Author: Daniel Clausen
Date: 12:58:51 12/09/99
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Hi On December 09, 1999 at 15:46:54, Dann Corbit wrote: >If I make a hash key of n bits, how can I make a smaller hash table than 2^n. > >I don't get it. (e.g. My question about shrinking the hash table was met with >"It does not matter how small the table is -- it is the size of the key that >matters."). This caused me to wonder why my brain is so tiny. I mean, how can >I have a hash table with a great big key and not allocate enough space to hold >it? Do you have a smaller hash leader (half-key, quarter-key, whatever) and then >throw the rest into a list of some kind? If you have a hash key of e.g 64 bits and a good algorithm to create it, all bits are of 'equal quality'. So you can for example use the 1st 20 bits for the index in a hash table of 2^20 entries. The index in the hashtable is "key & (hashEntries-1)". One hash entry should hold the complete hashkey. If you get a hash-hit, you should compare the complete hash-key in the hash table with the hash-key of the current position. If they're not equal, you got a collision. Kind regards, -sargon
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