I read the docs several times, and I still don't understand: how do I figure out how many computing units do I need?
I'm planning to use Spanner as the operational database for a webapp, so the storage should not be very big, definitely not in the beginning. But I do want to make sure I have enough RAM and CPU to handle a big load.
How do I know if 100 compute units are enough or I need 1000 units?
How do I know how much RAM and CPU is one compute unit?
Because instance sizing is dependent on workload and schema design, it is recommended to perform a benchmark, with some initial amount of processing units. First start out with a small amount of load and increase load until the CPU usage has reached the recommended limit [1]. Based on the operations/second observed from the benchmark supported by the amount of processing units allocated, one can estimate the processing units needed for the target load.
[1] https://cloud.google.com/spanner/docs/cpu-utilization#recommended-max
