- A
Define appropriate sort keys
Sort keys reduce the amount of data scanned.
- B
Increase the number of nodes
Why wrong: This increases cost and may improve performance but is not the most direct action.
- C
Use EVEN distribution style for all tables
Why wrong: Distribution style affects data distribution, not directly query performance.
- D
Use columnar compression
Compression reduces storage and I/O, improving performance.
- E
Run VACUUM command regularly
Why wrong: VACUUM reclaims space but does not directly speed up queries.
Question 1,659 of 1,786
Boost Amazon Redshift Query Performance with Sort Keys and Compression
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.
Which TWO actions can improve query performance on an Amazon Redshift cluster? (Choose two.)
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
✓
Define appropriate sort keys
Option A is correct because defining appropriate sort keys in Amazon Redshift physically orders data on disk by the sort key columns, enabling the query optimizer to use zone maps to skip large blocks of data that do not match query predicates. This drastically reduces the amount of data scanned, especially for range-restricted queries, improving I/O and overall 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
Why this is correct
Sort keys reduce the amount of data scanned.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the number of nodes
Why it's wrong here
This increases cost and may improve performance but is not the most direct action.
- ✗
Use EVEN distribution style for all tables
Why it's wrong here
Distribution style affects data distribution, not directly query performance.
- ✓
Use columnar compression
Why this is correct
Compression reduces storage and I/O, improving performance.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Run VACUUM command regularly
Why it's wrong here
VACUUM reclaims space but does not directly speed up queries.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse maintenance operations (VACUUM) or scaling actions (adding nodes) with direct query tuning techniques, while the exam specifically tests the understanding that sort keys and compression are the two primary table design choices that directly improve query performance.
Detailed technical explanation
How to think about this question
Sort keys in Redshift work with zone maps that store minimum and maximum values for each 1 MB block; when a query includes a filter on the sort key column, the optimizer can skip entire blocks that fall outside the filter range, reducing disk I/O by up to 99% in some cases. Columnar compression (Option D) reduces the physical storage size of data on disk, allowing more data to fit in memory and reducing the amount of data read from disk per query, which directly improves scan performance. Under the hood, Redshift uses a block-based columnar storage engine where each column is compressed independently using algorithms like AZ64, ZSTD, or LZO, and decompression happens on-the-fly during query execution.
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 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.
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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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Define appropriate sort keys — Option A is correct because defining appropriate sort keys in Amazon Redshift physically orders data on disk by the sort key columns, enabling the query optimizer to use zone maps to skip large blocks of data that do not match query predicates. This drastically reduces the amount of data scanned, especially for range-restricted queries, improving I/O and overall 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.
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 →
Same concept, more angles
1 more ways this is tested on DEA-C01
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. Which TWO actions can help improve query performance in Amazon Redshift? (Choose two.)
medium- ✓ A.Use appropriate sort keys for tables.
- B.Disable SSL encryption for connections.
- C.Use VARCHAR instead of CHAR for fixed-length strings.
- ✓ D.Apply compression encodings to columns.
- E.Increase the number of nodes in the cluster.
Why A: Option A is correct because defining appropriate sort keys in Amazon Redshift enables the query optimizer to use zone maps to skip irrelevant data blocks during table scans, significantly reducing the amount of data read from disk. Sort keys also improve the effectiveness of merge joins and the performance of range-restricted queries by physically co-locating rows with similar sort key values on disk.
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Last reviewed: Jul 4, 2026
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