AWS Certified Database – Specialty — Question 239

A company has an existing system that uses a single-instance Amazon DocumentDB (with MongoDB compatibility) cluster. Read requests account for 75% of the system queries. Write requests are expected to increase by 50% after an upcoming global release. A database specialist needs to design a solution that improves the overall database performance without creating additional application overhead.

Which solution will meet these requirements?

Answer options

• A. Recreate the cluster with a shared cluster volume. Add two instances to serve both read requests and write requests.
• B. Add one read replica instance. Activate a shared cluster volume. Route all read queries to the read replica instance.
• C. Add one read replica instance. Set the read preference to secondary preferred.
• D. Add one read replica instance. Update the application to route all read queries to the read replica instance.

Correct answer: C

Explanation

The correct answer, C, optimally balances read and write operations by using a read replica with secondary preferred read preference, allowing the system to handle increased write loads efficiently. Options A and B involve unnecessary complexity or do not fully utilize the read replica, while D requires application changes that can introduce overhead.