Temporal conditions and integrity constraints in active database systems
Aravinda Prasad Sistla, Ouri Wolfson · 1995
In this paper, we present a unified formalism, based on Past Temporal Logic, for specifying conditions and events in the rules for active database system. This language permits specification of many time varying properties of database systems. It also permits specification of temporal aggregates. We present an efficient incremental algorithm for detecting conditions specified in this language. The given algorithm, for a subclass of the logic, was implemented on top of Sybase. 0 1 Introduction The most popular model of rules in active database systems is the ECA model [41, 6, 28, 5, 14, 18]. It defines a rule to consist of three parts, event, condition, and action. The semantics is that whenever the event happens, the condition (which is usually a database query) is evaluated, and if satisfied then the action is taken. The event may be composite and temporal, such as, transaction A starts after transaction B ended. However, the condition is static in the sense that it refers to the cu...