PDE Ingesting and Processing the Data Practice Question
You are building a streaming pipeline to ingest real-time clickstream data from a website into BigQuery for immediate analysis. The data must be available in BigQuery within seconds and you need to handle late-arriving data (e.g., browser offline events) that may arrive hours later. Which approach should you use?
⚠ Common exam trap
Many exam-takers assume legacy streaming inserts (Option C) are sufficient for real-time needs, but they overlook the 1-hour buffer delay and lack of late-data handling, which are explicitly tested in the PDE exam's focus on streaming pipelines with out-of-order events.
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
✓
Use Pub/Sub with Dataflow, writing to BigQuery using the Storage Write API in committed mode.
Pub/Sub provides a scalable, durable ingestion layer for real-time clickstream data, and Dataflow can handle late-arriving data via its built-in watermark and trigger mechanisms. The Storage Write API in committed mode ensures exactly-once semantics and low-latency writes to BigQuery, meeting the sub-second availability requirement while preserving data consistency for delayed events.
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 Pub/Sub with Dataflow, writing to BigQuery using the Storage Write API in committed mode.
Why this is correct
This provides low-latency streaming, late data handling via Dataflow's triggers, and efficient writes.
- ✗
Use Cloud Logging to capture logs and export to BigQuery via a sink.
Why it's wrong here
This is for logs, not real-time clickstream data, and introduces minutes of delay.
- ✗
Use Pub/Sub with Cloud Functions, writing each event directly via BigQuery legacy streaming inserts.
Why it's wrong here
Cloud Functions have a timeout limit and are not ideal for high-throughput streaming; legacy streaming inserts have a 1-day quota and lack exactly-once semantics.
- ✗
Use Datastream to stream clickstream data from Cloud SQL to BigQuery.
Why it's wrong here
Datastream is for CDC from databases, not for web clickstream data.
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