Question 210 of 1,711
Redshift Table Design — Sort Keys and Distribution
A company is using Amazon Redshift for its data warehouse. The data engineering team needs to improve query performance for a large fact table that is frequently joined with multiple dimension tables. Which THREE strategies should be considered?
Quick Answer
The answer is to define sort keys on columns used in WHERE clauses, apply columnar compression, and choose an appropriate distribution style. Sort keys are correct because they enable Redshift’s zone maps to skip entire disk blocks that don’t match filter conditions, drastically reducing I/O for large fact tables. Columnar compression further shrinks storage and speeds scans by encoding similar data values efficiently, while a well-chosen distribution style—like KEY on a join column—minimizes data shuffling during joins with dimension tables. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of how physical table design directly impacts Redshift’s massively parallel processing architecture; a common trap is to focus only on indexing or caching, which Redshift does not use. Remember the mnemonic “Sort, Squeeze, Spread”—sort keys for pruning, compression for squeezing data, and distribution for spreading work across nodes.
⚠ Common exam trap
Many exam-takers assume DISTSTYLE EVEN is always the best choice for performance, but for frequently joined fact tables, a distribution key aligned with the join columns is critical to avoid network-heavy data shuffling.
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 sort keys on columns used in WHERE clauses.
Defining sort keys on columns used in WHERE clauses allows Amazon Redshift to use zone maps to skip large blocks of data that do not satisfy the filter condition, dramatically reducing the amount of data scanned. This is especially effective for large fact tables where selective filters can prune entire disk blocks, improving query performance without additional hardware.
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 sort keys on columns used in WHERE clauses.
Why this is correct
Improves filter efficiency.
- ✗
Use DISTSTYLE EVEN to distribute data evenly.
Why it's wrong here
EVEN distribution does not optimize joins.
- ✗
Increase the number of nodes in the cluster.
Why it's wrong here
Scaling is costly and may not address root cause.
- ✓
Choose an appropriate distribution key based on join columns.
Why this is correct
Reduces data movement during joins.
- ✓
Apply columnar compression to reduce storage and I/O.
Why this is correct
Compression reduces data scanned.
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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. A company uses Amazon Redshift for data warehousing. The data engineering team notices that queries are slow due to high disk I/O. The team wants to improve query performance without changing the cluster configuration. Which action should the team take?
medium- A.Increase the number of nodes in the cluster.
- ✓ B.Redesign tables with appropriate sort keys and distribution styles.
- C.Run the ANALYZE command to update table statistics.
- D.Run the VACUUM command to reclaim disk space.
Why B: Redesigning tables with appropriate sort keys and distribution styles directly addresses high disk I/O by minimizing data scanning and reducing data movement across nodes. Sort keys enable Redshift to skip irrelevant blocks via zone maps, while distribution styles (KEY, ALL, EVEN) optimize data locality for joins and aggregations, reducing I/O without changing cluster configuration.
Last reviewed: Jun 24, 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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