DEA-C01 Data Ingestion and Transformation Practice Question
A data engineer is troubleshooting a daily batch ingestion pipeline that uses AWS Glue to read CSV files from Amazon S3 and write Parquet files to another S3 bucket. The job runs successfully but takes significantly longer than expected. The engineer notices that the input data is highly skewed with many small files. Which is the most effective optimization to reduce job duration?
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
✓
Enable the 'groupFiles' option in the S3 source configuration
The 'groupFiles' option in AWS Glue's S3 source configuration allows Glue to combine small files into larger splits, reducing the number of tasks and the overhead associated with processing many small files. This directly addresses the high skew and small file issue, significantly reducing job duration. Option A is incorrect because changing the output format from Parquet to JSON would likely increase file size and processing time, not reduce it. Option C is incorrect because increasing DPUs may improve parallelism but does not solve the file-level overhead; it could even be wasteful if the bottleneck is task scheduling. Option D is incorrect because enabling the schema registry is unrelated to file grouping; it is used for schema management and validation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Change the output format to JSON
Why it's wrong here
The output format is not the bottleneck; Parquet is efficient.
- ✓
Enable the 'groupFiles' option in the S3 source configuration
Why this is correct
Grouping small files into larger splits reduces task overhead and improves performance.
- ✗
Increase the number of DPUs allocated to the job
Why it's wrong here
More DPUs may increase parallelism but do not reduce the overhead of processing many small files.
- ✗
Enable the 'use_glue_schema_registry' option
Why it's wrong here
Schema registry does not address file size issues.
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 |
Go deeper
Related to this question
About these practice questions
Courseiva writes every DEA-C01 question from scratch — 1,711 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. 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.