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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6809) Compressed Commit Log
Date Wed, 23 Apr 2014 21:34:15 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13978939#comment-13978939
] 

T Jake Luciani commented on CASSANDRA-6809:
-------------------------------------------

bq. All in all it's not a trivial change if we want to do it right, and it is probably not
going to benefit that many users, so I'm inclined to put this one on the back burner for now.

I'm inclined to agree, I'm not sure how big the gain would be so I'd like to experiment first
anyway.

> Compressed Commit Log
> ---------------------
>
>                 Key: CASSANDRA-6809
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6809
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Benedict
>            Assignee: T Jake Luciani
>            Priority: Minor
>              Labels: performance
>             Fix For: 3.0
>
>
> It seems an unnecessary oversight that we don't compress the commit log. Doing so should
improve throughput, but some care will need to be taken to ensure we use as much of a segment
as possible. I propose decoupling the writing of the records from the segments. Basically
write into a (queue of) DirectByteBuffer, and have the sync thread compress, say, ~64K chunks
every X MB written to the CL (where X is ordinarily CLS size), and then pack as many of the
compressed chunks into a CLS as possible.



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