The answer is to increase the read capacity units (RCU) for the global secondary index. This is correct because DynamoDB global secondary indexes (GSIs) have their own independent provisioned throughput settings, separate from the base table. When query latency is higher than expected despite high partition key cardinality, the bottleneck is often insufficient read capacity on the index itself, leading to throttling or queued requests that degrade performance. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your understanding that GSIs are not automatically scaled with the base table—a common trap is assuming high cardinality alone ensures speed, or that adding sort keys will help a GSI query. Instead, remember that each index is a separate table with its own RCU/ WCU allocation. A useful memory tip: “Index needs its own fuel”—if the base table is fast but the GSI is slow, check the index’s read capacity first.
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.
A web application uses Amazon DynamoDB as its database. The application frequently queries items using a secondary index. The index's partition key has high cardinality, but the query latency is higher than expected. Which action would MOST likely improve query performance?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the read capacity units (RCU) for the global secondary index.
DynamoDB secondary indexes have their own provisioned throughput. If the index's read capacity is insufficient, queries will be throttled or have higher latency. Increasing the read capacity for the index directly addresses this. Option A (adding more sort keys) doesn't apply to queries on a secondary index. Option C (changing to global secondary index) is not needed if it's already a GSI. Option D (switching to scan) is less efficient.
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.
✗
Use a Scan operation instead of Query to retrieve items from the index.
Why it's wrong here
Scan is less efficient and consumes more throughput than Query.
✗
Add additional sort key attributes to the index to better distribute the data.
Why it's wrong here
The index already has high cardinality; adding sort keys may not help and could increase costs.
✗
Convert the global secondary index to a local secondary index.
Why it's wrong here
Local secondary index shares throughput with the table, not improving latency if table is not throttled.
✓
Increase the read capacity units (RCU) for the global secondary index.
Why this is correct
Insufficient read capacity on the index can cause throttling and higher latency.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Increase the read capacity units (RCU) for the global secondary index. — DynamoDB secondary indexes have their own provisioned throughput. If the index's read capacity is insufficient, queries will be throttled or have higher latency. Increasing the read capacity for the index directly addresses this. Option A (adding more sort keys) doesn't apply to queries on a secondary index. Option C (changing to global secondary index) is not needed if it's already a GSI. Option D (switching to scan) is less efficient.
What should I do if I get this DBS-C01 question wrong?
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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