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Message-ID: <440EC8FF.9080201@logix-tt.com>
Date: Wed, 08 Mar 2006 13:07:27 +0100
From: Markus Schaber <schabi@logix-tt.com>
Organization: Logical Tracking and Tracing International AG, Switzerland
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To: Scott Marlowe <smarlowe@g2switchworks.com>
Cc: Bruce Momjian <pgman@candle.pha.pa.us>,
	Stephan Szabo <sszabo@megazone.bigpanda.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, "Milen A. Radev" <milen@radev.net>,
	pgsql-sql@postgresql.org, pgsql-hackers@postgresql.org
Subject: Re: [SQL] Interval subtracting
References: <200603012027.k21KRk423759@candle.pha.pa.us>
	<1141245396.18820.16.camel@state.g2switchworks.com>
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Hi, Scott,

Scott Marlowe wrote:

>>But it isn't '-2 months, -1 day'.  I think what you are saying is what I
>>am saying, that we should make the signs consistent.
> Pretty much.  It just seems wrong to have different signs in what is
> essentially a single unit.
> 
> We don't say 42 degrees, -12 minutes when measuring arc, do we?  Then
> again, maybe some folks do.  It just seems wrong to me.

But we say "quarter to twelve", at least in some areas on this planet.

The problem is that months have different lengths. '2 months - 1 day'
can be '1 month 27 days', '1 month 28 days', '1 month 29 days' or '1
month 30 days', depending on the timestamp we apply the interval.

Markus
-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org