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https://issues.apache.org/jira/browse/CASSANDRA-1034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13125379#comment-13125379
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T Jake Luciani commented on CASSANDRA-1034:
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@Sylvain This is all really confusing and I agree the core of the ticket is to 
make key->token 1:1

The core of the problem initially was explained in CASSANDRA-1733

bq. A Range object (which Hadoop splits generate) is start-exclusive. A Bounds 
object (which normal user scan queries generate) is start-inclusive.

So by making Token the only way to deal with keys it feels like a more 
consistent api.  Since Key can be null it needs to be Token that becomes the 
primary internal class. 

In your impl we now have DK, Token, RingPosition which too me is more confusing 
than having one Token class.



                
> Remove assumption that Key to Token is one-to-one
> -------------------------------------------------
>
>                 Key: CASSANDRA-1034
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1034
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Stu Hood
>            Assignee: Pavel Yaskevich
>            Priority: Minor
>             Fix For: 1.1
>
>         Attachments: 
> 0001-Make-range-accept-both-Token-and-DecoratedKey.patch, 
> 0002-LengthPartitioner.patch, 1034-1-Generify-AbstractBounds-v3.patch, 
> 1034-2-Remove-assumption-that-token-and-keys-are-one-to-one-v3.patch, 
> 1034_v1.txt, CASSANDRA-1034.patch
>
>
> get_range_slices assumes that Tokens do not collide and converts a KeyRange 
> to an AbstractBounds. For RandomPartitioner, this assumption isn't safe, and 
> would lead to a very weird heisenberg.
> Converting AbstractBounds to use a DecoratedKey would solve this, because the 
> byte[] key portion of the DecoratedKey can act as a tiebreaker. 
> Alternatively, we could make DecoratedKey extend Token, and then use 
> DecoratedKeys in places where collisions are unacceptable.

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