- A
Cloud Bigtable
Why wrong: Bigtable is not designed for mobile apps; it lacks offline sync and real-time capabilities.
- B
Cloud Spanner
Why wrong: Cloud Spanner is a globally distributed relational database; it does not provide mobile SDKs or offline sync.
- C
Firestore
Firestore offers real-time listeners, offline persistence, and automatic multi-region replication, ideal for mobile sync.
- D
Cloud SQL
Why wrong: Cloud SQL is relational and does not scale to millions of concurrent users or provide offline sync.
Question 366 of 1,000
PDE Storing the Data Practice Question
This PDE practice question tests your understanding of storing the data. 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 startup is building a mobile app that needs to sync user data across devices in real time. They expect millions of concurrent users and need a NoSQL database with offline support and automatic multi-region replication. Which Google Cloud service meets these requirements?
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
Firestore is a NoSQL, serverless document database that provides real-time synchronization, offline support via local persistence, and automatic multi-region replication. It is designed for mobile and web apps with millions of concurrent users, making it the ideal choice for this use case.
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.
- ✗
Cloud Bigtable
Why it's wrong here
Bigtable is not designed for mobile apps; it lacks offline sync and real-time capabilities.
- ✗
Cloud Spanner
Why it's wrong here
Cloud Spanner is a globally distributed relational database; it does not provide mobile SDKs or offline sync.
- ✓
Firestore
Why this is correct
Firestore offers real-time listeners, offline persistence, and automatic multi-region replication, ideal for mobile sync.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL is relational and does not scale to millions of concurrent users or provide offline sync.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Cloud Spanner's global SQL capabilities with NoSQL requirements, or assume Cloud Bigtable's NoSQL label fits all NoSQL workloads, ignoring the specific need for real-time sync and offline support.
Detailed technical explanation
How to think about this question
Firestore uses a real-time listener protocol based on gRPC streaming to push updates to clients, enabling sub-second synchronization. Its offline persistence layer leverages a local SQLite cache that automatically queues writes when disconnected and replays them upon reconnection, handling conflict resolution via last-write-wins or custom server-side timestamps. Multi-region replication is achieved through Google's global infrastructure, with automatic failover and strong consistency for queries within a region, though cross-region eventual consistency applies for global reads.
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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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.
- →
Storing the Data — study guide chapter
Learn the concepts, then practise the questions
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Storing the Data practice questions
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FAQ
Questions learners often ask
What does this PDE question test?
Storing the Data — This question tests Storing the Data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Firestore — Firestore is a NoSQL, serverless document database that provides real-time synchronization, offline support via local persistence, and automatic multi-region replication. It is designed for mobile and web apps with millions of concurrent users, making it the ideal choice for this use case.
What should I do if I get this PDE 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.
About these practice questions
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Last reviewed: Jul 4, 2026
This PDE 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 PDE exam.
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