Approaches for scheduling of triggered transactions in real-time active database systems

A real-time active database system (RTADBS) has to provide capabilities for timely trigger of time constrained transactions and at the same time to process them, concurrently with others transactions, in a real-time manner. Mostly, triggered transactions are critical transactions. It is highly important to commit them. Committing a triggered transaction requires meeting the deadline constraints of its triggering transaction and also the data deadlines of its accessed temporal data objects. However, the generations of triggered transactions decrease the predictability of the system as they increase the system workload and the probability of data conflicts. The authors propose different approaches for assigning deadlines and priorities to the triggered transactions with the objectives to satisfy the timing requirements of the triggered transactions especially for the more critical ones. The performance of the new approaches and their relationships with different coupling modes have been studied using simulation