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https://issues.apache.org/jira/browse/HBASE-17241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15719235#comment-15719235
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huaxiang sun commented on HBASE-17241:
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Thanks Ted. Yeah, it should be getFileCount() == 1 to decrement
selectedFileCount, will upload an update later.
> 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.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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