Thank you, but I have some notices about
static float
uuid_parts_distance(pg_uuid_t *a, pg_uuid_t *b)
{
pg_uuid_t ua, ub;
const double mp = pow(2, -64);
uuid_cnv(a, &ua);
uuid_cnv(b, &ub);
Assert(ua.v64[0] > ub.v64[0]);
uint64 high = ua.v64[0] - ub.v64[0];
uint64 low = ua.v64[1] - ub.v64[1];
if (low > ua.v64[1])
high--;
return (float) (ldexp(high, 64) + (double) low * mp);
}
First, variables (high and low) should not be declared in the middle of code.
Second, assert will fail if ua.v64[0] == ub.v64[0] and
ua.v64[1] > ub.v64[1] although it's a possible and allowed case. Third, actually
you multiply high value by 2^64 anf low by 2^-64. Seems, it's needed to do only
one multiplication.
Ildus Kurbangaliev wrote:
On Wed, 23 Dec 2015 16:36:23 -0800
Paul Jungwirth <p...@illuminatedcomputing.com> wrote:
On 12/23/2015 08:10 AM, Ildus Kurbangaliev wrote:
There is a more improved version of the patch. Main idea is to
present uuid as two uint64 values, and make comparisons and penalty
calculation based on these values. This approach is much faster
than using memcmp for uuid comparisons.
Thank you for picking this up! I'm sorry I was not able to work on it
the last few months. I'm very glad to see someone wrapping it up. I'm
not a reviewer, but personally it looks like a good change to me.
Happy holidays,
Paul
Thanks! The patch was almost done and ready. I attached new version of
the patch with compability changes.
--
Teodor Sigaev E-mail: teo...@sigaev.ru
WWW: http://www.sigaev.ru/
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