A certification protocol with low space overhead

Abstract

The performance of optimistic concurrency control schemes is sensitive to the transaction abort rate. The abort probability can be reduced by reordering in order to reduce read-write conflicts. However, a potential drawback of reordering schemes is the space overhead in maintaining timestamps, multiple versions or a serialization graph. Furthermore, some transactions in optimistic concurrency control schemes may perform unnecessary operations even after the transactions have accessed write-write conflicting data items, because aborts happen only in the validation phase. In this paper, we propose a new broadcast scheme called BOCC-RS (Broadcast Optimistic Concurrency Control with Re-ordering Scheme) that can reduce the abort probability with low space overhead. In our scheme, the server maintains only one timestamp per data item for reordering. Moreover, our scheme reduces unnecessary operations. This paper presents a simulation study which shows that our scheme outperforms BOCC.