hardMultiple ChoiceObjective-mapped
PDE Practice Question: A gaming company uses Pub/Sub to ingest player…
A gaming company uses Pub/Sub to ingest player events and Dataflow for real-time analytics. They notice that the Pub/Sub subscription backlog is growing despite the Dataflow pipeline running continuously. The pipeline has a 1-hour window for aggregations. What is the most effective way to reduce the backlog?
⚠ Common exam trap
Google Cloud often tests the misconception that changing window duration or subscription type can fix a throughput bottleneck, when the real solution is scaling compute resources to match the consumption rate.
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
✓
Increase the Dataflow pipeline's worker count via autoscaling.
Increasing the Dataflow pipeline's worker count via autoscaling directly addresses the backlog by adding more parallel processing capacity to consume messages from the Pub/Sub subscription faster. Since the pipeline is continuously running but the backlog grows, the bottleneck is processing throughput, not pipeline availability. Autoscaling allows Dataflow to dynamically allocate more workers based on the backlog size, matching consumption rate to the incoming message rate.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Increase the Dataflow pipeline's worker count via autoscaling.
Why this is correct
More workers increase parallelism and processing rate, reducing backlog.
- ✗
Use a push subscription instead of pull.
Why it's wrong here
Delivery mode does not affect pipeline processing speed.
- ✗
Decrease the window duration to 10 minutes.
Why it's wrong here
Smaller windows reduce latency but do not increase overall throughput.
- ✗
Enable Pub/Sub topic retention.
Why it's wrong here
Retention only stores messages longer, does not reduce backlog.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PDE 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 PDE exam.