[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Hash Tables vs. Alists

I ran some timing tests in Symbolics 6.1 (pre Genera) and found that alist
searching was better than hash tables when the number of keys was less than
75 or so.  This test used EQ and did not include the little extras like GC
overhead and the gork that transpired when worlds were saved and restored.
My guess is that the break even point would be much higher if all things
were considered.
	As to the fact that Genera skillfully switches representation: don't
forget that there is a significant overhead for going into and out of generic
functions, flavor methods, flavor functions, etc., to finally let the machine
coded alist search hum away.  I too would like to know where the current
trade off is since I quite using hash tables except for monsters.