From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Markus Bertheau ? <twanger@bluetwanger.de>
Cc: Joe Conway <mail@joeconway.com>
Cc: pgsql-hackers@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: [SQL] ARRAY() returning NULL instead of ARRAY[]
Date: Fri, 24 Jun 2005 21:50:23 -0400 (EDT)
Message-ID: <200506250150.j5P1oNO01032@candle.pha.pa.us> (raw)
In-Reply-To: <1118074367.5506.16.camel@dicaprio.akademie1.de>
Is this a TODO item?
---------------------------------------------------------------------------
Markus Bertheau ? wrote:
> ? ???, 06/06/2005 ? 08:58 -0700, Joe Conway ?????:
> > Joe Conway wrote:
> > > Actually, consistent with my last post, I think array_upper() on a
> > > zero-element array should return NULL. A zero-element array has a
> > > defined lower bound, but its upper bound is not zero -- it is really
> > > undefined.
> >
> > Just to clarify my response, this is what I propose:
> >
> > regression=# select array_upper('[2][1:]={{},{}}'::int[],1);
> > array_upper
> > -------------
> > 2
> > (1 row)
> >
> > regression=# select array_upper('[2][1:]={{},{}}'::int[],2) IS NULL;
> > ?column?
> > ----------
> > t
> > (1 row)
>
> Hmm, this gets really complicated and inconsistent. Complicated means
> unusable. What about modifying the dimension syntax such that the second
> number means number of elements instead of upper bound? That particular
> problem would go away then, and array_upper('[0:0]={}'::int[]) can
> return the correct 0 then.
>
> What I'm actually worrying about is that array_upper(array(select 1
> where false)) returns 0.
>
> An option would be to drop the possibility to let the array start at
> another index than 0. I don't know why it was decided to do that in the
> first place. It seems a rather odd feature to me.
>
> Markus
> --
> Markus Bertheau ? <twanger@bluetwanger.de>
>
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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To: pgsql-sql@postgresql.org
Cc: pgman@candle.pha.pa.us, twanger@bluetwanger.de, mail@joeconway.com, tgl@sss.pgh.pa.us
Subject: Re: [SQL] ARRAY() returning NULL instead of ARRAY[]
In-Reply-To: <200506250150.j5P1oNO01032@candle.pha.pa.us>
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