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https://issues.apache.org/jira/browse/CASSANDRA-5907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13746567#comment-13746567
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Jeremiah Jordan commented on CASSANDRA-5907:
--------------------------------------------
Reading the patch 10 times, I think that logic is right to skip doing parallel
L0 compactions if there is any overlap.
> Leveled compaction may cause overlap in L1 when L0 compaction get behind
> ------------------------------------------------------------------------
>
> Key: CASSANDRA-5907
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5907
> Project: Cassandra
> Issue Type: Bug
> Reporter: Yuki Morishita
> Assignee: Yuki Morishita
> Priority: Minor
> Fix For: 1.2.9
>
> Attachments: 5907-1.2.txt
>
>
> 1.2 makes LCS run parallel, though if L0 compaction get far behind and
> concurrent compactions at L0 where each compaction holds maximum number of
> SSTable to compact at L0(32), it will likely cause overlap in L1. There will
> be ERROR log as follows:
> {code}
> ERROR [CompactionExecutor:30] 2013-08-19 17:54:29,648 LeveledManifest.java
> (line 244) At level 1, SSTableReader(path='xxx-Data.db')
> [DecoratedKey(204853724659241194183955214890519, 30303132343830),
> DecoratedKey(69227335985728660912035125310473966323, 30393537373332)]
> overlaps SSTableReader(path='xxx-Data.db')
> [DecoratedKey(217896711032704014921095870827202, 30333635363932),
> DecoratedKey(71430242198281555888954138354238066233, 30333035343132)]. This
> is caused by a bug in Cassandra 1.1.0 .. 1.1.3. Sending back to L0. If you
> have not yet run scrub, you should do so since you may also have rows
> out-of-order within an sstable
> {code}
> We should send back compacted SSTables to L0 when compacting max SSTables at
> L0. Also, the above error message is confusing, at version 1.2, we can reduce
> to WARNing level without mentioning scrub.
> C* 2.0 performs Size-Tiered compaction on L0 when it has max SSTables and
> sends back compacted SSTable to L0, so I think we don't need to fix this on
> 2.0.
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