DEA-C01 Data Ingestion and Transformation Practice Question
A data engineer is using AWS Glue DataBrew to profile a dataset in Amazon S3. The dataset contains a column 'customer_id' that should be unique. The engineer runs a profile job and notices that the 'customer_id' column has a uniqueness metric of 98%. The engineer needs to identify the duplicate values. Which DataBrew feature should the engineer use to display the duplicate values?
⚠ Common exam trap
The trap here is assuming that the uniqueness metric or column statistics will list the duplicate values, when in fact you need to examine the value frequencies to see the actual duplicates.
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
✓
Use the 'Value frequencies' view in the profile job results to see the most frequent values.
AWS Glue DataBrew profile jobs include a 'Value frequencies' view that lists the most frequent values in a column with their counts. For a column that should be unique, this view directly reveals which customer_id values are duplicated. The other options provide summary statistics or rules but do not display the specific duplicate values.
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 'Column profile' view to see a histogram of values.
Why it's wrong here
The 'Column profile' view provides a histogram and distribution of values, which can show if there are duplicates but does not list the specific duplicate IDs. For categorical columns with many unique values, the histogram may not clearly identify duplicates. The 'Value frequencies' view is designed to show exact value counts.
- ✓
Use the 'Value frequencies' view in the profile job results to see the most frequent values.
Why this is correct
In AWS Glue DataBrew profile results, the 'Value frequencies' view displays the most common values in a column along with their counts. For a column like 'customer_id' with duplicates, this view will show which IDs appear more than once, allowing the engineer to identify the duplicate values. It is the correct feature for this purpose.
- ✗
Use the 'Column statistics' view in the profile job results to see the count of duplicates.
Why it's wrong here
The 'Column statistics' view in DataBrew profile results provides summary statistics such as count, distinct count, and uniqueness percentage. It does not list the actual duplicate values. To see the specific duplicate entries, a different feature is needed. This option is a common misconception because statistics are visible but not the detailed values.
- ✗
Use the 'Data quality rules' feature to create a rule that flags duplicates.
Why it's wrong here
Data quality rules can be used to define and monitor rules such as uniqueness, but they do not display the actual duplicate values in the profile results. They are used for ongoing validation and alerting. To visually inspect duplicates, the 'Value frequencies' view is more direct and immediate.
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 |
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.