You do not need a graphical desktop environment on the server; you only need the X11 libraries and basic utilities. On Debian, that means x11-common and x11-utils with their dependencies. There's no xterm, xclock, etc, let alone a a window manager like xfce or worse yet a full blown environment like GNOME or KDE. The actual DBA should connect in, run the utilities, and then be done with it. They can use whatever gui and whatever X11 server they want. The bulk of the load is on their desktop, not the server.