SHAFT: Supporting Transactions with Serializability and Fault-Tolerance in Highly-Available Datastores

Guaranteeing transaction semantics in a highly available and fault tolerant manner is desirable to application developers. Besides, it is a very valuable feature for database-backed applications. In this paper, we propose SHAFT to support transactions with serializability in highly-available datastores, which partition, distribute and replicate data across datacenters. SHAFT is a transactional replication protocol guaranteeing Serializability, High Availability and Fault Tolerance simultaneously for transactions. Laying its basis on the Paxos algorithm, SHAFT guarantees serializability by a two-phase locking procedure in a fault-tolerant manner. Different from other transactional replication protocols like MDCC, SHAFT allows a client to actively abort a transaction. SHAFT also allows flexible data partition, replication and distribution, a proper combination of which can reduce costs and improve performance. SHAFT performs well even under failures. Our experiments show that SHAFT outperforms MDCC, which outperforms other synchronous transactional replication protocols, e.g. Megastore.