[jira] [Commented] (CASSANDRA-3442) TTL histogram for sstable metadata

["B. Todd Burruss (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-3442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13493439#comment-13493439 ] 

B. Todd Burruss commented on CASSANDRA-3442:
--------------------------------------------

Will this patch force clean up *any* tombstoned data, or only because of columns that have expired because of their TTL?
                
> TTL histogram for sstable metadata
> ----------------------------------
>
>                 Key: CASSANDRA-3442
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3442
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Yuki Morishita
>            Priority: Minor
>              Labels: compaction
>             Fix For: 1.2.0 beta 1
>
>         Attachments: 3442-track-tombstones.txt, 3442-v3.txt, cassandra-1.1-3442.txt
>
>
> Under size-tiered compaction, you can generate large sstables that compact infrequently.  With expiring columns mixed in, we could waste a lot of space in this situation.
> If we kept a TTL EstimatedHistogram in the sstable metadata, we could do a single-sstable compaction aginst sstables with over 20% (?) expired data.

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