Cloud Digital Leader Google Cloud Products and Services Practice Question
A startup is building a mobile app and needs to store user profiles and preferences. The data is hierarchical and the app requires real-time synchronization across devices. Which Google Cloud database should they use?
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 document database designed for mobile apps, with real-time sync and offline support. Cloud SQL and Spanner are relational, not ideal for hierarchical data. Bigtable is for time-series/analytics, not mobile app data.
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 Spanner
Why it's wrong here
Cloud Spanner is a horizontally scalable, globally distributed relational database that provides strong consistency and SQL at planet scale. However, for a mobile app user profile store, this capability is overkill because it introduces schema rigidity, requires significant operational overhead, and lacks built-in offline sync or real-time change listeners that client apps expect. The latency and cost of global replication also do not align with simple profile reads and writes.
- ✓
Firestore
Why this is correct
Cloud Firestore is a flexible, serverless NoSQL document database designed specifically for mobile and web clients, with real-time synchronization via listen callbacks and automatic offline data persistence. Its hierarchical data model organizes user profiles naturally as documents within collections, and security rules integrate directly with client SDKs. Unlike global SQL options, Firestore provides built-in multi-device sync and conflict handling, making it the ideal fit for a mobile app storing user profiles.
- ✗
Cloud Bigtable
Why it's wrong here
Cloud Bigtable is a managed, wide-column NoSQL database optimized for high-throughput, low-latency analytical workloads such as time-series data, metrics, and large-scale operational applications. Its data model is a sparse map keyed by row key and column family, and it lacks secondary indexes, rich queries, and row-transaction semantics. Storing user profiles in Bigtable would force denormalized design and complex application code for simple lookups, while also offering no real-time client sync or offline support.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL provides a managed relational database (MySQL or PostgreSQL) with standard SQL and strong ACID transactions, making it a solid choice for traditional OLTP applications. However, for a mobile app's user profile, its fixed schema requires migrations as profile fields evolve, and it has no native offline synchronization or real-time push to clients. While it can be accessed via network protocols, you would need to build custom sync logic and connection pooling, which diverges from mobile-first requirements.
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Cloud Digital Transformation
Key term
SQL
SQL is a standardized programming language used to manage and manipulate relational databases, enabling querying, updating, and data retrieval.
Key term
Firestore
Firestore is a flexible, scalable, serverless NoSQL database from Google Cloud that automatically syncs data across applications in real time.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This GCDL 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 GCDL exam.