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Posted to commits@cassandra.apache.org by "Fabien Rousseau (Updated) (JIRA)" <ji...@apache.org> on 2011/10/06 12:34:29 UTC

[jira] [Updated] (CASSANDRA-3325) Compaction degrades key cache stats

     [ https://issues.apache.org/jira/browse/CASSANDRA-3325?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fabien Rousseau updated CASSANDRA-3325:
---------------------------------------

    Attachment: 001-CASSANDRA-3325.patch
    
> Compaction degrades key cache stats
> -----------------------------------
>
>                 Key: CASSANDRA-3325
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3325
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 0.8.6
>            Reporter: Fabien Rousseau
>            Priority: Minor
>         Attachments: 001-CASSANDRA-3325.patch
>
>
> When "compaction_preheat_key_cache" is set to true, then during compaction, it keep tracks of cached keys to to re-cache their new position.
> It does this by calling  the following method on every key of the compacted sstable :
> sstable.getCachedPosition(row.key)
> which also update cache stats, thus lowering hit rate
> Below is an attached patch allowing to know if the key is cached, but without updating the stats.

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