Issue No. 02 - March/April (2003 vol. 15)
<p><b>Abstract</b>—An <it>active database system</it> is a DBMS endowed with <it>active rules</it>, i.e., stored procedures activated by the system when specific events occur. The processing of active rules is characterized by two important properties: <it>termination</it> and <it>confluence</it>. We say that the processing of a set of active rules <it>terminates</it> if, given any initial active database state, the execution of the rules does not continue indefinitely; it is <it>confluent</it> if, for any initial database state, the final state is not influenced by the order of execution of the rules. Finding sufficient conditions for these properties to hold is a nontrivial problem, and the lack of a structured theory for the design of a system of active rules makes the analysis of the two properties more difficult. In this work, we translate a set of rules from any of the existing systems into an internal format; then, we translate the active rules into logical clauses, taking into account the system's execution semantics, and transfer to the active process known simple results about termination and determinism available in the literature for deductive rules.</p>
Active databases, database dynamics, deductive databases, termination, determinism.
L. Tanca and S. Comai, "Termination and Confluence by Rule Prioritization," in IEEE Transactions on Knowledge & Data Engineering, vol. 15, no. , pp. 257-270, 2003.