Re: Interval aggregate regression failure (expected seems - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Interval aggregate regression failure (expected seems
Date
Msg-id 200511150307.jAF37nN25508@candle.pha.pa.us
Whole thread Raw
In response to Re: Interval aggregate regression failure (expected seems  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> Michael Paesold <mpaesold@gmx.at> writes:
> > Would you mind reporting this to RedHat Bugzilla? I believe a bug report 
> > from you would have more weight then mine, because you actually 
> > understand what's going on here. :-)
> 
> Actually, given the thought that this may be an artifact of keeping an
> intermediate value in a wider-than-normal register rather than genuinely
> rearranging the computation, I'm not certain it is a compiler bug.
> We'd have to study it a lot more closely before filing it as one, anyway.
> 
> If you accept the idea that the pentium4 answer is the right one,
> then what we really need to do is focus on a better rounding rule than
> "strict truncation".  I was toying with the notion of adding the
> equivalent of half a microsecond to the fractional-day value before
> truncating it to integer.  But I'm not certain that that wouldn't have
> some bad effects in other cases.

Looking at the code, do we need additional rint() calls in there, or
rint(x + 0.5)?  Frankly, I am confused why interval_div() has caused
such problems for us?  Are we going at this the right way?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


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