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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-3234) LeveledCompaction has several performance problems
Date Thu, 22 Sep 2011 23:01:27 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-3234?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jonathan Ellis updated CASSANDRA-3234:
--------------------------------------

    Attachment: 0006-avoid-echoedRow-when-checking-shouldPurge-is-more-ex.patch

updated 06

> LeveledCompaction has several performance problems
> --------------------------------------------------
>
>                 Key: CASSANDRA-3234
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3234
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.0.0
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>             Fix For: 1.0.0
>
>         Attachments: 0001-optimize-single-source-case-for-MergeIterator.txt, 0002-add-TrivialOneToOne-optimization.txt,
0003-fix-leveled-BF-size-calculation.txt, 0004-avoid-calling-shouldPurge-unless-necessary.txt,
0005-use-Array-and-Tree-backed-columns-in-compaction-v2.patch, 0005-use-Array-and-Tree-backed-columns-in-compaction-v3.txt,
0005-use-Array-and-Tree-backed-columns-in-compaction-v4.patch, 0005-use-Array-and-Tree-backed-columns-in-compaction.txt,
0006-avoid-echoedRow-when-checking-shouldPurge-is-more-ex.patch
>
>
> Two main problems:
> - BF size calculation doesn't take into account LCS breaking the output apart into "bite
sized" sstables, so memory use is much higher than predicted
> - ManyToMany merging is slow.  At least part of this is from running the full reducer
machinery against single input sources, which can be optimized away.

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