Transaction Management Using Causal Snapshot Isolation in Partially Replicated Databases

Abstract

We present here a transaction management protocol using causal snapshot isolation in partially replicated multi-version databases. We consider here replicated databases consisting of multiple disjoint data partitions. A partition is not required to be replicated at all database sites, and a site may contain replicas for any number of partitions. Transactions can execute at any site and read or write data from any subset of the partitions, and its updates are propagated asynchronously to other sites. The protocol ensures that the snapshot observed by a transaction contains data versions that are causally consistent. The protocol requires propagating updates only to the sites replicating the updated items. In developing this protocol, we address the issues that are unique in supporting transactions with causal consistency together with the snapshot isolation model in partially replicated databases. Through experimental evaluations, we demonstrate the scalability of this model and its performance benefits over full replication models.