- A
Worker CPU utilization
Why wrong: Worker CPU utilization can indicate if workers are overloaded but does not directly differentiate between processing and sink bottlenecks.
- B
System lag
Why wrong: System lag reflects overall processing delay but increases regardless of whether the bottleneck is in processing or the sink; it cannot distinguish between the two.
- C
Element count
Why wrong: Element count shows the number of elements processed but does not indicate where the delay occurs.
- D
Data freshness
Data freshness (time since last output) directly indicates whether the sink is keeping up. High Data freshness suggests a sink bottleneck, while low Data freshness despite high System lag suggests a processing bottleneck.
Question 171 of 1,000
PDE System lag Practice Question
This PDE practice question tests your understanding of maintaining and automating data workloads. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: system lag. 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.
Your Dataflow streaming pipeline is experiencing increasing system lag over time. You have enabled autoscaling and the pipeline is using the default streaming engine. Which metric should you monitor in Cloud Monitoring to determine if the pipeline is falling behind due to slow processing or due to a bottleneck in the output sink?
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
✓
Data freshness
In Dataflow streaming pipelines, 'System lag' measures the maximum time an item waits to be processed, but it does not by itself distinguish between a processing bottleneck and a sink bottleneck. To differentiate, monitor 'Data freshness' (the time since the last output was written). If Data freshness is high while System lag is also high, the sink is likely the bottleneck. If System lag is high but Data freshness is low (recent output), the bottleneck is processing. Therefore, the metric that helps determine whether the pipeline is falling behind due to slow processing or a sink bottleneck is Data freshness.
Key principle: System lag
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Worker CPU utilization
Why it's wrong here
Worker CPU utilization can indicate if workers are overloaded but does not directly differentiate between processing and sink bottlenecks.
- ✗
System lag
Why it's wrong here
System lag reflects overall processing delay but increases regardless of whether the bottleneck is in processing or the sink; it cannot distinguish between the two.
- ✗
Element count
Why it's wrong here
Element count shows the number of elements processed but does not indicate where the delay occurs.
- ✓
Data freshness
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often assume System lag is the single metric for all delays, but to differentiate between processing and sink bottlenecks, you need to combine System lag with Data freshness.
Trap categories for this question
Command / output trap
Element count shows the number of elements processed but does not indicate where the delay occurs.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- System lag
- Data freshness
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
System lag
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. System lag Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review system lag, then practise related PDE questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PDE question test?
Maintaining and Automating Data Workloads — This question tests Maintaining and Automating Data Workloads — System lag.
What is the correct answer to this question?
The correct answer is: Data freshness — In Dataflow streaming pipelines, 'System lag' measures the maximum time an item waits to be processed, but it does not by itself distinguish between a processing bottleneck and a sink bottleneck. To differentiate, monitor 'Data freshness' (the time since the last output was written). If Data freshness is high while System lag is also high, the sink is likely the bottleneck. If System lag is high but Data freshness is low (recent output), the bottleneck is processing. Therefore, the metric that helps determine whether the pipeline is falling behind due to slow processing or a sink bottleneck is Data freshness.
What should I do if I get this PDE question wrong?
Review system lag, then practise related PDE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
System lag
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Last reviewed: Jul 4, 2026
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