Aurora vs RDS

Amazon Aurora and Amazon RDS are both managed relational database services on AWS, and Aurora is technically one of the engines you can run under the RDS umbrella. The practical choice is between Aurora's cloud-native engine and RDS's stock database engines.

It helps to remember that Aurora is offered through the RDS control plane, so the comparison is really between Aurora's reengineered storage-and-compute design and the standard, unmodified engines RDS otherwise runs. Both are fully managed; the difference is in the engine beneath.

Key Differences

The defining difference is the engine architecture. RDS runs standard, unmodified database engines, MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server, on EBS-backed storage. Aurora is a re-architected engine, compatible with MySQL and PostgreSQL, that separates compute from a distributed, auto-scaling storage layer replicated six ways across three Availability Zones.

This architecture gives Aurora advantages. It typically delivers higher throughput than stock engines, especially for read-heavy and concurrent workloads. Its storage grows automatically, and failover to a read replica is fast, often within seconds, compared to Multi-AZ failover on RDS, which can take longer. Aurora also supports up to 15 low-latency read replicas sharing the same storage.

RDS counters with breadth and cost. It supports five engines, including commercial Oracle and SQL Server, which Aurora does not. For smaller or cost-sensitive workloads, standard RDS is often cheaper, since Aurora carries a performance premium, though Aurora Serverless v2 narrows the gap for variable workloads.

Read scaling is one of Aurora's clearest advantages. Because Aurora replicas share the same distributed storage volume as the writer, they stay closely in sync and can be added quickly, up to fifteen, without the replication lag patterns typical of stock engine replicas on RDS. Aurora also offers features like Backtrack, which rewinds the database in time, and a Global Database for low-latency cross-region reads. Standard RDS, by contrast, supports a broader matrix of engines and versions, including commercial Oracle and SQL Server with their specific features.

When to Choose Aurora

Choose Aurora for high-throughput, high-availability MySQL or PostgreSQL workloads, when you need fast failover, auto-scaling storage, or many read replicas. It is the better fit for demanding production databases where performance and resilience justify the cost.

When to Choose RDS

Choose standard RDS for smaller or cost-sensitive workloads, when you need engines Aurora does not support (Oracle, SQL Server, MariaDB), or when stock-engine compatibility is important. It offers a simpler, often cheaper managed database.

Cost shapes the decision for many teams. Aurora's instances cost more than equivalent stock-engine RDS instances, and its I/O-based pricing, or the newer I/O-optimized tier, must be modeled for write-heavy workloads. For modest databases the premium may not be justified, while for demanding, high-availability MySQL or PostgreSQL workloads the performance and failover gains usually repay it, especially with Aurora Serverless v2 smoothing variable demand.

Verdict

Aurora is the premium, cloud-native option with superior performance, storage, and failover for MySQL/Postgres. RDS offers broader engine choice and lower cost for modest workloads. Choose Aurora when you need its performance and availability; choose RDS for cost efficiency, commercial engines, or simpler needs.