Author: Bruce Moreland
Date: 12:00:11 02/26/99
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On February 26, 1999 at 14:02:28, Dann Corbit wrote: >I have a notion about hashing I thought I might toss out. > >If you took (say) a 20 bit hash to create a million element table, those table >entries could be LRU caches instead of just lists. Each LRU cache would keep >the hottest entries on top, and the old ones would get flushed to disk. My >notion is to create a permanent hash file of (x) terabytes. I know that >conceivably, it would rapidly grow to infinite size. I doubt if that is >practially the case, however, since the real number of chess positions examined >in games is definitely very finite. > >Dumb idea? I know disk is thousands of times slower than ram, but if cache hits >were high it seems it might be a good idea [probably need a few hundred megs of >physical ram to make it practical]. Basically, you would never have a hash >collision. Either the position is there calculated already or it is not, and if >not, then you calc it and save it. I don't think this would work for beans. If you play a game, your hash table eventually fills up. If you play another one, it fills up, but with different stuff. The entries are shared, but the positions are radically different. After a few games you have lots of different entries for each hash element, none of which will ever happen again, practically. Now you are stuck doing a disk access per node, which is no fun. bruce
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