"Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> writes:
> It's actually a pretty common practice to install two versions for
> migration purposes.
Also, all the core developers routinely run multiple versions for the
purpose of testing back-branch bug fixes. The machine I'm typing this
on has, hm [ ... ps | grep ... ] ten postmasters running. They don't
have enough shared memory apiece to perform super-well ... but the point
is that you can be entirely sure that it works. Just install each
version in its own directory, point it at its own PGDATA directory,
and assign it its own port number.
regards, tom lane