The answer is choosing an appropriate distribution style, such as KEY or ALL, to minimize data movement during joins. This works because slow, disk-based operations in Amazon Redshift are typically caused by large volumes of data being broadcast or redistributed across nodes when tables are joined. By colocating related rows on the same slices using KEY distribution, or replicating smaller tables to every node with ALL distribution, you drastically reduce network traffic and avoid the disk spills that degrade performance. On the AWS Certified Data Engineer Associate DEA-C01 exam, this concept tests your understanding of how physical data layout directly impacts query execution plans—a common trap is assuming that EVEN distribution is always best, when in fact it can worsen join performance by forcing redistribution. A simple memory tip: KEY keeps joins local, ALL avoids movement, and EVEN is for uniform workloads.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 designing a data warehouse using Amazon Redshift. The workload includes complex queries that join large tables. The engineer notices that queries are slow due to disk-based operations. Which configuration change would MOST improve query performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Choose an appropriate distribution style (e.g., KEY or ALL) for the tables.
Option C is correct because choosing an appropriate distribution style (KEY or ALL) minimizes data movement between nodes during query execution. In Amazon Redshift, disk-based operations often result from large volumes of data being redistributed across the network for joins. By colocating related data on the same slices via KEY distribution or replicating small tables with ALL distribution, you reduce the need for broadcast or redistribution, which directly alleviates disk-based spills and improves 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.
✗
Define appropriate sort keys on the large tables.
Why it's wrong here
Sort keys optimize range-restricted scans but do not reduce disk-based joins.
✗
Increase the number of slices per node by choosing a different node type.
Why it's wrong here
Node types have fixed slice counts; changing node type may not help and could increase cost.
✓
Choose an appropriate distribution style (e.g., KEY or ALL) for the tables.
Why this is correct
Proper distribution minimizes data movement across nodes, reducing disk I/O for joins.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable compression on all columns.
Why it's wrong here
Compression is already default; it reduces storage but does not directly impact redistribution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse sort keys (which improve scan efficiency) with distribution keys (which reduce data movement), leading them to choose sort keys when the real bottleneck is disk-based operations from join-related data shuffling.
Detailed technical explanation
How to think about this question
Under the hood, Amazon Redshift distributes table rows across slices based on the distribution style. When joining large tables with mismatched distribution keys, Redshift must broadcast or redistribute entire tables across the network, causing intermediate results to spill to disk if they exceed memory. The KEY distribution style ensures that rows with the same distribution key land on the same slice, enabling collocated joins that avoid network shuffling, while ALL distribution replicates small tables to every slice, eliminating redistribution entirely. In real-world scenarios, a poorly chosen distribution style can lead to severe query degradation even with optimal sort keys and compression.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 an appropriate distribution style (e.g., KEY or ALL) for the tables. — Option C is correct because choosing an appropriate distribution style (KEY or ALL) minimizes data movement between nodes during query execution. In Amazon Redshift, disk-based operations often result from large volumes of data being redistributed across the network for joins. By colocating related data on the same slices via KEY distribution or replicating small tables with ALL distribution, you reduce the need for broadcast or redistribution, which directly alleviates disk-based spills and improves 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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