DBS-C01 Workload-Specific Database Design Practice Question
A company is designing a database for an IoT application that ingests millions of small sensor readings per second. The data is append-only and queries are primarily time-based aggregations with low latency requirements (under 10 ms). Which AWS database service is most suitable for this workload?
⚠ Common exam trap
A common mix-up: candidates choose Amazon DynamoDB for its low-latency and scalability reputation, overlooking that it lacks native time-series features like automatic retention policies and time-based aggregation functions, which are critical for this specific workload.
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 Timestream
Amazon Timestream is a purpose-built time-series database designed for IoT and operational applications that ingest high volumes of append-only data. It automatically manages storage tiers (in-memory and magnetic) and provides built-in time-based aggregation functions, enabling queries with sub-10 ms latency for recent data. This makes it the most suitable choice for the described workload of millions of sensor readings per second with low-latency aggregation queries.
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
Why it's wrong here
DynamoDB is a key-value store; time-series aggregations require complex queries.
- ✗
Amazon ElastiCache
Why it's wrong here
ElastiCache is for caching, not persistent time-series storage.
- ✗
Amazon Aurora
Why it's wrong here
Aurora is a relational database not optimized for high-velocity time-series data.
- ✓
Amazon Timestream
Why this is correct
Timestream is purpose-built for time-series data with fast ingestion and aggregation.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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