Analysis and optimization of active databases

We introduce a new formal semantics for active databases that relies on a transaction rewriting technique. A user de ned transaction, which is viewed here as a sequence of atomic database updates forming a semantic atomic unit, is translated by means of active rules into induced one(s). Those transactions embody active rule semantics which can be either immediate or deferred. Rule semantics, con uence, equivalence and optimization are then formally investigated and characterized in a solid framework that naturally extends a known model for relational database transactions.