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https://issues.apache.org/jira/browse/HBASE-533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12600880#action_12600880
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stack commented on HBASE-533:
-----------------------------

Looking at UI, I see this: 'Region split from : TestTable,,1212086527721 from 
server' (the 'from server' looks like it should be removed)

Put these two lines on a single line:

{code}
Master is the source of following events : creation,open,assignment

Regions are the source of following events : split,merge,compaction
{code}

Does the region run merges?  You should add flush.  Do you mean RegionServer in 
the above rather than Regions?

There are no creations any more.  Is that because happens elsewhere -- in 
parent? -- so doesn't show in a particular region.

A few times I clicked on a region that had been meantime been offlined (split). 
 Rather than an empty table, perhaps a message that says region no longer 
exists (And don't print the legend about master and regionserver if no events)

> Region Historian
> ----------------
>
>                 Key: HBASE-533
>                 URL: https://issues.apache.org/jira/browse/HBASE-533
>             Project: Hadoop HBase
>          Issue Type: Wish
>            Reporter: Bryan Duxbury
>            Assignee: Jean-Daniel Cryans
>            Priority: Minor
>         Attachments: hbase-533-v1-fix.patch, hbase-533-v1.patch, 
> hbase-533-v2.patch
>
>
> Whenever we try to debug region splitting, assignment, compaction, etc. 
> issues, we always end up having to look in 1-20 different log files for 
> cryptic names of regions and try to piece together the chain of events 
> ourselves. This is a challenging at best effort most of the time.
> What would be very useful would be a new utility I've nicknamed the Region 
> Historian. You give it the text name of a region, and it will track down the 
> log messages relevant to it in the master and regionserver logs. Then, it 
> will interleave the messages in such a way that the timestamps correctly list 
> the order of events. The result is a log summary that accurately describes 
> what happened to a region during it's lifetime, making it much easier to try 
> and figure out where something went wrong.
> Other things it could do would be replace cryptic log messages with simple 
> events like "the region was split into a and b", "the region was assigned to 
> server x", and trace the lineage of a region backwards to its parent before 
> it came into existence.
> I'm sure there are other things we would think up that would be useful as 
> well.

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