The correct answer is to change to DISTSTYLE KEY on the 'customer_id' column. This optimization works because setting the distribution key to the filter column ensures that rows with the same customer_id are physically collocated on the same compute slice, which eliminates the need to shuffle data across nodes when queries filter on that column. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how Redshift distribution styles directly impact query performance for selective filters, and it often appears as a trap where candidates mistakenly choose compound sort keys or ALL distribution. A common memory tip is to remember that DISTKEY is for WHERE clause equality filters, while SORTKEY is for range-based filters—so if your query filters on a specific ID, think "KEY on that ID."
DEA-C01 Data Store Management 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. 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 company uses Amazon Redshift for its data warehouse. The data engineering team notices that queries against a large fact table are slow. The table is distributed using DISTSTYLE EVEN and has multiple sort keys. After analyzing the query plans, they find that most queries filter on a specific column, 'customer_id'. Which change would most likely improve query performance for these filter operations?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change to DISTSTYLE KEY on the 'customer_id' column.
Option C is correct because using DISTSTYLE KEY on 'customer_id' collocates rows with the same customer_id on the same slice, reducing data shuffling for queries filtering on that column. Option A (EVEN distribution) does not help with filtering. Option B (ALL distribution) is for small dimension tables. Option D (compound sort key with other columns) may not help if the filter is only on 'customer_id'.
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.
✗
Add a secondary sort key on 'customer_id'.
Why it's wrong here
Sort keys help with range-restricted scans but not with distribution; data may still be scattered.
✓
Change to DISTSTYLE KEY on the 'customer_id' column.
Why this is correct
KEY distribution on the filtered column reduces data movement during queries.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change to DISTSTYLE EVEN with a different sort key.
Why it's wrong here
EVEN distributes rows randomly, not improving filter performance on a specific column.
✗
Change to DISTSTYLE ALL for the fact table.
Why it's wrong here
ALL distribution copies the entire table to all nodes, which is inefficient for large fact tables.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Change to DISTSTYLE KEY on the 'customer_id' column. — Option C is correct because using DISTSTYLE KEY on 'customer_id' collocates rows with the same customer_id on the same slice, reducing data shuffling for queries filtering on that column. Option A (EVEN distribution) does not help with filtering. Option B (ALL distribution) is for small dimension tables. Option D (compound sort key with other columns) may not help if the filter is only on 'customer_id'.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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