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From "Lars George (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-2165) Improve fragmentation display and implementation
Date Fri, 05 Feb 2010 16:35:27 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12830156#action_12830156
] 

Lars George commented on HBASE-2165:
------------------------------------

@Stack, I think that is why Ryan posted his new issue (which I closed as dupe and copied here).
The idea is to show the experienced (and that may be the crux) user what the tables are up
to. I recall being asked how many store files my .META. has and when I said 10 I heard "Why
too much! Do compact". With the UI I am trying to get anyone quick access to this sort of
information. As I said, it may not be the best way to do it as a write intense system will
always be fragmented. 

Maybe we print not the percentage but number of regions vs. storefiles to get a ratio that
could also be used to see how many files (on average then I guess) each table has. The other
issue I though is size. I am wondering often how large a table is, not rows but in terms of
storage. Sure a smart "hadoop dfs -du /hbase/tablename" or so gives the same. But the UI would
be a nice spot to have this sort of info. And if I scan every configurable interval N anyways
to see how many storefiles I have then the size is a free info. Also setting that interval
to 0 or -1 would disable the whole thing altogether and not worry anyone. Maybe we disable
it by default, that way no one wonders what that means and the experienced user can enable
it as an advanced feature. As I said above, when this is disabled I would even hide those
columns so that there is no constant "n/a" shown. Does this make more sense?

> Improve fragmentation display and implementation
> ------------------------------------------------
>
>                 Key: HBASE-2165
>                 URL: https://issues.apache.org/jira/browse/HBASE-2165
>             Project: Hadoop HBase
>          Issue Type: Improvement
>    Affects Versions: 0.20.4, 0.21.0
>            Reporter: Lars George
>            Priority: Minor
>             Fix For: 0.20.4, 0.21.0
>
>
> Improve by 
> - moving the "blocking" FS scan into a thread so that the UI loads fast and initially
displays "n/a" but once it has completed the scan it displays the proper numbers
> - explaining what fragmentation means to the user (better hints or help text in UI)
> - Switch -ROOT- (and maybe even .META.?) to simply say "Yes" or a tick that it is fragmented
as it only has 0% or 100% available (since it has only a single region)
> - also computing the space occupied by each table and the total and - if easily done
- add a graph to display it (Google Pie Chart would be nice but is an external link)

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