The answer is to use SQS to decouple the S3 trigger from the Lambda function and implement a batching strategy to DynamoDB. This resolves DynamoDB throttling from Lambda by buffering spikes in write traffic, allowing the function to batch records and retry failed operations without overwhelming the table’s 500 WCUs, while SQS’s low cost makes it the most cost-effective solution. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of decoupling patterns and cost optimization under the Well-Architected Framework; a common trap is to immediately increase WCUs or add DAX, but those address capacity or read latency, not the root cause of bursty writes. Remember the mnemonic “SQS Saves Spikes” to recall that a simple queue buffers throughput exceptions more cheaply than scaling write capacity.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company uses AWS Lambda to process files uploaded to an S3 bucket. The Lambda function writes results to a DynamoDB table. Over time, the function's execution time has increased, and some operations fail with ProvisionedThroughputExceededException. The function is configured with 1024 MB memory and a 5-minute timeout. The DynamoDB table has 1000 RCUs and 500 WCUs. The Lambda function performs reads and writes on the same table. What is the MOST cost-effective way to resolve the throttling without sacrificing performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use SQS to decouple the S3 trigger from the Lambda function and implement a batching strategy to DynamoDB
Option C is correct because increasing WCUs alone would cost more and might not be efficient if the issue is read-heavy. Option D (DAX) reduces read latency but doesn't increase write capacity. Option A (increase memory) increases CPU but not write capacity. Option B (SQS) decouples the writes, allowing retries and smoothing out spikes, which is cost-effective because SQS is cheap and prevents throttling by buffering requests.
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.
✗
Enable DynamoDB Accelerator (DAX) for the table
Why it's wrong here
DAX improves read performance but does not increase write throughput.
✓
Use SQS to decouple the S3 trigger from the Lambda function and implement a batching strategy to DynamoDB
Why this is correct
SQS buffers requests, allowing batch writes and reducing throttling.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase DynamoDB write capacity units to 1000 WCUs
Why it's wrong here
More costly and may not be needed if the issue is bursty.
✗
Increase the Lambda function memory to 2048 MB
Why it's wrong here
Increasing memory only improves CPU, not DynamoDB write capacity.
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 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 SAP-C02 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.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use SQS to decouple the S3 trigger from the Lambda function and implement a batching strategy to DynamoDB — Option C is correct because increasing WCUs alone would cost more and might not be efficient if the issue is read-heavy. Option D (DAX) reduces read latency but doesn't increase write capacity. Option A (increase memory) increases CPU but not write capacity. Option B (SQS) decouples the writes, allowing retries and smoothing out spikes, which is cost-effective because SQS is cheap and prevents throttling by buffering requests.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-C02 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.
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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