Consensus in Data Management: From Distributed Commit to Blockchain.

The problem of distributed consensus has played a major role in the development of distributed data management systems. This includes the development of distributed atomic commit and replication protocols. In this monograph, we present foundations of consensus protocols and the ways they were utilized to solve distributed data management problems. Also, we discuss how distributed consensus contributes to the development of emerging blockchain systems. This includes an exploration of consensus protocols and their use in systems with malicious actors and arbitrary faults. Our approach is to start with the basics of representative consensus protocols where we start from classic consensus protocols and show how they can be extended to support better performance, extended features, and/or adapt to different system models. Then, we show how consensus can be utilized as a tool in the development of distributed data management. For each data management problem, we start by showing a basic solution to the problem and highlighting its shortcomings that invites the utilization of consensus. Then, we demonstrate the integration of consensus to overcome these shortcomings and provide desired design features. We provide examples of each type of integration of consensus in distributed data management as well as an analysis of the integration and its implications.