Given an inconsistent database instance, i.e., that fails to satisfy a given set of integrity constraints, a repair is a new instance over the same schema that is consistent and is obtained after performing minimal changes on the original instance with the purpose of restoring consistency.
Database instances may be inconsistent, in the sense that they may not satisfy certain desirable integrity constraints. In order to make the database consistent, certain updates can be performed on the database instance. However, it is natural to expect that any new consistent instance obtained in this way does not differ too much from the original instance. The notion of repair of the original instance captures this intuition: it is an instance of the same schema that does satisfy the integrity constraints and differs from the original instance by a minimal set of changes. Depending on what is meant by minimal set of changes, different repair semantics can be obtained.
- 1.Arenas M, Bertossi L, Chomicki J. Consistent query answers in inconsistent databases. In: Proceedings of the 18th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems; 1999. p. 68–79.Google Scholar
- 3.Chomicki J. Consistent query answering: five easy pieces. In: Proceedings of the 11th International Conference on Database Theory; 2007. p. 1–17.Google Scholar