- A
Convert the files to Apache Parquet format using an AWS Glue ETL job.
Why wrong: Parquet is columnar and improves performance, but small files still cause overhead; this alone may not solve the issue.
- B
Run a compaction job to consolidate small files into fewer larger files (e.g., 128 MB each).
Consolidating small files reduces the overhead of listing and reading many objects, significantly improving Athena performance.
- C
Add more partitions by including hour and minute as partition keys.
Why wrong: More partitions increase the number of files to list and read, worsening performance.
- D
Use S3 Select to push down filtering to S3 before Athena processes the data.
Why wrong: S3 Select works on individual objects and is not designed for querying many objects simultaneously.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A data analyst needs to query a large Amazon S3 bucket containing CSV files using Amazon Athena. The bucket has millions of small files (less than 1 MB each). The analyst reports that queries are very slow and often time out. The data is partitioned by date and the partition columns are defined in the table. What is the most effective way to 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
Run a compaction job to consolidate small files into fewer larger files (e.g., 128 MB each).
Option D is correct because many small files cause high overhead for listing and reading files in Athena. Compacting small files into fewer larger files (e.g., 128 MB each) reduces the I/O operations and improves performance. Option A is wrong because file format conversion (e.g., to Parquet) helps but does not address the small file problem. Option B is wrong because increasing partitions would increase overhead. Option C is wrong because S3 Select is for retrieving subset of data from a single file, not for optimizing many files.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 files to Apache Parquet format using an AWS Glue ETL job.
Why it's wrong here
Parquet is columnar and improves performance, but small files still cause overhead; this alone may not solve the issue.
- ✓
Run a compaction job to consolidate small files into fewer larger files (e.g., 128 MB each).
Why this is correct
Consolidating small files reduces the overhead of listing and reading many objects, significantly improving Athena performance.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add more partitions by including hour and minute as partition keys.
Why it's wrong here
More partitions increase the number of files to list and read, worsening performance.
- ✗
Use S3 Select to push down filtering to S3 before Athena processes the data.
Why it's wrong here
S3 Select works on individual objects and is not designed for querying many objects simultaneously.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
- →
Data Operations and Support — study guide chapter
Learn the concepts, then practise the questions
- →
Data Operations and Support practice questions
Targeted practice on this topic area only
- →
All DEA-C01 questions
1,786 questions across all exam domains
- →
AWS Certified Data Engineer Associate DEA-C01 study guide
Full concept coverage aligned to exam objectives
- →
DEA-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related DEA-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Data Ingestion and Transformation practice questions
Practise DEA-C01 questions linked to Data Ingestion and Transformation.
Data Operations and Support practice questions
Practise DEA-C01 questions linked to Data Operations and Support.
Data Security and Governance practice questions
Practise DEA-C01 questions linked to Data Security and Governance.
Data Store Management practice questions
Practise DEA-C01 questions linked to Data Store Management.
DEA-C01 fundamentals practice questions
Practise DEA-C01 questions linked to DEA-C01 fundamentals.
DEA-C01 scenario practice questions
Practise DEA-C01 questions linked to DEA-C01 scenario.
DEA-C01 troubleshooting practice questions
Practise DEA-C01 questions linked to DEA-C01 troubleshooting.
Practice this exam
Start a free DEA-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this DEA-C01 question test?
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Run a compaction job to consolidate small files into fewer larger files (e.g., 128 MB each). — Option D is correct because many small files cause high overhead for listing and reading files in Athena. Compacting small files into fewer larger files (e.g., 128 MB each) reduces the I/O operations and improves performance. Option A is wrong because file format conversion (e.g., to Parquet) helps but does not address the small file problem. Option B is wrong because increasing partitions would increase overhead. Option C is wrong because S3 Select is for retrieving subset of data from a single file, not for optimizing many files.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More DEA-C01 practice questions
- A data pipeline uses Kinesis Data Firehose to deliver streaming data to an S3 bucket. The data volume spikes occasionall…
- An e-commerce company uses AWS Glue to run ETL jobs that transform clickstream data from Amazon S3. The job reads Parque…
- A data engineering team uses Amazon Kinesis Data Analytics for Apache Flink to process streaming data. They notice that…
- A company uses AWS Glue to process streaming data from Amazon Kinesis Data Streams. The job reads JSON records and write…
- A data engineer is designing a serverless data ingestion pipeline that uses Amazon Kinesis Data Firehose to deliver data…
- A company runs a nightly AWS Glue ETL job that reads from a JDBC source (PostgreSQL) and writes to S3 in Parquet format.…
Last reviewed: Jun 20, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.