- A
Use the 'dropDuplicates' transformation in the Glue ETL script, ordering by 'timestamp' descending to keep the latest record for each 'id'.
This removes duplicate IDs while preserving the most recent record.
- B
Set the write mode to 'overwrite' in the Glue job to replace the entire Redshift table.
Why wrong: Overwrite replaces the entire table, which is inefficient and does not handle duplicates within the new data.
- C
Load data into a staging table in Redshift and then use a MERGE operation to insert only new records.
Why wrong: This approach can work but is more complex and not directly supported in Glue without custom SQL; the question asks for the simplest approach.
- D
Disable primary key constraints on the Redshift table before loading.
Why wrong: Disabling constraints will skip the check but will still result in duplicate data in the table, which violates data integrity.
Quick Answer
The correct approach is to use the `dropDuplicates` transformation in the AWS Glue ETL script, ordering by `timestamp` descending to keep the latest record for each `id`. This works because `dropDuplicates` operates on a Spark DataFrame, allowing you to specify a subset of columns—here, the `id` column—and then apply an ordering within each group to retain only the first row, effectively removing duplicate keys before the write to Redshift. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how to handle data quality issues within Glue jobs, specifically the common trap of assuming Redshift constraints can be disabled or that overwrite mode solves row-level duplicates. A key memory tip is "order then drop": always sort your DataFrame by the latest timestamp before calling `dropDuplicates` on the key column, ensuring you keep the most recent record and avoid the duplicate key error.
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.
A data engineer is troubleshooting a failed AWS Glue ETL job that reads from Amazon S3 and writes to Amazon Redshift. The job fails with the error: 'ERROR: Cannot insert a duplicate key into unique index'. The Redshift table has a primary key on the 'id' column. The data in S3 contains multiple records with the same 'id'. The engineer needs to ensure that only the latest record for each 'id' is loaded into Redshift. The data has a 'timestamp' column. Which approach should the engineer take?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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 'dropDuplicates' transformation in the Glue ETL script, ordering by 'timestamp' descending to keep the latest record for each 'id'.
Option B is correct because using the AWS Glue 'dropDuplicates' transformation on the 'id' column, ordering by 'timestamp' descending, will remove duplicate 'id' values, keeping the latest record. Option A is wrong because disabling constraints does not prevent duplicates; it only defers the error. Option C is wrong because setting 'overwrite' mode replaces the entire table, not just duplicates. Option D is wrong because staging tables and MERGE require additional steps and are not directly available in Glue without custom logic.
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 'dropDuplicates' transformation in the Glue ETL script, ordering by 'timestamp' descending to keep the latest record for each 'id'.
Why this is correct
This removes duplicate IDs while preserving the most recent record.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set the write mode to 'overwrite' in the Glue job to replace the entire Redshift table.
Why it's wrong here
Overwrite replaces the entire table, which is inefficient and does not handle duplicates within the new data.
- ✗
Load data into a staging table in Redshift and then use a MERGE operation to insert only new records.
Why it's wrong here
This approach can work but is more complex and not directly supported in Glue without custom SQL; the question asks for the simplest approach.
- ✗
Disable primary key constraints on the Redshift table before loading.
Why it's wrong here
Disabling constraints will skip the check but will still result in duplicate data in the table, which violates data integrity.
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 Operations and Support — study guide chapter
Learn the concepts, then practise the questions
- →
Data Operations and Support practice questions
Targeted practice on this topic area only
- →
All DEA-C01 questions
1,786 questions across all exam domains
- →
AWS Certified Data Engineer Associate DEA-C01 study guide
Full concept coverage aligned to exam objectives
- →
DEA-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related DEA-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Data Ingestion and Transformation practice questions
Practise DEA-C01 questions linked to Data Ingestion and Transformation.
Data Operations and Support practice questions
Practise DEA-C01 questions linked to Data Operations and Support.
Data Security and Governance practice questions
Practise DEA-C01 questions linked to Data Security and Governance.
Data Store Management practice questions
Practise DEA-C01 questions linked to Data Store Management.
DEA-C01 fundamentals practice questions
Practise DEA-C01 questions linked to DEA-C01 fundamentals.
DEA-C01 scenario practice questions
Practise DEA-C01 questions linked to DEA-C01 scenario.
DEA-C01 troubleshooting practice questions
Practise DEA-C01 questions linked to DEA-C01 troubleshooting.
Practice this exam
Start a free DEA-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this DEA-C01 question test?
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: Use the 'dropDuplicates' transformation in the Glue ETL script, ordering by 'timestamp' descending to keep the latest record for each 'id'. — Option B is correct because using the AWS Glue 'dropDuplicates' transformation on the 'id' column, ordering by 'timestamp' descending, will remove duplicate 'id' values, keeping the latest record. Option A is wrong because disabling constraints does not prevent duplicates; it only defers the error. Option C is wrong because setting 'overwrite' mode replaces the entire table, not just duplicates. Option D is wrong because staging tables and MERGE require additional steps and are not directly available in Glue without custom logic.
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: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.