To achieve high availability and low latency, distributed data stores often geographically replicate data at multiple sites called replicas. However, this introduces the data consistency problem. Due to the fundamental tradeoffs among consistency, availability, and latency in the presence of network partition, no a one-size-fits-all consistency model exists. To meet the needs of different applications, many popular data stores provide tunable consistency, allowing clients to specify the consistency level per individual operation. In this paper, we propose tunable causal consistency (TCC). It allows clients to choose the desired session guarantee for each operation, from the well-known four session guarantees, i.e., read your writes, monotonic reads, monotonic writes, and writes follow reads. Specifically, we first propose a formal specification of TCC in an extended (vis,ar) framework originally proposed by Burckhardt et al. Then we design a TCC protocol and develop a prototype distributed key-value store called TCCSTORE. We evaluate TCCSTORE on Aliyun. The latency is less than 38ms for all workloads and the throughput is up to about 2800 operations per second. We also show that TCC achieves better performance than causal consistency and requires a negligible overhead when compared with eventual consistency.
翻译:为实现高可用性和低延迟度,分布式数据存储处经常在地理上复制多个地点称为复制站的数据,但由此出现了数据一致性问题。由于网络分区存在的一致性、可用性和长期性之间的根本权衡,不存在一刀切的统一模式。为满足不同应用的需要,许多流行数据存储处提供可调用的一致性,使客户能够具体确定每个操作的一致性水平。在本文件中,我们提议可调用因果一致(TCC)。它允许客户从众所周知的四期保证中选择每项操作所需的会话保证,即阅读你的书写、单曲、单曲、单曲写作和以下文字。具体地说,我们首先在Burckhardt等人最初提议的扩展(as,ar)框架中提出一个总合标准的正式规格。然后我们设计一个总合协议,并开发一个分发的关键价值商店,称为TCCSTORTE。我们评估Aliyun的TCSTORE。所有工作量的封存量少于38米,所有工作量都低于38米,单曲、单曲、单曲、单曲写和书写并写后写为下文。具体读。我们首先在扩展式框架框架中提出一个扩展要求达到28的操作达到最低程度的一致。我们最后需要达到28/直达。