Hi, On 2018-11-21 19:25:45 -0500, Stephen Frost wrote: > * Andres Freund (and...@anarazel.de) wrote: > > I feel like we ought to trim the support for a few old versions from > > pg_upgrade. In my particular case I don't really think it's reasonable > > to test < 9.0 versions for pg_largeobject_metadata migrations. But I > > think we should create a policy that's the default, leaving individual > > cases aside. > > I agree with having policies but I'm not sure that I agree with cutting > it quite that far back. We only just recently agree to drop support for > pg_dump from ancient versions and that seems like a pretty big deal to > me.
I don't really think the pg_dump part is actually a big deal - and I think pg_dump support for ancient versions is much more crucial than pg_upgrade support. > I'll also point out that I suspect the policy defined here will end up > having impacts elsewhere- how far back do we support btree version X? I don't think that's true - the on-disk data can be much older, even when upgrading from a newer cluster. As pg_upgrades don't touch the majority of the on-disk data, upgrading from a certain cluster version doesn't guarantee anything about the data. Fixing that by enforcing that there needs to be a vacuum (or other full table process) on old relations is a separate discussion imo (and obviously is only possible from 12+). > > I can see a few possible policies: > > > > 1) Support upgrading from the set of releases that were supported when > > the pg_upgrade target version was released. While some will argue that > > this is fairly short, people above it can still upgrade ~10 years > > worth of versions with a single intermediary upgrade. > > This is saying that we'll support pg_upgrade for 5 prior versions, > right? Version 15 will work with version 10, but not older, and v16 > won't work with v10 but will with v11? Yes. > > I personally think 1 is preferrable and 2 is acceptable. > > Given how closely pg_upgrade and pg_dump are intertwined, I'd rather we > keep the back-branch support the same for both. I don't buy this. The majority of the cross-version support in pg_dump doesn't have much to do with binary upgrade mode. And the version specific logic in pg_upgrade itself is independent. Which intertwinedness are you seeing? > At the same time, I don't like having a lot of support in the backend > for older versions of on-disk data. As I said, i don't see this being related. Greetings, Andres Freund
