The answer is to change the sort key to include customer_id as a compound sort key. This directly optimizes Redshift sort key optimization for frequently filtered columns because a compound sort key orders data by the first column listed, allowing the query engine to rapidly skip irrelevant blocks when filtering by that column. Since the table is already sorted by date but queries filter by customer_id, the current sort key provides no pruning benefit for those queries. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding that sort keys should match the most common filter predicates, not just the natural order of data. A common trap is assuming AUTO distribution or interleaved sort keys are always better, but for a single frequently filtered column, a compound sort key with that column first is simpler and more efficient. Memory tip: “First filter, first key”—the column you filter on most should be the first column in your compound sort key.
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 engineer notices that the most frequently accessed table is sorted by date, but queries often filter by customer_id. The table has 500 million rows and uses AUTO distribution style. What 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
✓
Change the sort key to include customer_id as a compound sort key.
Changing the sort key to include customer_id or using a compound sort key with customer_id first will improve performance for queries filtering by customer_id. Option A is wrong because AUTO distribution style is fine and may already distribute data well. Option B is wrong because changing to KEY distribution on customer_id might help but the question asks about sort key. Option D is wrong because interleaved sort key is useful for multiple predicates but compound sort key with customer_id as first key is simpler and likely more efficient given the access pattern.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 distribution style to KEY on customer_id.
Why it's wrong here
Distribution key helps with joins and data distribution, not filtering within a table.
✗
Change distribution style to EVEN.
Why it's wrong here
EVEN distribution spreads data evenly but doesn't improve filter performance.
✓
Change the sort key to include customer_id as a compound sort key.
Why this is correct
A compound sort key with customer_id first will optimize queries filtering by customer_id.
Related concept
Static NAT maps one inside address to one outside address.
✗
Change the sort key to an interleaved sort key on date and customer_id.
Why it's wrong here
Interleaved sort key can help but is more complex and may not be necessary if customer_id is the primary filter.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Data Store Management — This question tests Data Store Management — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Change the sort key to include customer_id as a compound sort key. — Changing the sort key to include customer_id or using a compound sort key with customer_id first will improve performance for queries filtering by customer_id. Option A is wrong because AUTO distribution style is fine and may already distribute data well. Option B is wrong because changing to KEY distribution on customer_id might help but the question asks about sort key. Option D is wrong because interleaved sort key is useful for multiple predicates but compound sort key with customer_id as first key is simpler and likely more efficient given the access pattern.
What should I do if I get this DEA-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Amazon Redshift for its data warehouse. The data engineer notices that queries are slow on a large table that is frequently filtered on a column 'transaction_date'. Which optimization technique best improves query performance?
hard
A.Apply compression encoding to 'transaction_date'.
✓ B.Set the sort key to 'transaction_date'.
C.Set the distribution key to 'transaction_date'.
D.Run VACUUM on the table.
Why B: Setting the sort key to 'transaction_date' organizes the table data physically by that column, which allows Redshift to use zone maps to skip blocks that don't match query filters. This dramatically reduces the amount of data scanned for range-restricted queries on 'transaction_date', improving query performance.
Last reviewed: Jun 20, 2026
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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.
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