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From "Mck SembWever (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-1034) Remove assumption that Key to Token is one-to-one
Date Sat, 20 Aug 2011 22:10:27 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13088280#comment-13088280
] 

Mck SembWever commented on CASSANDRA-1034:
------------------------------------------

What's the status on this? This issue and its relations back to CASSANDRA-2878 are the only
reason we're using OPP. I suspect other users setup with both cassandra and hadoop (or brisk)
could be in the same boat. Not only does OPP leave an unbalanced ring (i've had a case where
all data went to one node because the keys/tokens were longer than normal) it leaves poor
performance to hadoop jobs as tasks requirement on data locality has become stricter (w/ CASSANDRA-2388).

> 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: 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
>
>
> 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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