Encyclopedia of Database Systems

2009 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/10.1007/978-0-387-39940-9_756

Synonyms

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 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-based indexing. They differ on the...

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Recommended Reading

  1. 1.
    Manolopoulos Y., Theodoridis Y., and Tsotras V.J. Advanced Database Indexing. Kluwer, Dordrecht, 1999.Google Scholar
  2. 2.
    Elmasri R. and Navathe S.B. Fundamentals of Database Systems, 5th edn. Addisson-Wesley, Reading, MA, 2007.Google Scholar
  3. 3.
    Ramakrishnan R. and Gehrke J. Database Management Systems, 3rd edn. McGraw-Hill, New York, 2003.zbMATHGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Mirella M. Moro
    • 1
  • Donghui Zhang
    • 2
  • Vassilis J. Tsotras
    • 3
  1. 1.Federal University of Minas GeraisBelo HorizonteBrazil
  2. 2.Northeastern UniversityBostonUSA
  3. 3.University of CaliforniaRiversideUSA