Deriving optimized integrity monitoring triggers from dynamic integrity constraints

摘要

Modern approaches to integrity monitoring in active databases suggest the ideas of generating triggers from constraints as part of database design and utilizing constraint simplification techniques for trigger optimization. Such proposals, however, have been restricted to static conditions only. In this paper, we show how to derive triggers from dynamic integrity constraints which describe properties of state sequences and which can be specified by formulas in temporal logic. Such constraints can equivalently be transformed into transition graphs which describe such life cycles of database objects that are admissible with respect to the constraints: Nodes correspond to situations in life cycles and edges give the (changing) conditions under which a change into another situation is allowed. If object situations are stored, integrity monitoring triggers can be generated from transition graphs for all situations and all critical database operations. Additionally, new simplification techniques can be developed by identifying characteristic preconditions in the graphs and by utilizing invariants. Maintenance of object situations can be supported by triggers as well.