Re: Bug in aggregates in windowing context

Folks,

Elein Mustain mentioned this, and I came up with a short repro. The
SQL standard does not distinguish between what's available to
aggregates normally and in the windowing context. However...

SELECT count(DISTINCT i) FROM (VALUES (1),(2),(3),(1)) AS s(i);
count
-------
3
(1 row)

SELECT count(DISTINCT i) OVER () FROM (VALUES (1),(2),(3),(1)) AS s(i);
ERROR: DISTINCT is not implemented for window functions
LINE 1: SELECT count(DISTINCT i) OVER () FROM (VALUES (1),(2),(3),(1...
^

I see the error set up in src/backend/parser/parse_func.c, but no real
reasoning why.

Anyhow, I think it's a bug and needs back-patching.

Cheers,
David.
--
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David Fetter <david(at)fetter(dot)org> writes:
> SELECT count(DISTINCT i) OVER () FROM (VALUES (1),(2),(3),(1)) AS s(i);
> ERROR: DISTINCT is not implemented for window functions

Which part of that message isn't clear to you?

> Anyhow, I think it's a bug and needs back-patching.

"Not implemented" is not a bug. Nice try though.

regards, tom lane

On Wed, Sep 09, 2009 at 06:35:05PM -0400, Tom Lane wrote:
> David Fetter <david(at)fetter(dot)org> writes:
> > SELECT count(DISTINCT i) OVER () FROM (VALUES (1),(2),(3),(1)) AS s(i);
> > ERROR: DISTINCT is not implemented for window functions
>
> Which part of that message isn't clear to you?

A bug that's documented in the source code is still a bug.

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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David Fetter <david(at)fetter(dot)org> writes:
> A bug that's documented in the source code is still a bug.

Sorry, but we are not going to define every unimplemented feature in
SQL:2008 as being a back-patchable bug fix candidate. As for the "it's
not documented" argument, I direct you to section 4.2.8, which is pretty
explicit about what the allowed syntax is. (And btw, I'm equally
uninterested in the other omissions in that compared to SQL:2008.
We did what we could for 8.4.)

regards, tom lane

On Wed, Sep 9, 2009 at 6:24 PM, David Fetter<david(at)fetter(dot)org> wrote:
> Anyhow, I think it's a bug and needs back-patching.

I suspect if it were as easy as removing the error test it would have
been done already. Perhaps you'd care to submit a patch?

...Robert

On Wed, Sep 09, 2009 at 08:45:06PM -0400, Robert Haas wrote:
> On Wed, Sep 9, 2009 at 6:24 PM, David Fetter<david(at)fetter(dot)org> wrote:
> > Anyhow, I think it's a bug and needs back-patching.
>
> I suspect if it were as easy as removing the error test it would
> have been done already. Perhaps you'd care to submit a patch?

Working on that at the moment :)

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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