This gets worse before it gets better. You can actually use a linear combination of two hashes (for Bloom filters, not in general).
See http://en.wikipedia.org/wiki/Double_hashing On Mon, Apr 19, 2010 at 2:48 PM, Benson Margulies <[email protected]>wrote: > I just had to set up a Bloom filter. I found a seemingly cogent > implementation by one Bruno Martins, but it has a design decision that I > found difficult to swallow. > > To get the multiple hashes, he: > > 1: used Rabin fingerprints to get an hash. > 2: rehashed that hash with varying seeds to get the multiple hashes. > > In bear-of-little-brain mode, this struck me as approximately nuts. The > initial hash already threw out a ton of information. So how can messing > with > it further give truly distinctive slices? >
