DBS-C01 Workload-Specific Database Design Practice Question
A company needs to store and query time-series data from IoT sensors. The data is written continuously and queried by time range for dashboards. Which AWS database service is most cost-effective and scalable for this workload?
⚠ Common exam trap
Test-takers frequently choose DynamoDB for its scalability, overlooking that time-series workloads with sequential timestamps cause hot partitions and lack native time-series query capabilities, while Timestream is the only service specifically designed for this use case with automatic tiering and cost optimization.
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 purpose-built for time-series data, offering automatic tiering between in-memory and magnetic stores for cost efficiency, and built-in functions for time-based aggregations and windowed queries. It is serverless and scales automatically to handle continuous writes from IoT sensors and low-latency dashboard queries by time range, making it the most cost-effective and scalable choice.
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 ElastiCache for Redis with time-series data structures.
Why it's wrong here
In-memory, expensive for large volumes.
- ✗
Amazon DynamoDB with time-based partition keys.
Why it's wrong here
Can be used but not optimal; requires careful key design.
- ✓
Amazon Timestream.
Why this is correct
Managed time-series database with built-in analytics.
- ✗
Amazon RDS for PostgreSQL with time-based indexing.
Why it's wrong here
Not purpose-built; may have performance issues at scale.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Same concept, more angles
2 more ways this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company needs to store and query time-series data from IoT devices. The data arrives in high volume and requires efficient range queries over time. Which database is most appropriate?
easy- A.Amazon RDS for MySQL
- ✓ B.Amazon Timestream
- C.Amazon DynamoDB
- D.Amazon Redshift
Why B: Amazon Timestream is a purpose-built time-series database that automatically scales to handle high-volume IoT data and is optimized for efficient range queries over time. It separates storage into a memory store for recent data and a magnetic store for historical data, enabling fast queries across time ranges with built-in time-series functions.
Variation 2. A company needs to store time-series data from IoT sensors. Each sensor sends a reading every minute. The data is rarely accessed after 30 days. The query pattern is to retrieve all readings for a specific sensor within a time range. Which AWS database is most cost-effective?
easy- ✓ A.Amazon Timestream
- B.Amazon Redshift
- C.Amazon DynamoDB with Time-to-Live (TTL)
- D.Amazon RDS for PostgreSQL with partitioning
Why A: Amazon Timestream is purpose-built for time-series data, offering automatic tiered storage (in-memory for recent data and magnetic for historical data) and built-in time-series functions. For IoT sensors sending readings every minute with rare access after 30 days, Timestream's cost-effective storage tiering and efficient querying for a specific sensor within a time range make it the most suitable and economical choice.
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.