Databases Demystified Chapter 8 – Distributed Databases Part 3

Consensus refers to broad agreement on the truth in the context of distributed databases, ensuring that all nodes agree on the same values and provide consistent results to queries. The Two Generals Problem illustrates the difficulty of coordinating an agreement between two parties when there's a faulty communication channel. In distributed databases, consensus is generally a problem when multiple nodes operate simultaneously with unreliable network connections between them. Key strategies for making consensus happen include having individual nodes "elect" a leader node in charge of coordinating the log of operations and communicating "truth" to all other nodes. Two widely used consensus algorithms are Raft and Paxos, which involve multiple rounds of votes to reach agreement on an agreed-upon truth.