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From "Jonathan Ellis (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2917) expose calculate midrange for token in jmx
Date Tue, 07 Feb 2012 23:46:59 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202970#comment-13202970
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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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