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https://issues.apache.org/jira/browse/HBASE-2021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12796135#action_12796135
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Lars George commented on HBASE-2021:
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Good idea with the hidden config! Didn't think of that. Will add today.
> Add compaction details to master UI
> -----------------------------------
>
> Key: HBASE-2021
> URL: https://issues.apache.org/jira/browse/HBASE-2021
> Project: Hadoop HBase
> Issue Type: Improvement
> Reporter: Lars George
> Assignee: Lars George
> Priority: Minor
> Fix For: 0.20.3, 0.21.0
>
> Attachments: HBASE-2021-0.20-v2.patch, HBASE-2021-0.20.patch,
> HBASE-2021.patch
>
>
> There are two issues with this, first to detect that there is a compaction
> needed. You can currently use the little helper util that checks if a table
> has at least one colfam with more than one store file. I though about
> scanning all tables and all colfams in each and then compute the
> "fragmentation" ratio as a percentage of colfams with more than one store to
> the total number of colfams. That gives a "Table xyz is 33% fragmented"
> output. While minor percentage are normal under insert operations it is still
> important to know how bad the fragmentation is overall.
> Another idea is to weigh the number of files per store too, so that if you
> have two per colfam it is considered "low" and if you have more, for example
> 6-8 it is considered "high". Not sure how that can be done yet but noting the
> idea down here.
> Of course seeing the .META. fragmentation is useful to quickly debug
> performance issues (as JD told me on IRC).
> The other issue is that when you have started a compaction you have no idea
> how far it is and if it is still in progress. One indication of course is the
> above value. If it is 0% then all is done. But if you are at say 23%, is it
> still compacting? We could have a simple status that compactions are still in
> progress.
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