Temporal Triggers in Active Databases

In this paper we propose two languages, called Future Temporal Logic (FTL) and Past Temporal Logic (PTL), for specifying temporal triggers. Some examples of trigger conditions that can be speciied in our language are the following: \The value of a certain attribute increases by more than 10% in ten minutes", "A tuple that satisses a certain predicate is added to the database at least 10 minutes before another tuple, satisfying a diierent condition, is added to the database". Such triggers are important for monitor and control applications. In addition to the languages, we present algorithms for processing the trigger conditions speciied in these languages, namely, procedures for determining when the trigger conditions are satissed. These methods can be added as a "temporal" component to an existing database management systems. A preliminary prototype of the temporal component that uses the FTL language has been built on top of Sybase running on SUN workstations.