DEA-C01 Data Store Management Practice Question
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?
⚠ Common exam trap
Many exam-takers 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'.
Answer choices
Why each option matters
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.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DEA-C01 exam.