Magnus Hagander <magnus@hagander.net> writes:
> Specifically, I'm interested if I actually end up making my table any
> smaller if I move from 64-bit integer primary key to 32-bit.
Depends what else is in the row ... the overall row will get padded to
MAXALIGN, but if you were wasting 4 bytes on alignment before, then you
win.
regards, tom lane