Re: Hash function for numeric (WIP)

Neil Conway <neilc(at)samurai(dot)com> writes:
> On Sun, 2007-06-05 at 21:30 -0400, Tom Lane wrote:
>> It'd be a good idea if you repeat the previous number-of-collisions
>> experiment on this code.

> I repeated the same experiment, and got essentially the same number of
> collisions (829 collisions on ~2 million randomly generated numerics,
> with 273 duplicates). Since the modified hash still uses hash_any() and
> really only differs when there are leading/trailing zeros, this is
> consistent with what I'd expect.

Right, given that there presumably weren't any leading/trailing zeroes
in your sample, the digit hashing ought to be exactly the same. I was
just worried that the slightly different treatment of the weight might
somehow invalidate the results.

regards, tom lane