Research Report, RR-8858
, INRIA, Paris 6
Developers of cloud-scale applications face a difficult decision of which kind of storage to use, summarised by the CAP theorem. Currently the choice is between classical CP databases, which provide strong guarantees but are slow, expensive, and unavailable under partition; and NoSQL-style AP databases, which are fast and available, but too hard to program against. We present an alternative - Cure provides the highest level of guarantees that remains compatible with availability. These guarantees include - causal consistency (no ordering anomalies), atomicity (consistent multi-key updates), and high-level data types (developer friendly) with safe resolution of concurrent updates (guaranteeing convergence). These guarantees minimise the anomalies caused by parallelism and distribution, and facilitate the development of applications. This paper presents the protocols for highly available transactions , and an experimental evaluation showing that Cure is able to achieve performance similar to eventually-consistent NoSQL databases, while providing stronger guarantees.
Keywords : geo replication, fault tolerance, distributed database, transactions, causal consistency, CRDTPublication PDF