Amazon RDS: Relational Database Service

Amazon Relational Database Service (Amazon RDS) makes it easy to set up, operate, and scale a relational database in the cloud. It provides cost-efficient, resizable capacity while automating time-consuming administration tasks such as hardware provisioning, database setup, patching, and backups.

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Supported Engines

RDS supports six popular database engines:

Engine	Versions (example)	Notes
MySQL	5.7, 8.0	Most widely used open-source relational database
PostgreSQL	13, 14, 15, 16	Advanced open-source database with rich extension ecosystem
MariaDB	10.6, 10.11	Community-developed fork of MySQL
Oracle	19c, 21c	Enterprise engine; bring-your-own-licence (BYOL) or licence-included
SQL Server	2019, 2022	Microsoft's relational engine; Express, Web, Standard, Enterprise editions
Amazon Aurora	MySQL 8.0-compat, PostgreSQL 15-compat	AWS's cloud-native engine (covered in its own lesson)

Choosing an Engine

• MySQL / MariaDB — good default for web applications, WordPress, and general OLTP
• PostgreSQL — preferred when you need advanced data types (JSONB, arrays), PostGIS, or complex queries
• Oracle / SQL Server — when your organisation has existing investments, compliance requirements, or vendor-specific features

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Launching an RDS Instance

When you create an RDS instance you specify:

1. Engine and version
2. DB instance class — determines vCPU and memory (e.g., db.t3.micro for development, db.r6g.2xlarge for production)
3. Storage type — General Purpose SSD (gp3), Provisioned IOPS SSD (io1/io2), or magnetic
4. VPC and subnet group — the network in which the instance runs
5. Security group — controls inbound and outbound traffic (port 3306 for MySQL, 5432 for PostgreSQL, etc.)
6. Parameter group — engine-level configuration such as max_connections, innodb_buffer_pool_size
7. Option group — engine-specific features like Oracle TDE, SQL Server native backup

Instance Classes at a Glance

Family	Use Case	Example
db.t3 / db.t4g	Dev/test, burstable workloads	db.t3.micro (2 vCPU, 1 GiB)
db.m6g / db.m7g	General purpose production	db.m6g.xlarge (4 vCPU, 16 GiB)
db.r6g / db.r7g	Memory-optimised, large datasets	db.r6g.2xlarge (8 vCPU, 64 GiB)
db.x2g	Extreme memory	db.x2g.xlarge (4 vCPU, 64 GiB)

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Storage

General Purpose SSD (gp3)

• Baseline: 3,000 IOPS and 125 MiB/s throughput (included)
• Scale independently up to 16,000 IOPS and 1,000 MiB/s
• Cost-effective for most workloads

Provisioned IOPS SSD (io1 / io2)

• Up to 256,000 IOPS (io2 Block Express)
• Designed for I/O-intensive OLTP workloads
• Higher per-GB and per-IOPS cost

Storage Autoscaling

You can enable storage autoscaling so that RDS automatically increases storage when free space drops below a threshold. You set a maximum storage limit; RDS scales in 10 GiB increments (or 10% of current allocation, whichever is greater).

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Automated Backups and Snapshots

Automated Backups

• Enabled by default with a retention period of 1 to 35 days
• RDS takes a daily full snapshot and captures transaction logs every 5 minutes
• Supports point-in-time recovery (PITR) — you can restore to any second within the retention window

Manual Snapshots