Encyclopedia of Database Systems

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

Hash-Based Indexing

  • Mirella M. Moro
  • Donghui Zhang
  • Vassilis J. Tsotras
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_756

Synonyms

External hashing; Extensible hashing; Grid File (and Family); Hash file; Linear hashing

Definition

Consider a relation R with some attribute A taking values over domain D. A membership (or equality) query retrieves all tuples in R with A = x (xD). To enable fast processing of such equality selection queries, an access method that can group records by their value on attribute A is needed. A hash-based scheme maps the search-key values on a collection of buckets. The bucket to which a value is assigned (mapped) is determined by a function, called the hashing function.

Key Points

A major performance goal of a database management system is to minimize the number of I/O’s (i.e., blocks or pages transferred) between the disk and main memory when answering a query. To achieve such fast access, additional data structures called access methods (or indices) are designed per database file. There are two fundamental access methods, namely tree-based and hash-basedindexing. They...

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Recommended Reading

  1. 1.
    Manolopoulos Y, Theodoridis Y, Tsotras VJ. Advanced database indexing. Dordrecht: Kluwer; 2000.zbMATHCrossRefGoogle Scholar
  2. 2.
    Elmasri R, Navathe SB. Fundamentals of database systems. 6th ed. Reading: Addisson-Wesley; 2010.zbMATHGoogle Scholar
  3. 3.
    Ramakrishnan R, Gehrke J. Database management systems. 3rd ed. New York: McGraw-Hill; 2002.zbMATHGoogle Scholar

Copyright information

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

Authors and Affiliations

  • Mirella M. Moro
    • 1
  • Donghui Zhang
    • 2
  • Vassilis J. Tsotras
    • 3
  1. 1.Departamento de Ciencia da ComputaçaoUniversidade Federal de Minas Gerais – UFMGBelo HorizonteBrazil
  2. 2.Paradigm4, Inc.WalthamUSA
  3. 3.University of California-RiversideRiversideUSA

Section editors and affiliations

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