Re: timestamp patch to extend legal range of dates. - Mailing list pgsql-patches

On Tue, 2003-02-04 at 04:41, Tom Lane wrote:
> John Cochran <jdc@fiawol.org> writes:
> > Here is a patch that modifies how timestamp values are generated and
> > extends the legal range of timestamps. The overall effect is:
> >   1. For dates prior to Oct 15, 1582 it uses the Julian calendar.
> >   2. For dates on and after Oct 15, 1582, it uses the Gregorian calendar.
> >
> > The decision to have the switchover point be Oct 15, 1582 was made to cause
> > the new routines return the same values as the old routines for the largest
> > possible range. I did consider having the switchover be Sept 14, 1752 to
> > be consistent with Unix, but decided against it.
>
> This seems like rather an odd choice.  Isn't the 1752 date commonly
> recognized as the start of Gregorian dating?

In the 6th Century, Bede proposed a more accurate calendar than the
Julian calendar introduced by Julius Caesar.  In 1582, Pope Gregory
accepted a similar proposal and ordered the change across all the
Catholic world.  Since England had rejected papal authority and the pope
was encouraging Catholic powers to attack England, his order was not
effective here, nor in some other protestant countries.  It actually
took effect that year in France, Spain, Portugal and the Italian states;
parts of Germany, Belgium, the Netherlands, and Switzerland changed
within a couple of years and Hungary in 1587.  The Protestant parts of
Germany changed in 1700.

In 1752, England adopted the Gregorian calendar at last, causing popular
unrest ("Give us back our 11 days!").  The American colonies adopted it
at the same time.  Sweden changed in 1753 and Russia in 1918.

In 1751/2 England also changed from a new year date of 25th March to 1st
January as part of the same calendar change.  (The Inland Revenue didn't
change, which is why our tax year starts on April 6th.)  So in England
and America, 1751 ran from 25th March to 31st December; 1752 ran from
1st January to 2nd September and then 14th September to 31st December.
24th March 1750 was one day before 25th March 1751.

All of which adds up to: which you choose depends on what you are using
the date for.  Historical records of Catholic coutries need 1582; those
of England and English colonies need 1752.  Does anyone know how
historians cope when tracking both together?

--
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight, UK                             http://www.lfix.co.uk/oliver
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