Question 1,428 of 1,663
DBS-C01 Management and Operations Practice Question
A data engineer is troubleshooting a slow-running query on an Amazon Redshift cluster. The query involves large table joins and aggregations. Which diagnostic step should be taken FIRST to understand the query execution plan and identify bottlenecks?
⚠ Common exam trap
The trap here is that candidates often jump to checking table design (Option B) or historical logs (Option D) first, but the EXPLAIN command is the fastest way to see the actual query execution plan and pinpoint join or aggregation bottlenecks.
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 EXPLAIN command on the query to review the execution plan.
The EXPLAIN command is the first and most direct step to understand how Redshift plans to execute a query, including join types, data distribution, and aggregation strategies. It reveals the execution plan without running the query, allowing the engineer to identify bottlenecks like nested loop joins or missing sort key optimization before any other diagnostic step.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Monitor the WLM queue metrics for the query.
Why it's wrong here
WLM metrics show queuing, not the execution plan.
- ✗
Check the SVV_TABLE_INFO view for table distribution and sort keys.
Why it's wrong here
This provides table structure, not the query plan.
- ✓
Run the EXPLAIN command on the query to review the execution plan.
Why this is correct
EXPLAIN reveals how Redshift will execute the query.
- ✗
Query the STL_QUERY system table to review the query text.
Why it's wrong here
This shows the query but not the execution plan.
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Last reviewed: Jul 4, 2026
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