Re: [PATCHES] Bug: century/millenium still broken

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Bugs List <pgsql-bugs(at)postgresql(dot)org>, PostgreSQL Patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [PATCHES] Bug: century/millenium still broken
Date: 2004-08-20 03:45:17
Message-ID: 200408200345.i7K3jHu15657@candle.pha.pa.us
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Patch applied. Thanks.

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

Fabien COELHO wrote:
>
> Dear Tom,
>
> > After all that about numbering centuries and millenia correctly,
> > why does CVS tip still give me
> >
> > regression=# select extract(century from now());
> > date_part
> > -----------
> > 20
> > (1 row)
> > [ ... looks in code ... ]
> >
> > Apparently it's because you fixed only timestamp_part, and not
> > timestamptz_part. I'm not too sure about what timestamp_trunc or
> > timestamptz_trunc should do, but they may be wrong as well.
>
> Sigh... as usual, what is not tested does not work:-(
>
>
> > Could we have a more complete patch?
>
> Please find a submission attached. I hope it really fixes all decade,
> century and millenium issues for extract and *_trunc functions on interval
> and other timestamp types. If someone could check that the results
> are reasonnable, it would be great.
>
> I indeed overlooked the fact that there were two functions. The patch
> fixes the code so that both variants agree.
>
> I added comments to interval extractions, because it relies on the C
> division to have a negative remainder: -7/10 = 0 and remains -7.
>
> As for *_trunc functions, I have chosen to put the first year of the
> century or millennium: -100, 1, 101... 1001 2001 etc. Indeed, I don't
> think it would make sense to put 2000 (last year of the 2nd millennium)
> for rounding all years of the third millenium.
>
> I also fixed the code so that all decades last 10 years and decade 199
> means the 1990's.
>
> I have added some tests that are relevant to deal with tricky cases. The
> formula may be simplified, but all these cases must pass. Please keep
> them.
>
> Have a nice day,
>
> --
> Fabien Coelho - coelho(at)cri(dot)ensmp(dot)fr

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