Re: is any reason why only one columns subselect are allowed in array()?

From: David Fetter <david(at)fetter(dot)org>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, postgres hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: is any reason why only one columns subselect are allowed in array()?
Date: 2008-11-18 15:37:44
Message-ID: 20081118153744.GC24041@fetter.org
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On Tue, Nov 18, 2008 at 10:29:53AM -0500, Robert Haas wrote:
> On Tue, Nov 18, 2008 at 10:06 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> > Hello
> >
> > I am thinking about allowing 2D array from multicolumn subselect
> > (all columns have to share same type, ofcourse). Is there some
> > real limit, why this functionality is disallowed?
>
> Seems like you could just write SELECT ARRAY[col1, col2, col3]
> instead of SELECT col1, col2, col3.

If I understand this right, Pavel is thinking that

ARRAY(SELECT col1, col2, col3...)

should produce an array each element of which is the compound type
consisting of (col1, col2, col3), and if it doesn't produce one, we're
looking at a pretty large POLA violation.

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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