PDE Storing the Data Practice Question
A team wants to store semi-structured user profile data for a web application. The data is accessed via a REST API and requires security rules to control read/write access. Which database fits best?
⚠ Common exam trap
Google often tests the distinction between NoSQL databases optimized for different workloads (document vs. wide-column vs. analytical), and the trap here is assuming any NoSQL database (like Cloud Bigtable) is suitable for semi-structured user profiles without considering the need for built-in security rules and REST API integration.
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 that natively stores semi-structured data (JSON-like documents) and integrates directly with Firebase Authentication and security rules to control read/write access per document or collection. Its REST API support and real-time capabilities make it ideal for web application user profiles that require flexible schemas and fine-grained access control.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
BigQuery
Why it's wrong here
BigQuery is a serverless analytics warehouse for SQL querying over large datasets, not a transactional store for application profile documents behind a REST API. It is tempting because it handles semi-structured data, but Firestore's document model and security rules satisfy the read/write access requirement.
- ✓
Firestore
Why this is correct
Firestore stores semi-structured documents and enforces security rules directly at the database layer, satisfying the read/write access constraint without a separate authorisation tier. Its native REST API and real-time synchronisation suit web profile data, unlike relational engines requiring schema migrations or blob stores lacking granular rule enforcement.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL is a managed relational engine requiring fixed schemas and SQL DDL, which does not fit semi-structured profile documents accessed through a REST API. It is tempting because it offers strong access control, but Firestore's document model and security rules match the requirement directly.
- ✗
Cloud Bigtable
Why it's wrong here
Cloud Bigtable is a wide-column NoSQL store for high-throughput analytical and time-series workloads, and it lacks native per-document security rules for REST-accessed profile data. It is tempting because it is schemaless, but Firestore provides the document model and rule-based access control required.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.