Quick Answer
The correct actions are to convert all files to Parquet format, enable partition pruning on the date-partitioned data, and use job bookmarks to avoid reprocessing. Parquet’s columnar storage and compression drastically reduce I/O and storage costs, while partition pruning limits scanning to only the relevant date partitions, cutting both runtime and cost. Job bookmarks further optimize by tracking previously processed data, ensuring incremental transformations. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your ability to balance cost and performance in Glue ETL—a common scenario where candidates mistakenly increase DPUs or run unnecessary crawlers. The trap is thinking more compute solves performance issues, when the real gains come from data format and scan optimization. Remember the mnemonic: “P-P-J” for Parquet, Partition pruning, and Job bookmarks—the three pillars of Glue efficiency.
This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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 company wants to use AWS Glue to transform data stored in Amazon S3. The data is partitioned by date and includes both CSV and Parquet files. The transformation should be optimized for cost and performance. Which THREE actions should the data engineer take? (Choose THREE.)
Run a crawler to update the schema before each job run.
Why wrong: Unnecessary if schema is stable.
Use partition pruning by filtering on the date column in the ETL script.
Reduces data scanned.
Use job bookmarks to process only new data.
Avoids reprocessing.
Increase the number of DPUs to the maximum allowed.
Why wrong: Increases cost unnecessarily.
Convert all files to Parquet format before processing.
Parquet is more efficient.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use partition pruning by filtering on the date column in the ETL script.
Options A, C, and D are correct. Partition pruning reduces the amount of data scanned. Using Parquet improves performance and compression. Using a job bookmark prevents reprocessing of old data. Option B is wrong because increasing the number of DPUs may increase cost without optimization. Option E is wrong because a crawler is not needed if the schema is known.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Run a crawler to update the schema before each job run.
Why it's wrong here
Unnecessary if schema is stable.
Use partition pruning by filtering on the date column in the ETL script.
Why this is correct
Reduces data scanned.
Related concept
Read the scenario before looking for a memorised answer.
Use job bookmarks to process only new data.
Why this is correct
Avoids reprocessing.
Related concept
Read the scenario before looking for a memorised answer.
Increase the number of DPUs to the maximum allowed.
Why it's wrong here
Increases cost unnecessarily.
Convert all files to Parquet format before processing.
Why this is correct
Parquet is more efficient.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which DEA-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
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
The correct answer is: Use partition pruning by filtering on the date column in the ETL script. — Options A, C, and D are correct. Partition pruning reduces the amount of data scanned. Using Parquet improves performance and compression. Using a job bookmark prevents reprocessing of old data. Option B is wrong because increasing the number of DPUs may increase cost without optimization. Option E is wrong because a crawler is not needed if the schema is known.
Identify which DEA-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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 20, 2026
This DEA-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 DEA-C01 exam.
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