- A
Enable the crawler's partition index feature.
Partition indexes allow the crawler to efficiently discover new partitions without scanning the entire dataset.
- B
Manually add new partitions using ALTER TABLE ADD PARTITION in Athena.
Why wrong: Manual partition addition does not scale and requires constant monitoring.
- C
Use the Athena MSCK REPAIR TABLE command after the crawler runs.
Why wrong: MSCK REPAIR TABLE is a manual operation and does not solve the underlying issue of the crawler missing partitions.
- D
Increase the crawler's schedule to run every 30 minutes.
Why wrong: More frequent runs will increase cost and may still miss partitions if the crawler cannot keep up.
Question 69 of 1,755
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 AWS Glue crawlers to populate the AWS Glue Data Catalog from Amazon S3. The data is partitioned by year/month/day/hour. The crawler runs every hour and adds new partitions. However, the data engineer notices that the crawler is taking longer to run as the number of partitions grows, and sometimes it misses new partitions. What is the most cost-effective and reliable way to address this?
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 crawler's partition index feature.
Option A is correct because enabling the crawler's partition index feature allows AWS Glue to quickly find new partitions without re-scanning the entire table, reducing runtime and improving reliability. Option B is incorrect because manually adding partitions is error-prone and does not scale. Option C is incorrect because the MSCK REPAIR TABLE command is a manual step that does not automate the process. Option D is incorrect because increasing the crawler's frequency does not address the underlying issue of scanning overhead and may lead to resource contention.
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.
- ✓
Enable the crawler's partition index feature.
Why this is correct
Partition indexes allow the crawler to efficiently discover new partitions without scanning the entire dataset.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Manually add new partitions using ALTER TABLE ADD PARTITION in Athena.
Why it's wrong here
Manual partition addition does not scale and requires constant monitoring.
- ✗
Use the Athena MSCK REPAIR TABLE command after the crawler runs.
Why it's wrong here
MSCK REPAIR TABLE is a manual operation and does not solve the underlying issue of the crawler missing partitions.
- ✗
Increase the crawler's schedule to run every 30 minutes.
Why it's wrong here
More frequent runs will increase cost and may still miss partitions if the crawler cannot keep up.
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 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.
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: Enable the crawler's partition index feature. — Option A is correct because enabling the crawler's partition index feature allows AWS Glue to quickly find new partitions without re-scanning the entire table, reducing runtime and improving reliability. Option B is incorrect because manually adding partitions is error-prone and does not scale. Option C is incorrect because the MSCK REPAIR TABLE command is a manual step that does not automate the process. Option D is incorrect because increasing the crawler's frequency does not address the underlying issue of scanning overhead and may lead to resource contention.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 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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