- A
Remove partitioning from the output
Why wrong: Would worsen performance.
- B
Partition the input data in S3
Enables parallel processing.
- C
Use Amazon EMR instead of Glue
Why wrong: Would increase management overhead and cost.
- D
Convert input data to columnar format (e.g., Parquet)
Reduces data scanned and improves compression.
- E
Increase the number of DPUs (workers)
More parallelism reduces job duration.
Question 61 of 1,755
MLS-C01 Data Engineering Practice Question
This MLS-C01 practice question tests your understanding of data engineering. 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 engineering team uses AWS Glue to run ETL jobs. They notice that jobs are taking longer to complete as data volume grows. They want to optimize performance without increasing cost significantly. Which THREE strategies should they consider?
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 input data in S3
Partitioning input data in S3 (B) allows AWS Glue to use partition pruning, reading only the relevant subsets of data instead of scanning the entire dataset. This reduces I/O and processing time, directly addressing the performance degradation caused by growing data volumes.
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.
- ✗
Remove partitioning from the output
Why it's wrong here
Would worsen performance.
- ✓
Partition the input data in S3
Why this is correct
Enables parallel processing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use Amazon EMR instead of Glue
Why it's wrong here
Would increase management overhead and cost.
- ✓
Convert input data to columnar format (e.g., Parquet)
Why this is correct
Reduces data scanned and improves compression.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Increase the number of DPUs (workers)
Why this is correct
More parallelism reduces job duration.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume adding more DPUs (E) is the only way to speed up Glue jobs, overlooking that data optimization strategies (partitioning and columnar formats) can yield similar or better performance gains without increasing cost.
Detailed technical explanation
How to think about this question
Partition pruning works by leveraging Hive-style partitioning in S3 (e.g., year=2023/month=01/day=15), which Glue's pushdown predicate filter evaluates at the file system level before any data is read. Columnar formats like Parquet further reduce I/O by using row group statistics and predicate pushdown, allowing Glue to skip entire row groups that don't match filter criteria. In practice, combining S3 partitioning with Parquet can reduce data scanned by 90% or more, dramatically improving job runtime without additional compute cost.
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.
TExam Day Tips
- 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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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 |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this MLS-C01 question test?
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Partition the input data in S3 — Partitioning input data in S3 (B) allows AWS Glue to use partition pruning, reading only the relevant subsets of data instead of scanning the entire dataset. This reduces I/O and processing time, directly addressing the performance degradation caused by growing data volumes.
What should I do if I get this MLS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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.
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