AWS RDS: Fundamentals & Supported Engines

Amazon RDS (Relational Database Service) is a managed relational database service. AWS handles provisioning, patching, backups, and failover. You focus on schema, queries, and application logic.

RDS vs Self-Managed on EC2

• RDS: automated backups, Multi-AZ, read replicas, patching, monitoring — you give up OS access

• EC2 self-managed: full control (custom extensions, OS tuning), but you own all ops work

• RDS vs Aurora: Aurora is AWS-proprietary, MySQL/PostgreSQL-compatible, 5x faster than MySQL, auto-scales storage, costs more

• Choose RDS when you need standard PostgreSQL/MySQL features without Aurora pricing

Supported Engines

• PostgreSQL 11–17 (most feature-rich, recommended for new projects)

• MySQL 8.0 / MariaDB 10.6+ (popular, wide tooling support)

• Oracle — bring your own license or license-included (expensive)

• Microsoft SQL Server — Standard/Enterprise editions, Windows Auth support

• Db2 — IBM database, added 2023

Instance Classes

Family     | vCPU | RAM    | Use Case
-----------|------|--------|---------------------------
db.t3/t4g  | 2-8  | 1-32GB | Dev/test, burstable (cheap)
db.m6g/m7g | 2-96 | 8-384GB| General purpose production
db.r6g/r7g | 2-96 | 16-768GB| Memory-intensive (large caches)
db.x2g     | 4-128| 61-980GB| SAP, very large in-memory workloads

Storage Types

• gp3 (General Purpose SSD): baseline 3000 IOPS + 125 MB/s, configurable up to 16000 IOPS — default choice

• io1/io2 (Provisioned IOPS): up to 64000 IOPS, for OLTP with consistent low latency

• Storage autoscaling: set max threshold, RDS expands automatically when 10% free

Creating an RDS Instance

# Create PostgreSQL instance
aws rds create-db-instance \
  --db-instance-identifier my-postgres \
  --db-instance-class db.t3.medium \
  --engine postgres \
  --engine-version 16.1 \
  --master-username admin \
  --master-user-password "SecureP@ssw0rd" \
  --allocated-storage 100 \
  --storage-type gp3 \
  --db-subnet-group-name my-db-subnet-group \
  --vpc-security-group-ids sg-abc123 \
  --backup-retention-period 7 \
  --multi-az \
  --storage-encrypted \
  --no-publicly-accessible

# Wait for it to be available
aws rds wait db-instance-available --db-instance-identifier my-postgres

# Get endpoint
aws rds describe-db-instances \
  --db-instance-identifier my-postgres \
  --query 'DBInstances[0].Endpoint'

Connecting

# PostgreSQL
psql -h my-postgres.abc123.eu-west-1.rds.amazonaws.com \
  -U admin -d mydb -p 5432

# MySQL
mysql -h my-mysql.abc123.eu-west-1.rds.amazonaws.com \
  -u admin -p --port 3306 mydb

# From application (connection string)
# postgresql://admin:password@host:5432/mydb
# mysql://admin:password@host:3306/mydb

Parameter Groups & Option Groups

# Create custom parameter group
aws rds create-db-parameter-group \
  --db-parameter-group-name my-pg16-params \
  --db-parameter-group-family postgres16 \
  --description "Custom PostgreSQL 16 parameters"

# Tune key parameters
aws rds modify-db-parameter-group \
  --db-parameter-group-name my-pg16-params \
  --parameters \
    "ParameterName=shared_buffers,ParameterValue={DBInstanceClassMemory/4},ApplyMethod=pending-reboot" \
    "ParameterName=max_connections,ParameterValue=200,ApplyMethod=pending-reboot" \
    "ParameterName=log_min_duration_statement,ParameterValue=1000,ApplyMethod=immediate"

# Apply to instance
aws rds modify-db-instance \
  --db-instance-identifier my-postgres \
  --db-parameter-group-name my-pg16-params \
  --apply-immediately