Encyclopedia of Database Systems

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


  • Curtis E. DyresonEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_1050


Instant; Moment; Time quantum; Time unit


A chronon is the smallest, discrete, non-decomposable unit of time in a temporal data model. In a one-dimensional model, a chronon is a time interval or period, while in an n-dimensional model it is a non-decomposable region in n-dimensional time. Important special types of chronons include valid-time, transaction-time, and bitemporal chronons.

Key Points

Data models often represent a time line by a sequence of non-decomposable, consecutive time periods of identical duration. These periods are termed chronons. A data model will typically leave the size of each particular chronon unspecified. The size (e.g., 1 μs) will be fixed later by an individual application or by a database management system, within the restrictions posed by the implementation of the data model. The number of chronons is finite in a bounded model (i.e., a model with a minimum and maximum chronon), or countably infinite otherwise. Consecutive chronons may...

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Recommended Reading

  1. 1.
    Dyreson CE, Snodgrass RT. The base-line clock. In: The TSQLZ temporal query language. Kluwer; 1987. p. 73–92.Google Scholar
  2. 2.
    Dyreson CE, Snodgrass RT. Timestamp semantics and representation. Inf Syst. 1993;18(3):143–66.CrossRefGoogle Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Utah State UniversityLoganUSA

Section editors and affiliations

  • Richard T. Snodgrass
    • 1
  • Christian S. Jensen
    • 2
  1. 1.University of ArizonaTucsonUSA
  2. 2.Aalborg UniversityAalborg ØstDenmark