Re: [HACKERS] Interval aggregate regression failure (expected seems - Mailing list pgsql-patches

From Tom Lane
Subject Re: [HACKERS] Interval aggregate regression failure (expected seems
Date
Msg-id 27584.1157312867@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Interval aggregate regression failure  (Bruce Momjian <bruce@momjian.us>)
Responses Re: [HACKERS] Interval aggregate regression failure
List pgsql-patches
Bruce Momjian <bruce@momjian.us> writes:
> Is this non-datetime integer only or both?  I cannot reproduce the
> failure here.

On HPPA with float datetimes with today's code, Michael's case works
but it took me less than two minutes to find one that doesn't:

regression=# select interval '14 mon' * 8.2 as product_h;
            product_h
---------------------------------
 9 years 6 mons 23 days 24:00:00
(1 row)

I reiterate my comment that this approach will never work; any small
amount of experimentation will turn up cases that don't round correctly
on one platform or another.  Float arithmetic is inherently inexact.

            regards, tom lane

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