- A
Implement a saga pattern
Why wrong: Saga pattern is for distributed transactions, not caching.
- B
Use a two-phase commit between Spanner and Memorystore
Why wrong: Two-phase commit would introduce latency and defeats the purpose of caching.
- C
Implement a cache-aside pattern with TTL
Cache-aside with TTL is a standard pattern for maintaining eventual consistency.
- D
Use Spanner change streams to invalidate cache entries via Pub/Sub
Why wrong: While possible, this adds complexity. Cache-aside is simpler and more appropriate.
Question 672 of 980
PCD Practice Question: Manage a Solution that Can Span Multiple Database Systems
This PCD practice question tests your understanding of manage a solution that can span multiple database systems. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 uses Memorystore for Redis as a cache in front of Cloud Spanner. They want to ensure cache updates happen asynchronously when Spanner data changes. Which pattern is most appropriate?
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
✓
Implement a cache-aside pattern with TTL
The cache-aside pattern involves the application checking the cache first, and if not found, loading from the database and updating the cache. Eventual consistency is acceptable for cache. The saga pattern is for distributed transactions, not caching.
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.
- ✗
Implement a saga pattern
Why it's wrong here
Saga pattern is for distributed transactions, not caching.
- ✗
Use a two-phase commit between Spanner and Memorystore
Why it's wrong here
Two-phase commit would introduce latency and defeats the purpose of caching.
- ✓
Implement a cache-aside pattern with TTL
Why this is correct
Cache-aside with TTL is a standard pattern for maintaining eventual consistency.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use Spanner change streams to invalidate cache entries via Pub/Sub
Why it's wrong here
While possible, this adds complexity. Cache-aside is simpler and more appropriate.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Manage a Solution that Can Span Multiple Database Systems — study guide chapter
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FAQ
Questions learners often ask
What does this PCD question test?
Manage a Solution that Can Span Multiple Database Systems — This question tests Manage a Solution that Can Span Multiple Database Systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a cache-aside pattern with TTL — The cache-aside pattern involves the application checking the cache first, and if not found, loading from the database and updating the cache. Eventual consistency is acceptable for cache. The saga pattern is for distributed transactions, not caching.
What should I do if I get this PCD question wrong?
Identify which PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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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