MLS-C01 Data Engineering Practice Question
A company uses Amazon Redshift for data warehousing. The data engineering team notices that query performance has degraded over time. Which THREE actions should the team take to improve performance? (Choose THREE.)
⚠ Common exam trap
Test-takers frequently confuse scaling up (adding nodes) with performance tuning, but the MLS-C01 exam expects you to recognize that data engineering best practices—like proper sort keys, distribution keys, and updated statistics—are the primary levers for improving query performance in Redshift, not just adding more hardware.
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 on large tables
Sort keys in Amazon Redshift define the order in which data is stored on disk within each node. By defining appropriate sort keys on large tables, the query engine can use zone maps to skip entire blocks of data that do not match the query's filter predicates, dramatically reducing the amount of data scanned and improving 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.
- ✗
Increase the number of nodes in the Redshift cluster
Why it's wrong here
Adding nodes increases capacity but is not a tuning technique; it may be needed but is not one of the three best practices.
- ✓
Define appropriate sort keys on large tables
Why this is correct
Sort keys minimize the amount of data scanned, improving query performance.
- ✓
Define appropriate distribution keys on large tables
Why this is correct
Distribution keys minimize data movement during joins and aggregations.
- ✗
Delete old data that is no longer needed
Why it's wrong here
Deleting data frees space but does not directly improve query performance; vacuuming would be more relevant.
- ✓
Run the ANALYZE command to update table statistics
Why this is correct
Up-to-date statistics help the query optimizer choose efficient execution plans.
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Senior Network & Security Engineer · founder of Courseiva
This MLS-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 MLS-C01 exam.