- A
Use a sliding window of 5 minutes with 2-minute slide
Why wrong: Sliding windows are different; they create overlapping windows.
- B
Set the window duration to 7 minutes to account for lateness
Why wrong: That changes the windowing logic, not the intended design.
- C
Set the allowed lateness to 2 minutes with a trigger that fires on late data
Allowed lateness specifies how long to wait; a trigger can emit updates for late data.
- D
Use a global window and watermark
Why wrong: Global window is not suitable for fixed 5-minute windows.
Question 177 of 1,000
PDE Designing Data Processing Systems Practice Question
This PDE practice question tests your understanding of designing data processing systems. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 data engineer is designing a pipeline that reads from Cloud Pub/Sub, aggregates events into 5-minute windows, and writes the results to BigQuery. The engineer wants to ensure that late-arriving data (up to 2 minutes late) is included in the correct window. Which Dataflow feature should they configure?
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
✓
Set the allowed lateness to 2 minutes with a trigger that fires on late data
Option C is correct because Dataflow's allowed lateness feature (set to 2 minutes) ensures that late-arriving data within that threshold is still assigned to the correct 5-minute window. Combined with a trigger that fires on late data, the pipeline can emit updated results for the window after the watermark passes, which is exactly what the engineer needs to handle late-arriving events up to 2 minutes late.
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.
- ✗
Use a sliding window of 5 minutes with 2-minute slide
Why it's wrong here
Sliding windows are different; they create overlapping windows.
- ✗
Set the window duration to 7 minutes to account for lateness
Why it's wrong here
That changes the windowing logic, not the intended design.
- ✓
Set the allowed lateness to 2 minutes with a trigger that fires on late data
Why this is correct
Allowed lateness specifies how long to wait; a trigger can emit updates for late data.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a global window and watermark
Why it's wrong here
Global window is not suitable for fixed 5-minute windows.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse window duration adjustments (Option B) or sliding windows (Option A) with the proper late-data handling mechanism, not realizing that allowed lateness and triggers are the correct Dataflow primitives for including late-arriving data in the correct event-time window.
Detailed technical explanation
How to think about this question
Under the hood, Dataflow uses watermarks to track event time progress; allowed lateness extends the window's lifetime beyond the watermark so that late data can still be processed. The trigger on late data (e.g., AfterWatermark.pastEndOfWindow().withLateFirings()) re-emits the window's pane with updated results, which is critical for real-time dashboards where correctness matters despite network delays. In practice, this is essential for IoT sensor data or clickstream events that may arrive out of order due to buffering or retries.
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 PDE question test?
Designing Data Processing Systems — This question tests Designing Data Processing Systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set the allowed lateness to 2 minutes with a trigger that fires on late data — Option C is correct because Dataflow's allowed lateness feature (set to 2 minutes) ensures that late-arriving data within that threshold is still assigned to the correct 5-minute window. Combined with a trigger that fires on late data, the pipeline can emit updated results for the window after the watermark passes, which is exactly what the engineer needs to handle late-arriving events up to 2 minutes late.
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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Last reviewed: Jul 4, 2026
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.
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