- A
Set the retention duration on the Pub/Sub Lite topic to 7 days
Pub/Sub Lite topics allow setting message retention duration up to 7 days. Messages are retained in the topic's storage and can be re-delivered to subscriptions within that period.
- B
Set the retention duration on the Pub/Sub Lite subscription to 7 days
Why wrong: Pub/Sub Lite does not have per-subscription retention; retention is set on the topic. Subscriptions can have a retention duration, but in Pub/Sub Lite, topic retention is the primary setting.
- C
Enable exactly-once delivery on the Pub/Sub Lite topic to retain messages for 7 days
Why wrong: Exactly-once delivery does not extend retention; it ensures messages are not duplicated.
- D
Use a Pub/Sub Lite reservation with 7-day retention
Why wrong: Reservations allocate capacity (throughput) but do not affect message retention.
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 company wants to use Pub/Sub Lite to reduce costs for a high-throughput, low-latency streaming pipeline. However, they have a requirement to retain messages for up to 7 days for reprocessing. Which Pub/Sub Lite configuration supports this retention?
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 retention duration on the Pub/Sub Lite topic to 7 days
Pub/Sub Lite topics are the only entity where retention duration is configured; messages are retained in the topic's storage for the specified duration, allowing subscribers to replay messages within that window. Setting the retention duration to 7 days on the topic ensures messages are available for reprocessing for up to 7 days, meeting the requirement.
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.
- ✓
Set the retention duration on the Pub/Sub Lite topic to 7 days
Why this is correct
Pub/Sub Lite topics allow setting message retention duration up to 7 days. Messages are retained in the topic's storage and can be re-delivered to subscriptions within that period.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set the retention duration on the Pub/Sub Lite subscription to 7 days
Why it's wrong here
Pub/Sub Lite does not have per-subscription retention; retention is set on the topic. Subscriptions can have a retention duration, but in Pub/Sub Lite, topic retention is the primary setting.
- ✗
Enable exactly-once delivery on the Pub/Sub Lite topic to retain messages for 7 days
Why it's wrong here
Exactly-once delivery does not extend retention; it ensures messages are not duplicated.
- ✗
Use a Pub/Sub Lite reservation with 7-day retention
Why it's wrong here
Reservations allocate capacity (throughput) but do not affect message retention.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google often tests the distinction between topic-level and subscription-level retention in Pub/Sub Lite, where candidates mistakenly assume subscriptions control retention (as in standard Pub/Sub) rather than the topic itself.
Detailed technical explanation
How to think about this question
Under the hood, Pub/Sub Lite uses a segmented, append-only log stored in Google Cloud storage; the retention duration on the topic defines how long messages persist in these segments before being garbage-collected. A subtle behavior is that even if a subscription has no active subscribers, messages remain available for new subscribers as long as the topic retention window has not expired. In real-world scenarios, this allows reprocessing pipelines to catch up on failed batches without requiring additional storage or manual archiving.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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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Designing Data Processing Systems — study guide chapter
Learn the concepts, then practise the questions
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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 retention duration on the Pub/Sub Lite topic to 7 days — Pub/Sub Lite topics are the only entity where retention duration is configured; messages are retained in the topic's storage for the specified duration, allowing subscribers to replay messages within that window. Setting the retention duration to 7 days on the topic ensures messages are available for reprocessing for up to 7 days, meeting the requirement.
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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