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https://issues.apache.org/jira/browse/CASSANDRA-193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12777156#action_12777156
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Jun Rao commented on CASSANDRA-193:
-----------------------------------

Another complexity arises because you assume that the ranges in 2 different 
Merkle trees are different. Why can't you first build the key ranges from a 
sample of the keys in one node and then reuse those key ranges to build a 
Merkle on every replica? That would simplify both the computation and the diff 
of the hash values.

> Proactive repair
> ----------------
>
>                 Key: CASSANDRA-193
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-193
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Stu Hood
>             Fix For: 0.5
>
>         Attachments: 193-1-tree-preparation.diff, 193-2-tree.diff, 
> 193-3-aes-preparation.diff, 193-4-aes.diff, mktree-and-binary-tree.png
>
>
> Currently cassandra supports "read repair," i.e., lazy repair when a read is 
> done.  This is better than nothing but is not sufficient for some cases (e.g. 
> catastrophic node failure where you need to rebuild all of a node's data on a 
> new machine).
> Dynamo uses merkle trees here.  This is harder for Cassandra given the CF 
> data model but I suppose we could just hash the serialized CF value.

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