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https://issues.apache.org/jira/browse/HADOOP-2615?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12562823#action_12562823
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Billy Pearson commented on HADOOP-2615:
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noting I am not thanking of havening two compaction threads just two options a
compaction can take we still que up a compaction check on a memcache flush but
run compaction #2 above if oldest map file is > X days else check to see if
there are 2 or more new map files less then the max compaction MB set and run
#1 if true.
> Add max number of mapfiles to compact at one time giveing us a minor & major
> compaction
> ---------------------------------------------------------------------------------------
>
> Key: HADOOP-2615
> URL: https://issues.apache.org/jira/browse/HADOOP-2615
> Project: Hadoop Core
> Issue Type: Improvement
> Components: contrib/hbase
> Reporter: Billy Pearson
> Priority: Minor
> Fix For: 0.17.0
>
> Attachments: flag-v2.patch, flag.patch, twice.patch
>
>
> Currently we do compaction on a region when the
> hbase.hstore.compactionThreshold is reached - default 3
> I thank we should configure a max number of mapfiles to compact at one time
> simulator to doing a minor compaction in bigtable. This keep compaction's
> form getting tied up in one region to long letting other regions get way to
> many memcache flushes making compaction take longer and longer for each region
> If we did that when a regions updates start to slack off the max number will
> eventuly include all mapfiles causeing a major compaction on that region.
> Unlike big table this would leave the master out of the process and letting
> the region server handle the major compaction when it has time.
> When doing a minor compaction on a few files I thank we should compact the
> newest mapfiles first leave the larger/older ones for when we have low
> updates to a region.
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