Re: Expanding DELETE/UPDATE returning

On Mon, Feb 26, 2007 at 11:14:01PM -0500, Tom Lane wrote:
> Rusty Conover <rconover(at)infogears(dot)com> writes:
> > I didn't see this on the TODO list, but if it is my apologies. Is
> > it in the cards to expand the functionality of DELETE/UPDATE
> > returning to be able to sort the output of the rows returned?
>
> No.

Would this be something that windowing functions would need to take
into account?

> > Or allow delete and update to be used in sub-queries?
>
> That's been discussed but the implementation effort seems far from
> trivial. One big problem is that a sub-query can normally be
> re-executed multiple times, eg on the inner side of a join; whereas
> that's clearly not acceptable for an insert/update/delete.

What kinds of machinery would be needed in order for certain kinds of
subqueries to get executed only once and have the results cached?

<brain_storm>

INSERT/UPDATE/DELETE ... RETURNING wouldn't be the only possible uses
of such machinery. A data-changing function in a subquery could be
another. Maybe there could be some way to mark functions as "execute
once per subquery."

</>

Cheers,
D
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
phone: +1 415 235 3778 AIM: dfetter666
Skype: davidfetter

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