GuideTechnology
15 min read
Database Replication: Primary-Replica, Read Replicas, Lag and Failover
Why databases keep copies on several machines, and what those copies cost. Covers primary-replica replication, synchronous versus asynchronous replication, read replicas for scaling, replication lag and the read anomalies it causes, read-your-writes routing, failover and split brain, multi-leader and leaderless replication, and why replication is not a backup.