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https://issues.apache.org/jira/browse/CASSANDRA-18507?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17723295#comment-17723295
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David Capwell commented on CASSANDRA-18507:
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the trunk patch LGTM, +1

If [~marcuse] doesn't merge today, ill merge tomorrow; assuming he is +1 to 
trunk patch

> Partial compaction can resurrect deleted data
> ---------------------------------------------
>
>                 Key: CASSANDRA-18507
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-18507
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Local/Compaction
>            Reporter: Tobias Lindaaker
>            Assignee: Tobias Lindaaker
>            Priority: Normal
>
> If there isn't enough disk space available to compact all existing sstables, 
> Cassandra will attempt to perform a partial compaction by removing sstables 
> from the set of candidate sstables to be compacted, starting with the largest 
> one. It is possible that the sstable removed from the set of sstables to 
> compact contains data for which there are tombstones in another (more recent) 
> sstable. Since the overlaps between sstables is computed when the 
> {{CompactionController}} is created, and the {{CompactionController}} is 
> created before the removal of any sstables from the set of sstables to be 
> compacted this computed overlap will be outdated when checking which sstables 
> are covered by certain tombstones. This leads to the faulty conclusion that 
> the tombstones can be pruned during the compaction, causing the data to be 
> resurrected.
> The issue is present in Cassandra 4.0 and 4.1. Cassandra 3.11 creates the 
> {{CompactionController}} after the set of sstables to compact has been 
> reduced, and is thus not affected. {{trunk}} does not appear to support 
> partial compactions at all, but instead refuses to compact when the disk is 
> full.
> This regression appears to have been introduced by CASSANDRA-13068.



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