DEA-C01 Data Operations and Support Practice Question
A data engineer is troubleshooting a slow-running Amazon Athena query. The query scans a large amount of data. Which TWO actions can improve query performance? (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
✓
Convert the data to Parquet or ORC format.
Converting data to columnar formats like Parquet or ORC reduces the amount of data scanned, and partitioning the table on frequently filtered columns allows Athena to skip reading irrelevant partitions. Both actions improve query performance. Option B (encryption) does not affect performance. Option C (increasing timeout) only allows more time for a slow query, not improving performance. Option E (SELECT *) scans all columns, which increases data scanned and worsens 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.
- ✓
Convert the data to Parquet or ORC format.
Why this is correct
Columnar formats reduce I/O and improve compression.
- ✗
Enable encryption at rest.
Why it's wrong here
Encryption adds overhead and does not improve performance.
- ✗
Increase the Athena query timeout.
Why it's wrong here
Timeout does not affect performance; it only allows longer execution.
- ✓
Partition the table on frequently filtered columns.
Why this is correct
Partition pruning reduces data scanned.
- ✗
Use SELECT * to retrieve all columns.
Why it's wrong here
SELECT * scans all columns, increasing data scanned.
Go deeper
Related to this question
About these practice questions
One of 1,711 original DEA-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.