Re: [bailey-developers] SF.net SVN: bailey: [10] trunk/src

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

On Tue, Mar 18, 2008 at 11:01 AM, Ning Li <nin...@gm...> wrote:
> On Mon, Mar 17, 2008 at 7:28 PM, Yonik Seeley <yo...@ap...> wrote:
>  > Or did you mean represent the hash as a String?
>
>  Yes. :)

Ah, OK... so like a variable length int.
The ring management and passing of ranges with Strings would be easy enough,
but depending on what needs to be done on a node, it may be less efficient.

For example, to find a range of hashes (say to split of a piece for
rebalancing) we would probably use either the FieldCache, or a colum
stored field (upcoming) in Lucene, both of which would be more
efficient as an int.

>  Converting a string to a number while maintaining the string order,
>  on the other hand, is difficult.

If one wants each user in an email system to span a maximum of 1/8th
of the ring then the
hash could be hash =  (username.hashCode() << 29) | (id.hashCode() >> 3)

Or if the number of emails per user is small, hash = username.hashCode()

-Yonik