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https://issues.apache.org/jira/browse/CASSANDRA-12888?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jeff Jirsa updated CASSANDRA-12888:
-----------------------------------
    Comment: was deleted

(was: {quote}
What effect does the repairedAt flag have for future repairs except that a 
non-zero value means, that a table has been repaired at some time?
{quote}

It's used (heavily) for incremental repairs. CASSANDRA-9143 may be a starting 
point reading there (potentially).)

> 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
>            Assignee: Benjamin Roth
>            Priority: Critical
>             Fix For: 3.0.x, 3.11.x
>
>
> 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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