DEA-C01 Data Operations and Support Practice Question
A company runs a Redshift cluster and notices that query performance has degraded over time. The data engineer suspects that table statistics are stale. What should the engineer do to improve query performance?
⚠ Common exam trap
Test-takers frequently confuse the VACUUM command (which reorganizes physical storage) with the ANALYZE command (which updates query optimizer metadata), leading candidates to choose VACUUM when stale statistics are the actual culprit.
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
✓
Run the ANALYZE command on the tables
Stale table statistics cause the Redshift query optimizer to generate suboptimal execution plans, leading to degraded query performance. Running the ANALYZE command updates these statistics, allowing the optimizer to make better decisions about join order, distribution, and data scan strategies. This directly addresses the root cause of performance degradation over time.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Rebuild the tables by using CREATE TABLE AS
Why it's wrong here
Rebuilding is heavy and not a standard fix for stale stats.
- ✗
Increase the number of slices in the cluster
Why it's wrong here
Slices are fixed per node type and not a performance tuning knob for stale stats.
- ✓
Run the ANALYZE command on the tables
Why this is correct
ANALYZE updates table statistics for the optimizer.
- ✗
Run the VACUUM command on the tables
Why it's wrong here
VACUUM reclaims space but does not update statistics.
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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.