The answer is to increase the number of partitions in the data. When a Spark job fails with an OutOfMemory error, the root cause is often that a single partition holds more data than the executor’s allocated memory can handle, causing spills or crashes. By increasing partitions, you distribute the dataset into smaller chunks, reducing the per-executor memory pressure and allowing garbage collection to keep up. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of Spark memory tuning within Amazon EMR, a common trap being that engineers first increase executor memory or add more executors—but without repartitioning, each executor still processes oversized blocks. A key memory tip: think of partitions as “buckets”—more buckets mean each bucket holds less water, preventing overflow.
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 uses Amazon EMR to run Spark jobs on a transient cluster that processes data from S3. The jobs are failing with 'OutOfMemory' errors. The data engineer has already increased the executor memory. Which additional configuration change would MOST likely resolve the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 partitions in the data
Increasing the number of partitions can reduce the amount of data each executor processes, alleviating memory pressure. Option A is wrong because more executors may increase parallelism but not reduce per-executor data. Option C is wrong because increasing driver memory addresses driver-side issues. Option D is wrong because using fewer nodes may worsen the problem.
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.
✗
Use fewer, larger instance types for the core nodes
Why it's wrong here
Fewer nodes could concentrate data and worsen memory issues.
✓
Increase the number of partitions in the data
Why this is correct
More partitions means smaller data per task, reducing memory usage.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the driver memory
Why it's wrong here
OutOfMemory usually occurs in executors, not driver.
✗
Increase the number of executors
Why it's wrong here
More executors can help but may not reduce data per executor if parallelism is already high.
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 MLS-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 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 partitions in the data — Increasing the number of partitions can reduce the amount of data each executor processes, alleviating memory pressure. Option A is wrong because more executors may increase parallelism but not reduce per-executor data. Option C is wrong because increasing driver memory addresses driver-side issues. Option D is wrong because using fewer nodes may worsen the problem.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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