Title
Quantifying eventual consistency with PBS
Abstract
Data replication results in a fundamental trade-off between operation latency and consistency. At the weak end of the spectrum of possible consistency models is eventual consistency, which provides no limit to the staleness of data returned. However, anecdotally, eventual consistency is often \"good enough\" for practitioners given its latency and availability benefits. In this work, we explain this phenomenon and demonstrate that, despite their weak guarantees, eventually consistent systems regularly return consistent data while providing lower latency than their strongly consistent counterparts. To quantify the behavior of eventually consistent stores, we introduce Probabilistically Bounded Staleness (PBS), a consistency model that provides expected bounds on data staleness with respect to both versions and wall clock time. We derive a closed-form solution for version-based staleness and model real-time staleness for a large class of quorum replicated, Dynamo-style stores. Using PBS, we measure the trade-off between latency and consistency for partial, non-overlapping quorum systems under Internet production workloads. We quantitatively demonstrate how and why eventually consistent systems frequently return consistent data within tens of milliseconds while offering large latency benefits.
Year
DOI
Venue
2014
10.1145/2632792
The Vldb Journal
Keywords
DocType
Volume
Consistency,Replication,Quorum systems,Distributed databases,NoSQL,Staleness,Regular semantics,Dynamo,Prediction
Journal
57
Issue
ISSN
Citations 
8
1066-8888
9
PageRank 
References 
Authors
0.49
48
5
Name
Order
Citations
PageRank
Peter Bailis156349.89
Shivaram Venkataraman2108263.77
Michael J. Franklin3174231681.10
Joseph M. Hellerstein4140931651.14
I. Stoica5214061710.11