2008/12/21 Hitoshi Harada <umi.tanuki@gmail.com>:
> 2008/12/20 Tom Lane <tgl@sss.pgh.pa.us>:
>> I've been studying the grammar for the windowing patch a bit. It seems
>> to me that the <existing window name> option for <window specification>
>> got left out. I think that WindowDef needs to have two name fields,
>> one for the name (if any) defined by the window definition, and one
>> for the referenced window name if any. Also the "OVER name" syntax
>> seems like it maps to a referenced window name not a defined window
>> name.
>
> I completely missed this issue. If the <existing window name> is
> allowed in <window clause>, then does it mean this is possible?
>
> SELECT row_number() OVER w2 FROM t
> WINDOW w1 AS (PARTITION BY grp), w2(w1)
>
> And what if w1 refers to w2 and w2 refers to w1 cyclicly? And from
> what I read the spec, it seems to me that it effects only frame clause
> which is unlikely implemented for 8.4, because if <existing window
> name) is specified then <partition clause> and <order by clause> are
> both permitted in the window definition.
both "not" permitted in the window definition.
Sorry for my mistake.
--
Hitoshi Harada