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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5371) Perform size-tiered compactions in L0
Date Wed, 03 Apr 2013 22:19:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13621414#comment-13621414
] 

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

Alternate implementation pushed to http://github.com/jbellis/cassandra/commits/5371 with the
following improvements:

- Only applies STCS to L0 if L0 gets behind (defined as "accumulates more than MAX_COMPACTING_L0
sstables")
- Performs true STCS, rather than "compact in sets of four and then never again"
                
> 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: T Jake Luciani
>             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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