In distributed environment, data availability and concurrency control both are challenging issues. Data availability can be maintained by replicating data at several locations or sites that will improve the availability but at the same time it is very challenging task to maintain the consistency of it. In order to improve the performance of the system, it is required to execute multiple transactions concurrently on several sites. Therefore, we need to control these concurrent transactions for maintaining consistency of replica. Replica control become more complex for the environment where messages are delayed due to communication failure. In this paper, we develop formal model of fault-tolerant replica control protocol Using Event-B. Formal methods are mathematical techniques through which we can verify the correctness of model. Event-B is a formal method which is used to develop the model in distributed environment.
Postgres-R(SI): Combining Replica Control with Concurrency Control Based on Snapshot Isolation