Integrity Constraints in Multiversion Databases

This paper analyses the extension of integrity constraint mechanisms in order to maintain consistency in multiversion databases is studied. Unlike monoversion databases, a multiversion database represents several states of the modeled universe. Thus, both the notion of consistency and the means to maintain it have to be extended. To this aim, we consider new integrity constraints induced by versioning. Constraints are characterized according to several criteria, and a general framework for optimizing their checking in the context of ACID transactions is given. The database versions model CJ90] is used as it ooers a sound basis for the deenition of consistency.