The correct answer is to enable 'BatchApplyEnabled' and set 'TaskRecoveryTableEnabled' to false in the task settings. This resolves the duplicate key violation because when BatchApplyEnabled is active, AWS DMS batches multiple changes into a single transaction, reducing the chance of re-processing already-applied rows during recovery; setting TaskRecoveryTableEnabled to false prevents the task from storing recovery metadata that can cause it to re-attempt inserts of existing records after a restart. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how ongoing replication handles target table state after full load—a common trap is thinking you need to truncate or disable constraints, but those break data integrity or lose migrated data. Remember the memory tip: "Batch to avoid the clash, kill recovery to stop the rehash."
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 using AWS DMS to migrate a 2 TB Oracle database to Amazon Aurora PostgreSQL. The migration is running in full load mode with ongoing replication. After the full load completes, the ongoing replication task shows a 'TargetMetadata' error: 'ERROR: duplicate key value violates unique constraint'. The engineer verifies that the target table already contains the data. What should the engineer do to resolve this issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable 'BatchApplyEnabled' and set 'TaskRecoveryTableEnabled' to false in the task settings.
Option C is correct because the error indicates that the task is trying to insert rows that already exist. Enabling 'BatchApplyEnabled' and setting 'TaskRecoveryTableEnabled' to false prevents duplicate handling errors during replication. Option A is wrong because truncating would lose data. Option B is wrong because disabling constraints may cause data integrity issues. Option D is wrong because dropping indexes does not prevent duplicate key violations.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Enable 'BatchApplyEnabled' and set 'TaskRecoveryTableEnabled' to false in the task settings.
Why this is correct
Batch apply minimizes duplicate key errors, and disabling recovery table prevents re-application of already-applied changes.
Related concept
Standard ACLs match source addresses.
✗
Disable the unique constraint on the target table.
Why it's wrong here
Disabling constraints compromises data integrity.
✗
Truncate the target table and restart the full load.
Why it's wrong here
Truncating would lose data and require a full reload, which is disruptive.
✗
Drop the indexes on the target table and recreate them after the migration.
Why it's wrong here
Indexes are not the cause of duplicate key violations; constraints are.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Data Operations and Support — This question tests Data Operations and Support — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Enable 'BatchApplyEnabled' and set 'TaskRecoveryTableEnabled' to false in the task settings. — Option C is correct because the error indicates that the task is trying to insert rows that already exist. Enabling 'BatchApplyEnabled' and setting 'TaskRecoveryTableEnabled' to false prevents duplicate handling errors during replication. Option A is wrong because truncating would lose data. Option B is wrong because disabling constraints may cause data integrity issues. Option D is wrong because dropping indexes does not prevent duplicate key violations.
What should I do if I get this DEA-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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