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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4341) Small SSTable Segments Can Hurt Leveling Process
Date Thu, 14 Jun 2012 18:12:42 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13295202#comment-13295202
] 

Jonathan Ellis commented on CASSANDRA-4341:
-------------------------------------------

bq. Bringing the small files from L0 to L1 magnifies the issue

Meaning, they are so small that even after L0 compaction, what gets promoted to L1 is also
"small?"
                
> Small SSTable Segments Can Hurt Leveling Process
> ------------------------------------------------
>
>                 Key: CASSANDRA-4341
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4341
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Benjamin Coverston
>
> This concerns:
> static int MAX_COMPACTING_L0 = 32;
> Repair can create very small SSTable segments. We should consider moving to a threshold
that takes into account the size of the files brought into compaction rather than the number
of files for this and similar situations. Bringing the small files from L0 to L1 magnifies
the issue.
> If there are too many very small files in L0 perhaps even an intermediate compaction
would even reduce the magnifying effect of a L0 to L1 compaction.

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