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Date: Tue, 7 Feb 2012 23:46:59 +0000 (UTC)
From: "Jonathan Ellis (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (CASSANDRA-2917) expose calculate midrange for
 token in jmx
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    [ https://issues.apache.org/jira/browse/CASSANDRA-2917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202970#comment-13202970 ] 

Jonathan Ellis commented on CASSANDRA-2917:
-------------------------------------------

Thanks for the patch, Sam!

I think that like the bootstrap token calculator we want to skip the System keyspace here.  I've added a followup patch that does that over on https://github.com/jbellis/cassandra/tree/2917, with some refactoring to use the more-efficient CFS.keySamples method.  What do you think?

(P.S. As a style note, I also dropped the Transform business -- while I'm a fan of functional programmming, it's not always a great fit in Java and for simple cases like this is substantially more verbose than the imperative version.)

                
> expose calculate midrange for token in jmx
> ------------------------------------------
>
>                 Key: CASSANDRA-2917
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2917
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jackson Chung
>            Priority: Minor
>              Labels: lhf
>         Attachments: trunk-2917.txt
>
>
> currently there is no easy way to get midrange, especially for OPP. For simplicity, you could call OrderPreservingPartitioner.midpoint(Token, Token), that gives you a rough estimate (and you'd still need to remove non-utf8 characters.)
> A more accurate but difficult way is to sample the keys in that range and pick the midpoint of those. We should expose that via jmx, because without this, supporting OPP w/o this is quite challenging.

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