| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Troels Nielsen <bn(dot)troels(at)gmail(dot)com> |
| Cc: | Jeff Davis <pgsql(at)j-davis(dot)com>, Nicholas White <n(dot)j(dot)white(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Request for Patch Feedback: Lag & Lead Window Functions Can Ignore Nulls |
| Date: | 2013-06-24 18:38:31 |
| Message-ID: | CA+Tgmoaps9umoDpWid36506uH-7WQMZrc+Fdckx2XuJwitMeag@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Jun 21, 2013 at 6:29 PM, Troels Nielsen <bn(dot)troels(at)gmail(dot)com> wrote:
> The grammar conflict appears to be because of ambiguities in:
> 1. table_ref (used exclusively in FROM clauses)
> 2. index_elem (used exclusively in INDEX creation statements).
>
> Now, this doesn't seem to make much sense, as AFAICT window functions
> are explicitly disallowed in these contexts (transformWindowFuncCall
> will yield errors, and I can't really wrap my head around what a
> window function call would mean there).
>
> I therefore propose a simple rearrangement of the grammar,
> syntactically disallowing window functions in the outer part of those
> contexts (a_expr's inside can't and shouldn't be done much about)
> which will allow both RESPECT and IGNORE to become unreserved
> keywords, without doing any lexer hacking or abusing the grammar.
I reviewed this today and I think this is a very nice approach.
Thanks for working on it!
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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