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 a slow Amazon Redshift query that joins several large tables. The query plan shows a large number of broadcasts. Which design change would most likely reduce the broadcast 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 the DISTKEY on all tables to match the join column.
Option C is correct because setting the DISTKEY on all tables to the join column ensures that rows with the same join key value are co-located on the same compute node. This allows Redshift to perform a collocated join, eliminating the need to broadcast entire tables across the network, which is the primary cause of the slow query.
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.
✗
Change the SORT KEY on all tables to match the join column.
Why it's wrong here
SORT KEY only affects ordering, not distribution, so it does not reduce broadcasts.
✗
Change the DISTSTYLE to EVEN on all tables.
Why it's wrong here
EVEN distributes rows randomly across slices, which can increase broadcasts for joins.
✓
Change the DISTKEY on all tables to match the join column.
Why this is correct
Matching DISTKEY on join columns ensures data is co-located, avoiding broadcasts.
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 the DISTSTYLE to ALL on all large tables.
Why it's wrong here
DISTSTYLE ALL replicates the entire table to every node, which is inefficient for large tables and does not reduce broadcasts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse SORT KEY (which optimizes data skipping and range scans) with DISTKEY (which controls data distribution for joins), leading them to pick Option A, even though broadcast reduction is purely a distribution concern.
Detailed technical explanation
How to think about this question
Under the hood, Redshift uses a Massively Parallel Processing (MPP) architecture where each node slice processes a portion of data. When DISTKEYs match, Redshift can perform a collocated join within each slice without data redistribution; if they don't match, the query planner inserts a broadcast (DS_BCAST_INNER) or redistribution (DS_DIST_ALL_NONE) step, which moves data over the network. In practice, choosing the right DISTKEY is critical for fact tables joined to multiple dimension tables, as a single DISTKEY can only optimize one join pattern, so engineers often use DISTSTYLE KEY on the most frequent join column and consider interleaved sort keys for the rest.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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: Change the DISTKEY on all tables to match the join column. — Option C is correct because setting the DISTKEY on all tables to the join column ensures that rows with the same join key value are co-located on the same compute node. This allows Redshift to perform a collocated join, eliminating the need to broadcast entire tables across the network, which is the primary cause of the slow query.
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.
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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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.
Question Discussion
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