Re: BUG #15262: "unexpected end of tuplestore" error when using new GROUPS window function clause

=?utf-8?q?PG_Bug_reporting_form?= <noreply@postgresql.org> writes:
> This error can be reproduced easily as follows

>   postgres=# 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+YUhZ11XTj9rfxNiNDojjBx8Fjw@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