- A
Set the distribution style to KEY on the join column
Correct: Setting distribution style to KEY on the join column co-locates matching rows, avoiding redistribution during joins.
- B
Apply a SORTKEY on the join column
Correct: Applying a SORTKEY on the join column allows efficient merge joins and reduces scan size, improving performance.
- C
Use DISTKEY on the join column to co-locate data
Why wrong: Incorrect: This is essentially the same as option A (DISTKEY = distribution style KEY), so it is not a distinct action and does not provide additional benefit.
- D
Use DISTSTYLE ALL to replicate the table to all nodes
Correct: DISTSTYLE ALL replicates the table to all nodes, which can improve join performance by eliminating data movement, especially for smaller dimension tables.
- E
Change the column data type to a fixed-length CHAR
Why wrong: Incorrect: Changing the column data type to fixed-length CHAR does not improve join performance and may cause overhead.
DEA-C01 Distribution Style KEY Practice Question
This DEA-C01 practice question tests your understanding of data store management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: distribution Style KEY. 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 company is using Amazon Redshift for a data warehouse. The data engineer needs to improve query performance for a table that is frequently joined with other tables on a specific column. Which THREE actions would help improve join performance? (Choose THREE.)
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
Set the distribution style to KEY on the join column
Setting the distribution style to KEY on the join column (option A) ensures that rows with the same join key value are co-located on the same compute node, enabling collocated joins and avoiding costly redistribution. Applying a SORTKEY on the join column (option B) allows Redshift to use merge joins efficiently and reduce the data scanned. Using DISTSTYLE ALL (option D) replicates the entire table to every node, which can eliminate the need to redistribute data for joins when the table is small or a dimension table. Options A and C are essentially the same action (DISTKEY is the same as distribution style KEY), so they are not distinct; thus the correct set is A, B, and D.
Key principle: Distribution Style KEY
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set the distribution style to KEY on the join column
Why this is correct
Correct: Setting distribution style to KEY on the join column co-locates matching rows, avoiding redistribution during joins.
Related concept
Distribution Style KEY
- ✓
Apply a SORTKEY on the join column
Why this is correct
Correct: Applying a SORTKEY on the join column allows efficient merge joins and reduces scan size, improving performance.
Related concept
Distribution Style KEY
- ✗
Use DISTKEY on the join column to co-locate data
Why it's wrong here
Incorrect: This is essentially the same as option A (DISTKEY = distribution style KEY), so it is not a distinct action and does not provide additional benefit.
- ✓
Use DISTSTYLE ALL to replicate the table to all nodes
Why this is correct
Correct: DISTSTYLE ALL replicates the table to all nodes, which can improve join performance by eliminating data movement, especially for smaller dimension tables.
Related concept
Distribution Style KEY
- ✗
Change the column data type to a fixed-length CHAR
Why it's wrong here
Incorrect: Changing the column data type to fixed-length CHAR does not improve join performance and may cause overhead.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common trap is that candidates consider both 'distribution style KEY' and 'DISTKEY' as separate valid actions, but they are identical in Redshift. Therefore, the correct set of three distinct actions must include only one of them, along with SORTKEY and DISTSTYLE ALL.
Detailed technical explanation
How to think about this question
Under the hood, Redshift distributes table rows across nodes based on the distribution style. With KEY distribution, the hash of the join column determines the node, ensuring that matching join keys from both tables land on the same slice. The SORTKEY (option B) further accelerates joins by allowing Redshift to skip irrelevant blocks via zone maps, reducing the amount of data scanned. DISTKEY (option C) is synonymous with setting distribution style to KEY, so it is essentially the same action as option A—both co-locate data for the join column.
KKey Concepts to Remember
- Distribution Style KEY
- SORTKEY
- DISTSTYLE ALL
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
Distribution Style KEY
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Review distribution Style KEY, then practise related DEA-C01 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this DEA-C01 question test?
Data Store Management — This question tests Data Store Management — Distribution Style KEY.
What is the correct answer to this question?
The correct answer is: Set the distribution style to KEY on the join column — Setting the distribution style to KEY on the join column (option A) ensures that rows with the same join key value are co-located on the same compute node, enabling collocated joins and avoiding costly redistribution. Applying a SORTKEY on the join column (option B) allows Redshift to use merge joins efficiently and reduce the data scanned. Using DISTSTYLE ALL (option D) replicates the entire table to every node, which can eliminate the need to redistribute data for joins when the table is small or a dimension table. Options A and C are essentially the same action (DISTKEY is the same as distribution style KEY), so they are not distinct; thus the correct set is A, B, and D.
What should I do if I get this DEA-C01 question wrong?
Review distribution Style KEY, then practise related DEA-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Distribution Style KEY
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Last reviewed: Jun 24, 2026
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