DBS-C01 Scale out Practice Question
A company is using Amazon Redshift for data warehousing. The users report that queries are slow, and the CloudWatch metric 'CPUUtilization' shows high usage. The cluster has 4 dc2.large nodes. The administrator runs the following query: SELECT * FROM stl_query WHERE starttime > '2023-12-01' ORDER BY duration DESC LIMIT 10; This shows that the longest query runs for over 5 minutes. Which of the following is the MOST effective way to improve query performance?
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
✓
Add more nodes to the cluster (scale out)
Adding more nodes to the cluster (scale out) distributes the workload across additional compute resources, increasing parallelism and CPU capacity. This directly addresses the high CPU utilization and reduces query execution time. Option A is incorrect because the issue is CPU, not storage; increasing storage volume does not improve CPU performance. Option C is incorrect: VACUUM reclaims disk space and sorts data but does not directly improve query performance when the bottleneck is CPU. Option D is incorrect: increasing WLM concurrency allows more queries to run simultaneously but may actually increase contention and not improve the performance of individual long-running queries.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the size of the cluster volume by adding more storage
Why it's wrong here
Adding storage does not improve CPU-bound performance.
- ✓
Add more nodes to the cluster (scale out)
Why this is correct
Adding nodes increases compute capacity and parallelism.
- ✗
Run the VACUUM command to reclaim space and improve query performance
Why it's wrong here
Vacuum is for space management, not CPU performance.
- ✗
Modify the workload management (WLM) queue to increase concurrency
Why it's wrong here
Higher concurrency may worsen CPU contention.
Go deeper
Related to this question
About these practice questions
This DBS-C01 question is part of Courseiva's 1,663-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-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 DBS-C01 exam.