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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5371) Perform size-tiered compactions in L0
Date Fri, 03 May 2013 15:48:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13648508#comment-13648508
] 

Jonathan Ellis commented on CASSANDRA-5371:
-------------------------------------------

I'm not backporting this to a stable release.  It's a lot more involved than the 4KB proof
of concept.  You can probably collaborate w/ Jake on a 1.2-appropriate alternative though.

That said, the main benefit of this is not that it magically makes LCS faster (it doesn't),
but that when it does get behind your reads don't suffer so much.
                
> Perform size-tiered compactions in L0
> -------------------------------------
>
>                 Key: CASSANDRA-5371
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5371
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>             Fix For: 2.0
>
>         Attachments: HybridCompactionStrategy.java
>
>
> If LCS gets behind, read performance deteriorates as we have to check bloom filters on
man sstables in L0.  For wide rows, this can mean having to seek for each one since the BF
doesn't help us reject much.
> Performing size-tiered compaction in L0 will mitigate this until we can catch up on merging
it into higher levels.

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