- A
The DMS connection profile uses the wrong public IP.
Why wrong: Connectivity issues would show a different error (e.g., connection timeout).
- B
The source database is in read-only mode.
Why wrong: Read-only does not prevent WAL streaming, but would cause other issues.
- C
The source database does not have the pglogical extension installed.
Why wrong: pglogical is an alternative, but DMS uses built-in logical replication, not pglogical.
- D
The source database parameter wal_level is set to 'replica' instead of 'logical'.
wal_level must be set to 'logical' to enable logical replication slots.
Question 264 of 1,000
PCDOE Migrate Database Solutions Practice Question
This PCDOE practice question tests your understanding of migrate database solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 team is migrating an on-premises PostgreSQL 13 database to AlloyDB using DMS continuous migration. During the CDC phase, the migration job shows an error: 'ERROR: could not start WAL streaming: ERROR: replication slots are not enabled on the source.' The source is running in Google Cloud Compute Engine. 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 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
✓
The source database parameter wal_level is set to 'replica' instead of 'logical'.
DMS continuous migration for PostgreSQL requires logical replication, which uses replication slots. The error indicates that the source database does not have the necessary configuration to support replication slots (wal_level=logical, max_replication_slots > 0).
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 DMS connection profile uses the wrong public IP.
Why it's wrong here
Connectivity issues would show a different error (e.g., connection timeout).
- ✗
The source database is in read-only mode.
Why it's wrong here
Read-only does not prevent WAL streaming, but would cause other issues.
- ✗
The source database does not have the pglogical extension installed.
Why it's wrong here
pglogical is an alternative, but DMS uses built-in logical replication, not pglogical.
- ✓
The source database parameter wal_level is set to 'replica' instead of 'logical'.
Why this is correct
wal_level must be set to 'logical' to enable logical replication slots.
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.
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.
Trap categories for this question
Command / output trap
Connectivity issues would show a different error (e.g., connection timeout).
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which PCDOE 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.
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Migrate Database Solutions — study guide chapter
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FAQ
Questions learners often ask
What does this PCDOE question test?
Migrate Database Solutions — This question tests Migrate Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The source database parameter wal_level is set to 'replica' instead of 'logical'. — DMS continuous migration for PostgreSQL requires logical replication, which uses replication slots. The error indicates that the source database does not have the necessary configuration to support replication slots (wal_level=logical, max_replication_slots > 0).
What should I do if I get this PCDOE question wrong?
Identify which PCDOE 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.
About these practice questions
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Last reviewed: Jul 4, 2026
This PCDOE practice question is part of Courseiva's free Google Cloud 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 PCDOE exam.
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