Selecting Relational Database Engines: MySQL vs. PostgreSQL on AWS

This guide explores the critical decision-making process for selecting a database engine within Amazon RDS and Amazon Aurora, specifically focusing on the trade-offs between MySQL and PostgreSQL as required for the SAA-C03 exam.

Learning Objectives

By the end of this guide, you should be able to:

• Distinguish between the operational features of MySQL and PostgreSQL on AWS.
• Identify the appropriate engine for specific migration scenarios (e.g., Oracle to PostgreSQL).
• Compare Amazon Aurora's MySQL-compatible and PostgreSQL-compatible editions.
• Calculate storage IOPS requirements based on engine-specific page sizes.

Key Terms & Glossary

• Amazon RDS: Relational Database Service; a managed service for six popular database engines.
• Amazon Aurora: A MySQL and PostgreSQL-compatible relational database built for the cloud with a virtualized storage layer.
• InnoDB: The recommended storage engine for MySQL and MariaDB on RDS; the only one supported by Aurora MySQL.
• OLTP (Online Transaction Processing): Databases designed for high-frequency, small transactions (standard for RDS).
• License Included: A licensing model where the cost of the DB engine license is bundled into the AWS hourly rate.

The "Big Idea"

In the AWS ecosystem, choosing between MySQL and PostgreSQL isn't just about syntax—it's about migration compatibility and performance scaling. While both are open-source relational engines, MySQL is often the default for web-scale applications and