Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Functional Dependencies for Semistructured Data

  • Gillian DobbieEmail author
  • Tok Wang Ling
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_5040


Extended functional dependencies; Path functional dependencies


Functional dependencies are used in relational database design to show that the value of a set of attributes depends on the value of another set of attributes. Theory has been developed to manipulate a set of functional dependencies to describe equivalences of sets of functional dependencies. Semi-structured data differs from relational data in two important ways: semi-structured data is hierarchical and the structure of the data is less consistent. Traditional functional dependencies do not capture these differences so new functional dependencies with associated theory has been defined for semi-structured data.

Key Points

Functional dependencies for semi-structured data have been defined in the three recommended readings. While the syntax of functional dependencies defined over semi-structured data varies, the semantics is similar. In this article the syntax of Arenas and Libkin [ 1] is used but the...
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Recommended Reading

  1. 1.
    Arenas M, Libkin L. A normal form for XML documents. ACM Trans Database Syst. 2004;29(1):195–232.CrossRefGoogle Scholar
  2. 2.
    Lee ML, Ling TW, Low WL. Designing functional dependencies for XML. In: Advances in Database Technology, Proceedings of the 8th International Conference on Extending Database Technology; 2002. p. 124–41.CrossRefGoogle Scholar
  3. 3.
    Wu X, Ling TW, Lee SY, Lee ML, Dobbie G. NF-SS: a normal form for semistructured schema. In: Proceedings of the ER Workshops. 2001. p. 292–305.zbMATHCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.University of AucklandAucklandNew Zealand
  2. 2.National University of SingaporeSingaporeSingapore