Re: State of Beta 2

"Marc G. Fournier" <scrappy@postgresql.org> writes:
> hmmm ... k, is it feasible to go a release or two at a time without on
> disk changes?  if so, pg_upgrade might not be as difficult to maintain,
> since, unless someone an figure out a way of doing it, 'on disk change
> releases' could still require dump/reloads, with a period of stability in
> between?

Yeah, for the purposes of this discussion I'm just taking "pg_upgrade"
to mean something that does what Bruce's old script does, namely
transfer the schema into the new installation using "pg_dump -s" and
then push the user tables and indexes physically into place.  We could
imagine that pg_upgrade would later get some warts added to it to handle
some transformations of the user data, but that might or might not ever
need to happen.

I think we could definitely adopt a policy of "on-disk changes not
oftener than every X releases" if we had a working pg_upgrade, even
without doing any extra work to allow updates.  People who didn't
want to wait for the next incompatible release could have their change
sooner if they were willing to do the work to provide an update path.

> *Or* ... as we've seen more with this dev cycle then previous ones, how
> much could be easily back-patched to the previous version(s) relatively
> easily, without requiring on-disk changes?

It's very difficult to back-port anything beyond localized bug fixes.
We change the code too much --- for instance, almost no 7.4 patch will
apply exactly to 7.3 or before because of the elog-to-ereport changes.

But the real problem IMHO is we don't have the manpower to do adequate
testing of back-branch changes that would need to be substantially
different from what gets applied to HEAD.  I think it's best to leave
that activity to commercial support outfits, rather than put community
resources into it.

(Some might say I have a conflict of interest here, since I work for Red
Hat which is one of said commercial support outfits.  But I really do
think it's more reasonable to let those companies do this kind of
gruntwork than to expect the community hackers to do it.)

            regards, tom lane