DBS-C01 Workload-Specific Database Design Practice Question
A company runs a time-series application on Amazon DynamoDB. The data has a pattern of frequent writes for recent data and rare reads for older data. They want to optimize storage costs and query performance for the time-series data. Which THREE strategies should they implement? (Choose THREE.)
⚠ Common exam trap
Watch out — candidates often confuse increasing read capacity (Option C) as a performance fix for older data, but the question specifically targets cost optimization and query performance for rarely accessed historical data, where offloading to S3 and using TTL are the correct strategies.
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 DynamoDB Time to Live (TTL) to automatically delete old data after a certain period
DynamoDB Time to Live (TTL) automatically expires and deletes old items after a defined timestamp, reducing storage costs without manual intervention. This is ideal for time-series data where older records are rarely accessed, as TTL offloads the deletion process to DynamoDB in the background, freeing up provisioned throughput.
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 DynamoDB Time to Live (TTL) to automatically delete old data after a certain period
Why this is correct
TTL removes items without consuming WCU and reduces storage costs.
- ✓
Store historical data in Amazon S3 and query with Amazon Athena
Why this is correct
Athena can query S3 data efficiently, offloading old data from DynamoDB.
- ✗
Increase DynamoDB read capacity units to improve query performance
Why it's wrong here
This increases cost and does not optimize storage.
- ✓
Archive old data to Amazon S3 Glacier using AWS Lambda and DynamoDB Streams
Why this is correct
Archiving to Glacier is cost-effective for rarely accessed data.
- ✗
Decrease DynamoDB write capacity units to reduce cost
Why it's wrong here
Decreasing WCU may cause write throttling; not a strategy for storage optimization.
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