AWS Certified Cloud Practitioner / Databases & Analytics

RDS & Aurora Overview

🗃️ Amazon RDS

Amazon RDS (Relational Database Service) is AWS's fully managed service for running relational (SQL) databases — create, operate, and scale without managing the server yourself.

🛠️ Supported Engines

  • 🐘 PostgreSQL

  • 🐬 MySQL

  • 🦭 MariaDB

  • 🔶 Oracle

  • 🪟 SQL Server

  • 🟦 IBM Db2

  • ⚡ Amazon Aurora (AWS's own engine — covered below)

🎯 Exam tip: Any of these engines = relational + SQL.

❓ Why RDS Instead of DB-on-EC2?

You can install MySQL/PostgreSQL on EC2 — but then you're the DBA: installs, patches, backups, monitoring, failure recovery.

With RDS, AWS is your DBA (Database Administrator)

🚫 What RDS Won't Let You Do

You cannot SSH into an RDS instance — no OS-level access, no custom software installs, no OS modifications. AWS owns the infrastructure; you just connect via SQL client/app.

💡 Quick Tip: Use RDS for easy management and high availability. Use EC2 only when you need full server control.

🎯 Exam Tip: Need SSH or OS-level access? Choose EC2, not RDS.

🏗️ Where Amazon RDS Fits?

Let's see where Amazon RDS fits within a typical AWS architecture.

🔄 How It Works

  • Users send requests to your application.

  • The Elastic Load Balancer (ELB) distributes incoming traffic across multiple EC2 instances.

  • The EC2 instances process the application's business logic.

  • Whenever structured data needs to be stored or retrieved, the EC2 instances communicate with Amazon RDS.

  • All EC2 instances share the same database, ensuring consistent and up-to-date information.

💡 This three-tier architecture is one of the most common application architectures used on AWS.

⚡ Amazon Aurora

AWS's own cloud-native relational database — MySQL/PostgreSQL-compatible, but built for much higher performance, scalability, and availability.

🔗 Engine Compatibility

  • 🐬 MySQL

  • 🐘 PostgreSQL

Existing apps often migrate over with little to no code changes.

🚀 Why Aurora?

  • Up to 5× faster than MySQL on RDS

  • Up to 3× faster than PostgreSQL on RDS

📦 Auto Storage Scaling

Grows automatically in 10 GB steps up to 256 TB — no manual resizing.

💰 Cost

~20% more than standard RDS, but often cheaper overall thanks to better performance/efficiency.

🎯 RDS vs Aurora

Amazon RDS

Amazon Aurora

Multiple relational engines

AWS's own proprietary engine

Managed version of familiar DBs

Cloud-native, built by AWS

Solid for general SQL workloads

Higher performance + auto storage scaling

📌 Both are managed relational databases — Aurora just adds cloud-native performance.

🚀 Amazon Aurora Serverless

No instances to provision — AWS auto-creates and scales capacity based on demand. Great for infrequent, unpredictable, or spiky workloads.

✅ Benefits

  • ⚡ Auto capacity management — no manual sizing

  • 📈 Auto scaling — up and down, no intervention

  • 🖥️ No server management — AWS handles it all

  • 💰 Pay-per-second — only for what you use

⚙️ How Aurora Serverless Works

App connects like normal — AWS handles provisioning, scaling, and shared storage behind the scenes.

🎯 Exam tip: "No server management," "auto scaling," "pay for actual usage," "unpredictable workload" → Aurora Serverless.