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Date: Mon, 3 Feb 2014 14:24:15 +0000 (UTC)
From: "Marcus Eriksson (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Commented] (CASSANDRA-5351) Avoid repairing
 already-repaired data by default
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    [ https://issues.apache.org/jira/browse/CASSANDRA-5351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13889498#comment-13889498 ] 

Marcus Eriksson commented on CASSANDRA-5351:
--------------------------------------------

if its unclear, purpose of the Prepare step is that we want to do anticompaction on all ranges involved in the repair, if we did not do that, we would have to anticompact 3 times for a "nodetool repair" with RF=3 (and 3*256 times with 256 vnodes (i think))

> Avoid repairing already-repaired data by default
> ------------------------------------------------
>
>                 Key: CASSANDRA-5351
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5351
>             Project: Cassandra
>          Issue Type: Task
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Lyuben Todorov
>              Labels: repair
>             Fix For: 2.1
>
>         Attachments: 5351_node1.log, 5351_node2.log, 5351_node3.log, 5351_nodetool.log
>
>
> Repair has always built its merkle tree from all the data in a columnfamily, which is guaranteed to work but is inefficient.
> We can improve this by remembering which sstables have already been successfully repaired, and only repairing sstables new since the last repair.  (This automatically makes CASSANDRA-3362 much less of a problem too.)
> The tricky part is, compaction will (if not taught otherwise) mix repaired data together with non-repaired.  So we should segregate unrepaired sstables from the repaired ones.


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