Encyclopedia of Database Systems

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

Hierarchy

  • Torben Bach Pedersen
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_887

Definition

A hierarchy is a structure specifying the containment relationships of a number of values (or nodes or elements). A hierarchy has a single root (or top or ALL) value. A value in a hierarchy may be linked to one or more children and a non-top value is linked to one or more parents. The links between values thus specify the containment structure. Hierarchies are essential for specifying dimensions in multidimensional cubes.

Key Points

The notion of a dimension is an essential and distinguishing concept for multidimensional cubes. Dimensions are used for two purposes: the selection of data and the groupingof data at a desired level of detail. As an example, a three-dimensional cube for capturing product sales may have a Product dimension, a Time dimension, and a Store dimension. The Product dimension captures information about the product sold, such as textual description, color, weight, etc., as well as groupings of products (product groups, product families, departments,...

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Recommended Reading

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    Jensen CS, Pedersen TB, Thomsen C. Multidimensional databases and data warehousing, Synthesis Lectures on Data Management. San Rafael: Morgan Claypool; 2010.zbMATHCrossRefGoogle Scholar
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    Lenz H, Shoshani A. Summarizability in OLAP and statistical data bases. In: Proceedings of the 9th International Conference on Scientific and Statistical Database Management; 1997. p. 39–48.Google Scholar
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    Pedersen TB, Jensen CS, Dyreson CE. A foundation for capturing and querying complex multidimensional data. Inf Syst. 2001;26(5):383–423.zbMATHCrossRefGoogle Scholar
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    Pedersen TB. Managing complex multidimensional data. In: Aufaure M-A, Zimányi E, editors. Business intelligence – second European Summer School, eBISS 2012, Brussels, Belgium, July 15–21, 2012, Tutorial Lectures, LNBIB. Brussels: Springer; 2013.Google Scholar
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    Vaisman A, Zimányi E. Data warehouse systems – design and implementation. Berlin: Springer; 2014.Google Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Department of Computer ScienceAalborg UniversityAalborgDenmark

Section editors and affiliations

  • Torben Bach Pedersen
    • 1
  • Stefano Rizzi
    • 2
  1. 1.Department of Computer ScienceAalborg UniversityAalborgDenmark
  2. 2.DISIUniv. of BolognaBolognaItaly