Encyclopedia of Database Systems

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

Valid Time

  • Christian S. Jensen
  • Richard T. Snodgrass
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_1066

Synonyms

Application time; Business time Data time; Intrinsic time; Logical time; Real-world time

Definition

The valid time of a fact is the time when the fact is true in the modeled reality. Any subset of the time domain may be associated with a fact as its valid time. Thus, valid timestamps may be sets of time instants and time intervals, with single instants and intervals being important special cases. Valid times are usually supplied by users.

Main Text

While other temporal aspects have been proposed, such as “decision time” and “event time,” closer analysis indicates that the decision and event time of a fact can be captured as either a valid time or a transaction time of some related fact.

For example, consider a valid-time Faculty table with attributes Name and Position (i.e., either Assistant Professor, Associate Professor, or Professor) that captures the positions of faculty members. The valid time then captures when a faculty member held a specific position.

The “decision...

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Recommended Reading

  1. 1.
    Jensen CS, Dyreson CE (eds). Böhlen M, Clifford J, Elmasri R, Gadia SK, Grandi F, Hayes P, Jajodia S, Käfer W, Kline N, Lorentzos N, Mitsopoulos Y, Montanari A, Nonen D, Peressi E, Pernici B, Roddick JF, Sarda NL, Scalas MR, Segev A, Snodgrass RT, Soo MD, Tansel A, Tiberio R, Wiederhold G. A consensus glossary of temporal database concepts—February 1998 version. In: Etzion O, Jajodia S, Sripada S, editors. Temporal databases: research and practice. LNCS, vol. 1399. Berlin/New York: Springer; 1998. p. 367–405.Google Scholar
  2. 2.
    Kulkari K, Michels J-E. Temporal features in SQL:2011. ACM SIGMOD Rec. 2012;41(3):34–43.CrossRefGoogle Scholar
  3. 3.
    Melton J (editor). ISO/IEC 9075, Database Language SQL:2011 Part 2: SQL/Foundation; Dec 2011.Google Scholar
  4. 4.
    Snodgrass RT, Ahn I. A taxonomy of time in databases. In: Proceedings of the ACM-SIGMOD International Conference on Management of Data; 1985; p. 236–46.Google Scholar
  5. 5.
    Snodgrass RT, Ahn I. Temporal databases. IEEE Comput. 1986;19(9):35–42.zbMATHCrossRefGoogle Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Department of Computer ScienceAalborg UniversityAalborgDenmark
  2. 2.Department of Computer ScienceUniversity of ArizonaTucsonUSA
  3. 3.Dataware VenturesTucsonUSA