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. -- Serguei A. Mokhov | /~\ The ASCII Computer Science Department | \ / Ribbon Campaign Concordia University | X Against HTML Montreal, Quebec, Canada | / \ Email! ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
