An Analytic Model for Performance Analysis of Concurrency Control Strategies in Mobile Environments

Many performance studies have shown that locking based protocols outperform other concurrency control protocols in most database configurations and workloads. However, in mobile environments there are many special characteristics, such as long network delay and the expensive wireless communication. Besides, transactions may be aborted due to forced termination when handoff occurs for the consideration of concurrency control. The performances of concurrency control strategies should be re-evaluated in such environments. In this paper, we develop an analytic model to evaluate the performances of concurrency control strategies. The accuracy of this model is verified by simulation. According to the experimental results we show that the behavior of mobile users and the degree of data contention have a significant impact on the relative performances of the concurrency control strategies. In particular, we point out that the optimistic concurrency control strategy outperforms other strategies over a wide range of system configurations. We also explain why the optimistic algorithm is well suited in mobile environments.