On Fri, Jan 30, 2015 at 6:59 AM, Geoff Winkless <pgsqladmin@geoff.dj> wrote:
> I appreciate the work you're doing and (as a user rather than a
> pg-hacker) don't want to butt in but if it would be possible to allow
> support for IGNORE for unique but not exclusion constraints that would
> be really helpful for my own use cases, where being able to insert
> from a dataset into a table containing unique constraints without
> having to first check the dataset for uniqueness (within both itself
> and the target table) is very useful.
>
> It's possible that I've misunderstood anyway and that you mean purely
> that exclusion constraint IGNORE should be shelved until 9.6, in which
> case I apologise.
Well, the issue is that we can't really add exclusion constraints to
the IGNORE case later. So the fact that we cannot do exclusion
constraints kind of implies that we can either shelve IGNORE and maybe
look at it later, or accept that we'll never support exclusion
constraints with IGNORE. We'd then include IGNORE without exclusion
constraint support now and forever. I tend to think that we'll end up
doing the latter anyway, but I really don't want to add additional
risk of this not getting into 9.5 by arguing about that now. It
doesn't matter that much.
> I suppose there's no reason why we couldn't use a no-op ON CONFLICT
> UPDATE anyway
Right. IGNORE isn't really all that compelling for that reason. Note
that this will still lock the unmodified row, though.
--
Peter Geoghegan