This PCDE practice question tests your understanding of monitor and optimize database performance. 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.
Your Bigtable cluster is experiencing high CPU utilization and write latency during a daily batch job that writes 500 GB of data. The job uses bulk mutations with 1000 rows per request. What is the most effective way to reduce CPU usage?
Disable write-ahead logs
Why wrong: Cannot disable WAL in Bigtable; it's essential for durability.
Increase the number of rows per mutation to 10,000
Fewer RPCs reduce CPU overhead.
Increase the number of nodes temporarily
Why wrong: More nodes distribute load but each row still causes overhead.
Create a new cluster in a different zone
Why wrong: Doesn't directly reduce CPU usage.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Increase the number of rows per mutation to 10,000
Option B is correct because larger mutations reduce overhead per row. Option A is wrong because increasing nodes would help but is not as efficient as optimizing the write pattern. Option C is wrong because increasing cluster size doesn't reduce CPU per request. Option D is wrong because write-ahead logs are internal; tuning them doesn't reduce CPU for writes.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Disable write-ahead logs
Why it's wrong here
Cannot disable WAL in Bigtable; it's essential for durability.
Increase the number of rows per mutation to 10,000
Why this is correct
Fewer RPCs reduce CPU overhead.
Related concept
Static NAT maps one inside address to one outside address.
Increase the number of nodes temporarily
Why it's wrong here
More nodes distribute load but each row still causes overhead.
Create a new cluster in a different zone
Why it's wrong here
Doesn't directly reduce CPU usage.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCDE NAT questions on configuration and troubleshooting.
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FAQ
Monitor and optimize database performance — This question tests Monitor and optimize database performance — Static NAT maps one inside address to one outside address..
The correct answer is: Increase the number of rows per mutation to 10,000 — Option B is correct because larger mutations reduce overhead per row. Option A is wrong because increasing nodes would help but is not as efficient as optimizing the write pattern. Option C is wrong because increasing cluster size doesn't reduce CPU per request. Option D is wrong because write-ahead logs are internal; tuning them doesn't reduce CPU for writes.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCDE NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 24, 2026
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