The answer is Cloud Pub/Sub and Cloud Pub/Sub Lite. Both services are designed for high throughput messaging, capable of handling millions of messages per second, and integrate natively with Cloud Functions and Dataflow, making them the two correct choices for an event-driven application requiring pub/sub semantics. The key technical distinction is that Cloud Pub/Sub offers a fully managed, serverless architecture with automatic scaling and exactly-once delivery, ideal for unpredictable workloads, while Pub/Sub Lite provides a lower-cost, zonal option with predictable capacity and throughput, suited for steady-state, high-volume streaming. On the Google Professional Data Engineer exam, this question tests your ability to differentiate between the two managed messaging services under the “Designing for Data Processing” domain; a common trap is selecting only Cloud Pub/Sub and forgetting that Pub/Sub Lite is also a valid, cost-optimized alternative for high throughput. Memory tip: think of Pub/Sub as “unlimited, serverless” and Pub/Sub Lite as “fixed-cost, zonal” — both handle millions of messages, but your budget and workload predictability dictate the choice.
PDE Practice Question: Building and operationalizing data processing systems
This PDE practice question tests your understanding of building and operationalizing data processing 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.
Your company is evaluating managed messaging services for a new event-driven application. The application requires pub/sub semantics, high throughput (millions of messages per second), and integration with Google Cloud services like Cloud Functions and Dataflow. Which TWO services should you consider? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud Pub/Sub
Cloud Pub/Sub (A) is the correct choice because it provides fully managed, highly scalable pub/sub messaging with exactly-once delivery semantics and support for millions of messages per second. It integrates natively with Cloud Functions and Dataflow, making it ideal for event-driven architectures requiring high throughput and decoupled communication.
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 Pub/Sub
Why this is correct
Cloud Pub/Sub is a fully managed, scalable pub/sub messaging service with native Google Cloud integration.
Related concept
Read the scenario before looking for a memorised answer.
✗
Cloud Scheduler
Why it's wrong here
Cloud Scheduler is a cron job scheduler, not a messaging service.
✓
Cloud Pub/Sub Lite
Why this is correct
Cloud Pub/Sub Lite is a lower-cost, zonal option still offering pub/sub semantics and integration.
Related concept
Read the scenario before looking for a memorised answer.
✗
Cloud Functions
Why it's wrong here
Cloud Functions is a compute service that can be triggered by Pub/Sub, but is not a messaging service itself.
✗
Cloud Tasks
Why it's wrong here
Cloud Tasks is a task queue for distributed task execution, not a pub/sub message broker.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between managed messaging services (Pub/Sub vs. Pub/Sub Lite) and other Google Cloud services like Cloud Tasks or Cloud Scheduler, where candidates mistakenly select compute or scheduling services for messaging needs.
Detailed technical explanation
How to think about this question
Cloud Pub/Sub uses a pull/push model with at-least-once delivery and supports message ordering via message ordering keys, while Cloud Pub/Sub Lite offers lower cost for high-volume, zonal workloads with exactly-once delivery and no cross-region replication. Under the hood, Pub/Sub leverages Google's global infrastructure to achieve sub-100ms latency and auto-scale to handle spikes, whereas Pub/Sub Lite uses pre-provisioned capacity for predictable throughput. A real-world scenario: a financial trading platform uses Pub/Sub to stream millions of trade events per second to Dataflow for real-time analytics and Cloud Functions for alerting, where Pub/Sub Lite would be chosen for cost-sensitive, zonal data pipelines.
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.
Building and operationalizing data processing systems — This question tests Building and operationalizing data processing systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cloud Pub/Sub — Cloud Pub/Sub (A) is the correct choice because it provides fully managed, highly scalable pub/sub messaging with exactly-once delivery semantics and support for millions of messages per second. It integrates natively with Cloud Functions and Dataflow, making it ideal for event-driven architectures requiring high throughput and decoupled communication.
What should I do if I get this PDE 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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