The answer is to add more nodes or upgrade to a larger node type, because the symptoms of low CPU utilization paired with high disk I/O point directly to disk spills caused by insufficient memory. When Redshift runs out of memory for operations like large scans and aggregations, it spills intermediate data to disk, dramatically slowing performance regardless of the number of nodes. This scenario tests your understanding of Redshift’s memory management and the relationship between node count, memory, and disk spill behavior—a core concept for the AWS Certified Data Engineer Associate DEA-C01 exam. A common trap is to assume that simply adding nodes always improves speed, but if the workload is memory-bound, more nodes of the same size may not help unless total cluster memory increases. The key memory tip: “Low CPU, high I/O? Think disk spill—add memory, not concurrency.”
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 financial services company uses Amazon Redshift for its data warehouse. The cluster has two nodes and is used for complex analytical queries. The company recently migrated from a single-node cluster to a two-node cluster to improve performance. After the migration, the data engineer notices that query performance has not improved as expected. Some queries are even slower than before. The engineer checks the workload management (WLM) queue configuration and sees that there is only one queue with a concurrency level of 5. The queries are mostly large scans and aggregations. The cluster's CPU utilization is low, but disk I/O is high. What should the data engineer do to improve query performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add more nodes or upgrade to a larger node type to increase memory and reduce disk spills.
Option C is correct because high disk I/O and low CPU utilization indicate that the cluster is spilling to disk due to insufficient memory. Increasing the number of nodes or upgrading to a larger node type (e.g., dc2.large to dc2.8xlarge) increases memory. Option A is wrong because increasing concurrency would increase contention. Option B is wrong because distribution style is unlikely the main issue. Option D is wrong because manual compression is not needed; Redshift automatically applies compression.
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.
✗
Apply compression to the tables to reduce the amount of data scanned.
Why it's wrong here
Redshift already uses columnar compression; manual compression is not needed.
✗
Increase the concurrency level in the WLM queue to allow more queries to run simultaneously.
Why it's wrong here
Higher concurrency can increase disk I/O and memory pressure, worsening performance.
✓
Add more nodes or upgrade to a larger node type to increase memory and reduce disk spills.
Why this is correct
More memory reduces disk I/O by allowing intermediate results to stay in memory.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the distribution style of large tables to DISTSTYLE ALL to avoid data redistribution.
Why it's wrong here
While this can help, the primary issue is memory spilling.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 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.
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: Add more nodes or upgrade to a larger node type to increase memory and reduce disk spills. — Option C is correct because high disk I/O and low CPU utilization indicate that the cluster is spilling to disk due to insufficient memory. Increasing the number of nodes or upgrading to a larger node type (e.g., dc2.large to dc2.8xlarge) increases memory. Option A is wrong because increasing concurrency would increase contention. Option B is wrong because distribution style is unlikely the main issue. Option D is wrong because manual compression is not needed; Redshift automatically applies compression.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 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.
About these practice questions
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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.
Question Discussion
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