huaxiang sun created HBASE-17241:
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Summary: 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
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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