Question 162 of 1,446
Cloud Spanner Multi-Region Configuration for Global Write Scaling
A retail company uses Cloud Spanner to handle global transaction processing. The database has a single regional instance in us-central1. The company expects a 10x increase in write traffic from a new mobile app. The database engineer needs to design for low latency writes globally and high availability. What should the Database Engineer do?
Quick Answer
The correct choice is to change the instance configuration to a multi-region configuration like nam3 (us-central1, us-east1, us-west1) and configure a dedicated write region. This works because Cloud Spanner’s multi-region configurations use synchronous replication within the write region for strong consistency and fast local writes, while asynchronously replicating to other regions for global read availability—enabling global write scaling without sacrificing low latency. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of how to scale write capacity across geographies; a common trap is choosing a single-region upgrade or a read-only replica, which cannot handle the 10x write increase globally. Remember the key distinction: multi-region configurations are for write scaling and availability, not just read distribution. A useful memory tip is “write where you commit, read where you sit”—the dedicated write region handles all commits, so place it near your primary user base.
⚠ Common exam trap
Watch out — candidates often confuse scaling nodes (Option D) with geographic distribution, or assume read replicas (Option B) can handle write scaling, when in fact Cloud Spanner requires a multi-region configuration to achieve both global write low latency and high availability.
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
✓
Change the instance configuration to a multi-region configuration like nam3 (us-central1, us-east1, us-west1) and configure a dedicated write region.
A multi-region configuration like nam3 (us-central1, us-east1, us-west1) with a dedicated write region provides low-latency writes globally by using Google's managed replication and automatic failover. This design ensures high availability and meets the 10x write traffic increase without sacrificing write performance, as writes are processed in the designated write region and asynchronously replicated to other regions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Shard the database across multiple regional instances based on user geography.
Why it's wrong here
Sharding across instances complicates schema and transactions, and Spanner multi-region is the recommended approach.
- ✗
Create read replicas in other regions to offload read traffic and keep writes in the primary region.
Why it's wrong here
Read replicas do not help with write latency or write capacity.
- ✓
Change the instance configuration to a multi-region configuration like nam3 (us-central1, us-east1, us-west1) and configure a dedicated write region.
Why this is correct
Multi-region configurations provide low-latency writes by placing processing close to users and ensure high availability.
- ✗
Increase the number of nodes in the existing regional instance to handle the increased write capacity.
Why it's wrong here
This only scales within one region; write latency from other regions will still be high.
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Same concept, more angles
1 more way this is tested on PCDE
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A global gaming company uses Cloud Spanner for user profiles and game state. They have a single-region instance in us-central1. Recently, they launched in Europe and notice high latency for European users. They also need to ensure data locality compliance (GDPR). The database is heavily written with throughput spikes. They want to minimize latency without sacrificing write throughput. They consider adding a secondary index on region column. What is the best course of action?
hard- A.Shard the database by region into separate Spanner instances.
- B.Use Cloud CDN to cache read data.
- C.Create a read-only replica in Europe using Cloud Spanner's read replica feature.
- ✓ D.Create a multi-region configuration spanning US and Europe, and modify application to read from closest region.
Why D: A multi-region Cloud Spanner configuration with regional endpoints allows the application to read from the closest region, reducing latency for European users while maintaining strong consistency and write throughput. Spanner's multi-region configurations use synchronous replication across all regions, ensuring GDPR compliance by keeping European user data within Europe for reads. Write throughput is not sacrificed because Spanner's architecture is designed for high scalability and uses synchronous replication efficiently.
Last reviewed: Jun 11, 2026
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