Re: [HACKERS] regressin failure on latest CVS

Rocco Altier wrote:
> That still does not fix it for me.
>
> This patch is still using a computed float value (month_remainder and
> day_remainder), which is cauing the rounding errors.
>
> There are now 6 machines on the build farm that are failing from the
> rounding:
> Wallaroo (OSX/G4), asp(AIX/powerpc), viper(FC3/x86_64),
> platypus(FBSD/amd64), kookaburra(AIX/powerpc), oriole(FC4/x86).
>
> All of these are using enable-integer-datetimes.
>
> What was wrong with the patch I sent? I am doing as much as I can with
> integer math.

OK, new patch, please test. Yea, I know your patch works, but we
usually keep at it until we have a clean, understood solution. Thanks.

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

>
> -rocco
>
> > -----Original Message-----
> > From: Bruce Momjian [mailto:pgman(at)candle(dot)pha(dot)pa(dot)us]
> > Sent: Saturday, July 23, 2005 2:51 PM
> > To: Rocco Altier
> > Cc: Michael Glaesemann; pgsql-patches(at)postgresql(dot)org; ohp(at)pyrenet(dot)fr
> > Subject: Re: [HACKERS] regressin failure on latest CVS
> >
> >
> >
> > Would you please try the attached patch and let me know if it
> > fixes the
> > problem? I avoided accumulating into a float8.
> >
> > --------------------------------------------------------------
> > -------------
> >
> > Rocco Altier wrote:
> > > This still does not fix the problem.
> > >
> > > I had done my patch to try to mimic the way 8.0 had handled the math
> > > with the remainders, but to carry it over another bucket (day).
> > >
> > > The problem that I see is that we are taking day_remainder and
> > > multiplying by USECS_PER_DAY. Which is a double * int64,
> > thus there is
> > > the precision loss there.
> > >
> > > I think initial division by the factor can't be helped, but
> > repeatedly
> > > doing more floating point math on with it is causing the
> > rounding error.
> > >
> > > Thanks,
> > > -rocco
> > >
> > > > -----Original Message-----
> > > > From: Bruce Momjian [mailto:pgman(at)candle(dot)pha(dot)pa(dot)us]
> > > > Sent: Saturday, July 23, 2005 10:54 AM
> > > > To: Rocco Altier
> > > > Cc: Michael Glaesemann; pgsql-patches(at)postgresql(dot)org;
> > > > pgsql-hackers(at)postgresql(dot)org; ohp(at)pyrenet(dot)fr
> > > > Subject: Re: [HACKERS] regressin failure on latest CVS
> > > >
> > > >
> > > > Rocco Altier wrote:
> > > > > This patch fixes the interval regression on my AIX box
> > > > (kookaburra) by
> > > > > only doing integer math on the interval, instead of
> > > > float/double math.
> > > > >
> > > > > I think this is the correct way to handle this, since it's
> > > > an integer
> > > > > data type.
> > > > >
> > > > > I don't know if it will fix Olivier's problem, since I
> > > > wasn't able to
> > > > > reproduce it.
> > > > >
> > > >
> > > > I have changed the way I compute the remainder values ---
> > instead of
> > > > using multiplication, I use division and then subtraction.
> > > > This should
> > > > fix your rounding problem. Looking at your fix, I don't see
> > > > how adding
> > > > USECS changes things because the factor is already a float,
> > > > but I think
> > > > the problem was more the way I was computing the remainders.
> > > >
> > > > Patch attached --- let me know if it does not fix your problem.
> > > >
> > > > --------------------------------------------------------------
> > >
> > >
> > > ---------------------------(end of
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> > >
> >
> > --
> > Bruce Momjian | http://candle.pha.pa.us
> > pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
> > + If your life is a hard drive, | 13 Roberts Road
> > + Christ can be your backup. | Newtown Square,
> > Pennsylvania 19073
> >
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073