In the epidemic model an update is initiated on a single site, and is propagated to other sites in a lazy manner. When combined with version vectors and event logs, this propagation mechanism delivers updates in causal order despite communication failures. We integrate quorums into the epidemic model to processes transactions on replicated data.
Causal order helps establish the global serialization order on transactions.
Our approach enforces serializability by aborting transactions that may cause inconsistency. In the absence of conflict a transaction can commit as soon as it is known to a quorum of sites. Doc 98 Epidemic Algorithms for Replicated Database Maintenance - Demers, Greene et al. The dangers of replication and a solution - Gray, Helland et al. Doc 72 IEEE Transactions on Knowledge and Data Engineering - Agrawal, Abbadi et al.