Declarative specification of constraint maintenance

Integrity repair is a pragmatic alternative to integrity checking, already proposed by relational and Codasyl standards and supported by several commercial systems, although for a small number of constraint types. This paper proposes to integrate constraint languages with the declarative specifications of their integrity repair actions. We introduce a rather powerful, predicate-based language for specifying integrity constraints, then we discuss the semantics of repair actions as computations which react to constraint violations, then we establish sufficient conditions for ensuring their termination, and finally we show how repair actions can be integrated in the SQL2 standard and implemented by means of relational triggers (written in Oracle).