This PCDE practice question tests your understanding of plan and manage database infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Your company is deploying a new application on Google Cloud and needs to choose a database solution. The application requires strong transactional consistency, complex SQL queries, and the ability to scale horizontally for read-heavy workloads. Which database service should you recommend?
Cloud Spanner
Cloud Spanner offers strong consistency, SQL, and horizontal scaling.
BigQuery
Why wrong: BigQuery is for analytical workloads, not transactional applications.
Cloud SQL
Why wrong: Cloud SQL does not support horizontal scaling for read-heavy workloads.
Cloud Firestore
Why wrong: Firestore is a NoSQL database and does not support complex SQL queries.
Answer choices
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 provides strong transactional consistency (ACID) across globally distributed nodes, supports complex SQL queries with standard SQL syntax, and offers horizontal scaling for read-heavy workloads through automatic sharding and read replicas. Unlike other options, Spanner uniquely combines these three requirements—strong consistency, SQL, and horizontal scaling—in a single managed service.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Cloud Spanner
Why this is correct
Cloud Spanner offers strong consistency, SQL, and horizontal scaling.
Related concept
Read the scenario before looking for a memorised answer.
BigQuery
Why it's wrong here
BigQuery is for analytical workloads, not transactional applications.
Cloud SQL
Why it's wrong here
Cloud SQL does not support horizontal scaling for read-heavy workloads.
Cloud Firestore
Why it's wrong here
Firestore is a NoSQL database and does not support complex SQL queries.
Common exam traps
Google Cloud often tests the misconception that Cloud SQL can scale horizontally for read-heavy workloads, but Cloud SQL's read replicas are limited and do not provide true horizontal scaling or strong consistency across replicas, unlike Spanner's built-in distributed architecture.
Detailed technical explanation
Cloud Spanner uses TrueTime, a globally synchronized clock based on GPS and atomic clocks, to enforce external consistency across distributed transactions, ensuring that all reads see a consistent snapshot of data. Under the hood, Spanner automatically partitions data into splits and uses Paxos-based replication to achieve horizontal scaling while maintaining ACID properties, making it ideal for applications like global financial systems or inventory management that require both strong consistency and high read throughput.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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FAQ
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Cloud Spanner — Cloud Spanner is the correct choice because it provides strong transactional consistency (ACID) across globally distributed nodes, supports complex SQL queries with standard SQL syntax, and offers horizontal scaling for read-heavy workloads through automatic sharding and read replicas. Unlike other options, Spanner uniquely combines these three requirements—strong consistency, SQL, and horizontal scaling—in a single managed service.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCDE 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 PCDE exam.
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