Good morning Robert I presume that you are the acting project manager, in the sense of vetting changes or commentary. The pdf guide has only one statement concerning julian dates. I feel that more is required.
Julian dates are used as follows. Working days between two dates is (the difference of the day numbers * 5/7) , with minor adjustment for rounding and weekend start-end considerations. Julian date conversion is used for this type of calculation. It would be nice to see more in the manual about Julian dates, such as tests if a day is a weekend day, or to determine the day of the week for a specific Gregorian calendar date and vice-versa. Regarding the julian bug(let), I will raise it as a comment on the code buglist. ------------------ Regards Leslie Mr. Leslie Satenstein mailto:lsatenst...@yahoo.com mailto leslie.satenst...@itbms.biz / lesl...@itbms.biz www.itbms.biz --- On Wed, 12/29/10, Robert Haas <robertmh...@gmail.com> wrote: > From: Robert Haas <robertmh...@gmail.com> > Subject: Re: [DOCS] Some comments about Julian Dates and possible bug. Please > provide feedback. > To: "Leslie S Satenstein" <lsatenst...@yahoo.com> > Cc: "pgsql-docs" <pgsql-docs@postgresql.org> > Date: Wednesday, December 29, 2010, 6:58 AM > On Mon, Dec 27, 2010 at 9:23 PM, > Leslie S Satenstein > <lsatenst...@yahoo.com> > wrote: > > I found the Julian date code that is programmed in > Postgres, to be accurate and fast except for one situation. > But, I do have one or two questions. 1) Which calendar is > being used? > > > > In the Gregorian Calendar, January 1, 0001 is lowest > positive date. > > The day before 1/1/0001, according to the Gregorian > calendar is December 31,-0001 in which the year has a value > of negative one --- there is no zero year in the Gregorian > Calendar. (zero year is an error) > > > > I tested and found the algorithm in Postgres to have > the day before January 1,0001 calculating as December > 31,0000 even though the world calculates the day before > January 1,0001 as December 31,-0001. > > > > 2) Is the algorithm in Postgres correct? I think > not, as the calculations for the difference in days between > January 1, 0001 and December 31,-0001 is not 367 days, but > just the value 1. > > > > To convert the code to work with the Gregorian > calendar takes two fixes to two sub-routines. Each fix is > two lines of C code. > > > > I have tested the PG Date C language routines > with/without my fix, starting with the year around -4713 to > several centuries into the future. As long as both versions > calculate Julian dates that are later than 1/1/0001, both > the PG and my fixed versions respecting Gregorian algorithms > produce identical results. > > > > 3) Does PG want to fully follow the Gregorian Calendar > rule? If so, > > 4) do they want my one patch with two fixes6 > > This seems like it'd be more appropriate for pgsql-bugs or > pgsql-hackers rather than here. I can't really figure > out exactly > what change you're proposing, so I'm not entirely sure > whether it's > right or wrong. Perhaps you could post your patch, > and some examples. > > -- > Robert Haas > EnterpriseDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company > > -- > Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-docs > -- Sent via pgsql-docs mailing list (pgsql-docs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs
