Hi,
if my client (swing, web, etc...) wants to update a Person, do i need to load the Person so i can update it?

Suppose the following code in my fa

Yes. However if the object was loaded previously for displaying the info to your UI you probably do not require to load the object again.

Even if you are forced to load the object if you set you Data cache correctly the performance might not be impacted.

No, you don't have to load the object, you can just do session.update(p1)

Michael,
just doing session.update() doesn't work for me.

It simply doesn't understand that is the same object (and it actually is, i made myself sure of it specifying the correct id).

It's clear when i use saveORupdate method, hibernate creates another object (as my table is using auto_increment, it simply ignores the id of my object and stores a new one in db) and doesn't update the other one.

What would be a explanation for this?

Set unsaved-value, see documentation.