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Re: Imprecision of DAYS_PER_MONTH

From: "Dann Corbit" <DCorbit(at)connx(dot)com>
To: "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>,"Greg Stark" <gsstark(at)mit(dot)edu>
Cc: "Tino Wildenhain" <tino(at)wildenhain(dot)de>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org>,"Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
Subject: Re: Imprecision of DAYS_PER_MONTH
Date: 2005-07-21 20:47:29
Message-ID: D425483C2C5C9F49B5B7A41F8944154757CF3F@postal.corporate.connx.com (view raw or flat)
Thread:
Lists: pgsql-hackers
In round figures:

Since there are 365.2422 days per tropical year, there are 31556926
seconds per year (give or take leap seconds).

Ref:
http://www.grc.nasa.gov/WWW/K-12/Numbers/Math/Mathematical_Thinking/cale
ndar_calculations.htm


So 31557600 seems to be off by quite a bit.

> -----Original Message-----
> From: pgsql-hackers-owner(at)postgresql(dot)org [mailto:pgsql-hackers-
> owner(at)postgresql(dot)org] On Behalf Of Bruce Momjian
> Sent: Thursday, July 21, 2005 1:35 PM
> To: Greg Stark
> Cc: Tino Wildenhain; Tom Lane; PostgreSQL-development; Marc G.
Fournier
> Subject: Re: [HACKERS] Imprecision of DAYS_PER_MONTH
> 
> Greg Stark wrote:
> >
> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> >
> > > > > BTW, if you actually wanted to improve readability, defining a
> > > > > SECS_PER_YEAR value and replacing the various occurrences of
> > > > > "36525 * 864" with it would help.
> > > > >
> > > > IIRC the number of seconds in a year is far from a constant.
> > >
> > > Yes, I added a comment mentioning that we don't track leap
seconds.
> > > And this doesn't handle crossing uneven daylight savings time
> intervals.
> >
> > It doesn't even represent leap years, never mind leap seconds.
> 
> Good, point, mention added.
> 
> --
>   Bruce Momjian                        |  http://candle.pha.pa.us
>   pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
>   +  If your life is a hard drive,     |  13 Roberts Road
>   +  Christ can be your backup.        |  Newtown Square, Pennsylvania
> 19073
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