Google PCA Design and plan a cloud solution architecture Practice Question
A multinational e-commerce company needs a globally distributed database that provides strong consistency and transactional support for order processing. Which Google Cloud database service should they use?
⚠ Common exam trap
A common mix-up: candidates confuse Cloud Spanner with Cloud SQL, assuming that a traditional relational database like Cloud SQL can be scaled globally by adding replicas, but they miss that Cloud SQL replicas are read-only and cannot provide the strong consistency and write scalability needed for a globally distributed transactional system.
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
✓
Cloud Spanner
Cloud Spanner is the correct choice because it is a globally distributed, horizontally scalable relational database service that provides strong consistency and full ACID transactional support across regions. Unlike other Google Cloud databases, Spanner uses synchronous replication and the TrueTime API to guarantee external consistency, making it ideal for order processing systems that require both global scale and transactional integrity.
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 SQL
Why it's wrong here
Cloud SQL is regional, so it cannot serve a globally distributed workload with strong consistency across continents. It is tempting because it offers full transactional ACID support on PostgreSQL, MySQL, or SQL Server, making it correct for single-region transactional applications, not the global distribution this scenario demands.
- ✓
Cloud Spanner
Why this is correct
Cloud Spanner satisfies both constraints simultaneously: global distribution and strong consistency with ACID transactions. Its TrueTime-based synchronisation delivers external consistency across regions, unlike Cloud SQL (regional) or Firestore, which offers strong consistency only within limited configurations.
- ✗
Cloud Bigtable
Why it's wrong here
Cloud Bigtable delivers high-throughput, low-latency access for analytical workloads but provides no multi-row ACID transactions or strong cross-region consistency. It is tempting because it scales globally and handles massive time-series and IoT data, making it correct for analytics rather than order processing requiring transactional integrity.
- ✗
Cloud Firestore
Why it's wrong here
Cloud Firestore provides strong consistency within a single region but multi-region replication is eventually consistent, failing the global strong-consistency requirement. It is tempting because it offers ACID transactions and global distribution, making it suitable for mobile and web apps where eventual consistency across regions is acceptable.
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Key term
Cloud Spanner
Cloud Spanner is a fully managed, globally distributed relational database service from Google Cloud that combines the benefits of relational database structure with horizontal scalability and strong consistency.
Key term
Relational database
A relational database organizes data into tables with rows and columns, where each table relates to others using unique keys, allowing efficient storage, retrieval, and manipulation of structured information.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.