- A
Cloud Spanner
Spanner is the only option with global distribution, strong consistency, horizontal scaling, and 99.999% SLA.
- B
Cloud SQL
Why wrong: Cloud SQL is a regional, vertically scalable relational database without global distribution or 99.999% SLA.
- C
Cloud Bigtable
Why wrong: Bigtable is a NoSQL database with eventual consistency and no built-in global distribution.
- D
Firestore
Why wrong: Firestore is a NoSQL document database with multi-region replication but eventual consistency by default.
Question 655 of 980
PCD Practice Question: Design Scalable and Highly Available Cloud Database Solutions
This PCD practice question tests your understanding of design scalable and highly available cloud database solutions. 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.
A company needs a globally distributed, strongly consistent relational database with horizontal scaling and a 99.999% SLA for a financial application. Which Google Cloud database should they choose?
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 provides a globally distributed, strongly consistent relational database with horizontal scaling and a 99.999% SLA. It combines the benefits of relational database structure (ACID transactions and SQL queries) with horizontal scalability across regions, making it ideal for financial applications that require strict consistency and high availability.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Spanner
Why this is correct
Spanner is the only option with global distribution, strong consistency, horizontal scaling, and 99.999% SLA.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL is a regional, vertically scalable relational database without global distribution or 99.999% SLA.
- ✗
Cloud Bigtable
Why it's wrong here
Bigtable is a NoSQL database with eventual consistency and no built-in global distribution.
- ✗
Firestore
Why it's wrong here
Firestore is a NoSQL document database with multi-region replication but eventual consistency by default.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Cloud Spanner's strong consistency with Cloud Bigtable's eventual consistency, or assume Cloud SQL can be horizontally scaled by adding read replicas, but Cloud SQL does not support automatic sharding or global distribution with strong consistency.
Detailed technical explanation
How to think about this question
Cloud Spanner uses TrueTime, a globally synchronized clock service based on GPS and atomic clocks, to enforce external consistency across distributed transactions. This allows Spanner to provide serializable isolation and strong consistency even when data is replicated across continents, which is critical for financial ledgers and audit trails. Under the hood, Spanner automatically handles sharding and replication using Paxos-based consensus, ensuring that reads and writes are consistent without manual partitioning.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCD question test?
Design Scalable and Highly Available Cloud Database Solutions — This question tests Design Scalable and Highly Available Cloud Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cloud Spanner — Cloud Spanner is the correct choice because it provides a globally distributed, strongly consistent relational database with horizontal scaling and a 99.999% SLA. It combines the benefits of relational database structure (ACID transactions and SQL queries) with horizontal scalability across regions, making it ideal for financial applications that require strict consistency and high availability.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
This PCD 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 PCD exam.
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