INTEGRITY CHECKING FOR MULTIPLE UPDATES.

In this paper we generalize methods for fast checking of integrity constraints to deal with multiple updates. This enables us to consider practically important cases when updates are neither restricted to single range (relation) nor to single tuple and could be grouped in possibly complex transactions. We provide simplification method for arbitrary transactions, and also for arbitrary constraints expressed in prenex normal form in relational tuple calculus with no restrictions on the number of variables ranging over the same relation. Based on the prefix of a constraint, our algorithms transform the constraint into an AND-OR combination of simpler constraints which are easier to check. The analysis of certain patterns in the prefixes of constraints enables us to conclude when no simplication is possible at all and when a significant improvement can be achieved.