From: Hannu Krosing <hannu@skype.net>
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Milen A. Radev <milen@radev.net>
Cc: pgsql-sql@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: [SQL] Interval subtracting
Date: Wed, 01 Mar 2006 22:28:39 +0200
Message-ID: <1141244920.3737.10.camel@localhost.localdomain> (raw)
In-Reply-To: <200603012018.k21KIhi22006@candle.pha.pa.us>
References: <200603012018.k21KIhi22006@candle.pha.pa.us>
Ühel kenal päeval, K, 2006-03-01 kell 15:18, kirjutas Bruce Momjian:
> Stephan Szabo wrote:
> > > justify_days doesn't currently do anything with this result --- it
> > > thinks its charter is only to reduce day components that are >= 30 days.
> > > However, I think a good case could be made that it should normalize
> > > negative days too; that is, the invariant on its result should be
> > > 0 <= days < 30, not merely days < 30.
> >
> > What about cases like interval '1 month -99 days', should that turn into
> > interval '-3 mons +21 days' or '-2 mons -9 days'?
>
> I think it should be the later. It is best to have a single sign, and I
> think it is possible in all cases:
>
> '2 mons -1 days'
>
> could be adjusted to '1 mons 29 days'.
But unfortunately '2 mons -1 days' <> '1 mons 29 days'
If I want something to happen 1 day less than two months from dome date,
then the only way to say that consistently *is* '2 mons -1 days'.
--------------
Hannu
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To: pgsql-sql@postgresql.org
Cc: hannu@skype.net, pgman@candle.pha.pa.us, sszabo@megazone.bigpanda.com, tgl@sss.pgh.pa.us, milen@radev.net, pgsql-hackers@postgresql.org
Subject: Re: [SQL] Interval subtracting
In-Reply-To: <1141244920.3737.10.camel@localhost.localdomain>
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