Re: Overhaul of type attributes modification

On Sat, 2011-07-09 at 17:54 +0100, Thom Brown wrote:
> On 9 July 2011 13:26, Thom Brown <thom(at)linux(dot)com> wrote:
> > On 9 July 2011 13:25, Guillaume Lelarge <guillaume(at)lelarge(dot)info> wrote:
> >> On Sat, 2011-07-09 at 13:14 +0100, Thom Brown wrote:
> >>> > The major issue is why we use the "drop all, add all" method. Let's say
> >>> > I have a composite type declared like this:
> >>> >
> >>> > CREATE TYPE s1.ty2 AS
> >>> > (c1 integer,
> >>> > c2 integer,
> >>> > c3 text,
> >>> > c4 integer);
> >>> >
> >>> > If I change c3's type (but it could be c1 or c2), I get this SQL query:
> >>> >
> >>> > ALTER TYPE s1.ty2
> >>> > ADD ATTRIBUTE c3 xml;
> >>> > ALTER TYPE s1.ty2
> >>> > DROP ATTRIBUTE c3;
> >>> >
> >>> > Remember that, on pgAdmin, it shows the list this way:
> >>> > c1 integer,
> >>> > c2 integer,
> >>> > c3 xml,
> >>> > c4 integer
> >>> >
> >>> > I click OK, and get back to the properties dialog. pgAdmin now shows the
> >>> > list this way:
> >>> > c1 integer,
> >>> > c2 integer,
> >>> > c4 integer
> >>> > c3 xml,
> >>> >
> >>> > Which is true. We drop the attribute and add another one, which will be
> >>> > at the end of the list.
> >>>
> >>> I have a solution. It seems I overlooked the alter attribute
> >>> capabilities. We can just do:
> >>>
> >>> ALTER TYPE s1.ty2
> >>> ALTER ATTRIBUTE c3 TYPE xml;
> >>>
> >>> That will preserve its position without ever having to drop it. I'm
> >>> not sure why I didn't see it before.
> >>>
> >>
> >> Can you fix your patch to also use this syntax?
> >
> > Yes, I'll try to fix both issues. Thanks for testing it. I'll be
> > back with a patch shortly.
>
> Okay, looks like it needed more work than I realised. There are quite
> a few extra changes in this one. I've moved the various checks (such
> as ensuring there are at least 2 attributes) out of the block for
> creating a type so that the same rules apply to modifying types. This
> is because you shouldn't be able to modify a type so that there are
> less than 2 attributes.
>
> But please try to break this. I've tried various combinations of
> actions (adding, renaming and changing type, just renaming, just
> changing type, removing an original attribute, removing all and adding
> back in, removing none and just adding additional ones) and can't find
> anything wrong now. But maybe there's something I missed.
>
> Revised patch attached.
>

Quick question, are you using the master branch, or 1.14? I keep getting
issues when I apply this on 1.14. And it seems more a big issue to me,
than a new feature.

--
Guillaume
http://blog.guillaume.lelarge.info
http://www.dalibo.com