read replicas

Read replicas are a core scaling strategy for PostgreSQL on Azure, as demonstrated by OpenAI's production architecture. The setup uses a single primary writer with dozens of read-only replicas to offload read traffic and optimize performance. WAL streaming keeps replicas synchronized while the primary handles writes. This approach reduces latency for read-heavy workloads and improves overall throughput. Key considerations include managing replication lag, choosing the right number of replicas, and tuning queries for replica-friendly execution. Azure Database for PostgreSQL simplifies replica management but still requires careful planning for consistency and failover. The tag covers real-world deployment patterns, performance trade-offs, and operational best practices for read replicas in cloud environments.