The correct answer involves setting the groupFiles option to inPartition and using the AWS Glue Data Catalog to store a consistent schema. When a Glue job fails with a SchemaDetectionException, it typically means the job cannot infer a unified schema from the source files, often because it samples only a subset of small files. Setting groupFiles to inPartition forces the job to combine all small files within a partition before schema detection, ensuring the full dataset is considered. Pairing this with the Data Catalog allows you to define and enforce a consistent schema manually, bypassing unreliable automatic inference. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of Glue’s schema inference behavior and how to control it with job parameters. A common trap is assuming that increasing parallelism or converting file formats fixes schema detection, but those actions do not address the root cause of incomplete sampling. Remember: when small files cause schema headaches, groupFiles inPartition and the Data Catalog are your fix.
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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 to process data from Amazon S3. The Glue job fails with a 'SchemaDetectionException'. The data engineer wants to ensure the schema is correctly inferred. Which TWO actions should the engineer take? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the Glue Data Catalog as the source for schema definition.
Options A and D are correct. Option A ensures the job reads all files for schema inference. Option D uses the Glue Data Catalog to store a consistent schema. Option B is wrong because adding a separate column does not help schema detection. Option C is wrong because converting to Parquet may change the schema but does not guarantee correct inference. Option E is wrong because increasing parallelism does not affect schema detection.
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 the Glue Data Catalog as the source for schema definition.
Why this is correct
Data Catalog provides a predefined schema.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add a column with a default value to the data.
Why it's wrong here
Adding a column does not help schema detection.
✗
Increase the number of Glue DPUs to speed up processing.
Why it's wrong here
DPUs affect performance, not schema detection.
✗
Convert all input files to Parquet format.
Why it's wrong here
Parquet has its own schema but doesn't guarantee correct inference.
✓
Set the 'groupFiles' option to 'inPartition' to combine small files.
Why this is correct
Grouping files helps infer schema from all files.
Related concept
Read the scenario before looking for a memorised answer.
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 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.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the Glue Data Catalog as the source for schema definition. — Options A and D are correct. Option A ensures the job reads all files for schema inference. Option D uses the Glue Data Catalog to store a consistent schema. Option B is wrong because adding a separate column does not help schema detection. Option C is wrong because converting to Parquet may change the schema but does not guarantee correct inference. Option E is wrong because increasing parallelism does not affect schema detection.
What should I do if I get this DEA-C01 question wrong?
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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