[jira] [Commented] (CASSANDRA-7272) Add "Major" Compaction to LCS

["Marcus Eriksson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-7272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14249984#comment-14249984 ] 

Marcus Eriksson commented on CASSANDRA-7272:
--------------------------------------------

patch is here, needs rebase so not setting patch available yet

https://github.com/krummas/cassandra/commits/marcuse/7019-2

> Add "Major" Compaction to LCS 
> ------------------------------
>
>                 Key: CASSANDRA-7272
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7272
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: T Jake Luciani
>            Priority: Minor
>              Labels: compaction
>             Fix For: 3.0
>
>
> LCS has a number of minor issues (maybe major depending on your perspective).
> LCS is primarily used for wide rows so for instance when you repair data in LCS you end up with a copy of an entire repaired row in L0.  Over time if you repair you end up with multiple copies of a row in L0 - L5.  This can make predicting disk usage confusing.  
> Another issue is cleaning up tombstoned data.  If a tombstone lives in level 1 and data for the cell lives in level 5 the data will not be reclaimed from disk until the tombstone reaches level 5.
> I propose we add a "major" compaction for LCS that forces consolidation of data to level 5 to address these.



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