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PDE Practice Question: A financial company processes transactions in…
A financial company processes transactions in real-time and requires exactly-once processing semantics. They also need to reprocess historical data for backtesting. Which Google Cloud service should they use?
⚠ Common exam trap
Google Cloud often tests the misconception that Cloud Pub/Sub (A) provides exactly-once delivery, but in reality it offers at-least-once delivery, and candidates overlook Dataflow's unified batch/streaming model for reprocessing historical data.
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
✓
Cloud Dataflow
Cloud Dataflow (D) is correct because it provides exactly-once processing semantics via its distributed snapshot mechanism (based on the MillWheel paper) and supports both real-time streaming and batch processing for historical backtesting under a unified programming model. This allows the company to reprocess historical data using the same pipeline code, ensuring consistency across real-time and batch modes.
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 it's wrong here
No processing capability.
- ✗
Cloud Functions
Why it's wrong here
Not for large-scale streaming.
- ✗
Cloud Dataproc
Why it's wrong here
Not designed for exactly-once streaming.
- ✓
Cloud Dataflow
Why this is correct
Supports exactly-once and batch/streaming.
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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.