Re: Support UPDATE table SET(*)=...

On Fri, Oct 17, 2014 at 7:45 PM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:

> On Wed, Oct 15, 2014 at 3:48 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> wrote:
> >
> >
> > On Wednesday, October 15, 2014, Marti Raudsepp <marti(at)juffo(dot)org> wrote:
> >>
> >> Hi
> >>
> >> On Wed, Oct 15, 2014 at 11:02 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com>
> wrote:
> >> > Please find attached a patch which implements support for UPDATE
> table1
> >> > SET(*)=...
> >>
> >> I presume you haven't read Tom Lane's proposal and discussion about
> >> multiple column assignment in UPDATE:
> >> http://www.postgresql.org/message-id/1783.1399054541@sss.pgh.pa.us
> >> (Assigning all columns was also discussed there)
> >>
> >> And there's a WIP patch:
> >> http://www.postgresql.org/message-id/20930.1402931841@sss.pgh.pa.us
> >
> > Thanks for the links, but this patch only targets SET(*) case, which, if
> I
> > understand correctly, the patch you mentioned doesn't directly handle
> (If I
> > understand correctly, the target of the two patches is different).
>
> Yeah -- in fact, there was some discussion about this exact case.
> This patch solves a very important problem: when doing record
> operations to move data between databases with identical schema
> there's currently no way to 'update' in a generic way without building
> out the entire field list via complicated and nasty dynamic SQL.

Thanks!

> I'm
> not sure about the proposed syntax though; it seems a little weird to
> me. Any particular reason why you couldn't have just done:
>
> UPDATE table1 SET * = a,b,c, ...
>
> also,
>
> UPDATE table1 t SET t = (SELECT (a,b,c)::t FROM...);
>

I honestly have not spent a lot of time thinking about the exact syntax
that may be acceptable. If we have arguments for or against a specific
syntax, I will be glad to incorporate them.

>
>