Re: Making joins involving ctid work for the benefit of UPSERT

On 2014-07-18 11:14:34 -0700, Peter Geoghegan wrote:
> On Fri, Jul 18, 2014 at 11:06 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> > I don't see why you'd need such a node at all if we had a fully builtin
> > UPSERT. The whole stuff with ON CONFLICT SELECT FOR UPDATE and then
> > UPDATE ... FROM c CONFLICTS is too complicated and exposes stuff that
> > barely anybody will understand, let alone use correctly in queries they
> > write themselves.
>
> I accept that there will be a need for certain restrictions. Most
> obviously, if you update the target table referencing a CTE like this,
> not using the special CONFLICTS clause in the UPDATE (or DELETE) is an
> error. And as I mentioned, you may only join the projected duplicates
> to the UPDATE ModifyTable - an attempt to join any more relations is
> an error. In short, this *is* a fully built-in upsert.

Meh. A understandable syntax wouldn't require the pullups with a special
scan node and such. I think you're attempting a sort of genericity
that's making your (important!) goal much harder to reach.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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