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https://issues.apache.org/jira/browse/CASSANDRA-18824?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17763173#comment-17763173
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Szymon Miezal commented on CASSANDRA-18824:
-------------------------------------------
Well it has been shipped like that already with
https://issues.apache.org/jira/browse/CASSANDRA-15935 ;) but I get the point we
should strive to apply a scout rule.
What I think makes sense is to add another commit where we either:
* extract the "population" logic to a common place OR
* implement something that does the same job locally at CleanupFailureTest
(this approach has the disadvantage that it will probably require to just
reinvent the wheel).
and then we merge this particular commit only to versions >= 4.x.
Having said that I think I will create a PR as it a much better place to
discuss implementation details.
> Backport CASSANDRA-16418: Cleanup behaviour during node decommission caused
> missing replica
> -------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-18824
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18824
> Project: Cassandra
> Issue Type: Bug
> Components: Consistency/Bootstrap and Decommission
> Reporter: Szymon Miezal
> Assignee: Szymon Miezal
> Priority: Normal
> Fix For: 3.0.x, 3.11.x
>
>
> Node decommission triggers data transfer to other nodes. While this transfer
> is in progress,
> receiving nodes temporarily hold token ranges in a pending state. However,
> the cleanup process currently doesn't consider these pending ranges when
> calculating token ownership.
> As a consequence, data that is already stored in sstables gets inadvertently
> cleaned up.
> STR:
> * Create two node cluster
> * Create keyspace with RF=1
> * Insert sample data (assert data is available when querying both nodes)
> * Start decommission process of node 1
> * Start running cleanup in a loop on node 2 until decommission on node 1
> finishes
> * Verify of all rows are in the cluster - it will fail as the previous step
> removed some of the rows
> It seems that the cleanup process does not take into account the pending
> ranges, it uses only the local ranges -
> [https://github.com/apache/cassandra/blob/caad2f24f95b494d05c6b5d86a8d25fbee58d7c2/src/java/org/apache/cassandra/db/compaction/CompactionManager.java#L466].
> There are two solutions to the problem.
> One would be to change the cleanup process in a way that it start taking
> pending ranges into account. Even thought it might sound tempting at first it
> will require involving changes and a lot of testing effort.
> Alternatively we could interrupt/prevent the cleanup process from running
> when any pending range on a node is detected. That sounds like a reasonable
> alternative to the problem and something that is relatively easy to implement.
> The bug has been already fixed in 4.x with CASSANDRA-16418, the goal of this
> ticket is to backport it to 3.x.
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