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https://issues.apache.org/jira/browse/HBASE-11646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14087205#comment-14087205
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Jonathan Hsieh commented on HBASE-11646:
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The most important thing is that hbase serves the correct data regardless of
whether we move data into or out of the mob write path. My gut says we'd want
to put a new copy of the mob them back into normal hfiles if the threshold is
changed -- having it only go one way and being irreversible seems inconsistent.
Can you come up with a case where we wouldn't want or expect the copy back
into hfiles behavior?
> Handle the MOB in compaction
> ----------------------------
>
> Key: HBASE-11646
> URL: https://issues.apache.org/jira/browse/HBASE-11646
> Project: HBase
> Issue Type: Sub-task
> Components: Compaction
> Reporter: Jingcheng Du
> Assignee: Jingcheng Du
>
> In the updated MOB design however, admins can set CF level thresholds that
> would force cell values > the threshold to use the MOB write path instead of
> the traditional path. There are two cases where mobs need to interact with
> this threshold
> 1) How do we handle the case when the threshold size is changed?
> 2) Today, you can bulkload hfiles that contain MOBs. These cells will work
> as normal inside hbase. Unfortunately the cells with MOBs in them will never
> benefit form the MOB write path.
> The proposal here is to modify compaction in mob enabled cf's such that the
> threshold value is honored with compactions. This handles case #1 --
> elements that should be moved out of the normal hfiles get 'compacted' into
> refs and mob hfiles, and values that should be pulled into the cf get derefed
> and written out wholy in the compaction. For case #2, we can maintain the
> same behavior and compaction would move data into the mob writepath/lifecycle.
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