Google ACE Deploying and implementing a cloud solution Practice Question
This ACE practice question tests your understanding of deploying and implementing a cloud solution. 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 engineering team is deploying a streaming Dataflow pipeline that reads from Pub/Sub and writes to BigQuery. They need to ensure that each event is processed exactly once, even in the event of failures. Which Dataflow feature should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Rely on Dataflow's exactly-once processing guarantees
Dataflow's streaming engine provides built-in exactly-once processing guarantees for sources like Pub/Sub and sinks like BigQuery. This is achieved through a combination of checkpointing, deterministic replay, and idempotent writes, ensuring that each record is processed exactly once even during worker failures or pipeline updates. No additional configuration or external deduplication is required.
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.
✗
Enable at-least-once delivery on the Pub/Sub subscription
Why it's wrong here
At-least-once could result in duplicates; exactly-once requires deduplication.
✗
Set the Dataflow pipeline to use the 'exactly_once' parameter in the pipeline options
Why it's wrong here
There is no such parameter; exactly-once is inherent in Dataflow's design.
✓
Rely on Dataflow's exactly-once processing guarantees
Why this is correct
Dataflow ensures exactly-once processing for streaming pipelines using its consistent model.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Cloud Functions to deduplicate messages before sending to Dataflow
Why it's wrong here
Adding an extraneous component is not the Dataflow-native approach.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that exactly-once processing requires explicit configuration or external deduplication, when in fact Dataflow provides it as a default behavior for supported sources and sinks.
Detailed technical explanation
How to think about this question
Dataflow's exactly-once processing relies on the 'commit window' mechanism in the streaming engine, where the pipeline state is periodically checkpointed to persistent storage (e.g., Spanner for metadata). When a worker fails, the pipeline resumes from the last consistent checkpoint, replaying only unacknowledged records. For BigQuery sinks, Dataflow uses streaming inserts with insertId for deduplication, ensuring that even if a record is replayed, BigQuery will not create duplicate rows.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this ACE question in full detail.
Deploying and implementing a cloud solution — This question tests Deploying and implementing a cloud solution — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Rely on Dataflow's exactly-once processing guarantees — Dataflow's streaming engine provides built-in exactly-once processing guarantees for sources like Pub/Sub and sinks like BigQuery. This is achieved through a combination of checkpointing, deterministic replay, and idempotent writes, ensuring that each record is processed exactly once even during worker failures or pipeline updates. No additional configuration or external deduplication is required.
What should I do if I get this ACE 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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