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

From: Sam Mason <sam(at)samason(dot)me(dot)uk>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: is any reason why only one columns subselect are allowed in array()?
Date: 2008-11-18 16:01:59
Message-ID: 20081118160158.GO2459@frubble.xen.chris-lamb.co.uk
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On Tue, Nov 18, 2008 at 07:37:44AM -0800, David Fetter wrote:
> On Tue, Nov 18, 2008 at 10:29:53AM -0500, Robert Haas wrote:
> > 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.

I've used this syntax before and got a surprising message back. I'd
expect to be able to do the following:

ARRAY((SELECT col1, col2 FROM (VALUES ('a',1), ('b',2)) x(col1,col2)));

and get the following back {"(a,1)","(b,2)"}. So I think I'm with
David.

Sam

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