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Date: Tue, 4 Feb 2014 06:20:16 +0000 (UTC)
From: "Yuki Morishita (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.12637095.1363298653424.32471.1391494816645@arcas>
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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=13890438#comment-13890438 ] 

Yuki Morishita commented on CASSANDRA-5351:
-------------------------------------------

bq. Dropping sstable to UNREPAIRED during major compaction means that all repaired data status is cleared for the node.

That's what I meant. Current major compaction produces one SSTable and I think changing that behavior would confuse users, maybe. My opinion is to keep it as is, but .

Additional review comments:

* Does PrepareMessage needs to carry around dataCenters? Only coordinator sends out messages so I think you can drop it(also from ParentRepairSession).
* CF ID is preferred to use over Keyspace name/CF name pair.
* PrepareMessage is sent per CF but it can produce a lot of round trip. Isn't one message per replica node enough?
* I think we need clean up for parentRepairSessions when something bad happened. Otherwise ParentRepairSession in the map keep reference to SSTables.

I just worked on the first one above and the commit is here(on top of your branch): https://github.com/yukim/cassandra/commit/7c65e532dd69f9f4c1ea2d3fdf0401ed70291361


> 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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