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https://issues.apache.org/jira/browse/CASSANDRA-12888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15653899#comment-15653899
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Stefan Podkowinski commented on CASSANDRA-12888:
------------------------------------------------

What also puzzles me is that MVs are getting repaired just as usual tables 
would, in case of running repair for a single keyspace. Once CFs have been 
retrieved for a KS, no filtering for MVs seem to happen and they'll be repaired 
just as regular tables. I'm not sure if that's intentional. There should be 
really just a single way to repair MVs, either by depending on keeping them 
consistent with the base table and exclusively following the mutation based 
approach as described in this ticket, or by treating MVs just a regular tables 
during repairs. However, in the second case we'd have to make sure to always 
include all MVs for repaired tables in a repair session, in order to keep them 
consistent. 

> Incremental repairs broken for MVs and CDC
> ------------------------------------------
>
>                 Key: CASSANDRA-12888
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12888
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Streaming and Messaging
>            Reporter: Stefan Podkowinski
>            Priority: Critical
>
> SSTables streamed during the repair process will first be written locally and 
> afterwards either simply added to the pool of existing sstables or, in case 
> of existing MVs or active CDC, replayed on mutation basis:
> As described in {{StreamReceiveTask.OnCompletionRunnable}}:
> {quote}
> We have a special path for views and for CDC.
> For views, since the view requires cleaning up any pre-existing state, we 
> must put all partitions through the same write path as normal mutations. This 
> also ensures any 2is are also updated.
> For CDC-enabled tables, we want to ensure that the mutations are run through 
> the CommitLog so they can be archived by the CDC process on discard.
> {quote}
> Using the regular write path turns out to be an issue for incremental 
> repairs, as we loose the {{repaired_at}} state in the process. Eventually the 
> streamed rows will end up in the unrepaired set, in contrast to the rows on 
> the sender site moved to the repaired set. The next repair run will stream 
> the same data back again, causing rows to bounce on and on between nodes on 
> each repair.
> See linked dtest on steps to reproduce. An example for reproducing this 
> manually using ccm can be found 
> [here|https://gist.github.com/spodkowinski/2d8e0408516609c7ae701f2bf1e515e8]



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