The answer is designing for adaptive capacity to handle uneven access patterns, along with leveraging Time to Live (TTL) for data retention and choosing an appropriate partition key to distribute writes evenly. This is correct because DynamoDB’s adaptive capacity automatically scales to accommodate traffic spikes common in time-series workloads, while TTL deletes expired items without consuming write throughput, reducing storage costs and eliminating custom cleanup scripts. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your ability to balance hot partitions and lifecycle management—a common trap is assuming you need a separate deletion mechanism or that a timestamp alone as a partition key is sufficient. Remember the mnemonic “PAT” for time-series design: Partition key for even distribution, Adaptive capacity for uneven access, and TTL for automatic expiration.
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE of the following are key considerations when designing a time-series database using Amazon DynamoDB? (Select THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable Time to Live (TTL) to automatically expire old data
Option B is correct because Amazon DynamoDB's Time to Live (TTL) feature automatically deletes expired items without consuming write throughput, making it ideal for managing data retention in time-series workloads. This eliminates the need for custom cleanup scripts and reduces storage costs over time.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Always use strongly consistent reads for accurate time-series data
Why it's wrong here
Eventually consistent reads are often sufficient and cheaper.
✓
Enable Time to Live (TTL) to automatically expire old data
Why this is correct
Automatically deletes data after a specified time.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use a composite primary key with a high-cardinality partition key and a sort key that includes a truncated timestamp
Why this is correct
Allows efficient range queries on time.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use local secondary indexes for aggregating data across partitions
Why it's wrong here
LSIs are scoped to a partition; GSIs are needed for cross-partition.
✓
Design for adaptive capacity to handle uneven access patterns
Why this is correct
Adaptive capacity allows DynamoDB to handle hot partitions.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that strongly consistent reads are mandatory for time-series accuracy, when in fact eventually consistent reads are acceptable for most time-series patterns and provide better performance and cost efficiency.
Detailed technical explanation
How to think about this question
DynamoDB TTL evaluates the TTL attribute (epoch timestamp) within 48 hours of expiration, and expired items are deleted asynchronously, typically within a few minutes to a day. For time-series designs, using a composite primary key with a high-cardinality partition key (e.g., device ID) and a sort key containing a truncated timestamp (e.g., YYYY-MM-DD) enables efficient range queries and avoids hot partitions by distributing writes across many partitions.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable Time to Live (TTL) to automatically expire old data — Option B is correct because Amazon DynamoDB's Time to Live (TTL) feature automatically deletes expired items without consuming write throughput, making it ideal for managing data retention in time-series workloads. This eliminates the need for custom cleanup scripts and reduces storage costs over time.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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