From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: pgsql-hackers@postgresql.org
Subject: Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in
 targetlist handling)
In-reply-to: <20160912174443.w5w55mkmcyfp67w2@alap3.anarazel.de>
References: <20160523005327.v2tr7obytitxcnna@alap3.anarazel.de>
 <20160822214023.aaxz5l4igypowyri@alap3.anarazel.de>
 <20160827214829.zo2dfb5jaikii5nw@alap3.anarazel.de>
 <5460.1473696601@sss.pgh.pa.us>
 <20160912165403.vshr7tazhr6wrpp4@alap3.anarazel.de>
 <8136.1473701180@sss.pgh.pa.us>
 <20160912174443.w5w55mkmcyfp67w2@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 12 Sep 2016 10:44:43 -0700"
Date: Mon, 12 Sep 2016 13:48:05 -0400
Message-ID: <9209.1473702485@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

Andres Freund <andres@anarazel.de> writes:
> On 2016-09-12 13:26:20 -0400, Tom Lane wrote:
>> Andres Freund <andres@anarazel.de> writes:
> On 2016-09-12 12:10:01 -0400, Tom Lane wrote:
>>>> I can't say that I like the proposed syntax much.

>>> Me neither. But I haven't really found a better approach.  It seems
>>> kinda consistent to have ROWS FROM (... AS ()) change the picked out
>>> columns to 0, and just return the whole thing.

>> I just remembered that we allow zero-column composite types, which
>> makes this proposal formally ambiguous.  So we really need a different
>> syntax.  I'm not especially in love with the cast-to-record idea, but
>> it does dodge that problem.

> I kind of like ROWS FROM (... AS VALUE), that seems to confer the
> meaning quite well. As VALUE isn't a reserved keyword, that'd afaik only
> really work inside ROWS FROM() where AS is required.

Hm, wouldn't ... AS RECORD convey the meaning better?

(Although once you look at it that way, it's just a cast spelled in
an idiosyncratic fashion.)

			regards, tom lane


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