Commit-order oriented validation scheme for transaction scheduling in teleputing systems

Abstract

In this thesis, we propose a new validation scheme, COOV, for scheduling transactions optimistically in client-server based mobile database systems. In the mobile environment, it cannot be guaranteed reliable message transfers due to various latency factors in wireless channels. The delays in transferring commit requests could result in serious performance degradation in validation processes for transaction scheduling. Unlike the validation method in the other optimistic concurrency control schemes, COOV removes the waiting time in validation process induced from the delays on basis of the notion of commit reordering. Another version of COOV, $R^2COOV$, is also devised to reduce the abort ratio in COOV by rearranging the serializable order of committed transactions without destroying serializability. For implementing COOV and $R^2COOV$,we also present a new scheme for assigning transaction number, SORT. It enables COOV and $R^2COOV$ to validate transactions irrespective of the delays and moreover to guarantee serializability corresponding to the substantial execution order.