- A
Firestore
Firestore handles high concurrency for user profiles.
- B
Cloud SQL
Cloud SQL supports complex queries for the product catalog.
- C
Cloud Bigtable
Why wrong: Bigtable is not ideal for user profiles or product catalog; it's for time-series.
- D
Memorystore (Redis)
Memorystore provides low-latency access for session data.
- E
Cloud Spanner
Why wrong: Spanner is for globally distributed transactions; not needed here.
Question 109 of 1,000
PCDOE Firestore Practice Question
This PCDOE practice question tests your understanding of design and plan database solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: firestore. 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 a monolithic application to a microservices architecture and plans to use multiple Google Cloud databases. The application has the following workloads: (1) user profiles with high read/write concurrency, (2) product catalog with complex queries, (3) session data that requires low-latency access. Which three Google Cloud databases should be used? (Choose three.)
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
✓
Firestore
Cloud SQL is correct for the product catalog with complex queries because it is a fully managed relational database that supports standard SQL, enabling complex joins and aggregations. Firestore is correct for user profiles with high read/write concurrency because it is a NoSQL document database that scales horizontally and provides strong consistency. Memorystore (Redis) is correct for session data requiring low-latency access because it is an in-memory cache delivering sub-millisecond response times. Cloud Bigtable is designed for high-throughput time-series or key-value data, not complex queries, and Cloud Spanner is more suited for globally distributed transactional workloads.
Key principle: Firestore
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Firestore
Why this is correct
Firestore handles high concurrency for user profiles.
Related concept
Firestore
- ✓
Cloud SQL
Why this is correct
Cloud SQL supports complex queries for the product catalog.
Related concept
Firestore
- ✗
Cloud Bigtable
Why it's wrong here
Bigtable is not ideal for user profiles or product catalog; it's for time-series.
- ✓
Memorystore (Redis)
Why this is correct
Memorystore provides low-latency access for session data.
Related concept
Firestore
- ✗
Cloud Spanner
Why it's wrong here
Spanner is for globally distributed transactions; not needed here.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google often tests the misconception that Cloud Bigtable can handle both high concurrency and complex queries, but it is optimized for wide-column storage and simple key-based lookups, not relational queries or low-latency session caching.
Detailed technical explanation
How to think about this question
Firestore uses a distributed consensus protocol (based on Paxos) to ensure strong consistency across regions, while its real-time listeners leverage WebSockets for instant updates. Cloud SQL for the product catalog supports complex queries via full SQL syntax, including JOINs and aggregations, which is not possible in NoSQL databases like Firestore or Bigtable. Memorystore (Redis) stores session data entirely in RAM, achieving sub-millisecond latency by avoiding disk I/O, and supports key expiration for automatic session cleanup.
KKey Concepts to Remember
- Firestore
- Cloud SQL
- Memorystore (Redis)
- Database selection
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
Firestore
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.
Review firestore, then practise related PCDOE questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Design and Plan Database Solutions — This question tests Design and Plan Database Solutions — Firestore.
What is the correct answer to this question?
The correct answer is: Firestore — Cloud SQL is correct for the product catalog with complex queries because it is a fully managed relational database that supports standard SQL, enabling complex joins and aggregations. Firestore is correct for user profiles with high read/write concurrency because it is a NoSQL document database that scales horizontally and provides strong consistency. Memorystore (Redis) is correct for session data requiring low-latency access because it is an in-memory cache delivering sub-millisecond response times. Cloud Bigtable is designed for high-throughput time-series or key-value data, not complex queries, and Cloud Spanner is more suited for globally distributed transactional workloads.
What should I do if I get this PCDOE question wrong?
Review firestore, then practise related PCDOE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Firestore
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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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