The correct choice is to use a composite primary key with a partition key that has high cardinality, such as a user ID, because this design naturally distributes high write throughput across multiple partitions, preventing any single partition from becoming a hot spot. When a partition key has low cardinality, all writes target the same partition, leading to throttling; a high-cardinality key like a user ID ensures each write lands on a different physical partition, avoiding DynamoDB hot partitions under heavy load. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this question tests your understanding of DynamoDB’s internal partitioning model and the common trap of confusing GSIs or LSIs with write distribution—neither solves hot partitions, as they are designed for query flexibility, not write balancing. Remember the memory tip: “High cardinality, no partiality”—a diverse partition key spreads the load and keeps throttling away.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 startup is building a serverless application using AWS Lambda for business logic and Amazon DynamoDB for data storage. The application must process a high volume of writes to a single DynamoDB table. The development team is concerned about throttling due to hot partitions. Which design should the team implement to avoid throttling?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a composite primary key with a partition key that has high cardinality, such as a user ID.
Using a composite key with a partition key that has high cardinality, such as a user ID, distributes writes evenly across partitions. Option B (LSI) doesn't help with write distribution. Option C (DAX) is a cache, not a solution for hot partitions. Option D (GSI) is for querying, not for write distribution.
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) to cache write operations.
Why it's wrong here
DAX is a read cache; it does not prevent write throttling.
✓
Use a composite primary key with a partition key that has high cardinality, such as a user ID.
Why this is correct
High cardinality partition keys distribute writes evenly across partitions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a global secondary index (GSI) as the primary index for writes.
Why it's wrong here
GSIs are for querying, and they don't affect write distribution.
✗
Add a local secondary index (LSI) to the table.
Why it's wrong here
LSIs are for querying, not for improving write distribution.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a composite primary key with a partition key that has high cardinality, such as a user ID. — Using a composite key with a partition key that has high cardinality, such as a user ID, distributes writes evenly across partitions. Option B (LSI) doesn't help with write distribution. Option C (DAX) is a cache, not a solution for hot partitions. Option D (GSI) is for querying, not for write distribution.
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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