Question 1,659 of 1,711
DEA-C01 Data Store Management Practice Question
Which TWO actions can improve query performance on an Amazon Redshift cluster? (Choose two.)
⚠ Common exam trap
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.
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
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.
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.
- ✗
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.
- ✗
Run VACUUM command regularly
Why it's wrong here
VACUUM reclaims space but does not directly speed up queries.
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Same concept, more angles
1 more way 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: 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.
Last reviewed: Jul 4, 2026
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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