This comparison is really relational vs NoSQL, and the exam tests it by workload shape and access pattern.
When to pick each
RDS is relational (SQL) — use it for structured data with complex queries, joins, and transactions. DynamoDB is NoSQL key-value/document — use it for simple, high-scale, low-latency access patterns where you know how you’ll query the data. Complex joins and reporting → RDS. Massive scale with predictable key lookups → DynamoDB.
Test yourself
An app needs a database for a simple, extremely high-traffic key-value access pattern with single-digit millisecond latency at any scale. Which is best?
- Amazon RDS
- Amazon DynamoDB
- Amazon Redshift
- Amazon Athena
👉 Click to reveal the answer & explanation
Correct answer: B. DynamoDB delivers single-digit millisecond key-value access at massive scale — ideal for that pattern. RDS (A) suits complex relational queries, not extreme key-value scale; Redshift (C) is a warehouse; Athena (D) queries S3.
Related topics
Amazon RDS · Amazon DynamoDB · Amazon Aurora
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