On Wed, 2004-09-01 at 13:50, Jan Wieck wrote:
> On 9/1/2004 1:51 PM, Serguei A. Mokhov wrote:
>
> > Date: Tue, 31 Aug 2004 23:35:18 -0400
> >
> > On 8/31/2004 9:38 PM, Andrew Rawnsley wrote:
> >
> >> On Aug 31, 2004, at 6:23 PM, Marc G. Fournier wrote:
> >>
> >>> On Tue, 31 Aug 2004, Josh Berkus wrote:
> >>>
> >>>> Andrew,
> >>>>
> >>>>> If I were loony enough to want to make an attempt at a version
> >>>>> updater
> >>>>> (i.e. migrate a
> >>>>> 7.4 database to 8.0 without an initdb), any suggestions on where to
> >>>>> poke first? Does a
> >>>>> catalog/list of system catalog changes exist anywhere? Any really
> >>>>> gross
> >>>>> problems immediately
> >>>>> present themselves? Is dusting off pg_upgrade a good place to start,
> >>>>> or
> >>>>> is that a dead end?
> >>>>
> >>>> Join the Slony project? Seriously, this is one of the uses of
> >>>> slony. All
> >>>> you'd need would be a script that would:
> >>>>
> >>
> >> I thought of this quite a bit when I was working over eRServer a while
> >> back.
> >>
> >> Its _better_ than a dump and restore, since you can keep the master up
> >> while the
> >> 'upgrade' is happening. But Mark is right - it can be quite
> >> problematic from an equivalent
> >> resource point of view. An in-place system (even a faux setup like
> >> pg_upgrade) would be
> >> easier to deal with in many situations.
> >
> > | There is something that you will not (or only under severe risk) get
> > | with an in-place upgrade system. The ability to downgrade back in the
> > | case, your QA missed a few gotchas. The application might not instantly
> > | eat the data, but it might start to sputter and hobble here and there.
> > |
> > | With the Slony system, you not only switch over to the new version. But
> > | you keep the old system as a slave. That means that if you discover 4
> > | hours after the upgrade that the new version bails out with errors on a
> > | lot of queries from the application, you have the chance to switch back
> > | to the old version and have lost no single committed transaction.
> >
> > Just asking: how far back in time Slony can "downgrade" or keep the older
> > servers in "slavery"? 6.5? I haven't tried it yet, hence, the question.
> >
>
> Slony runs on 7.3.3 and better.
If you're willing to put some time into removing schema references,
Slony will function on 7.2 -- but it's not pretty.
