Re: [PATCHES] extension for sql update - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [PATCHES] extension for sql update
Date
Msg-id 200607272202.k6RM2RB09421@momjian.us
Whole thread Raw
In response to Re: [PATCHES] extension for sql update  (Jim Nasby <jnasby@pervasive.com>)
List pgsql-hackers
Jim Nasby wrote:
> On Jul 27, 2006, at 7:30 AM, Tom Lane wrote:
> > Susanne Ebrecht <miracee@miracee.de> writes:
> >> ... We could provide the mixed update syntax and leave the
> >> typed row value expression for the next release. Do you agree?
> >
> > I don't really see the point --- the patch won't provide any new
> > functionality in anything like its current form, because you can
> > always just write the separate expressions in the simple one to
> > one way.  If we do offer the row-on-the-left syntax then people
> > will try to put sub-selects on the right, and won't get anything
> > beyond an unhelpful "syntax error" message.  So my vote would be
> > to leave it alone until we have a more complete implementation.
>
> While the patch doesn't provide any new functionality, I would still
> welcome it simply because I find it a lot easier and cleaner to group
> fields together when updating multiple fields at once.
>
> Even if we would have to rip this patch back out in order to fully
> support the spec, we've got a (mostly) working patch right now, and
> it sounds like it would take minimal effort to finish it.
>
> In any case, it sounds like there should be a TODO item out of this.

We already had it on the TODO list, but I didn't realize about the
subselect issue.  I added a sentence to clarify that:

        o Allow UPDATE tab SET ROW (col, ...) = (...) for updating multiple
          columns

new-->    A subselect can also be used as the value source.

--
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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