Comparing RAFT, PAXOS, and Calvin Consensus Algorithms: Why CockroachDB Chose RAFT

Consensus algorithms are essential for distributed databases, enabling nodes in the cluster to agree on a single version of the data. RAFT, PAXOS, and Calvin are three popular consensus algorithms used in distributed systems. In this blog post, we will compare these algorithms and discuss why CockroachDB chose RAFT as its consensus algorithm.

RAFT:

RAFT is a consensus algorithm that uses a leader-based approach to consensus. In RAFT, a single node is designated as the leader, which is responsible for coordinating the replication of data across the cluster. If the leader fails, a new leader is elected by the remaining nodes. RAFT provides several benefits, including ease of understanding, leader election, and a strong focus on fault tolerance.

PAXOS:

PAXOS is another consensus algorithm that is widely used in distributed systems. PAXOS uses a peer-to-peer approach to consensus, where all nodes in the cluster participate in the decision-making process. PAXOS provides several benefits, including a strong focus on fault tolerance, high availability, and scalability.

Calvin:

Calvin is a consensus algorithm that uses a distributed transactional model. In Calvin, all nodes in the cluster have the same status, and transactions are processed in parallel. Calvin provides several benefits, including high scalability, low latency, and strong consistency.

Why CockroachDB Chose RAFT:

CockroachDB is a distributed SQL database that uses RAFT as its consensus algorithm. The decision to use RAFT was based on several factors, including:

1. Simplicity: RAFT is easy to understand and implement, making it an ideal choice for a distributed database.
2. Fault tolerance: RAFT provides strong fault tolerance by ensuring that data is replicated across the cluster and that a new leader can be elected in case of failure.
3. Scalability: RAFT can scale to large clusters without compromising performance or consistency.
4. Compatibility: RAFT is compatible with other distributed systems and can be used in conjunction with other technologies, such as Kubernetes and Docker.

Conclusion:

In summary, RAFT, PAXOS, and Calvin are three popular consensus algorithms used in distributed systems. While each algorithm has its strengths and weaknesses, CockroachDB chose RAFT as its consensus algorithm due to its simplicity, fault tolerance, scalability, and compatibility with other distributed technologies. By using RAFT, CockroachDB can provide a highly available, scalable, and consistent distributed SQL database.