DEA-C01 Data Store Management Practice Question
A company is using Amazon DynamoDB with on-demand capacity for a gaming application. During a new game launch, write traffic spikes to 50,000 writes per second, but the application experiences throttling. The DynamoDB table has a partition key of 'game_id' and a sort key of 'timestamp'. What is the MOST likely cause of throttling?
⚠ Common exam trap
It's easy for candidates to assume on-demand capacity eliminates all throttling, but they overlook DynamoDB's per-partition throughput limits, which can cause throttling on hot partitions even with on-demand mode.
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
✓
Hot partitions due to a skewed access pattern on the partition key 'game_id'.
DynamoDB on-demand capacity automatically scales to handle traffic spikes, but it still has per-partition throughput limits. With 'game_id' as the partition key, a single popular game can create a hot partition where all writes target the same partition, exceeding the partition's maximum write capacity (1,000 write capacity units per partition) and causing throttling, even though the overall table capacity is sufficient.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The table has not enabled auto-scaling for writes.
Why it's wrong here
On-demand capacity does not use auto-scaling; it adjusts automatically.
- ✗
The table's on-demand capacity is insufficient for the write spike.
Why it's wrong here
On-demand capacity scales automatically, but still has partition-level limits.
- ✓
Hot partitions due to a skewed access pattern on the partition key 'game_id'.
Why this is correct
If many writes go to the same partition key, that partition can be throttled even with on-demand capacity.
- ✗
The sort key is not optimal for write-heavy workloads.
Why it's wrong here
Sort key does not affect write distribution.
Go deeper
Related to this question
About these practice questions
One of 1,711 original DEA-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on DEA-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
hard- A.Switch the table to DynamoDB on-demand capacity mode.
- B.Enable DynamoDB Accelerator (DAX) to cache read queries.
- C.Increase the provisioned read capacity on the main table.
- ✓ D.Redesign the GSI partition key to include a random suffix to distribute load across multiple partitions.
Why D: 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.
JA
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.