PCDE Monitor and optimize database performance Practice Question
This PCDE practice question tests your understanding of monitor and optimize database performance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Your team uses Cloud Bigtable for a time-series data analytics platform. You observe that the write throughput has dropped significantly, and Cloud Monitoring shows that most of the CPU usage is concentrated on a few nodes. The remaining nodes have low CPU usage. The data model uses sequential timestamps as row keys, and the application writes data for many different sensors. Each sensor ID is part of the row key. What is the most effective action to resolve this hot spotting?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Prepend a hash of the sensor ID to the row key to distribute writes evenly.
Option A is correct: Adding a hash prefix to row keys will distribute writes across nodes, preventing hot spotting. Option B (increasing nodes) may spread load but without fixing row key design, hot spots may persist. Option C (using a different cluster) doesn't address the design issue. Option D (reducing write batch size) may reduce latency but not the uneven distribution.
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.
✗
Reduce the batch size of writes to decrease the load on each node.
Why it's wrong here
Smaller batches won't fix the uneven distribution of keys; the hot node will still receive more writes.
✗
Use a different Bigtable cluster and migrate data.
Why it's wrong here
A new cluster with the same row key design will still have the same issue.
✗
Increase the number of nodes in the cluster to provide more CPU capacity.
Why it's wrong here
More nodes may temporarily reduce pressure on overloaded nodes, but the hot spotting will persist because the row key design is sequential.
✓
Prepend a hash of the sensor ID to the row key to distribute writes evenly.
Why this is correct
This breaks the sequential key pattern and distributes writes across all nodes, eliminating hot spotting.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which PCDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Monitor and optimize database performance — This question tests Monitor and optimize database performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Prepend a hash of the sensor ID to the row key to distribute writes evenly. — Option A is correct: Adding a hash prefix to row keys will distribute writes across nodes, preventing hot spotting. Option B (increasing nodes) may spread load but without fixing row key design, hot spots may persist. Option C (using a different cluster) doesn't address the design issue. Option D (reducing write batch size) may reduce latency but not the uneven distribution.
What should I do if I get this PCDE question wrong?
Identify which PCDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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