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From: David Rowley <dgrowleyml@gmail.com>
Date: Mon, 30 May 2022 14:38:43 +1200
Message-ID: 
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Subject: Re: BUG #17502: View based on window functions returns wrong results
 when queried
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: =?UTF-8?Q?Daniel_Farka=C5=A1?= <daniel.farkas@datoris.com>,
	Magnus Hagander <magnus@hagander.net>,
	PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
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On Mon, 30 May 2022 at 14:19, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> David Rowley <dgrowleyml@gmail.com> writes:
> > The problem seems to be down to the fact that
> > remove_unused_subquery_outputs() does not check if the to-be-removed
> > target entry references WindowClauses which contain set-returning
> > functions.
>
> I was sort of wondering why we allow SRFs in this context in the
> first place.  The results don't seem terribly well-defined to me.
> In particular, a WindowFunc invocation is not supposed to change the
> number of rows in the query result, and yet this one is doing so.

That would certainly be an easier fix for the reported problem.

Do you think it would fly to add such a restriction in the backbranches?

David