SAA-C03 Design High-Performing Architectures Practice Question
A company is designing a high-performance database architecture for an e-commerce platform that experiences rapid spikes in read traffic during flash sales. The database must handle millions of reads per second with sub-millisecond latency. The data is key-value in nature, with a small number of attributes per item. Which three options should be included in the architecture? (Choose three.)
⚠ Common exam trap
Test-takers frequently choose Amazon RDS with Read Replicas for read scaling, but they fail to recognize that relational databases cannot achieve sub-millisecond latency for millions of reads per second, and that DynamoDB with caching layers is the correct high-performance key-value solution.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon DynamoDB as the primary database.
Amazon DynamoDB is a fully managed NoSQL key-value database that delivers single-digit millisecond latency at any scale, making it ideal for high-traffic e-commerce platforms with key-value data. DynamoDB Accelerator (DAX) is an in-memory cache that sits in front of DynamoDB, reducing read latency to microseconds for millions of reads per second. Amazon ElastiCache for Redis with cluster mode enabled provides a distributed in-memory cache that can offload read traffic from the primary database, further reducing latency and handling spikes during flash sales.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Amazon DynamoDB as the primary database.
Why this is correct
Amazon DynamoDB is a fully managed, serverless NoSQL database designed for high-performance applications requiring single-digit millisecond latency at any scale. Its flexible schema and automatic scaling capabilities make it an ideal primary database for e-commerce, efficiently handling unpredictable traffic spikes and diverse data access patterns for product catalogs, user profiles, and order processing.
- ✗
Amazon RDS for MySQL with Multi-AZ and Read Replicas.
Why it's wrong here
Amazon RDS for MySQL, while offering high availability with Multi-AZ and improved read scalability with Read Replicas, is a relational database. For extremely high-performance e-commerce with massive scale and rapidly evolving data models, the inherent limitations of a fixed schema and the complexities of scaling writes in a relational database may not meet the most stringent low-latency, high-throughput requirements compared to a purpose-built NoSQL solution.
- ✓
DynamoDB Accelerator (DAX) as an in-memory cache.
Why this is correct
DynamoDB Accelerator (DAX) is a fully managed, highly available in-memory cache specifically optimized for Amazon DynamoDB. It provides microsecond-level response times for read-heavy workloads by caching frequently accessed items, significantly reducing the operational load on the underlying DynamoDB table and further enhancing the overall performance of an e-commerce application, particularly for popular product listings.
- ✓
Amazon ElastiCache for Redis with cluster mode enabled.
Why this is correct
Amazon ElastiCache for Redis, especially with cluster mode enabled, provides a highly scalable and performant in-memory data store for various caching needs beyond just DynamoDB. It delivers sub-millisecond latency for use cases like session management, leaderboards, or general-purpose object caching. Cluster mode allows horizontal scaling of the cache, distributing data across multiple nodes to handle massive throughput and storage requirements typical of large e-commerce platforms.
- ✗
Amazon S3 as a primary data store accessed via Select and Range queries.
Why it's wrong here
Amazon S3 is an object storage service primarily designed for durability, availability, and cost-effectiveness for unstructured data, not as a transactional primary database. While S3 Select allows querying data within objects and range queries can retrieve parts of objects, its latency profile and access patterns are fundamentally unsuitable for the real-time, low-latency, high-throughput transactional reads and writes required by a primary e-commerce database.
- ✗
Amazon Redshift with auto-scaling for real-time reads.
Why it's wrong here
Amazon Redshift is a fully managed, petabyte-scale data warehouse service optimized for complex analytical queries over large datasets, not for real-time operational reads and writes. Its architecture is geared towards batch loading and analytical processing, making it an inappropriate choice for the low-latency, high-concurrency transactional demands of a primary e-commerce database that requires immediate data access and modification.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.