DEA-C01 Data Store Management Practice Question
A company uses Amazon DynamoDB as its primary data store for a web application. The application experiences high latency during peak hours. The data engineer notices that the table has a large number of items with the same partition key. Which DynamoDB feature should the engineer use to improve performance?
⚠ Common exam trap
Test-takers frequently confuse caching solutions (DAX) or scaling mechanisms (auto scaling) with the need to fix the data model itself, which is the only way to resolve a hot partition caused by a skewed partition key.
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 partition key to use a composite key that includes a timestamp or random suffix.
The high latency is caused by a hot partition, where many items share the same partition key, overwhelming a single DynamoDB partition. Redesigning the partition key to include a timestamp or random suffix distributes the workload evenly across partitions, improving throughput and reducing latency. This directly addresses the root cause of the performance issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Redesign the partition key to use a composite key that includes a timestamp or random suffix.
Why this is correct
A well-designed partition key prevents hot spots by distributing writes evenly.
- ✗
Enable DynamoDB Accelerator (DAX) to cache read requests.
Why it's wrong here
DAX caches reads but does not fix the hot partition issue.
- ✗
Create a global table to replicate data across multiple Regions.
Why it's wrong here
Global tables improve availability, not partition distribution.
- ✗
Enable auto scaling on the table to increase write capacity.
Why it's wrong here
Auto scaling adjusts throughput but does not redistribute data.
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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 uses Amazon DynamoDB for a gaming application. The table has a partition key of 'user_id' and a sort key of 'game_timestamp'. The application frequently queries by 'user_id' and filters by 'game_timestamp' within a specific date range. The queries are slow. The table has a global secondary index (GSI) on 'game_timestamp'. What is the most likely cause of the slow queries?
hard- A.The GSI has insufficient read capacity.
- B.The GSI is used instead of the base table for queries on 'user_id'.
- ✓ C.A hot partition exists due to uneven access pattern on 'user_id'.
- D.The sort key is not used in the query.
Why C: The slow queries are most likely caused by a hot partition on the base table. Even though the query uses 'user_id' as the partition key, if a small number of 'user_id' values receive a disproportionate amount of traffic, those specific partitions become overloaded, causing throttling and high latency. The GSI on 'game_timestamp' is not used for these queries because the filter is on the sort key of the base table, and DynamoDB can efficiently query by partition key and filter by sort key without needing a GSI.
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.