Implementation of a virtual time synchronizer for distributed databases

The availability of high speed networks and improved microprocessor performance have made it possible to build inexpensive cluster of workstations as an appealing platform for parallel and distributed computing. In this paper, we study the performance of a distributed database system synchronized by virtual time (VT) mechanism by experimenting on a LAN-connected collection of 12 Sun-SPARCS workstations. Our experimental results demonstrate that the VT synchronization protocol is a viable concurrency control method, and it yields about 25-30% reduction in the response time, when compared with a widely used, multiversion (MV) concurrency control scheme based on timestamps order. The reason for comparing with the MV approach is that both virtual time and multiversion protocols are based upon the concept of timestamps, and attain high performance by using multiple version of data objects