Difference between Authentication, session, outer and current user in postgres

Question

I know about the users in postgres but don't have correct idea about them. The difference I know is

• Authenticated user - The user who enters his credentials to login into postgres database.
• Session user - The user who owns the session but I am confused whats the difference between session and auth user
• Outer user - It's something related to function definer but don't have exact idea
• Current user - The person who is executing the query

Can someone correct me in the above definitions and if some example can be given it will also be helpful

Answer 1

"Authenticated user" is the same as "session user", except that the latter can be changed with SET SESSION AUTHORIZATION by a superuser. The "current user" is the currently active role and can be changed with SET ROLE and by executing a SECURITY DEFINER function. I have never heard of an "outer user".