[jira] [Commented] (CASSANDRA-8739) Don't check for overlap with sstables that have had their start positions moved in LCS

["Marcus Eriksson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8739?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14345034#comment-14345034 ] 

Marcus Eriksson commented on CASSANDRA-8739:
--------------------------------------------

the new compacting L0 calculation takes the sstable *instances* from the datatracker compacting set - these instances are not the same as the ones in LCS L0 (the LCS L0 can have had their start positions moved), hoping to fix that in CASSANDRA-8764

> Don't check for overlap with sstables that have had their start positions moved in LCS
> --------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-8739
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8739
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Marcus Eriksson
>            Assignee: Marcus Eriksson
>             Fix For: 2.1.4
>
>         Attachments: 0001-8739.patch
>
>
> When picking compaction candidates in LCS, we check that we won't cause any overlap in the higher level. Problem is that we compare the files that have had their start positions moved meaning we can cause overlap. We need to also include the tmplink files when checking this.
> Note that in 2.1 overlap is not as big problem as earlier, if adding an sstable would cause overlap, we send it back to L0 instead, meaning we do a bit more compaction but we never actually have overlap.



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