Re: [BUGS] BUG #2846: inconsistent and confusing

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Roman Kononov <kononov195-pgsql(at)yahoo(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [BUGS] BUG #2846: inconsistent and confusing
Date: 2006-12-28 01:45:33
Message-ID: 200612280145.kBS1jXS17301@momjian.us
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Roman Kononov wrote:
> On 12/27/2006 05:19 PM, Tom Lane wrote:
> > Roman Kononov <kononov195-pgsql(at)yahoo(dot)com> writes:
> >> On 12/27/2006 03:23 PM, Bruce Momjian wrote:
> >>> Are you sure? As I remember, computation automatically upgrades to
> >>> 'double'. See this program and output:
> >
> >> This is platform- and compiler- dependent:
> >
> > ... and probably irrelevant, too. We should store the result into a
> > float4 variable and then test for isinf() on that; that eliminates the
> > question of whether the compiler did the multiply in a wider format or
> > not.
>
> You are right provided that you want to ignore underflows and silently
> produce zeros instead.
>
> If you go this way, I recommend to ignore overflows as well, and silently
> produce infinities and NaNs.

While IEEE seems fine with that, I don't think this is good for SQL. It
is best to produce a meaningful error. The major issue is that our
current code is buggy because it doesn't have consistent behavior, as
Roman outlined.

--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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