From: | Andrew Borodin <borodin(at)octonica(dot)com> |
---|---|
To: | Greg Stark <stark(at)mit(dot)edu> |
Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Михаил Бахтерев <mob(at)k(dot)imm(dot)uran(dot)ru>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Михаил Бахтерев <mike(dot)bakhterev(at)gmail(dot)com> |
Subject: | Re: GiST penalty functions [PoC] |
Date: | 2016-09-10 18:19:16 |
Message-ID: | CAJEAwVFgUnE+hk8P0MCUmuzm05731jg2ZeqTA5stPPYUFQ8w-g@mail.gmail.com |
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Lists: | pgsql-hackers |
>Personally I wouldn't be very happy about an IEEE754 assumption.
Ok, so let's avoid autoconf man. There is no real explanations of the
ground for this assumption, just a reference to paper of David
Goldberg (and there is no metion about IEEE754 is absoulte
everywhere). BTW, may be we can ask David Goldberg how to hack that
float properly? I do not see any math sense in this:
pack_float(float actualValue, int realm)
{
...
int realmAjustment = *((int*)&actualValue)/4;
float something = *((float*)&realmAdjustment)
...
}
No wonder it's not in libs.
Nither I see a way to implement it with ldexp siblings.
>I did go to the trouble of testing Postgres on a VAX and we fixed the few
instances where it had such dependencies for a net gain.
Greg, could you please point out those places to see how exaclty it
should be #ifdef'd?
Regrads, Andrey Borodin.
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