Re: Collation versioning

On Thu, Sep 17, 2020 at 5:41 AM Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
> On Tue, Sep 15, 2020 at 2:26 PM Peter Eisentraut
> <peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> > I'm confused now. I think we had mostly agreed on the v28 patch set,
> > without this additional AM flag. There was still some discussion on
> > what the AM flag's precise semantics should be. Do we want to work that
> > out first?
>
> That was my understanding too, but since Michael raised a concern I
> wrote some initial implementation for that part. I'm assuming that
> this new flag will raise some new discussion, and I hope this can be
> discussed later, or at least in parallel, without interfering with the
> rest of the patchset.

If we always record dependencies we'll have the option to invent
clever ways to ignore them during version checking in later releases.

> > Btw., I'm uneasy about the term "stable collation order". "Stable" has
> > an established meaning for sorting. It's really about whether the AM
> > uses collations at all, right?
>
> Well, at the AM level I guess it's only about whether it's using some
> kind of sorting or not, as the collation information is really at the
> opclass level. It makes me realize that this approach won't be able
> to cope with an index built using (varchar|text)_pattern_ops, and
> that's probably something we should handle correctly.

Hmm.