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Data Engineering →easyMultiple ChoiceObjective-mapped

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 data pipeline uses AWS Glue to crawl an S3 bucket and create a table in the AWS Glue Data Catalog. The data is in Parquet format with partitions by date. After a new partition is added to S3, the crawler runs but the new partition is not reflected in the table. What is the most likely cause?

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.

A
The crawler requires an AWS Lambda trigger to be configured for new partitions.
Why wrong: Glue crawlers do not need Lambda triggers; they can run on schedule.
B
The Parquet schema in the new partition does not match the existing table schema.
Why wrong: Glue crawlers can merge schemas if configured, but the partition would still be added.
C
The new partition folder does not follow the Hive-style partition naming convention expected by the crawler.
Glue crawlers require partition folders to follow the key=value pattern to automatically detect partitions.
D
The S3 bucket has too many partitions, exceeding the Glue crawler limit.
Why wrong: Glue crawlers support up to 10 million partitions.

Full breakdown with real-world context →

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

✓

The new partition folder does not follow the Hive-style partition naming convention expected by the crawler.

The most likely cause is that the new partition folder does not follow the Hive-style partition naming convention expected by the crawler. AWS Glue crawlers expect partition directories to be named in the format key=value (e.g., date=2023-01-01). If the partitions are named differently, the crawler will not recognize them as partitions. Option A is incorrect because Glue crawlers do not require Lambda triggers. Option B is incorrect because schema mismatch would cause a different error, not just missing partitions. Option D is incorrect because while there is a limit on partitions, it is high enough that 'too many partitions' is less likely than a naming issue.

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.

✗
The crawler requires an AWS Lambda trigger to be configured for new partitions.
Why it's wrong here
Glue crawlers do not need Lambda triggers; they can run on schedule.
✗
The Parquet schema in the new partition does not match the existing table schema.
Why it's wrong here
Glue crawlers can merge schemas if configured, but the partition would still be added.
✓
The new partition folder does not follow the Hive-style partition naming convention expected by the crawler.
Why this is correct
Glue crawlers require partition folders to follow the key=value pattern to automatically detect partitions.
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.
✗
The S3 bucket has too many partitions, exceeding the Glue crawler limit.
Why it's wrong here
Glue crawlers support up to 10 million partitions.

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.

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.

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.

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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: The new partition folder does not follow the Hive-style partition naming convention expected by the crawler. — The most likely cause is that the new partition folder does not follow the Hive-style partition naming convention expected by the crawler. AWS Glue crawlers expect partition directories to be named in the format key=value (e.g., date=2023-01-01). If the partitions are named differently, the crawler will not recognize them as partitions. Option A is incorrect because Glue crawlers do not require Lambda triggers. Option B is incorrect because schema mismatch would cause a different error, not just missing partitions. Option D is incorrect because while there is a limit on partitions, it is high enough that 'too many partitions' is less likely than a naming issue.

What should I do if I get this MLS-C01 question wrong?

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.