DEA-C01 Data Operations and Support Practice Question
A data engineer is troubleshooting a data pipeline that uses Amazon Kinesis Data Firehose to deliver data to Amazon S3. The engineer notices that the S3 bucket contains many small files (less than 1 MB). This is causing performance issues in downstream processing. What is the BEST way to reduce the number of small files?
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
✓
Increase the buffer size to at least 128 MB in the Firehose delivery stream configuration.
Increasing the buffer size (e.g., to 128 MB) causes Firehose to deliver fewer, larger files, reducing the number of small files. Option B is incorrect because using a Lambda transformation does not inherently change buffering behavior. Option C is incorrect because changing the compression format (e.g., from GZIP to Snappy) affects storage size but not the number of files delivered. Option D is incorrect because decreasing the buffer interval would cause more frequent deliveries, creating more small files.
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 buffer size to at least 128 MB in the Firehose delivery stream configuration.
Why this is correct
Larger buffer size leads to fewer, larger files.
- ✗
Use an AWS Lambda function to transform the data before delivery.
Why it's wrong here
Lambda transforms data but does not affect buffering behavior.
- ✗
Change the compression format from GZIP to Snappy.
Why it's wrong here
Compression affects file size but not the number of files.
- ✗
Decrease the buffer interval in the Firehose delivery stream configuration.
Why it's wrong here
Decreasing interval creates more frequent deliveries, resulting in more small files.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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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.