Encyclopedia of Database Systems

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

Implicit Event

  • Jonas Mellin
  • Mikael Berndtsson
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_516

Definition

In active databases, an implicit event is an event that is implied by an ECA rule definition.

Key Points

ECA rules were developed as an optimization of condition action rules. The performance of rule evaluation was improved by allowing, or even requiring, explicit definition of when rules should be triggered in the form of events. However, it turns out that it is possible to derive events from the condition in a meaningful way in some cases, and, thus, there are events that can be implied by the ECA rule definition. For example, if the condition is a logical expression A = 5 ∧ B = 3, then a disjunction of the events representing update to the variables can trigger the rule. That is, with implicit events (IFA = 5 ∧ B = 3 DO action) is equivalent to (ONupdateAorupdateBIFA = 5 ∧ B = 3 DO action) with explicit events.

Cross-References

Copyright information

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

Authors and Affiliations

  1. 1.University of SkövdeThe Informatics Research CentreSkövdeSweden
  2. 2.University of SkövdeSchool of InformaticsSkövdeSweden

Section editors and affiliations

  • M. Tamer Özsu
    • 1
  1. 1.Cheriton School of Computer ScienceUniversity of WaterlooWaterlooCanada