On Tue, 27 Jul 2010 15:43:47 -0400 zMan <zedgarhoo...@gmail.com> wrote:
:>OK, I have a splitting headache and may be dense anyway: how is it easier to :>look it up once it's hashed? What am I missing? Not easier, faster. Assume 100000 strings. A serial search will take on average 50000 compares. A mod64 hash should reduce it on average to under 800 compares, hash to slot and run the alias chain. A b-tree would be better but then there is the issue of balancing it while others are busy transversing it. :>On Tue, Jul 27, 2010 at 3:36 PM, Binyamin Dissen <bdis...@dissensoftware.com :>> wrote: :>> On Tue, 27 Jul 2010 15:32:24 -0400 zMan <zedgarhoo...@gmail.com> wrote: :>> :>What's the goal of the hashing -- obfuscation? Shortening the data? :>> Lookup. :>> Does the entry exist, and if so what are its attributes. If does not exist, :>> add. :>> :>On Tue, Jul 27, 2010 at 3:18 PM, Binyamin Dissen < :>> bdis...@dissensoftware.com :>> :>> wrote: :>> :>> Is there a preferred hashing algorithm for such strings? The strings :>> will :>> :>> be :>> :>> fixed length with trailing blanks. :>> :>> I was thinking of simply doing a MOD64 (or higher) of the sum of the :>> :>> non-blank :>> :>> part of the string by words, but as this is text with a limited :>> character :>> :>> set, :>> :>> would this lead to excessive alias chains? Has research been done in :>> this :>> :>> area? There will mostly be search activity but also add activity. -- Binyamin Dissen <bdis...@dissensoftware.com> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
