Transactional Replication in Hybrid Data Store Architectures

We present a transactional and concurrent replication scheme that is designed for hybrid data store architectures. The system design and the requirements are motivated by the real business cases we encountered during the development of our commercial database product. We consider two databases where the original database handles read/write transactional application workloads while the second database handles read-only workloads from the same applications over the data periodically replicated from the original database. The main requirement is ensuring the application of the updates on the replica database in the exact same order they were executed in the original database, which is called executiondefined order. Although this requirement could easily be satisfied by the serial execution of the updates in the commit order, doing so in an e cient manner by exploiting concurrency is a challenging problem. We present a novel concurrency control algorithm to addresses that problem by also allowing the read-only workloads on the replica database to interleave with the concurrent replication. The extensive experiments show the e cacy of the proposed solution.