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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17241) Avoid compacting already compacted mob files with _del files
Date Mon, 05 Dec 2016 04:03:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15721158#comment-15721158
] 

Ted Yu commented on HBASE-17241:
--------------------------------

Test failure was not related to the patch.

> Avoid compacting already compacted  mob files with _del files
> -------------------------------------------------------------
>
>                 Key: HBASE-17241
>                 URL: https://issues.apache.org/jira/browse/HBASE-17241
>             Project: HBase
>          Issue Type: Improvement
>          Components: mob
>    Affects Versions: 2.0.0
>            Reporter: huaxiang sun
>            Assignee: huaxiang sun
>         Attachments: HBASE-17241-master-002.patch, HBASE-17241-master-003.patch, HBASE-17241.master.001.patch
>
>
> Today if there is only one file in the partition, and there is no _del files, the file
is skipped. With del file, the current logic is to compact the already-compacted file with
_del file. Let's say there is one mob file regionA20161101***, which was compacted. On 12/1/2016,
there is _del file regionB20161201**_del, mob compaction kicks in, regionA20161101*** is less
than the threshold, and it is picked for compaction. Since there is a _del file, regionA20161101****
and regionB20161201***_del are compacted into regionA20161101**_1 . After that, regionB20161201**_del
cannot be deleted since it is not a allFile compaction. The next mob compaction, regionA20161101**_1
and regionB20161201**_del will be picked up again and be compacted into regionA20161101***_2.
So in this case, it will cause more unnecessary IOs.



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