Question about fetch data from disk


Dear all:

I am fresh user for scidb. I am trying to study and modify the buffer management coding part. When I go deep into the code, I totally lost.
So I have question when we do query operation, if I want to fetch data from the disk, the process have to go through the buffer managerment, right?
whick part of code control buffer management?
For example, when I do scidb query , multiply(test1, test2).
which function control the process of fetching data from disk? Does the ConstRLEPayload class control it?

Thanks & Best Regards