mediumMultiple SelectObjective-mapped
PCD Practice Question: A financial services company uses BigQuery for…
A financial services company uses BigQuery for analytics but needs to store transactional data with strong consistency and sub-millisecond latency. They are considering Cloud SQL, Cloud Spanner, Bigtable, Memorystore, and Firestore. Which service meets all requirements?
⚠ Common exam trap
A common misconception is that Cloud SQL can meet sub-millisecond latency at scale, but candidates forget that Cloud SQL is limited by single-region deployment and cannot horizontally scale writes, making it unsuitable for high-throughput transactional systems.
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 service that provides both strong consistency and sub-millisecond latency for transactional workloads. It uses TrueTime for global strong consistency and supports ACID transactions with low latency. Cloud SQL offers strong consistency but cannot achieve sub-millisecond latency at scale due to single-region limits. Bigtable provides low latency but only eventual consistency. Memorystore is a caching layer, not a transactional database. Firestore provides strong consistency but typically does not guarantee sub-millisecond latency for high-throughput transactional data, especially under financial workload requirements.
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
Cloud Spanner meets both strong consistency and sub-millisecond latency for transactional data, making it ideal for financial systems.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL provides strong consistency but its latency is typically above sub-millisecond, especially under high throughput or cross-region scenarios.
- ✗
Bigtable
Why it's wrong here
Bigtable offers low latency but only eventual consistency, which does not satisfy the strong consistency requirement.
- ✗
Memorystore
Why it's wrong here
Memorystore is an in-memory cache and not a transactional database; it does not provide strong consistency or durability for transactional data.
- ✗
Firestore
Why it's wrong here
Firestore provides strong consistency but its latency is not guaranteed to be sub-millisecond for high-throughput transactional workloads, and it is not designed for financial transactional systems requiring such strict latency.
Go deeper
Related to this question
About these practice questions
Courseiva writes every PCD question from scratch — 964 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.