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Subject: Hashing idea

Author: Dann Corbit

Date: 11:02:28 02/26/99


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.



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