DEA-C01 Data Operations and Support Practice Question
A data engineer is monitoring an Amazon Redshift cluster and notices that the 'WLM query wait time' metric is consistently high during peak hours. The cluster uses automatic WLM. The engineer wants to reduce query wait times without changing the cluster size. Which action is MOST effective?
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
✓
Enable concurrency scaling.
Enabling concurrency scaling (Option A) is the most effective action because it automatically adds transient cluster capacity during peak loads, allowing more queries to run concurrently without increasing wait times. This is specifically designed to reduce WLM query wait time. Option B (manual WLM) requires tuning and does not add capacity. Option C (increasing max queries per queue) could increase concurrency but may lead to resource contention and longer wait times if the cluster is already saturated. Option D (short query acceleration) prioritizes short queries, which does not address overall wait times for all queries. Therefore, A is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable concurrency scaling.
Why this is correct
Concurrency scaling adds capacity to handle concurrent queries.
- ✗
Change WLM to manual mode and increase the number of queues.
Why it's wrong here
Manual WLM may not help without proper resource allocation.
- ✗
Increase the maximum number of queries per queue.
Why it's wrong here
More queries without more resources can increase contention.
- ✗
Enable short query acceleration (SQA).
Why it's wrong here
SQA prioritizes short queries but does not reduce overall wait times significantly.
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Variation 1. A data engineer is monitoring an Amazon Redshift cluster and notices that queries are taking longer than expected. The engineer checks the system tables and sees that many queries are waiting for 'WLM' resources. What is the most likely cause and recommended fix?
hard- A.The table sort keys are poorly designed; recreate tables with better sort keys.
- B.The distribution style is set to ALL; change to KEY distribution.
- ✓ C.The WLM queue concurrency is set too low; increase the concurrency level.
- D.The cluster is running low on disk space; resize the cluster.
Why C: A wait for WLM (Workload Management) resources indicates that queries are being throttled due to insufficient concurrency slots. Increasing the WLM queue concurrency allows more queries to run simultaneously. Option A is incorrect because sort keys affect query scan efficiency, not WLM queue waits. Option B is incorrect because distribution style affects data redistribution, not concurrency throttling. Option D is incorrect because low disk space would cause different errors, not specifically WLM queue waits.
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.