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From "Jeff Ferland (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-10979) LCS doesn't do L0 STC on new tables while an L0->L1 compaction is in progress
Date Wed, 20 Jan 2016 19:01:40 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-10979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15109177#comment-15109177
] 

Jeff Ferland commented on CASSANDRA-10979:
------------------------------------------

Applied the patch to a node that had just come up from streaming and was 700+ tables in L0.
After restart, observed that as L0 was shifted into L1, L0 continued to compact new tables
to prevent the extreme growth of tables.

Thank you. Again still requesting a merge into 2.1 since streaming and repair with LCS are
practically broken for us without this patch.

> LCS doesn't do L0 STC on new tables while an L0->L1 compaction is in progress
> -----------------------------------------------------------------------------
>
>                 Key: CASSANDRA-10979
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10979
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Compaction
>         Environment: 2.1.11 / 4.8.3 DSE.
>            Reporter: Jeff Ferland
>            Assignee: Carl Yeksigian
>              Labels: compaction, leveled
>             Fix For: 3.x
>
>         Attachments: 10979-2.1.txt
>
>
> Reading code from https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
and comparing with behavior shown in https://gist.github.com/autocracy/c95aca6b00e42215daaf,
the following happens:
> Score for L1,L2,and L3 is all < 1 (paste shows 20/10 and 200/100, due to incremental
repair).
> Relevant code from here is
>     if (Sets.intersection(l1overlapping, compacting).size() > 0)
>         return Collections.emptyList();
> Since there will be overlap between what is compacting and L1 (in my case, pushing over
1,000 tables in to L1 from L0 SCTS), I get a pile up of 1,000 smaller tables in L0 while awaiting
the transition from L0 to L1 and destroy my performance.
> Requested outcome is to continue to perform SCTS on non-compacting L0 tables.



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