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Date: Mon, 06 Jun 2005 08:58:28 -0700
From: Joe Conway <mail@joeconway.com>
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	Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: [SQL] ARRAY() returning NULL instead of ARRAY[] resp.
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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)


Joe