
Can Hash Tables really be O(1)? - tosh
http://stackoverflow.com/questions/2771368/can-hash-tables-really-be-o1
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dekhn
I remember a guy insisting hash tables were o(1). The resulting argument
taught me a lot about computer science and its lack of relationship to
reality- hash tables are only o(1) under very limited conditions which are
uncommon.

Most of the hash tables I've used- ones that ran large-scale machine learning
systems with sparse data- depend greatly on the nature of the hashed item, and
much less on the length of the chains.

