Replication

Database replication is the process of creating and maintaining copies of a database on multiple servers. The primary types are: synchronous replication (all replicas confirm writes before committing, ensuring consistency at the cost of latency), asynchronous replication (the primary confirms writes immediately and replicas catch up later, offering better performance with eventual consistency), and semi-synchronous replication (at least one replica confirms before the primary commits). Replication serves multiple purposes: high availability (if the primary fails, a replica takes over), read scaling (distribute read queries across replicas), disaster recovery (geographic redundancy), and analytics isolation (run heavy queries on a replica without affecting production).