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https://issues.apache.org/jira/browse/CASSANDRA-7409?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14077156#comment-14077156
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Carl Yeksigian commented on CASSANDRA-7409:
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I have a first cut of this working now at
https://github.com/carlyeks/cassandra/tree/overlapping
This adds a new compaction strategy called 'Overlapping', which operates mostly
the same as 'Leveled' when max_overlapping_level is configured to 0, except L0
does not do any STCS. When max_overlapping_level is set to non-zero, it will
compact without selecting non-overlapping sstables, and will not include any
sstables from an upper level.
Also, added a new nodetool command to list the sstables in each level for both
leveled and overlapping.
I haven't benchmarked this strategy yet to compare with regular leveled; that's
going to be what I work on next for this.
> Allow multiple overlapping sstables in L1
> -----------------------------------------
>
> Key: CASSANDRA-7409
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7409
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Carl Yeksigian
> Assignee: Carl Yeksigian
>
> 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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