Definition
The concept of user-defined time denotes time-valued attributes of database items with which the data model and query language associate no special semantics. Such attributes may have as their domains all domains that reference time, e.g., date and time. The domains may be instant-, period-, and interval-valued. For example, user-defined time attributes include “birthday,” “hiring date,” and “contract duration.” Thus, user-defined time attributes are parallel to attributes that record, e.g., salary, using domain “money” and publication count, using domain “integer.” User-defined time attributes contrast transaction-time and valid-time attributes, which carry special semantics.
Key Points
The valid time and transaction time attributes of a database item are “about” the other attributes of the database item. The valid time records when the information recorded by the attributes is true in the modeled reality, and the transaction time captures when the data item was part of the...
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Recommended Reading
Jensen CS, Dyreson CE, editors. 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: Springer; 1998. p. 367–405.
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.
Snodgrass RT, Ahn I. Temporal databases. IEEE Comput. 1986;19(9):35–42.
Author information
Authors and Affiliations
Corresponding authors
Editor information
Editors and Affiliations
Section Editor information
Rights and permissions
Copyright information
© 2018 Springer Science+Business Media, LLC, part of Springer Nature
About this entry
Cite this entry
Jensen, C.S., Snodgrass, R.T. (2018). User-Defined Time. In: Liu, L., Özsu, M.T. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-8265-9_1065
Download citation
DOI: https://doi.org/10.1007/978-1-4614-8265-9_1065
Published:
Publisher Name: Springer, New York, NY
Print ISBN: 978-1-4614-8266-6
Online ISBN: 978-1-4614-8265-9
eBook Packages: Computer ScienceReference Module Computer Science and Engineering