DBS-C01 Workload-Specific Database Design Practice Question
A company is designing a database for an IoT application that receives millions of sensor readings per second. Each reading is a small JSON payload (timestamp, device_id, metric, value). The primary query pattern retrieves the most recent reading for a given device. Which AWS database service is BEST suited for this workload?
⚠ Common exam trap
A common mix-up: candidates choose ElastiCache for Redis because they assume 'most recent reading' implies a caching solution, but the question specifies a database for the workload, and Redis lacks the durability and query flexibility (e.g., filtering by timestamp range) needed for a primary data store of sensor readings.
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
Amazon DynamoDB is best suited because it is a fully managed NoSQL key-value database that delivers single-digit millisecond latency at any scale. The primary query pattern—retrieving the most recent reading for a given device—maps directly to a DynamoDB table with a composite primary key (device_id as partition key, timestamp as sort key) and a Query operation with ScanIndexForward=false and Limit=1. This design handles millions of writes per second with consistent performance, unlike relational databases that struggle with such high-velocity ingestion.
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 Aurora
Why it's wrong here
Relational database, not designed for extremely high write volumes of small records.
- ✓
Amazon DynamoDB
Why this is correct
Handles high write throughput and supports efficient point queries with sort key.
- ✗
Amazon ElastiCache for Redis
Why it's wrong here
Cache, not durable; data loss risk.
- ✗
Amazon RDS for MySQL
Why it's wrong here
Relational database not optimized for high-velocity time-series writes.
Go deeper
Related to this question
About these practice questions
Courseiva writes every DBS-C01 question from scratch — 1,663 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 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 DBS-C01 exam.