Design innovative, scalable, and highly available cloud database solutions →hardMultiple SelectObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
An online payment processing system uses Cloud SQL for MySQL with a 1 TB database. The system experiences high write throughput (~5000 writes/sec) and needs sub-10ms latency. The current instance has 8 vCPUs and 32 GB RAM. Which two metrics would indicate that the instance needs a larger tier? (Choose TWO.)
⚠ Common exam trap
Google Cloud often tests the misconception that high memory usage or low latency alone indicates a need for a larger tier, but the key metrics are CPU saturation and I/O limit exhaustion, which directly impact write throughput and latency.
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
✓
CPU utilization consistently above 80%.
Sustained CPU utilization above 80% indicates the instance is compute-bound, which can lead to queuing and increased latency for write operations. In Cloud SQL for MySQL, high CPU usage often means the instance lacks sufficient vCPUs to handle the write throughput, necessitating a larger tier with more CPU cores.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Memory usage is 50% of 32 GB.
Why it's wrong here
Memory usage at 50% is fine; not a scaling trigger.
- ✓
CPU utilization consistently above 80%.
Why this is correct
High CPU indicates need for more vCPUs.
- ✓
Disk IOPS is consistently reaching the instance's I/O limit.
Why this is correct
Reaching I/O limit requires a larger tier with more IOPS.
- ✗
Average query latency of 5 ms.
Why it's wrong here
5 ms is acceptable; not a trigger for scaling.
- ✗
Network traffic is 100 Mbps.
Why it's wrong here
Network is usually not a bottleneck for Cloud SQL.
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This PCDE 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 PCDE exam.