Re: Support for dates before 4713 BC - Mailing list pgsql-general

From Tom Lane
Subject Re: Support for dates before 4713 BC
Date
Msg-id 4161384.1661105052@sss.pgh.pa.us
Whole thread Raw
In response to Support for dates before 4713 BC  ("Watzinger, Alexander" <Alexander.Watzinger@oeaw.ac.at>)
Responses Re: Support for dates before 4713 BC
List pgsql-general
"Watzinger, Alexander" <Alexander.Watzinger@oeaw.ac.at> writes:
> Any chance to add support for dates before 4713 BC? We really would appreciate that.

I'm a little skeptical of the value of applying the Gregorian calendar
before 1582 AD, let alone thousands of years before the Romans invented
anything looking even vaguely like it.

Are you sure there's going to be any point whatsoever in trying to name
individual days that far back?  ISTM you'd be lucky to assign a year
accurately.

> The 4713 BC limit feels very arbitrary, what is the reason for this exact limit?

There are existing equations for calculating Gregorian month/day/year from
Julian day count [1].  They work back to Julian day zero, at least if
you grant that proleptic Gregorian dates are sensible that far back.
Nobody around here has looked into whether they'd work for negative Julian
day numbers (I suspect not though, at least not without work that seems
rather pointless).

            regards, tom lane

[1] https://en.wikipedia.org/wiki/Julian_day



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