Formal Analysis of Database Trigger Systems Using Event-B

Abstract

Most modern relational database systems use triggers to implement automatic tasks in response to specific events happening inside or outside a system. A database trigger is a human readable block code without any formal semantics. Frequently, people can check if a trigger is designed correctly after it is executed or by manual checking. In this article, the authors introduce a new method to model and verify database trigger systems using Event-B formal method at design phase. First, the authors make use of similar mechanism between triggers and Event-B events to propose a set of rules translating a database trigger system into Event-B constructs. Then, the authors show how to verify data constraint preservation properties and detect infinite loops of trigger execution with RODIN/Event-B. The authors also illustrate the proposed method with a case study. Finally, a tool named Trigger2B which partly supports the automatic modeling process is presented.