Re: horo(r)logy test fail on solaris (again and solved)

On Wed, Sep 27, 2006 at 04:09:18PM +0200, Zdenek Kotala wrote:
> Tom Lane napsal(a):
> >Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
> >>The problem was generated, because -fast option was set only for the 
> >>compiler and not for the linker. Linker takes wrong version of 
> >>libraries. If   -fast is set for both then horology test is OK, but 
> >>question was if float optimalization should generate some problems.
> >
> >So FAQ_Solaris needs to tell people to put -fast in both CFLAGS and
> >LDFLAGS?
> 
> Exactly, but I want to sure, that float optimalization is safe and 
> should be applied for postgres, because -fast breaks IEE754 standard. If 
> it is OK I will adjust FAQ_Solaris.
> 
>     Zdenek
> 
Unless the packager understands the floating point usage of every
piece and module included and the effect that the -fast option will
have on them, please do not recommend it for anything but extremely
well tested dedicated use-cases. When it causes problems, it can
be terrible if the problems are not detected immediately. Massive
data corruption could occur.

Given these caveats, in a well tested use-case the -fast option can
squeeze a bit more from the CPU and could be used. I have had to
debug the fallout from the -fast option in other software in the
past. Let's just say, backups are a good thing.

I would vote not to recommend it without very strong cautions similar
to was Sun includes in the compiler manual pages.

Ken