The answer is to redesign the GSI partition key to include a random suffix, which resolves DynamoDB GSI hot partition throttling by distributing the workload across multiple physical partitions. This is correct because the GSI on the low-cardinality 'category' attribute creates a hot partition—all reads for a popular category hit the same physical shard, causing throttling even when the main table’s consumed capacity is well below its limit. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding that a GSI has its own provisioned capacity and that non-zero ReadThrottleEvents on the table metric often point to a GSI issue, not the base table. A common trap is to assume auto scaling will fix everything, but it cannot prevent hot partitions caused by skewed access patterns. Memory tip: think “GSI needs its own shuffle”—if your GSI key has low cardinality, add a random suffix to scatter the load.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. 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 runs an e-commerce platform on AWS. The product catalog is stored in Amazon DynamoDB with a table that has a partition key of 'product_id' and a sort key of 'category'. The application frequently queries products by category and by product_id. Recently, the operations team noticed that read latency has increased significantly for queries that filter by category. The DynamoDB table has auto scaling enabled. The data engineer examines the CloudWatch metrics and sees that the ReadThrottleEvents metric is non-zero for the table, but the consumed read capacity is well below the provisioned limit. The table has a global secondary index (GSI) on the 'category' attribute. Which action is most likely to resolve the latency issue?
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
✓
Redesign the GSI partition key to include a random suffix to distribute load across multiple partitions.
The issue is that the GSI on 'category' is experiencing hot partitions because 'category' has low cardinality, causing uneven data distribution. The non-zero ReadThrottleEvents on the GSI (not the main table) indicate throttling on the GSI's provisioned capacity, even though the main table's consumed read capacity is below its limit. Adding a random suffix to the GSI partition key distributes reads across multiple physical partitions, reducing hot spots and latency.
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.
✗
Switch the table to DynamoDB on-demand capacity mode.
Why it's wrong here
On-demand handles spikes but does not resolve hot partition issue on GSI.
✗
Enable DynamoDB Accelerator (DAX) to cache read queries.
Why it's wrong here
DAX caches main table reads, but GSIs are not cached by default.
✗
Increase the provisioned read capacity on the main table.
Why it's wrong here
Throttling is on the GSI, not the main table.
✓
Redesign the GSI partition key to include a random suffix to distribute load across multiple partitions.
Why this is correct
This prevents a hot partition on the GSI.
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
The trap here is that candidates assume throttling always relates to the base table's provisioned capacity, overlooking that GSIs have independent capacity and can throttle even when the base table is underutilized, especially with low-cardinality sort keys like 'category'.
Detailed technical explanation
How to think about this question
DynamoDB GSIs have their own provisioned read/write capacity, separate from the base table. When a GSI's partition key (e.g., 'category') has low cardinality, a single partition can become a hot spot, exceeding its 3,000 RCU or 1,000 WCU per partition limit, causing throttling. Adding a random suffix (e.g., 'Electronics#A', 'Electronics#B') distributes items across more partitions, allowing the GSI to utilize its full provisioned capacity without hitting per-partition limits.
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.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Redesign the GSI partition key to include a random suffix to distribute load across multiple partitions. — The issue is that the GSI on 'category' is experiencing hot partitions because 'category' has low cardinality, causing uneven data distribution. The non-zero ReadThrottleEvents on the GSI (not the main table) indicate throttling on the GSI's provisioned capacity, even though the main table's consumed read capacity is below its limit. Adding a random suffix to the GSI partition key distributes reads across multiple physical partitions, reducing hot spots and latency.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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