Quick Answer
The answer is to use a Dataflow pipeline with a BigQuery subscription. This approach is correct because it leverages Dataflow’s fully managed, serverless architecture to stream pubsub to bigquery with minimal latency, while the BigQuery subscription—often deployed via the Pub/Sub to BigQuery template—automatically handles message ingestion and table writes without requiring custom code or cluster management. On the Google Professional Data Engineer exam, this scenario tests your understanding of operational simplicity versus custom development; a common trap is choosing a solution that involves manual scaling or complex code, which contradicts the constraint of limited operational resources. The key insight is that Dataflow’s autoscaling, checkpointing, and exactly-once semantics directly address the need for low-latency streaming with minimal overhead. Memory tip: think “Dataflow does the heavy lifting” — when the team is small and resources are tight, the managed service is always the best fit.
This PDE practice question tests your understanding of designing data processing systems. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 stream data from Cloud Pub/Sub into BigQuery with minimal latency. They have a small team and limited operational resources. Which approach is best?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Write a custom application on Compute Engine that polls Pub/Sub and writes to BigQuery.
Why wrong: Requires management.
Create a Dataproc cluster running a Spark Streaming job.
Why wrong: Operational overhead.
Create a Cloud Function that writes to BigQuery.
Why wrong: Not suitable for high throughput.
Use a Dataflow pipeline with a BigQuery subscription.
Serverless and low maintenance.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use a Dataflow pipeline with a BigQuery subscription.
Option D is correct because a Dataflow pipeline with a BigQuery subscription provides a fully managed, serverless streaming solution that directly ingests messages from Pub/Sub and writes them to BigQuery with minimal latency. Dataflow handles autoscaling, checkpointing, and exactly-once semantics, which aligns with the team's limited operational resources. The BigQuery subscription (via the Pub/Sub to BigQuery template) eliminates the need for custom code or cluster management, ensuring low-latency streaming without operational overhead.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Write a custom application on Compute Engine that polls Pub/Sub and writes to BigQuery.
Why it's wrong here
Requires management.
Create a Dataproc cluster running a Spark Streaming job.
Why it's wrong here
Operational overhead.
Create a Cloud Function that writes to BigQuery.
Why it's wrong here
Not suitable for high throughput.
Use a Dataflow pipeline with a BigQuery subscription.
Why this is correct
Serverless and low maintenance.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Google Cloud often tests the misconception that a simple serverless function (Cloud Function) is sufficient for streaming workloads, but candidates overlook that Cloud Functions are designed for event-driven, short-lived tasks and lack the state management, exactly-once guarantees, and sustained throughput needed for continuous data ingestion into BigQuery.
Detailed technical explanation
Under the hood, Dataflow uses the Apache Beam SDK with a Pub/Sub unbounded source and a BigQuery sink that leverages streaming inserts (tabledata.insertAll) for low-latency writes, achieving end-to-end latencies as low as 2–3 seconds. The BigQuery subscription is a pre-built Dataflow template that configures a streaming pipeline with auto-scaling workers, checkpointing via Cloud Storage, and exactly-once processing using Pub/Sub snapshots and BigQuery's deduplication by insertId. In a real-world scenario, this approach handles sudden traffic spikes by automatically scaling workers up to 1000+ without manual intervention, whereas a custom Compute Engine solution would require complex auto-scaling policies and risk data loss during failures.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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FAQ
Designing data processing systems — This question tests Designing data processing systems — Read the scenario before looking for a memorised answer..
The correct answer is: Use a Dataflow pipeline with a BigQuery subscription. — Option D is correct because a Dataflow pipeline with a BigQuery subscription provides a fully managed, serverless streaming solution that directly ingests messages from Pub/Sub and writes them to BigQuery with minimal latency. Dataflow handles autoscaling, checkpointing, and exactly-once semantics, which aligns with the team's limited operational resources. The BigQuery subscription (via the Pub/Sub to BigQuery template) eliminates the need for custom code or cluster management, ensuring low-latency streaming without operational overhead.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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