How to properly manage the connection pool?

Question

Database

Good afternoon, dear ones!
Can you please tell me how you set up a connection pool for your subd? (Postgre,Oracle)
I'm familiar with the options that can be set (min, max, etc).
The question is, based on what considerations do you set these parameters? How do you know how many resources will be consumed? How, based on the load, do you understand that let's say you need to use 100 connections, not 75, and so on, that 50 threads will be active, not 10. (For example).

Answer 1

Based on current load, predicted load and load testing.
Those. it is necessary to establish the fact that at load N your software will utilize M connections from the pool.