Incongruent hash

Georg Gollmann gollmann at edvz.tuwien.ac.at
Mon Feb 9 15:31:51 UTC 1998


At 10:02 Uhr -0500 09.02.1998, David N. Smith wrote:
>Most hash algorithms are way too simple. Take, for example, the hash for
>strings in Squeak:
....
>So, basically it looks at most at two characters. This makes for quick
>hashes, but poor hashing. What one saves by doing a poor hash one then
>probably throws away by having a lot of values hash to the same spot in the
>collection. This forces the collection to search (and search and search)
>sequentially looking for an empty spot.

String>crc16 has made it into 1.3. Maybe we could/should switch over to
that. It is a bit tricky though since one is pulling the rug from under the
running system.

Georg

----
Dipl.Ing. Georg Gollmann                   TU-Wien, EDV-Zentrum

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