Priority assignment in real-time active databases

Abstract

Active databases and real-time databases have been important areas of research in the recent past. It has been recognized that many benefits can be gained by integrating active and real-time database technologies. However, there has not been much work done in the area of transaction processing in active real-time databases. This paper deals with an important aspect of transaction processing in active real-time databases, namely the problem of assigning priorities to transactions. In these systems, time-constrained transactions trigger other transactions during their execution. We present various policies for assigning priorities to parent, immediate and deferred transactions executing on a multiprocessor system and then evaluate the policies using simulation. The simulator has been validated by comparing to three sets of published results. Our new results demonstrate that dynamically changing the priorities of transactions depending on their behavior (triggering rules), yields a substantial improvement in the number of triggering transactions that meet their deadline.