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From Jimmy Mårdell (JIRA) <>
Subject [jira] [Commented] (CASSANDRA-7272) Add "Major" Compaction to LCS
Date Wed, 07 Jan 2015 16:16:35 GMT


Jimmy Mårdell commented on CASSANDRA-7272:

Haven't looked into the details yet, but is it possible to backport this patch to 2.0? I.e.
it's not dependent on new 2.1/3.0 features?

> Add "Major" Compaction to LCS 
> ------------------------------
>                 Key: CASSANDRA-7272
>                 URL:
>             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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