AWS Certified Developer – Associate — Question 45

A company is building an application for stock trading. The application needs sub-millisecond latency for processing trade requests. The company uses Amazon
DynamoDB to store all the trading data that is used to process each trading request.
A development team performs load testing on the application and finds that the data retrieval time is higher than expected. The development team needs a solution that reduces the data retrieval time with the least possible effort.
Which solution meets these requirements?

Answer options

• A. Add local secondary indexes (LSIs) for the trading data.
• B. Store the trading data in Amazon S3, and use S3 Transfer Acceleration.
• C. Add retries with exponential backoff for DynamoDB queries.
• D. Use DynamoDB Accelerator (DAX) to cache the trading data.

Correct answer: D

Explanation

The correct answer is D because DynamoDB Accelerator (DAX) provides in-memory caching, which significantly speeds up data retrieval times, making it ideal for applications requiring low latency. Option A may improve some query performance but doesn't guarantee sub-millisecond latency. Option B is not suitable since Amazon S3 is not designed for low-latency access like DynamoDB. Option C would not effectively reduce retrieval time, as adding retries does not address the underlying latency issue.