The answer is that the source CSV file has fewer columns than the target Redshift table. This is the most likely cause because the Glue to Redshift column count mismatch error occurs when the number of columns in the source data does not match the schema defined in the target Redshift table, triggering a validation failure during the write operation. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how AWS Glue ETL jobs handle schema mapping and the common pitfalls when moving data from semi-structured sources like CSV into a structured Redshift table. A frequent trap is confusing column count errors with data type mismatches or permission issues, but the error message explicitly references a count mismatch, not a type conversion or access problem. To fix Glue to Redshift column count mismatch errors, always verify that the source file’s column count matches the target table’s schema before running the job. Memory tip: count columns, not types—if the error says “mismatch,” think “missing columns.”
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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.
Network Topology
Refer to the exhibit. A data engineer runs a Glue ETL job that reads from a CSV file and writes to a Redshift table. The job fails with the error shown. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The source CSV file has fewer columns than the target table.
Option A is correct because the error indicates a column count mismatch. The source file has 10 columns but the target expects 12. Option B is wrong because the error is about column count, not data type. Option C is wrong because there is no mention of partition count. Option D is wrong because the error is about validation, not permissions.
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 source CSV file has fewer columns than the target table.
Why this is correct
Error says columns (10) does not match expected (12).
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 IAM role for the Glue job does not have permission to write to Redshift.
Why it's wrong here
Error is about data validation, not permissions.
✗
The target Redshift table has mismatched data types for some columns.
Why it's wrong here
Error mentions column count, not data type.
✗
The Glue job is using an incorrect number of partitions for the source data.
Why it's wrong here
Partitions are not related to column count.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The source CSV file has fewer columns than the target table. — Option A is correct because the error indicates a column count mismatch. The source file has 10 columns but the target expects 12. Option B is wrong because the error is about column count, not data type. Option C is wrong because there is no mention of partition count. Option D is wrong because the error is about validation, not permissions.
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.
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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Question Discussion
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