AUTOMATIC-GENERATION OF PRODUCTION RULES FOR INTEGRITY MAINTENANCE

In this article we present an approach to integrity maintenance, consi sting of automatically generating production rules for integrity enfor cement. Constraints are expressed as particular formulas of Domain Rel ational Calculus; they are automatically translated into a set of repa ir actions, encoded as production rules of an active database system. Production rules may be redundant (they enforce the same constraint in different ways) and conflicting (because repairing one constraint may cause the violation of another constraint). Thus, it is necessary to develop techniques for analyzing the properties of the set of active r ules and for ensuring that any computation of production rules after a ny incorrect transaction terminates and produces a consistent database state. Along these guidelines, we describe a specific architecture fo r constraint definition and enforcement. The components of the archite cture include a Rule Generator, for producing all possible repair acti ons, and a Rule Analyzer and Selector, for producing a collection of p roduction rules such that their execution after an incorrect transacti on always terminates in a consistent state (possibly by rolling back t he transaction); moreover, the needs of applications are modeled, so t hat integrity-enforcing rules reach the final state that better repres ents the original intentions of the transaction's supplier. Specific i nput from the designer can also drive the process and integrate or mod ify the rules generated automatically by the method. Experimental resu lts of a prototype implementation of the proposed architecture are als o described.