yury Soldak
    • 1
  • Maxim Lukichev
    • 1
  1. 1.Department of Computer ScienceUniversity of Saint-PetersburgRussian Federation

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