From: Tom Lane <tgl@sss.pgh.pa.us>
To: Milen A. Radev <milen@radev.net>
Cc: pgsql-sql@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: [SQL] Interval subtracting
Date: Sat, 18 Feb 2006 13:30:14 -0500
Message-ID: <20402.1140287414@sss.pgh.pa.us> (raw)
In-Reply-To: <43F7330E.1060907@radev.net>
References: <200602181444.06009.milorad.poluga@cores.co.yu>
<43F72E27.2060408@radev.net>
<200602181536.20605.milorad.poluga@cores.co.yu>
<43F7330E.1060907@radev.net>
"Milen A. Radev" <milen@radev.net> writes:
> Milorad Poluga написа:
>>> SELECT '10 years 1 mons 1 days'::interval - '9 years 10 mons 15 days'::interval
>>> ?column?
>>> ---------------
>>> 3 mons -14 days
>>>
>>> Why not '2 mons 16 days' ?
> Please read the last paragraph in section 8.5.1.4 of the manual
> (http://www.postgresql.org/docs/8.1/static/datatype-datetime.html#AEN4775)
> . It mentions the functions named "justify_days" and "justify_hours"
> that could do what you need.
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. Similarly for justify_hours.
Comments anyone? Patch anyone?
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, milen@radev.net, pgsql-hackers@postgresql.org
Subject: Re: [SQL] Interval subtracting
In-Reply-To: <20402.1140287414@sss.pgh.pa.us>
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