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https://issues.apache.org/jira/browse/CASSANDRA-13052?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stefan Podkowinski updated CASSANDRA-13052:
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    Attachment: 13052-2.1.patch

> Repair process is violating the start/end token limits for small ranges
> -----------------------------------------------------------------------
>
>                 Key: CASSANDRA-13052
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13052
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Streaming and Messaging
>         Environment: We tried this in 2.0.14 and 3.9, same bug.
>            Reporter: Cristian P
>            Assignee: Stefan Podkowinski
>         Attachments: 13052-2.1.patch, ccm_reproduce-13052.txt, 
> system-dev-debug-13052.log
>
>
> We tried to do a single token repair by providing 2 consecutive token values 
> for a large column family. We soon notice heavy streaming and according to 
> the logs the number of ranges streamed was in thousands.
> After investigation we found a bug in the two partitioner classes we use 
> (RandomPartitioner and Murmur3Partitioner).
> The midpoint method used by MerkleTree.differenceHelper method to find ranges 
> with differences for streaming returns abnormal values (way out of the 
> initial range requested for repair) if the repair requested range is small (I 
> expect smaller than 2^15).
> Here is the simple code to reproduce the bug for Murmur3Partitioner:
> Token left = new Murmur3Partitioner.LongToken(123456789L);
> Token right = new Murmur3Partitioner.LongToken(123456789L);
> IPartitioner partitioner = new Murmur3Partitioner();
> Token midpoint = partitioner.midpoint(left, right);
> System.out.println("Murmur3: [ " + left.getToken() + " : " + 
> midpoint.getToken() + " : " + right.getToken() + " ]");
> The output is:
> Murmur3: [ 123456789 : -9223372036731319019 : 123456789 ]
> Note that the midpoint token is nowhere near the suggested repair range. This 
> will happen if during the parsing of the tree (in 
> MerkleTree.differenceHelper) in search for differences  there isn't enough 
> tokens for the split and the subrange becomes 0 (left.token=right.token) as 
> in the above test.



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