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From "Jingcheng Du (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11861) Native MOB Compaction mechanisms.
Date Thu, 11 Dec 2014 07:13:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14242256#comment-14242256
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Jingcheng Du commented on HBASE-11861:
--------------------------------------

Thanks Jon. [~jmhsieh]
bq. I think the bulk load approach avoids the potential race on mob compaction and normal
compaction.
I think we still have the race condition even if we use the bulkload in mob compaction.
# We have a mob cell#1 in the hbase.
# Now the mob compaction happens, and the mob file file#1 which has the cell#1 is merged into
a bigger file file#2. and we write this new cell#1 with value file#2(use the file name) into
a new store file, but not start to bulkload yet.
# Users delete cell#1, and major compaction happens then, this cell#1 is not existent in the
HBase.
# The mob compaction bulkloads this new store file.
# The cell#1 is back to the HBase again.

This is why I insist to run the mob compaction in regions. If we do the mob compaction out
of region or across regions, we have to locks the major compactions globally.

> Native MOB Compaction mechanisms.
> ---------------------------------
>
>                 Key: HBASE-11861
>                 URL: https://issues.apache.org/jira/browse/HBASE-11861
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver, Scanners
>    Affects Versions: 2.0.0
>            Reporter: Jonathan Hsieh
>         Attachments: 141030-mob-compaction.pdf, mob compaction.pdf
>
>
> Currently, the first cut of mob will have external processes to age off old mob data
(the ttl cleaner), and to compact away deleted or over written data (the sweep tool).  
> From an operational point of view, having two external tools, especially one that relies
on MapReduce is undesirable.  In this issue we'll tackle integrating these into hbase without
requiring external processes.



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