Question 26
Domain 3: Design High-Performing ArchitecturesAn application requires sub-millisecond latency for database queries. The data is accessed in a key-value pattern. Which database solution should be used?
Correct answer: B
Explanation
DynamoDB fits a “key-value pattern” because it is a non-relational database service, and the guide lists “Amazon DynamoDB” under database types and services. DAX adds an in-memory cache for DynamoDB, matching the need for “sub-millisecond latency” by reducing read access time for repeated key-value queries.
Why each option is right or wrong
A. Amazon RDS with read replicas
B. DynamoDB with DAX (DynamoDB Accelerator)
Amazon DynamoDB is the correct database type for a key-value access pattern because AWS explicitly classifies it as a non-relational database service suited to that model, and the exam guide lists DynamoDB under the database types/services to choose from. The latency requirement is met by adding DAX, which is an in-memory cache for DynamoDB that serves repeated reads from cache and is designed to reduce read latency to microseconds, i.e., well below the sub-millisecond target.
C. Amazon Aurora
D. Amazon Redshift