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PDE Practice Question: A data engineer is monitoring a Dataflow…
A data engineer is monitoring a Dataflow streaming pipeline and notices that the 'System Lag' metric is increasing. Which TWO actions should be taken to diagnose the issue?
⚠ Common exam trap
Google Cloud often tests the distinction between diagnostic actions and remedial actions; the trap here is that candidates confuse scaling up workers (a fix) with diagnosing the root cause of the lag.
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
✓
Check the Dataflow monitoring UI for each stage's throughput and backlog.
The Dataflow monitoring UI provides per-stage metrics such as throughput and backlog, which directly indicate where data is accumulating. By examining these metrics, you can identify the specific stage causing the increasing system lag, enabling targeted troubleshooting without unnecessary pipeline changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check the Dataflow monitoring UI for each stage's throughput and backlog.
Why this is correct
Identifies bottleneck stages.
- ✗
Cancel the pipeline and restart with a larger initial worker count.
Why it's wrong here
Loses state; not diagnostic.
- ✗
Increase the maximum number of workers to handle backlog.
Why it's wrong here
Scaling may not fix the root cause like a hot key.
- ✓
Examine the worker logs for error messages or stack traces.
Why this is correct
Errors can cause processing stalls.
- ✗
Increase the BigQuery quota for streaming inserts.
Why it's wrong here
Sink quota may cause backpressure, but not the first diagnostic step.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.