DBS-C01 Workload-Specific Database Design Practice Question
A company is using Amazon DynamoDB to store IoT sensor data. The application writes a large volume of data and needs to read recent data by timestamp. The table has a partition key of device_id and a sort key of timestamp. The access pattern is to read the latest data for a specific device. Which TWO design patterns will optimize read performance and reduce costs?
⚠ Common exam trap
Watch out — candidates often confuse auto scaling with adaptive capacity, or assume a GSI is always beneficial, not realizing that duplicating the base table key structure adds cost without performance gain.
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
✓
Use adaptive capacity to evenly distribute traffic across partitions.
Adaptive capacity allows DynamoDB to automatically manage partition traffic distribution, preventing hot partitions when a single device_id receives a high volume of writes. This ensures consistent read performance without manual partition management. Option B is correct because DAX provides an in-memory cache for the most frequently accessed data, reducing read latency and read capacity unit consumption for repeated queries of recent sensor data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use adaptive capacity to evenly distribute traffic across partitions.
Why this is correct
Adaptive capacity helps handle hot partitions, improving performance and cost efficiency.
- ✓
Use DynamoDB Accelerator (DAX) to cache the most recent reads.
Why this is correct
DAX caches reads, reducing read capacity units consumed.
- ✗
Enable auto scaling for the table to handle spikes.
Why it's wrong here
Auto scaling manages capacity but does not reduce costs or optimize read performance directly.
- ✗
Use DynamoDB Transactions for consistent reads.
Why it's wrong here
Transactions consume more capacity and are not needed for this pattern.
- ✗
Create a global secondary index (GSI) with device_id as partition key and timestamp as sort key.
Why it's wrong here
This duplicates the base table; no performance gain.
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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.