Paper 7
Inconsistency-tolerant Database Repairs and Simplied Repair Checking by Measure-based Integrity CheckingAuthors: Hendrik Decker |
AbstractDatabase states may be inconsistent, i.e., their integrity may be violated. Database repairs are updates such that all integrity constraints become satisfied, while keeping the necessary changes to a minimum. Updates intending to repair inconsistency may go wrong. Repair checking is to find out if a given update is a repair, i.e., if the updated state is free of integrity violations and if the changes are minimal. However, integrity violations may be numerous, complex or opaque, so that attaining a complete absence of inconsistency is not realistic. We discuss inconsistency-tolerant concepts of repair and repair checking. Repairs are no longer asked to be total, i.e., only some but not all inconsistency is supposed to disappear by a repair. For checking if an update reduces the amount of inconsistency, integrity violations need to be comparable. For that, we use measure-based integrity checking. Both the inconsistency reduction and the minimality of inconsistency-tolerant repair candidates can be verified or falsified by measure-based integrity checkers that simplify the evaluation of constraints. As opposed to total repair checking, which evaluates integrity constraints brute-force, simplified repair checking exploits the incrementality of updates. |