[webkit-dev] Git meeting notes

Maciej Stachowiak mjs at apple.com
Tue Apr 13 00:18:23 PDT 2010

On Apr 12, 2010, at 9:44 PM, Maciej Stachowiak wrote:

> On Apr 12, 2010, at 8:15 PM, Timothy Hatcher wrote:
>> Only the first 5-7 characters are needed to identify a single  
>> commit (enough of the hash prefix to be unique). So REGRESSION 
>> (96c3b0) vs REGRESSION(r12345).
> How long will 7 characters last before you hit the birthday paradox?

And to answer my own question (because I'm a nerd), a 7 hex digit hash  
prefix has a 50% chance of at least one pair of revisions colliding  
when there are at least 19290 revs. So we're already past the birthday  
paradox threshold to be using only 7 digits (assuming the hashes are  
uniformly distributed).

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