Write notification for certification protocol based on time-stamp history

Abstract

The performance of optimistic concurrency control schemes is sensitive to the transaction abort rate. The abort probability can be reduced by back-shifting the time-stamp for certification from the time of requesting a commit in order to reduce read-write conflicts. However even if this approach can reduce the abort probability, some transactions continuously perform unnecessary operations even after the transactions accessed write-write conflicting data items. The reason is that the abort only happens in the validation phase. In addition, the validation time in the time-stamp history based certification scheme is too long. Our primary goal is to enhance the performance of the certification protocol by reducing the unnecessary operations and validation overhead. In this paper we propose a protocol that can abort the transaction during the execution phase when it accesses write-write conflicting data items by using the write notification approach. Additionally, we also propose an extended protocol that can reduce the validation overhead.