- A
Migrate to a NoSQL database like Firestore for better read performance.
Why wrong: Migrating to a different database is a significant architecture change, not a schema design change within Cloud SQL.
- B
Create a materialized view that joins users and posts, refreshed periodically.
Why wrong: Materialized views reduce join cost but require refreshing and add complexity; they are not a schema design change but a query optimization.
- C
Add GIN indexes on the posts table for faster full-text search.
Why wrong: GIN indexes are for full-text search and do not help with join performance.
- D
Denormalize by embedding commonly accessed user fields (e.g., username, avatar URL) into the posts table.
Denormalization reduces joins, improving read performance for read-heavy workloads.
Quick Answer
The answer is to denormalize by embedding commonly accessed user fields like username and avatar URL directly into the posts table. This is correct because denormalization for read performance in Cloud SQL eliminates expensive JOIN operations between the users and posts tables, allowing the database to serve timeline queries from a single table scan, which drastically reduces latency under heavy read volume. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of when to trade normalization for performance in relational databases, often appearing as a trap where candidates overcomplicate solutions with materialized views or NoSQL migrations—remember that Cloud SQL for PostgreSQL supports denormalization natively without changing the application logic. A key memory tip is "JOINs are slow, denormalize for show"—meaning if your read workload is heavy and the data is mostly static (like usernames), store it where it’s queried.
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 social media platform uses Cloud SQL for PostgreSQL for its user and post data. The schema has a normalized design with separate 'users' and 'posts' tables. Queries that fetch a user's timeline (joining users and posts) are slow due to heavy read volume. The team wants to optimize the schema for this read-heavy workload without changing the application logic significantly. What schema design change is most appropriate?
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
Denormalize by embedding commonly accessed user fields (e.g., username, avatar URL) into the posts table.
Option D is correct because denormalizing by storing relevant user data (e.g., username, avatar) directly in the posts table reduces the need for JOINs, significantly improving read performance. Option A (materialized view) could help but may introduce staleness and overhead; Option B (NoSQL) is a major architectural change; Option C (GIN indexes) are for full-text search, not join performance.
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.
- ✗
Migrate to a NoSQL database like Firestore for better read performance.
Why it's wrong here
Migrating to a different database is a significant architecture change, not a schema design change within Cloud SQL.
- ✗
Create a materialized view that joins users and posts, refreshed periodically.
Why it's wrong here
Materialized views reduce join cost but require refreshing and add complexity; they are not a schema design change but a query optimization.
- ✗
Add GIN indexes on the posts table for faster full-text search.
Why it's wrong here
GIN indexes are for full-text search and do not help with join performance.
- ✓
Denormalize by embedding commonly accessed user fields (e.g., username, avatar URL) into the posts table.
Why this is correct
Denormalization reduces joins, improving read performance for read-heavy workloads.
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.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which PCDE 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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FAQ
Questions learners often ask
What does this PCDE question test?
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: Denormalize by embedding commonly accessed user fields (e.g., username, avatar URL) into the posts table. — Option D is correct because denormalizing by storing relevant user data (e.g., username, avatar) directly in the posts table reduces the need for JOINs, significantly improving read performance. Option A (materialized view) could help but may introduce staleness and overhead; Option B (NoSQL) is a major architectural change; Option C (GIN indexes) are for full-text search, not join performance.
What should I do if I get this PCDE question wrong?
Identify which PCDE 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.
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Last reviewed: Jun 24, 2026
This PCDE 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 PCDE exam.
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