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https://issues.apache.org/jira/browse/CASSANDRA-5351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13665995#comment-13665995
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Charlie Groves commented on CASSANDRA-5351:
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bq. So the two options that I see are (1) making ranges repaired, rather than
sstables, or (2) "anti-compacting" repaired parts into new sstables.
I don't believe either of these fix the problem of getting all repairs to nodes
other than the coordinator. If node A is coordinating a repair for ranges held
by nodes A, B, and C, B and C don't attempt to repair each other's ranges. If
those ranges were marked as repaired on all nodes then, B and C would never
repair each other.
Maybe the way to fix that is to make first node more of an initiator than a
coordinator. The first node initiates the repair of a given range, and every
node getting that request performs essentially the same repair the coordinator
is doing now. That way all the ranges go between all the involved nodes, and
they can safely mark the ranges repaired when all involved nodes finish. They'd
only need to build the merkle tree once per initiated request, so it shouldn't
be any extra work.
> 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
> Labels: repair
> Fix For: 2.1
>
>
> 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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