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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-1034) Remove assumption that Key to Token is one-to-one
Date Fri, 08 Apr 2011 20:57:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13017638#comment-13017638
] 

Jonathan Ellis commented on CASSANDRA-1034:
-------------------------------------------

bq. RP.toSplitValue() returns for a given token the value that splits the range: for a token
range it's the token itself, but for a DK range, it's the largest DK having this token. The
null keys is related: even though we don't mix DK and token in range, we need to be able to
have a range of DK that includes everything from x token to y token

This feels messy and error-prone to me. I wonder if we haven't found the right approach yet.

> 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: Sylvain Lebresne
>            Priority: Minor
>             Fix For: 0.8
>
>         Attachments: 0001-Generify-AbstractBounds.patch, 0001-Make-range-accept-both-Token-and-DecoratedKey.patch,
0002-LengthPartitioner.patch, 0002-Remove-assumption-that-token-and-keys-are-one-to-one-v2.patch,
0002-Remove-assumption-that-token-and-keys-are-one-to-one.patch, 1034_v1.txt
>
>
> 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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