- A
The source database is not configured for logical replication (e.g., wal_level is not logical).
Logical replication requires wal_level=logical.
- B
Insufficient disk space on the source for WAL files.
CDC generates WAL; if disk fills, replication can stall.
- C
Cloud SQL Auth Proxy is not installed on the source.
Why wrong: Auth Proxy is used for client connections, not DMS replication; DMS uses private IP or peering.
- D
The replication slot is exhausted or not created.
pglogical requires a replication slot; if it's full or missing, replication fails.
- E
The source database is MySQL.
Why wrong: The scenario specifies PostgreSQL; MySQL would be irrelevant.
Question 786 of 1,000
PCDOE Migrate Database Solutions Practice Question
This PCDOE practice question tests your understanding of migrate database solutions. 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 company is migrating an on-premises PostgreSQL database to Cloud SQL using Database Migration Service with continuous replication. The source database has binary logging enabled and uses the pglogical plugin. The migration job is failing after the full dump phase. Which THREE common issues should the engineer check? (Choose 3 correct answers.)
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 is not configured for logical replication (e.g., wal_level is not logical).
For PostgreSQL CDC migration, DMS uses pglogical. Common issues include: logical replication slot not created or exhausted, insufficient disk space for WAL files, and network connectivity issues (e.g., firewall blocking replication port 5432). Cloud SQL Auth Proxy is not needed for DMS to Cloud SQL connectivity if using private IP/peering. Source database must be PostgreSQL, not MySQL.
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 database is not configured for logical replication (e.g., wal_level is not logical).
Why this is correct
Logical replication requires wal_level=logical.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Insufficient disk space on the source for WAL files.
Why this is correct
CDC generates WAL; if disk fills, replication can stall.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Cloud SQL Auth Proxy is not installed on the source.
Why it's wrong here
Auth Proxy is used for client connections, not DMS replication; DMS uses private IP or peering.
- ✓
The replication slot is exhausted or not created.
Why this is correct
pglogical requires a replication slot; if it's full or missing, replication fails.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The source database is MySQL.
Why it's wrong here
The scenario specifies PostgreSQL; MySQL would be irrelevant.
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
Scenario analysis trap
The scenario specifies PostgreSQL; MySQL would be irrelevant.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 is not configured for logical replication (e.g., wal_level is not logical). — For PostgreSQL CDC migration, DMS uses pglogical. Common issues include: logical replication slot not created or exhausted, insufficient disk space for WAL files, and network connectivity issues (e.g., firewall blocking replication port 5432). Cloud SQL Auth Proxy is not needed for DMS to Cloud SQL connectivity if using private IP/peering. Source database must be PostgreSQL, not MySQL.
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.
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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