Distributed rule processing in active databases

Processing rules in a distributed active database involves three design issues: how to decompose rules, how to distribute rules to sites, and how to evaluate distributed rules correctly. The authors study these three issues for complicated rules, which are complex and time-consuming to evaluate. They propose a relational operator, AND, and the associated algebraic manipulations of this operator to find independent parts of a rule query, which can be distributed among sites. Due to geographical dispersion in a distributed system, correct evaluation of distributed rules is not trivial. A distributed evaluation algorithm is preferred, which guarantees the correctness of the evaluation result of the distributed rule by collecting consistent local results from sites to form a global view