Re: Imprecision of DAYS_PER_MONTH - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Imprecision of DAYS_PER_MONTH
Date
Msg-id 200507220506.j6M56cL08183@candle.pha.pa.us
Whole thread Raw
In response to Re: Imprecision of DAYS_PER_MONTH  ("Dann Corbit" <DCorbit@connx.com>)
List pgsql-hackers
Dann Corbit wrote:
> 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.


We can look at improving these numbers, but that is more of a behavior
change rather than a code clarity change, and I am not sure we want to
get into that now.  I will add a TODO to review this for 8.2.

---------------------------------------------------------------------------


> 
> > -----Original Message-----
> > From: pgsql-hackers-owner@postgresql.org [mailto:pgsql-hackers-
> > owner@postgresql.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@candle.pha.pa.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@candle.pha.pa.us               |  (610) 359-1001
> >   +  If your life is a hard drive,     |  13 Roberts Road
> >   +  Christ can be your backup.        |  Newtown Square, Pennsylvania
> > 19073
> > 
> > ---------------------------(end of
> broadcast)---------------------------
> > TIP 4: Have you searched our list archives?
> > 
> >                http://archives.postgresql.org
> 

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


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