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https://issues.apache.org/jira/browse/CASSANDRA-12888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15736599#comment-15736599
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Paulo Motta commented on CASSANDRA-12888:
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Thanks for your investigation Benjamin. As discussed on the mailing list and
CASSANDRA-12905 we cannot ensure view consistency with sstable-based streaming
of base/MVs in all scenarios, specially with repair, so I'm afraid this is not
a viable solution just yet (needs to be further discussed). An alternative is
to provide an option for repair to allow repairing base and MV separately when
you *know what you are doing*©.
While we work on improving MV streaming overhead in a separate ticket, I'd like
to focus here on fixing the problem with MV/CDC repair stated in the
description. What do you think of the previous proposal of just skipping the
write path for base table mutations and keeping the sstables? While this is
still a bit expensive it will allow users to incrementally repair
moderately-sized MVs, specially after CASSANDRA-12905.
Your observations from large scale MV streaming in the context of bootstrap
will be pretty useful, would you mind adding them to the follow-up streaming
improvement ticket for MVs?
By the way, congrats for the baby! :-)
> 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.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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