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https://issues.apache.org/jira/browse/CASSANDRA-7409?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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jxjgssylsg updated CASSANDRA-7409:
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    Test and Documentation Plan: test
                         Status: Patch Available  (was: Open)

> Allow multiple overlapping sstables in L1
> -----------------------------------------
>
>                 Key: CASSANDRA-7409
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7409
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Local/Compaction
>            Reporter: Carl Yeksigian
>            Assignee: Carl Yeksigian
>            Priority: Normal
>              Labels: compaction, lcs
>             Fix For: 4.x
>
>
> Currently, when a normal L0 compaction takes place (not STCS), we take up to 
> MAX_COMPACTING_L0 L0 sstables and all of the overlapping L1 sstables and 
> compact them together. If we didn't have to deal with the overlapping L1 
> tables, we could compact a higher number of L0 sstables together into a set 
> of non-overlapping L1 sstables.
> This could be done by delaying the invariant that L1 has no overlapping 
> sstables. Going from L1 to L2, we would be compacting fewer sstables together 
> which overlap.
> When reading, we will not have the same one sstable per level (except L0) 
> guarantee, but this can be bounded (once we have too many sets of sstables, 
> either compact them back into the same level, or compact them up to the next 
> level).
> This could be generalized to allow any level to be the maximum for this 
> overlapping strategy.



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