in reply to Re: [OT] The statistics of hashing. (birthday)
in thread [OT] The statistics of hashing.
Odds Inserts ---- ------- 1% ~28e6 10% ~45e6 50% ~65e6 90% ~83e6 99% ~96e6
By those values, the odds against not having seen a duplicate by the time you reached 100 million inserts are so low as to be a pretty damn good definition of 'impossible'.
And yet, empirically, none had been seen by the time I reached 779,967,210.
And after 1.5 billion inserts, that calculation suggests that the odds of finding a value that doesn't match would be minuscule, and the "possible dups" count should be growing at almost the same rate as the new inserts are being tested.
The reality is that I've only had 1323 collisions after 1.5 billion inserts. These are the last 8:
... 1585072919 1585138596 1585355107 1585418593 1585422956 1585468018 1585558107 1585577984
They are coming much more regularly now, but they are actually still within the bounds of usability.
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Re^3: [OT] The statistics of hashing. (4<10)
by tye (Sage) on Apr 01, 2012 at 19:00 UTC | |
by BrowserUk (Patriarch) on Apr 01, 2012 at 19:39 UTC | |
by tye (Sage) on Apr 01, 2012 at 21:32 UTC | |
by BrowserUk (Patriarch) on Apr 01, 2012 at 21:56 UTC | |
by tye (Sage) on Apr 01, 2012 at 22:17 UTC |