Re: Multi calendar system for pgsql

m(dot)alimomeni(at)gmail(dot)com (Mohsen Alimomeni) writes:
> I want to try to add a multi calendar system for pgsql. I want to
> know if it will be accepted as a patch to pgsql?

I would expect there to be nearly zero chance of such, at least in the
form of a change to how dates are stored.

As long as there is commonality in epochs and some continuity of
calculations of dates relative to epochs, there shouldn't be any
fundamental problem in adding on functions to do the following sorts
of things:

- Calculate what the UNIX date is for a given date in a given
calendar

- Output a UNIX date in the form indicated by a given calendar

You should avail yourself of the book, _Calendrical Calculations_, by
Edward M Reingold and Nachum Deerschowitz; it presents details of
calculations and conversions of dates between the following calendars:

- Gregorian
- Julian
- Coptic
- Ethiopic
- ISO
- Islamic
- Hebrew
- Ecclesiastical Calendars, for dates of Christian holidays such as Easter
- Old Hindu
- Modern Hindu
- Mayan
- Balinese Pawukon
- Persian
- Baha'i
- French Revolution
- Chinese

It would seem a whole lot preferable to create functions like (and
there may be better names!):

create function parse_date (locale, text) returns timestamp
create function output_date (local, timestamp) returns text

Thus, you might expect the following:

select parse_date('Islamic', 'Miharram 1, AH 1');

parse_date
-------------------------
622-07-16 00:00:00

Or

select output_date('Persian', '622-03-19'::timestamp);

output_date
-------------------------
1 Farvardin AH 1

(It is entirely likely that I'm fracturing spellings of things!
Apologies if I am!)

http://emr.cs.uiuc.edu/home/reingold/calendar-book/index.shtml
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