Exam Professional Cloud Database Engineer topic 1 question 93 discussion

https://cloud.google.com/spanner/docs/instance-configurations#multi-region-best-practices Best practices For optimal performance, follow these best practices: Design a schema that prevents hotspots and other performance issues. For optimal write latency, place compute resources for write-heavy workloads within or close to the default leader region. For optimal read performance outside of the default leader region, use staleness of at least 15 seconds. To avoid single-region dependency for your workloads, place critical compute resources in at least two regions. A good option is to place them next to the two different read-write regions so that any single region outage will not impact all of your application. Provision enough compute capacity to keep high priority total CPU utilization under 45% in each region.

For optimal performance, follow these best practices: Design a schema that prevents hotspots and other performance issues. For optimal write latency, place compute resources for write-heavy workloads within or close to the default leader region. For optimal read performance outside of the default leader region, use staleness of at least 15 seconds. To avoid single-region dependency for your workloads, place critical compute resources in at least two regions. A good option is to place them next to the two different read-write regions so that any single region outage will not impact all of your application. Provision enough compute capacity to keep high priority total CPU utilization under 45% in each region. For the amount of throughput per Spanner node, see performance for multi-region configurations.

A. For optimal read (not write) performance outside of the default leader region, use staleness of at least 15 seconds. Eliminate B. CPU capacity is not mentioned as an issue. Eliminate D. When you create a Spanner instance, u can choose to add additional read-only replicas. Once the instance is created, you can change the instance name and add processing units. You can’t add more read-write replicas. Eliminate C. That leaves A. The link provided by sp57 is spot on.

A. For optimal write latency, place compute resources for write-heavy workloads within or close to the default leader region B is applicable to reads C will add load/latency D is only applicable to "high priority" tasks

https://cloud.google.com/spanner/docs/instance-configurations#multi-region-best-practices

D: Keep the total CPU utilization under 45% in each region. For optimal performance, follow these best practices: • Design a schema that prevents hotspots and other performance issues. • Place critical compute resources within the same region as your Spanner instance. • Provision enough compute capacity to keep high priority total CPU utilization ***** under 65%.