Google PCA Design and plan a cloud solution architecture Practice Question
A company is migrating on-premises workloads to Google Cloud. They have a critical application that requires consistent low-latency access to a database, with read replicas in multiple regions for disaster recovery. The application is expected to grow by 10x over the next year. Which database service and configuration should the architect choose to meet these requirements?
⚠ Common exam trap
Candidates often confuse Cloud Spanner's multi-region capabilities with simpler replication options like Cloud SQL read replicas or Bigtable's eventual consistency, failing to recognize that only Spanner provides strong global consistency and horizontal scaling for transactional workloads.
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
✓
Use Cloud Spanner with multi-region configuration
Cloud Spanner with a multi-region configuration is the correct choice because it provides strong global consistency, low-latency reads and writes across regions, and automatic horizontal scaling to handle a 10x growth in workload. Its multi-region replication ensures synchronous replication for disaster recovery while maintaining ACID transactions, which is critical for a database requiring consistent low-latency access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Cloud Bigtable with multi-region replication
Why it's wrong here
Bigtable is a wide-column NoSQL store without SQL joins or relational read replicas; its multi-region replication serves key-range scans, not a transactional application database. It tempts for 10x scale, but the stem's low-latency relational access with regional read replicas points to Cloud Spanner.
- ✗
Use Cloud SQL for PostgreSQL with cross-region read replicas
Why it's wrong here
Cloud SQL read replicas are asynchronous, so cross-region replicas can lag and cannot serve consistent low-latency reads at 10x growth; a single primary also caps write scaling. It tempts as the familiar managed PostgreSQL path, but Spanner's synchronous regional replicas meet the consistency requirement.
- ✓
Use Cloud Spanner with multi-region configuration
Why this is correct
Cloud Spanner's multi-region configuration synchronously replicates data across regions using TrueTime, delivering strong consistency with low read latency and automatic failover for disaster recovery. Its horizontally scalable architecture handles 10x growth without manual sharding, satisfying the stem's combined demands for consistent low latency, multi-region replicas and elastic scale.
- ✗
Use Firestore in native mode with multi-region location
Why it's wrong here
Firestore is a document NoSQL database; it lacks relational schemas, joins and SQL, so it cannot host the existing application's relational workload. Its multi-region mode tempts for global low-latency reads, but the stem needs relational consistency, which Cloud Spanner provides.
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Key term
Multi-region
Multi-region refers to a deployment strategy where IT resources, applications, or data are hosted in multiple geographic locations to improve availability, disaster recovery, and performance.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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