Roll Back Mechanism in Multi Version Locking in Distributed Database

In the distributed database multiple sites are interconnected to provide a resource sharing environment. The different sites at each site coexist in order to access the resources. Concurrency control methods are adopted to control the simultaneous execution of multiple transactions. In this paper we investigate multi version locking protocol in distributed environment. Multi version database has the potential to significantly increase the amount of concurrency in transaction processing as they can avoid read write conflict by completing the read requests with older versions of data while the write operation is in progress. In this paper we have presented a detailed review of multi version locking algorithm. We look into the extent to which they endow with the increase in the level of concurrency. We have given an improvement on the algorithm proposed by wang to prevent the rollback situation. We have not imposed any restriction on the waiting of the transaction to prevent rollback as discussed by wang rather we have suggested that check point based mechanism and proper re-sequencing of the transaction can be done to prevent the rollback of the transaction in multi version locking.