On Specifying the Reactive Behavior on Constraint Violations

Recent approaches to integrity enforcement in active databases suggest not only to check for inconsistencies by triggers but also to utilize triggers to perform repair actions on constraint violations. Typically, respective repairing triggers are derived automatically from constraint specifications following almost fixed derivation strategies. However, in order to incorporate more semantic knowledge of the application these approaches often require refinements or even revisions of already derived integrity checking and inconsistency repairing triggers by the designer. In this paper we argue that analyzing and specifying repair actions on constraint violations should be also a design task and exclusively be carried out in the conceptual design. For this purpose, we provide a declarative specification language for repair actions on inconsistencies with an operational semantics, suitable to express most of the designers’ intentions on the behavior on constraint violations. We describe a design methodology for reaction specifications and show how integrity checking and inconsistency repairing triggers can be derived from these specifications.