- A
Configure Pub/Sub Lite to directly connect to Spanner change streams.
Why wrong: Pub/Sub Lite does not have a direct connector to Spanner change streams; Dataflow is needed.
- B
Use a Cloud Function to query the Spanner table every minute and publish changes to Pub/Sub.
Why wrong: Polling is inefficient, not real-time, and can miss changes.
- C
Create a Spanner change stream and use Dataflow to read from the change stream and publish to Pub/Sub.
This is the recommended architecture: Spanner change streams feed into Dataflow, which can write to Pub/Sub.
- D
Enable Cloud SQL change data capture on the Spanner table and push changes to Pub/Sub.
Why wrong: Cloud SQL CDC cannot be used with Spanner; Spanner has its own change streams.
Question 376 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. 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 company uses Cloud Spanner for its global financial application. They want to capture all changes to a Spanner table and stream them to Pub/Sub for downstream processing by a Dataflow pipeline. What is the recommended approach?
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
✓
Create a Spanner change stream and use Dataflow to read from the change stream and publish to Pub/Sub.
Option C is correct because Spanner change streams are the native, built-in mechanism for capturing row-level changes in Cloud Spanner. Dataflow can directly read from a Spanner change stream using the Spanner change streams connector, and then publish the changes to Pub/Sub for downstream processing. This approach is fully managed, scalable, and avoids the latency and consistency issues of polling or external CDC tools.
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.
- ✗
Configure Pub/Sub Lite to directly connect to Spanner change streams.
Why it's wrong here
Pub/Sub Lite does not have a direct connector to Spanner change streams; Dataflow is needed.
- ✗
Use a Cloud Function to query the Spanner table every minute and publish changes to Pub/Sub.
Why it's wrong here
Polling is inefficient, not real-time, and can miss changes.
- ✓
Create a Spanner change stream and use Dataflow to read from the change stream and publish to Pub/Sub.
Why this is correct
This is the recommended architecture: Spanner change streams feed into Dataflow, which can write to Pub/Sub.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Enable Cloud SQL change data capture on the Spanner table and push changes to Pub/Sub.
Why it's wrong here
Cloud SQL CDC cannot be used with Spanner; Spanner has its own change streams.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between native Spanner change streams and external CDC tools; the trap here is assuming that Cloud SQL's CDC feature can be applied to Spanner, or that a simple polling function is sufficient for reliable change capture.
Detailed technical explanation
How to think about this question
Spanner change streams use a transactional commit timestamp-based mechanism to capture mutations, and Dataflow reads them via the SpannerIO connector, which provides exactly-once semantics and handles sharding automatically. The Dataflow pipeline can then write to Pub/Sub with at-least-once delivery, ensuring no data loss even during pipeline restarts. In a real-world scenario, this architecture is critical for global financial applications where low-latency, ordered, and consistent change capture is required for fraud detection or real-time analytics.
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?
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: Create a Spanner change stream and use Dataflow to read from the change stream and publish to Pub/Sub. — Option C is correct because Spanner change streams are the native, built-in mechanism for capturing row-level changes in Cloud Spanner. Dataflow can directly read from a Spanner change stream using the Spanner change streams connector, and then publish the changes to Pub/Sub for downstream processing. This approach is fully managed, scalable, and avoids the latency and consistency issues of polling or external CDC tools.
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
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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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