Programming Languages & Frameworks

A session is the logical entity that services a specific db client connection.
A process is the physical entity that executes a session.
With dedicated server, each session has its own physical process for execution. 1:1 relationship. A 100 sessions mean a 100 processes.
With shared server, sessions share a pool of processes, where any idle process can be tasked to execute any shared server session. A 100 processes in the pool can service a 1000 shared sessions. However, if all 100 processes are busy, then 900 sessions need to wait for an idle process in order to to be serviced.

And What is the method of setting these two parameters in Oracle architectures?

Thank you dear Billy Verreynne.
As a result, it can be said that dedicated architecture is better for projects with a large number of users?

Basic parameters for shared server are DISPATCHERS and SHARED_SERVERS.
Shared Server is ideal for supporting a large number of OLTP type users, servicing 1000s of user requests that are of short duration to service. Note that UGA memory is stored in the SGA.
Dedicated Server is ideal for supporting OLAP type users, servicing 100s of user requests that are of long duration to service. Note that UGA memory is stored in the PGA.
The Oracle database can use both architectures at the same time.