Encyclopedia of Database Systems

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

Linear Hashing

  • Donghui Zhang
  • Yannis Manolopoulos
  • Yannis Theodoridis
  • Vassilis J. Tsotras
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_742

Definition

Linear Hashing is a dynamically updateable disk-based index structure which implements a hashing scheme and which grows or shrinks one bucket at a time. The index is used to support exact match queries, i.e., find the record with a given key. Compared with the B+-tree index which also supports exact match queries (in logarithmic number of I/Os), Linear Hashing has better expected query cost O(1) I/O. Compared with Extendible Hashing, Linear Hashing does not use a bucket directory, and when an overflow occurs, it is not always the overflown bucket that is split. The name Linear Hashing is used because the number of buckets grows or shrinks in a linear fashion. Overflows are handled by creating a chain of pages under the overflown bucket. The hashing function changes dynamically and at any given instant there can be at most two hashing functions used by the scheme.

Historical Background

A hash table is an in-memory data structure that associates keys with values. The primary...

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Recommended Reading

  1. 1.
    Griswold WG, Townsend GM. The design and implementation of dynamic hashing for sets and tables in icon. Softw Pract Ex. 1993;23(4):351–67.CrossRefGoogle Scholar
  2. 2.
    Litwin W. Linear hashing: a new tool for file and table addressing. In: Proceedings of the Sixth International Conference on Very Large Databases; 1980. p. 212–23.Google Scholar
  3. 3.
    Manolopoulos Y, Lorentzos N. Performance of linear hashing schemes for primary key retrieval. Inf Syst. 1994;19(5):433–46.CrossRefGoogle Scholar
  4. 4.
    Schneider DA., DeWitt DJ. Tradeoffs in processing complex join queries via hashing in multiprocessor database machines. In: Proceedings of the 16th International Conference on Very Large Databases; 1990. p. 469–80.Google Scholar

Copyright information

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

Authors and Affiliations

  • Donghui Zhang
    • 1
  • Yannis Manolopoulos
    • 2
  • Yannis Theodoridis
    • 3
  • Vassilis J. Tsotras
    • 4
  1. 1.Paradigm4, Inc.WalthamUSA
  2. 2.Aristotle University of ThessalonikiThessalonikiGreece
  3. 3.University of PiraeusPiraeusGreece
  4. 4.University of California-RiversideRiversideUSA

Section editors and affiliations

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