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Primary Index

  • Living reference work entry
  • First Online:
Encyclopedia of Database Systems

  • 33 Accesses

Synonyms

Clustering index; Sparse index

Definition

A tree-based index is called a primary index if its order is the same as the order of the file which it indexes Consider a relation R with some numeric attribute A taking values over an (ordered) domain D. Assume that relation R has been physically stored as an ordered file, following the order of the values of attribute A. Furthermore, assume that a tree-based index (e.g., B +-tree) has been created on attribute A. Then this index is primary.

Key Points

Tree-based indices are built on numeric attributes and maintain an order among the indexed search-key values. They are further categorized by whether their search-key ordering is the same with the file’s physical order (if any). Note that a file may or may not be ordered. Ordered is a file whose records are stored in pages according to the order of the values of an attribute. Obviously, a file can have at most a single such order since it is physically stored once. For example, if the Employee...

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Recommended Reading

  1. Elmasri R, Navathe SB. Fundamentals of database systems. 5th ed. Boston: Addisson-Wesley; 2007.

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  2. Manolopoulos Y, Theodoridis Y, Tsotras VJ. Advanced database indexing. Dordrecht: Kluwer; 1999.

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  3. Ramakrishnan R, Gehrke J. Database management systems. 3rd ed. New York: McGraw-Hill; 2003.

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Author information

Authors and Affiliations

  1. Aristotle University, Thessaloniki, Greece

    Yannis Manolopoulos

  2. University of Piraeus, Piraeus, Greece

    Yannis Theodoridis

  3. University of California-Riverside, Riverside, MA, USA

    Vassilis J. Tsotras

Authors
  1. Yannis Manolopoulos
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  2. Yannis Theodoridis
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  3. Vassilis J. Tsotras
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Corresponding author

Correspondence to Yannis Manolopoulos .

Editor information

Editors and Affiliations

  1. Georgia Institute of Technology College of Computing, Atlanta, Georgia, USA

    Ling Liu

  2. University of Waterloo School of Computer Science, Waterloo, Ontario, Canada

    M. Tamer Özsu

Section Editor information

  1. University of California-Riverside, Riverside, MA, USA

    Vassilis J. Tsotras

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© 2017 Springer Science+Business Media LLC

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Manolopoulos, Y., Theodoridis, Y., Tsotras, V.J. (2017). Primary Index. In: Liu, L., Özsu, M. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4899-7993-3_757-2

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  • DOI: https://doi.org/10.1007/978-1-4899-7993-3_757-2

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  • Publisher Name: Springer, New York, NY

  • Print ISBN: 978-1-4899-7993-3

  • Online ISBN: 978-1-4899-7993-3

  • eBook Packages: Springer Reference Computer SciencesReference Module Computer Science and Engineering

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