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https://issues.apache.org/jira/browse/HBASE-22648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16882360#comment-16882360
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Viraj Jasani commented on HBASE-22648:
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| * Associate TTL in sec with Snapshot argument. e.g. snapshot 'table', 
'snapshot', \{TTL => 20}
 * If not specified, default TTL to be taken for Snapshot. Specified here: 
HConstants.DEFAULT_SNAPSHOT_TTL
 * If Snapshot is never meant to get expired, specify negative value for TTL. 
snapshot 'table', 'snapshot', \{TTL => -2}|
 

> Snapshot TTL
> ------------
>
>                 Key: HBASE-22648
>                 URL: https://issues.apache.org/jira/browse/HBASE-22648
>             Project: HBase
>          Issue Type: New Feature
>          Components: snapshots
>    Affects Versions: 3.0.0
>            Reporter: Andrew Purtell
>            Assignee: Viraj Jasani
>            Priority: Minor
>             Fix For: 3.0.0
>
>         Attachments: HBASE-22648-master.patch
>
>
> Snapshots have a lifecycle that is independent from the table from which they 
> are created. Although data in a table may be stored with TTL the data files 
> containing them become frozen by the snapshot. Space consumed by expired 
> cells will not be reclaimed by normal table housekeeping like compaction. 
> While this is expected it can be inconvenient at scale. When many snapshots 
> are under management and the data in various tables is expired by TTL some 
> notion of optional TTL (and optional default TTL) for snapshots could be 
> useful. It will help prevent the accumulation of junk files by automatically 
> dropping the snapshot after the assigned TTL, making their data files 
> eligible for cleaning. More comprehensive snapshot lifecycle management may 
> be considered in the future but this one case is expected to be immediately 
> useful given TTls on data are commonly applied for similar convenience. 



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