The Dynamics of Active Database Rules: Models and Refinements

Semantics represents a major problem area for active databases inasmuch as (i) there is no formal framework for defining the abstract semantics of active rules, and (ii) the various systems developed so far have ad-hoc operational semantics that are widely different from each other. This situation contributes to the difficulty of predicting the run-time behavior of sets of rules: thus, ensuring the termination of a given set of rules is currently recognized as a major research issue. This situation hampers the applicability of this powerful technology in critical application areas. In this paper, we introduce a durable change semantics for active database rules; this semantics improves Starburst’s deferred activation notion with concepts taken from Postgres and Heraclitus and the semantic foundations of deductive databases. We provide a formal logicbased model for this transaction-oriented semantics, show that it is amenable to efficient implementation, and prove that it solves the non-termination problem.