Message-ID: <42A4F764.9010705@joeconway.com>
Date: Mon, 06 Jun 2005 18:24:52 -0700
From: Joe Conway <mail@joeconway.com>
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To: =?UTF-8?B?TWFya3VzIEJlcnRoZWF1IOKYrQ==?= <twanger@bluetwanger.de>
Cc: pgsql-hackers@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: [SQL] ARRAY() returning NULL instead of ARRAY[]	resp.
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Markus Bertheau ☭ wrote:
> 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.
> 

Actually I like both of these ideas, and have advocated the second one 
myself before. But it isn't backward compatible -- anyone else have an 
opinion? SQL2003 actually specifies that an array *should* start at 1:

4.10.2 Arrays
An array is a collection A in which each element is associated with 
exactly one ordinal position in A. If n is the cardinality of A, then 
the ordinal position p of an element is an integer in the range 1 (one) 
≤ p ≤ n.


Joe