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From "Lars George (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-2021) Add compaction details to master UI
Date Thu, 31 Dec 2009 12:55:29 GMT

     [ https://issues.apache.org/jira/browse/HBASE-2021?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Lars George updated HBASE-2021:
-------------------------------

    Fix Version/s: 0.20.3

Added 0.20.3 again in an attempt to get that metric also included. Punt if you do not like
it. Will add a new patch for 0.21 based on the above discussion, so we leave this issue open
once the 0.20 patch is applied by moving it then to 0.21 only? 

> 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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