Update to version 3.3 on servers that already has Postgresql

Hi, i've got a multi server installation for the different web applications we got, but all our systems use Postgresql, because of that we got Postgre in all our server.

My question is, what will happen if i try to do the update this version (3.3), that has postgresql support?.

Should i do a different thing in the update process?, or the update will detect that i've already has postgres and ask for the credentials?

As a note, for each server i've got a different password for the postgresql master user.