Achieving Consistency in Active Databases

Consistency is an important property of database application systems. Given some integrity constraint on a database schema the problem is to guarantee that all transactions preserve this constraint. In this paper we regard rule triggering systems and provide a theoretical analysis of their power with respect to the enforcement of constraints. We show that for certain constraint sets the effect of the rules is equivalent to canonically specializing transactions. Moreover, we present a theoretical extension of this specialization idea that captures also critical sets of constraints. However, the price for this generality is high, since linguistic ref lection seems to be the only reasonable implementation technique. 1 Introduction Consistency is an important property of database transactions. Suppose we are given a database schema and some static integrity constraints on that schema, then consistency requires that only those database instances are allowed that satisfy all constraints. H..