- A
Bigtable
Why wrong: Bigtable does not support ACID transactions across regions.
- B
Cloud SQL
Why wrong: Cloud SQL has 99.95% SLA for HA and is regional, not global.
- C
Firestore
Why wrong: Firestore offers strong consistency but not 99.999% SLA.
- D
Cloud Spanner
Spanner meets all requirements: 99.999% SLA, global, ACID.
Question 424 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.
You need a database that provides 99.999% availability SLA, global distribution, and supports ACID transactions across regions. Which Google Cloud database meets these requirements?
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 only Google Cloud database that provides 99.999% availability SLA, global distribution via automatic synchronous replication across regions, and full ACID transactions across regions using TrueTime and Paxos-based consensus. It combines horizontal scalability with strong consistency, making it ideal for globally distributed applications requiring transactional integrity.
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.
- ✗
Bigtable
Why it's wrong here
Bigtable does not support ACID transactions across regions.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL has 99.95% SLA for HA and is regional, not global.
- ✗
Firestore
Why it's wrong here
Firestore offers strong consistency but not 99.999% SLA.
- ✓
Cloud Spanner
Why this is correct
Spanner meets all requirements: 99.999% SLA, global, ACID.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Firestore's multi-region mode with true global ACID transactions, but Firestore only offers strong consistency within a single region and eventual consistency across regions, while Cloud Spanner is the only service that guarantees ACID across regions with a 99.999% SLA.
Detailed technical explanation
How to think about this question
Cloud Spanner achieves global ACID transactions through TrueTime, a globally synchronized clock that assigns commit timestamps with bounded uncertainty, and the Paxos protocol for synchronous replication across zones. This allows Spanner to provide external consistency (the strongest form of consistency) even across continents, which is critical for applications like financial trading or inventory management that require accurate, globally ordered transactions.
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 only Google Cloud database that provides 99.999% availability SLA, global distribution via automatic synchronous replication across regions, and full ACID transactions across regions using TrueTime and Paxos-based consensus. It combines horizontal scalability with strong consistency, making it ideal for globally distributed applications requiring transactional integrity.
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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