AWS Certified Solutions Architect – Associate (SAA-C03) — Question 325
A company has deployed a web application on AWS. The company hosts the backend database on Amazon RDS for MySQL with a primary DB instance and five read replicas to support scaling needs. The read replicas must lag no more than 1 second behind the primary DB instance. The database routinely runs scheduled stored procedures.
As traffic on the website increases, the replicas experience additional lag during periods of peak load. A solutions architect must reduce the replication lag as much as possible. The solutions architect must minimize changes to the application code and must minimize ongoing operational overhead.
Which solution will meet these requirements?
Answer options
- A. Migrate the database to Amazon Aurora MySQL. Replace the read replicas with Aurora Replicas, and configure Aurora Auto Scaling. Replace the stored procedures with Aurora MySQL native functions.
- B. Deploy an Amazon ElastiCache for Redis cluster in front of the database. Modify the application to check the cache before the application queries the database. Replace the stored procedures with AWS Lambda functions.
- C. Migrate the database to a MySQL database that runs on Amazon EC2 instances. Choose large, compute optimized EC2 instances for all replica nodes. Maintain the stored procedures on the EC2 instances.
- D. Migrate the database to Amazon DynamoDB. Provision a large number of read capacity units (RCUs) to support the required throughput, and configure on-demand capacity scaling. Replace the stored procedures with DynamoDB streams.
Correct answer: A
Explanation
Amazon Aurora MySQL features a shared storage architecture where the primary instance and Aurora Replicas access the same underlying storage volume, reducing replication lag to virtually zero (typically under 100 milliseconds). Migrating to Amazon DynamoDB or adding Amazon ElastiCache would require extensive application code rewrites, failing the requirement to minimize code changes. Transitioning to self-managed MySQL on Amazon EC2 greatly increases ongoing operational overhead compared to a fully managed service like Aurora.