Modern distributed databases employ leader-based consensus protocols to achieve consistency, entailing certain trade-offs: typically either a scalability bottleneck or weak isolation. Leaderless protocols have been proposed to address these and other shortcomings of leader-based techniques, but these have not yet materialized into production systems.
This paper outlines compromises entailed by existing leaderless protocols versus leader-based protocols and proposes general techniques for addressing them. A new protocol, called Accord, is proposed with optimal failure tolerance that, under reasonable assumptions, achieves optimal latency of two message delays for transactions initiated by coordinators in any region, under any level of competing transactions and maximal tolerated process failures.
Karthik Ranganathan is a founder and CTO of YugabyteDB, a globally distributed, strongly consistent database. Prior to Yugabyte, Karthik was at Facebook, where he built the Cassandra database. In this talk, Karthik will discuss Yugabyte’s use of time synchronization and Raft protocol along with some optimizations that enable high-performance distributed transactions.
ACID transactions are a fundamental building block when developing business-critical, user-facing applications. They simplify the complex task of ensuring data integrity while supporting highly concurrent operations. While they are taken for granted in monolithic SQL databases, most distributed DBs would forsake them completely.
Fortunately, this is no longer the case. The trend started with Google Spanner, which offered distributed transactions using GPS based atomic clocks – unheard of in the database world before. Now, distributed transactions – without requiring atomic clocks – are offered by distributed SQL databases. One such example of a fully open source database offering this is YugabyteDB. Using the example of YugabyteDB, this talk will explain how distributed ACID transactions can be achieved without atomic clocks – without compromising on performance.
Stateright is a software framework for analyzing and systematically verifying distributed systems. Its name refers to its goal of verifying that a system’s collective state always satisfies a correctness specification, such as “operations invoked against the system are always linearizable.” Cloud service providers like AWS and Azure leverage verification software such as the TLA+ model checker to achieve the same goal, but whereas that solution can verify a high level system design, Stateright is able to systematically verify the underlying system implementation in addition to the design.
In this talk, Stateright’s author Jonathan Nadal will introduce the project, demo its usage, and discuss upcoming improvements. Jonathan has been in the cloud space since 2012 when he joined Amazon Web Services to work on S3. There he met Chris Newcombe, who introduced TLA+ to the company, and was immediately hooked by that technology. Jonathan later joined Oracle to help build Oracle Cloud Infrastructure, where he is currently a director of engineering and a proponent of model checking techniques within and outside his own teams. Stateright is a personal project not affiliated with Oracle or Amazon.
Our reading groups takes place over Zoom every Wednesday at 2:00 pm EST. We have a slack group where we post papers, hold discussions and most importantly manage Zoom invites to the papers. Please join the slack group to get involved!