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CLF-045
Which AWS service is most appropriate when you want to use a managed relational database?
Choices
Explanation and answer
Read the explanation and correct answer (spoiler — try answering first)
Correct answer: A. Amazon RDS
Explanation
Amazon RDS is a service that lets you run relational databases such as MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server as a managed service.
Per-choice explanations
A. Amazon RDS
Correct. RDS is a managed relational database service.
B. Amazon CloudFront
CloudFront is a CDN service.
C. AWS CloudTrail
CloudTrail is a service that records AWS API call history.
D. Amazon S3
S3 is object storage. It is not a relational database.
Practical Use
Amazon RDS (Relational Database Service) is a service that provides relational databases as a managed offering. It supports six database engines: MySQL, PostgreSQL, MariaDB, Oracle Database, Microsoft SQL Server, and Amazon Aurora (the AWS-developed engine with MySQL and PostgreSQL compatibility). AWS handles operational tasks such as OS patching, minor database engine version upgrades, automated backups, snapshot creation, and failover during outages, so users can focus on schema design, query tuning, and application logic. On the exam, Amazon RDS is the expected answer for the prompt asking which service to choose when you want a managed relational database. Common distractors include services that are not data stores, such as Amazon S3 (object storage), Amazon CloudFront (CDN), and AWS CloudTrail (recording API call history). When the keyword "relational" is explicit, document database Amazon DocumentDB, key-value or document NoSQL Amazon DynamoDB, and data warehouse Amazon Redshift do not fit, so even if they appear among the choices they can be eliminated. In practice, the criterion for selection is the difference in responsibility between self-hosting a database on Amazon EC2 and using Amazon RDS. With a self-hosted database on Amazon EC2, the user is responsible for patching, backup, and failover design. With Amazon RDS, those tasks fall under AWS responsibility. CLF-C02 frequently asks about the principle in the shared responsibility model that "the more managed the service, the lower the operational burden on the user," as well as the difference in role between Amazon RDS Multi-AZ deployments (high availability) and read replicas (distributing read load). The distinction between Amazon RDS and Amazon DynamoDB (relational versus key-value or NoSQL) should also be understood.