The answer is to keep the existing foreign keys and triggers as-is in Cloud SQL for PostgreSQL. This is the correct approach because Cloud SQL for PostgreSQL is a fully managed, native PostgreSQL engine, meaning foreign key constraints and triggers operate identically to an on-premises PostgreSQL instance, preserving all referential integrity and data validation logic without any schema rewrites. On the Google Professional Cloud Database Engineer exam, this question tests your understanding that Cloud SQL is not a fork or a stripped-down version—it provides full PostgreSQL compatibility, so the common trap is assuming you must simplify or remove database objects for the cloud. Instead, the key insight is that minimizing migration effort means leveraging this compatibility to keep foreign keys and triggers exactly as they are. Memory tip: think “Cloud SQL = Same SQL” for constraints and triggers.
PCDE Design and implement database schemas Practice Question
This PCDE practice question tests your understanding of design and implement database schemas. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 database to Cloud SQL for PostgreSQL. The existing schema uses a large number of foreign key constraints and triggers for data validation. The team wants to minimize migration effort and maintain data integrity. Which schema design approach is most appropriate for Cloud SQL?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Keep the existing foreign keys and triggers as-is in Cloud SQL for PostgreSQL
Option A is correct because Cloud SQL for PostgreSQL is fully compatible with the PostgreSQL engine, meaning foreign key constraints and triggers operate identically to on-premises PostgreSQL. This approach minimizes migration effort by preserving the existing schema logic and maintaining referential integrity without requiring application changes or data validation rewrites.
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.
✓
Keep the existing foreign keys and triggers as-is in Cloud SQL for PostgreSQL
Why this is correct
Cloud SQL supports these features, minimizing migration effort.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Migrate to Cloud Spanner and use interleaved tables to simulate foreign keys
Why it's wrong here
Cloud Spanner does not support triggers and interleaved tables are not a direct replacement.
✗
Remove all foreign keys and triggers and implement validation in the application layer
Why it's wrong here
Increases application complexity and risk of data inconsistency.
✗
Convert the schema to use Firestore in Datastore mode with composite indexes
Why it's wrong here
Firestore is NoSQL and does not support foreign keys or triggers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume managed cloud databases require schema simplification or NoSQL conversion, but Cloud SQL for PostgreSQL is a direct lift-and-shift target that preserves all relational features like foreign keys and triggers.
Detailed technical explanation
How to think about this question
Cloud SQL for PostgreSQL runs a managed version of the standard PostgreSQL engine, so foreign key constraints are enforced via the same internal mechanism (e.g., triggers on parent tables for referential actions like CASCADE). Triggers in PostgreSQL are stored procedures executed on table events, and Cloud SQL supports all trigger types (BEFORE, AFTER, INSTEAD OF) without modification, making the migration a straightforward dump-and-restore process using pg_dump and pg_restore.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design and implement database schemas — This question tests Design and implement database schemas — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Keep the existing foreign keys and triggers as-is in Cloud SQL for PostgreSQL — Option A is correct because Cloud SQL for PostgreSQL is fully compatible with the PostgreSQL engine, meaning foreign key constraints and triggers operate identically to on-premises PostgreSQL. This approach minimizes migration effort by preserving the existing schema logic and maintaining referential integrity without requiring application changes or data validation rewrites.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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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