  In this paper we propose a novel approach to manage the throughput vs latency
tradeoff that emerges when managing updates in geo-replicated systems. Our
approach consists in allowing full concurrency when processing local updates
and using a deferred local serialisation procedure before shipping updates to
remote datacenters. This strategy allows to implement inexpensive mechanisms to
ensure system consistency requirements while avoiding intrusive effects on
update operations, a major performance limitation of previous systems. We have
implemented our approach as a variant of Riak KV. Our extensive evaluation
shows that we outperform sequencer-based approaches by almost an order of
magnitude in the maximum achievable throughput. Furthermore, unlike previous
sequencer-free solutions, our approach reaches nearly optimal remote update
visibility latencies without limiting throughput.
