Re: [bailey-developers] Features and their design

[Yonik S. <yo...@ap...>]

On Tue, Mar 11, 2008 at 5:49 PM, Doug Cutting <cu...@ap...> wrote:
>  > An example application can be an online email system.
>  > The keys of a user's emails are prefixed by the user name,
>  > so a user's emails are located together on the ring. When
>  > a user searches his/her emails, the query is only sent to
>  > servers which cover that range, instead of the entire ring.
>
>  We could just define doc ids as 128-bit numbers rather than strings.
>  Then user-provided hash values wouldn't be a special case.  A
>  constructor could convert string ids to 128-bit ids, and also store the
>  original string in a field named "id".

Allowing the user to specify a hash value doesn't seem so different
from allowing them to specify a numeric id... it's just 32 bits vs 128
bits.  Ning's use case doesn't seem to require collision-free hashes.

Perhaps there are other advantages to a numeric id that also serves as
the hash though.

-Yonik

>  128-bits is big enough that we shouldn't see collisions.
>
>  http://en.wikipedia.org/wiki/Birthday_attack
>
>  By my reading, it would take over a trillion collections of a trillion
>  documents each before a collision is probable.