Commit Processing in Distributed Real-Time Database Systems

We investigate here the performance implications of supporting transaction atomicity in a distributed real-time database system. Using a detailed simulation model of a firm-deadline distributed real-time database sgstem, we profile the real-time performance of a repre-sentative set of commit protocols. A new commit proto-col that is designed for the real-time domain and allows transactions to “optimistically ” read uncommitted data is also proposed and evaluated, The experimental results show that data distribution has a significant influence on the real-time performance and that the choice of commit protocol clearly affects the magnitude of this injluence. Among the protocols evaluated, the new optimistic commit protocol provides the best performance for a variety of workloads and sys-tem configurations. 1