Re: Bug Fix: COLLATE with multiple ORDER BYs in aggregates

On 2013-04-25 13:42:32 -0400, Tom Lane wrote:
> David Fetter <david(at)fetter(dot)org> writes:
> > While testing the upcoming FILTER clause for aggregates, Erik Rijkers
> > uncovered a long-standing bug in $subject, namely that this case
> > wasn't handled. Please find attached a patch by Andrew Gierth and
> > myself which fixes this issue and adds a regression test to ensure it
> > remains fixed.
>
> I don't find this patch to be a good idea.
>
> The argument for it seems to be that
>
> array_agg(a COLLATE "C" ORDER BY b COLLATE "POSIX")
>
> should not throw an error, but why not?

Uh. Why should it? SELECT foo COLLATE "C" FROM ... ORDER BY bar COLLATE
"POSIX" doesn't throw one either?

> And what does that have to do with whacking around the code for CASE?

I guess that's to avoid to repeat that already triplicated block of code
once more. The goal seems to make sense to me, although I am not 100%
that thats the nicest solution to get of the repetition.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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