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 data engineer is troubleshooting slow query performance on an Amazon Redshift cluster. The cluster has 10 nodes and is using automatic distribution style. The engineer suspects that data distribution is causing excessive data movement. Which steps should the engineer take to diagnose and resolve the issue? (Choose THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Choose appropriate distribution keys for large tables
Option A is correct because choosing appropriate distribution keys for large tables ensures that data is evenly distributed across the cluster slices, minimizing the need for data redistribution during joins and aggregations. Automatic distribution style may not always select the optimal key, leading to excessive data movement and slow query performance.
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.
✓
Choose appropriate distribution keys for large tables
Why this is correct
Proper distribution keys minimize data movement.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use the EXPLAIN command to analyze query plans
Why this is correct
EXPLAIN shows distribution and data movement.
Related concept
Read the scenario before looking for a memorised answer.
✗
Run the VACUUM command to reclaim space
Why it's wrong here
VACUUM does not address distribution.
✓
Query the STL_DIST and STL_BCAST system tables
Why this is correct
These tables show data redistribution statistics.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the number of nodes in the cluster
Why it's wrong here
Adding nodes may not fix distribution skew.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse VACUUM (which only reorganizes data within slices) with distribution optimization, or assume scaling out nodes automatically resolves distribution-related performance issues without addressing the underlying key choice.
Detailed technical explanation
How to think about this question
Under the hood, Redshift distributes data across slices based on the distribution style (KEY, ALL, EVEN, or AUTO). When large tables use suboptimal distribution keys, queries that join or aggregate across nodes trigger extensive redistribution via the network, visible in STL_DIST and STL_BCAST system tables. The EXPLAIN command reveals these redistribution steps (e.g., DS_DIST_ALL_NONE or DS_DIST_NONE) and allows the engineer to pinpoint the exact cause of excessive data movement.
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.
TExam Day Tips
→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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Choose appropriate distribution keys for large tables — Option A is correct because choosing appropriate distribution keys for large tables ensures that data is evenly distributed across the cluster slices, minimizing the need for data redistribution during joins and aggregations. Automatic distribution style may not always select the optimal key, leading to excessive data movement and slow query performance.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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