- A
AlloyDB
AlloyDB combines high-speed OLTP with built-in columnar analytics, ideal for hybrid HTAP.
- B
BigQuery
Why wrong: BigQuery is an analytics data warehouse, not designed for real-time transactional reads.
- C
Cloud Bigtable
Why wrong: Bigtable is NoSQL and does not support SQL analytics.
- D
Cloud Spanner
Why wrong: Spanner provides strong consistency but typical latencies are in milliseconds, not sub-millisecond.
Question 868 of 980
Design Scalable and Highly Available Cloud Database Solutions →mediumMultiple ChoiceObjective-mapped
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 financial services firm needs a database for real-time fraud detection. The workload requires sub-millisecond read latency on transactions and the ability to run complex SQL analytics on the same data. Which 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
✓
AlloyDB
AlloyDB is correct because it combines PostgreSQL-compatible SQL analytics with sub-millisecond read latency for transactional workloads, using a columnar engine for analytical queries and a memory-optimized row store for real-time transactions. This dual-engine architecture allows the same data to serve both OLTP and OLAP requirements without data movement or latency trade-offs.
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.
- ✓
AlloyDB
Why this is correct
AlloyDB combines high-speed OLTP with built-in columnar analytics, ideal for hybrid HTAP.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
BigQuery
Why it's wrong here
BigQuery is an analytics data warehouse, not designed for real-time transactional reads.
- ✗
Cloud Bigtable
Why it's wrong here
Bigtable is NoSQL and does not support SQL analytics.
- ✗
Cloud Spanner
Why it's wrong here
Spanner provides strong consistency but typical latencies are in milliseconds, not sub-millisecond.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a single database cannot serve both real-time transactions and complex analytics, leading candidates to choose BigQuery for analytics or Cloud Spanner for transactions, without recognizing AlloyDB's hybrid transactional/analytical processing (HTAP) capability.
Detailed technical explanation
How to think about this question
AlloyDB achieves sub-millisecond reads by using a log-structured merge-tree (LSM) with a memory-resident buffer and adaptive indexing, while its columnar engine offloads analytical queries to a separate set of nodes that access the same underlying storage via a shared-vault architecture. This design avoids the traditional trade-off between transactional and analytical workloads, enabling real-time fraud detection that requires both immediate lookups and complex pattern analysis on streaming data.
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
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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: AlloyDB — AlloyDB is correct because it combines PostgreSQL-compatible SQL analytics with sub-millisecond read latency for transactional workloads, using a columnar engine for analytical queries and a memory-optimized row store for real-time transactions. This dual-engine architecture allows the same data to serve both OLTP and OLAP requirements without data movement or latency trade-offs.
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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