Read replication
Read replication is the replication of database data from a writable primary instance to one or more instances that serve read operations.
Amazon Web Services in Action, Third Edition: An in-depth guide to AWS
A read replica is a replicated database instance that serves read-only queries and can be promoted to primary in supported configurations.
- How it is used
- Uses replicas to increase read throughput for applications that generate many more reads than writes.
- How deep it goes
- Explains asynchronous replication, application routing, creation steps, lag monitoring, promotion, and billing, but not replica internals.
- Examples
- Uses an RDS WordPress database, HyperDB, AWS CLI commands, distributed read requests, and a Redis gaming application with measurable lag.
- What you can do after
- Apply it via Amazon RDS by creating replicas, routing reads, monitoring lag, and promoting or deleting replicas when appropriate.
Kubernetes for Developers
A read replica is a synchronized database instance that serves read operations separately from a primary writable instance.
- How it is used
- Offloads SELECT queries from the primary database to reduce strain during application scaling.
- How deep it goes
- Provides an implementation pattern with separate connections and permissions, but does not detail replication internals.
- Examples
- Uses two connections to one database first, then redirects the read-only connection to a deployed replica.
- What you can do after
- Configure an application for read scaling by separating read-only and primary database connections.
Read how Kubernetes for Developers explains read replication →
Related concepts
- Amazon Relational Database Service (RDS)used by · Amazon Relational Database Service is an AWS-managed service for deploying, operating, and scaling relational databases.
- replication laguses · Replication lag is the elapsed delay between a change being applied or committed at a source and becoming applied or visible at a replication target.
- primary nodecontrasts with · A primary node is a designated authoritative or coordinating member of a distributed system, typically responsible for accepting operations or coordinating replicated state.
- load balancingused by · Load balancing is the distribution of requests or computational work across multiple resources to manage demand, reduce workload imbalance, and improve utilization or availability.
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