PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 plans to migrate an on-premises PostgreSQL database to Cloud SQL. The database is 2 TB in size and requires minimal downtime. Which migration approach should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Database Migration Service with a continuous migration job.
Database Migration Service (DMS) with a continuous migration job is the correct approach because it supports minimal-downtime migrations from on-premises PostgreSQL to Cloud SQL. DMS uses logical replication (via PostgreSQL's pgoutput plugin) to continuously sync changes from the source to the target, allowing a short cutover window. For a 2 TB database, this avoids the lengthy downtime required by a full dump-and-load method.
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.
✗
Export the database using pg_dump and import into Cloud SQL using psql.
Why it's wrong here
This approach causes significant downtime and is not minimal for a 2 TB database.
✗
Use Datastream to stream data into Cloud SQL.
Why it's wrong here
Datastream is designed for change data capture and real-time streaming, not bulk initial load of existing data.
✓
Use Database Migration Service with a continuous migration job.
Why this is correct
Database Migration Service supports virtually zero-downtime migrations through continuous replication.
Related concept
Read the scenario before looking for a memorised answer.
✗
Copy the data files to Cloud Storage and use gcloud to load into Bigtable.
Why it's wrong here
Bigtable is a NoSQL database; PostgreSQL is relational, so this is not a valid migration path.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose pg_dump (Option A) because it is familiar and works for smaller databases, but they overlook the minimal-downtime requirement and the impracticality of exporting 2 TB without significant service interruption.
Detailed technical explanation
How to think about this question
Database Migration Service uses PostgreSQL's native logical replication slots and the pgoutput plugin to capture changes at the transaction level, ensuring consistency without locking the source database for extended periods. During the continuous migration phase, DMS applies incremental changes to the Cloud SQL replica, and the cutover involves stopping writes on the source and promoting the replica, typically completing in under a minute. This approach is ideal for large databases (e.g., 2 TB) where minimizing downtime is critical, as it avoids the full table scan and rebuild required by pg_dump.
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.
TExam Day Tips
→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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Database Migration Service with a continuous migration job. — Database Migration Service (DMS) with a continuous migration job is the correct approach because it supports minimal-downtime migrations from on-premises PostgreSQL to Cloud SQL. DMS uses logical replication (via PostgreSQL's pgoutput plugin) to continuously sync changes from the source to the target, allowing a short cutover window. For a 2 TB database, this avoids the lengthy downtime required by a full dump-and-load method.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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