AWS Certified Database – Specialty — Question 292

Application developers have reported that an application is running slower as more users are added. The application database is running on an Amazon Aurora
DB cluster with an Aurora Replica. The application is written to take advantage of read scaling through reader endpoints. A database specialist looks at the performance metrics of the database and determines that, as new users were added to the database, the primary instance CPU utilization steadily increased while the Aurora Replica CPU utilization remained steady.
How can the database specialist improve database performance while ensuring minimal downtime?

Answer options

• A. Modify the Aurora DB cluster to add more replicas until the overall load stabilizes. Then, reduce the number of replicas once the application meets service level objectives.
• B. Modify the primary instance to a larger instance size that offers more CPU capacity.
• C. Modify a replica to a larger instance size that has more CPU capacity. Then, promote the modified replica.
• D. Restore the Aurora DB cluster to one that has an instance size with more CPU capacity. Then, swap the names of the old and new DB clusters.

Correct answer: C

Explanation

Scaling up an existing replica and then promoting it to the primary role (Option C) ensures the primary instance gets more CPU capacity with minimal downtime, as the failover process completes in about 30 seconds. Modifying the primary instance directly (Option B) causes a much longer disruption because the database must be taken offline during the resize. Adding more replicas (Option A) will not resolve the high CPU utilization on the primary instance, which is handling write traffic, and restoring a new cluster (Option D) introduces unnecessary complexity and downtime.