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https://issues.apache.org/jira/browse/CASSANDRA-12778?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15569810#comment-15569810
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Sharvanath Pathak commented on CASSANDRA-12778:
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[~krummas] can you take a look?

> Tombstones not being deleted when only_purge_repaired_tombstones is enabled
> ---------------------------------------------------------------------------
>
>                 Key: CASSANDRA-12778
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12778
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Arvind Nithrakashyap
>            Assignee: Marcus Eriksson
>            Priority: Critical
>
> When we use only_purge_repaired_tombstones for compaction, we noticed that 
> tombstones are no longer being deleted.
> {noformat}compaction = {'class': 
> 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy', 
> 'only_purge_repaired_tombstones': 'true'}{noformat}
> The root cause for this seems to be caused by the fact that repair itself 
> issues a flush which in turn leads to a new sstable being created (which is 
> not in the repair set). It looks like we do have some old data in this 
> sstable because of this, only tombstones older than that timestamp are 
> getting deleted even though many more keys have been repaired. 
> Fundamentally it looks like flush and repair can race with each other and 
> with leveled compaction, the flush creates a new sstable at level 0 and 
> removes the older sstable (the one that is picked for repair). Since repair 
> itself seems to issue multiple flushes, the level 0 sstable never gets 
> repaired and hence tombstones never get deleted. 
> We have already included the fix for CASSANDRA-12703 while testing. 



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