Three Cases for Query Decorrelation in XQuery

  • Norman May
  • Sven Helmer
  • Guido Moerkotte
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2824)


We present algebraic equivalences that allow to unnest nested algebraic expressions for order-preserving algebraic operators. We illustrate how these equivalences can be applied successfully to unnest nested queries given in the XQuery language. Measurements illustrate the performance gains possible our approach.


Query Language Query Plan XPath Expression Semistructured Data Algebraic Operator 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Norman May
    • 1
  • Sven Helmer
    • 1
  • Guido Moerkotte
    • 1
  1. 1.Universität MannheimMannheimGermany

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