MLS-C01 Data Engineering Practice Question
Which TWO of the following are valid ways to reduce query costs in Amazon Athena? (Choose 2)
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
✓
Partition the data in S3
(partitioning data) and Option D (using columnar formats like Parquet) are correct because both reduce the amount of data scanned by Athena queries, directly lowering costs. Option A (UNLOAD) exports results but does not reduce query costs. Option C (increasing query timeout) does not affect data scanned. Option E (encryption at rest) does not reduce costs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use UNLOAD to export query results to S3
Why it's wrong here
UNLOAD is for results, not cost reduction.
- ✓
Partition the data in S3
Why this is correct
Partitioning limits data scanned per query.
- ✗
Increase the query timeout limit
Why it's wrong here
Timeout doesn't reduce data scanned.
- ✓
Use columnar storage formats like Parquet
Why this is correct
Columnar formats reduce I/O and data scanned.
- ✗
Enable encryption at rest on S3
Why it's wrong here
Encryption doesn't affect cost.
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JA
Written by Johnson Ajibi, MSc IT Security
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.