From: Tom Lane <tgl@sss.pgh.pa.us>
To: lukas.eder@gmail.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #15262: "unexpected end of tuplestore" error when using new
 GROUPS window function clause
In-reply-to: <153086788677.17476.8002640580496698831@wrigleys.postgresql.org>
References: <153086788677.17476.8002640580496698831@wrigleys.postgresql.org>
Comments: In-reply-to =?utf-8?q?PG_Bug_reporting_form?=
 <noreply@postgresql.org>
	message dated "Fri, 06 Jul 2018 09:04:46 -0000"
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Date: Mon, 09 Jul 2018 18:29:34 -0400
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=3D?utf-8?q?PG_Bug_reporting_form?=3D <noreply@postgresql.org> writes:
> This error can be reproduced easily as follows

>   postgres=3D# SELECT count(*) OVER (GROUPS 1 PRECEDING) FROM (VALUES (1=
),
> (2), (2)) t(v);
>   ERROR:  unexpected end of tuplestore

In an assert-enabled build I get an assert failure from this.  I think
this is the same problem Masahiko Sawada noted in

https://www.postgresql.org/message-id/CAD21AoDrWqycq-w_+Bx1cjc+YUhZ11XTj9r=
fxNiNDojjBx8Fjw@mail.gmail.com

and as in that thread, I think what we really should be doing here is
giving a parse error.  What would you expect GROUPS mode to do without
an ORDER BY to define the grouping?

			regards, tom lane