Encyclopedia of Database Systems

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

Dense Index

  • Mirella M. MoroEmail author
  • Vassilis J. Tsotras
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_760


Consider a tree-based index on some numeric attribute A of a relation R. This index is called dense if every search-key value of attribute A in relation R also appears in the index. Hence, for every search-key value x in A, there is an index record of the form <x, pointer>, where pointer points to the first record (if many such exist) in relation R that has R.A = x.

Key Points

Tree-based indices are built on numeric attributes and maintain an order among the indexed search-key values. Hence, they provide efficient access to the records of a relation by attribute value. Consider, for example, an index built on attribute A of relation R. The leaf pages of the index contain index-records of the form <search-key, pointer>, where search-key corresponds to a value from the indexed attribute A and pointer points to the respective record in the indexed relation R with that attribute value. If all distinct values that appear in R.A also appear in index records, this index is dense;...

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Recommended Reading

  1. 1.
    Elmasri R, Navathe SB. Fundamentals of database systems. 6th ed. Reading: Addisson-Wesley; 2010.zbMATHGoogle Scholar
  2. 2.
    Manolopoulos Y, Theodoridis Y, Tsotras VJ. Advanced database indexing. Dordecht: Kluwer; 2000.CrossRefzbMATHGoogle Scholar
  3. 3.
    Silberschatz A, Korth H, Sudarshan S. Database system concepts. 6th ed. New York: McGraw-Hill; 2010.zbMATHGoogle Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Departamento de Ciencia da ComputaçaoUniversidade Federal de Minas Gerais – UFMGBelo HorizonteBrazil
  2. 2.University of California-RiversideRiversideUSA

Section editors and affiliations

  • Vassilis J. Tsotras
    • 1
  1. 1.University of California-RiversideRiversideUSA