Atomic commitment in transactional DHTs

Abstract

We investigate the problem of atomic commit in transactional database systems built on top of Distributed Hash Tables. DHTs provide a decentralized way to store and look up data. To solve the atomic commit problem we propose to use an adaption of Paxos commit as a non-blocking algorithm. We exploit the symmetric replication technique existing in the DKS DHT to determine which nodes are necessary to execute the commit algorithm. By doing so we achieve a lower number of communication rounds and a reduction of meta-data in contrast to traditional Three-Phase-Commit protocols. We also show how the proposed solution can cope with dynamism due to churn in DHTs. Our solution works correctly relying only on an inaccurate failure detection of node failure which is necessary for systems running over the Internet