The answer is Cloud Spanner. This is the correct choice because it is the only Google Cloud database service that delivers globally distributed, strongly consistent SQL transactions while scaling horizontally to handle thousands of writes per second, using synchronous replication across regions and TrueTime-based clock synchronization to guarantee external consistency. On the Google Associate Cloud Engineer exam, this question tests your ability to distinguish between Cloud Spanner and other database services like Cloud SQL or Bigtable; a common trap is choosing Cloud SQL for global distribution, but Cloud SQL is regional and cannot provide strong consistency across continents. Remember the memory tip: "Spanner spans the globe with strong consistency," linking its name to its global span and the "S" in Spanner to "strongly consistent" SQL.
Google ACE Planning and configuring a cloud solution Practice Question
This ACE practice question tests your understanding of planning and configuring a cloud solution. 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 financial trading platform must support globally distributed, strongly consistent SQL transactions at thousands of writes per second, with no downtime for planned maintenance. Which GCP database service meets all these requirements?
Why wrong: Cloud SQL scales reads with replicas but doesn't scale writes horizontally — it's limited to vertical scaling for write throughput.
B
Cloud Bigtable
Why wrong: Bigtable offers massive scalability for analytics workloads but doesn't support SQL or full ACID transactions required by a financial trading platform.
C
Cloud Firestore
Why wrong: Cloud Firestore provides strong consistency for document operations but doesn't support SQL queries or the write throughput of a high-frequency trading platform.
D
Cloud Spanner
Cloud Spanner uniquely combines externally consistent ACID transactions, horizontal write scalability, SQL support, and a 99.999% SLA — all required for financial trading platforms.
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 GCP database service that provides globally distributed, strongly consistent SQL transactions with horizontal scaling, supporting thousands of writes per second. It uses synchronous replication across regions and TrueTime-based clock synchronization to ensure external consistency, while also offering 99.999% availability with no planned downtime for maintenance.
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 SQL with synchronous read replicas
Why it's wrong here
Cloud SQL scales reads with replicas but doesn't scale writes horizontally — it's limited to vertical scaling for write throughput.
✗
Cloud Bigtable
Why it's wrong here
Bigtable offers massive scalability for analytics workloads but doesn't support SQL or full ACID transactions required by a financial trading platform.
✗
Cloud Firestore
Why it's wrong here
Cloud Firestore provides strong consistency for document operations but doesn't support SQL queries or the write throughput of a high-frequency trading platform.
✓
Cloud Spanner
Why this is correct
Cloud Spanner uniquely combines externally consistent ACID transactions, horizontal write scalability, SQL support, and a 99.999% SLA — all required for financial trading platforms.
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 Cloud Spanner's global strong consistency with Cloud SQL's regional strong consistency, or mistakenly think that NoSQL services like Bigtable or Firestore can support SQL transactions and global writes at scale.
Detailed technical explanation
How to think about this question
Cloud Spanner achieves global strong consistency using the TrueTime API, which provides globally synchronized clocks with bounded uncertainty, enabling external-consistent transactions without locking overhead. Under the hood, Spanner uses Paxos-based synchronous replication across zones and regions, and its distributed query execution engine allows SQL joins and secondary indexes to work seamlessly across shards. A real-world scenario is a global financial trading platform that must execute atomic, isolated transactions across continents while maintaining ACID compliance and sub-second latency.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this ACE question in full detail.
Planning and configuring a cloud solution — This question tests Planning and configuring a cloud solution — 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 GCP database service that provides globally distributed, strongly consistent SQL transactions with horizontal scaling, supporting thousands of writes per second. It uses synchronous replication across regions and TrueTime-based clock synchronization to ensure external consistency, while also offering 99.999% availability with no planned downtime for maintenance.
What should I do if I get this ACE 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.
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Question Discussion
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