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MLS-C01 Data Engineering Practice Question

This MLS-C01 practice question tests your understanding of data engineering. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company is using AWS Glue to run ETL jobs that transform data from multiple sources into a data lake on S3. The jobs are scheduled to run hourly. Recently, the jobs have been failing intermittently with 'MemoryError' exceptions. The data volume has grown over time. The data engineer needs to resolve this issue cost-effectively. Which action should be taken?

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 number of DPUs allocated to the Glue job and use a larger worker type.

The 'MemoryError' exception indicates that the Glue job is running out of memory as data volume grows. Increasing the number of DPUs (Data Processing Units) and using a larger worker type (e.g., from Standard to G.1X or G.2X) provides more memory and compute capacity per worker, allowing the job to handle larger datasets without failing. This is the most cost-effective approach because it scales resources only as needed, avoiding over-provisioning.

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.

  • Increase the number of DPUs allocated to the Glue job and use a larger worker type.

    Why this is correct

    More DPUs and larger worker types provide more memory to handle larger data volumes.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Increase the S3 timeout settings in the Glue job configuration.

    Why it's wrong here

    Timeout settings do not affect memory allocation.

  • Switch the Glue job type from Spark to Python shell to reduce memory overhead.

    Why it's wrong here

    Python shell uses less memory and will likely fail on large datasets.

  • Repartition the data using Spark's repartition method before processing.

    Why it's wrong here

    Repartitioning may help but may not resolve memory errors if the overall memory is insufficient.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may confuse memory errors with data skew or partitioning issues, leading them to choose repartitioning (Option D) instead of recognizing that the root cause is insufficient total memory for the growing dataset.

Detailed technical explanation

How to think about this question

AWS Glue uses Apache Spark under the hood, where each worker (DPU) has a fixed memory allocation (e.g., 16 GB for Standard workers). When data volume exceeds the aggregate memory of all workers, Spark's executor may throw OutOfMemoryError. Increasing DPUs or switching to G.2X workers (which provide 32 GB per DPU) increases the total heap space available for shuffles and transformations. A subtle behavior is that Glue's auto-scaling can help, but explicit DPU allocation is needed for predictable workloads.

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.

Visual reference

Client Recursive Resolver Root DNS (13 root servers) TLD DNS (.com, .org, …) Authoritative example.com query IP addr answer

Quick reference

AWS S3 Storage Class Comparison

Storage ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-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: Increase the number of DPUs allocated to the Glue job and use a larger worker type. — The 'MemoryError' exception indicates that the Glue job is running out of memory as data volume grows. Increasing the number of DPUs (Data Processing Units) and using a larger worker type (e.g., from Standard to G.1X or G.2X) provides more memory and compute capacity per worker, allowing the job to handle larger datasets without failing. This is the most cost-effective approach because it scales resources only as needed, avoiding over-provisioning.

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

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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.