Message-ID: <396e990fa8ae32bf5c1e3bf2473778e6e296fbfe.camel@cybertec.at>
Subject: Re: Duplicates being removed from intarray on subtraction of
 another intarray
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: tbogusiak@gmail.com, pgsql-docs@lists.postgresql.org
Date: Mon, 18 Mar 2024 17:01:32 +0100
In-Reply-To: <171075007381.7104.7931589808177869854@wrigleys.postgresql.org>
References: <171075007381.7104.7931589808177869854@wrigleys.postgresql.org>
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On Mon, 2024-03-18 at 08:21 +0000, PG Doc comments form wrote:
> Page: https://www.postgresql.org/docs/16/intarray.html
>=20
> Hi,
> I recently ran into an unusual issue with the intarray extension where if
> you subtract one array from another the result is *also* sorted and
> de-duplicated. The documentation does not seem to imply that this should =
be
> the case, stating only that the operator "removes elements of the right
> array from the left array" and not that it also de-duplicates and sorts t=
he
> result... It seems to only occur when subtracting an array. Is this the
> intended behavior?
>=20
> SELECT '{3,1,1,2,2,2}'::int[] - 1; --> {3,2,2,2} as you would expect
> SELECT '{3,1,1,2,2,2}'::int[] - '{1}'::int[]; --> {2,3} instead of
> {3,2,2,2}

There is no harm in documenting that; I propose the attached patch.

Yours,
Laurenz Albe

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