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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5583) Master restart on create table with splitkeys does not recreate table with all the splitkey regions
Date Sat, 30 Mar 2013 06:41:19 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13618002#comment-13618002

ramkrishna.s.vasudevan commented on HBASE-5583:

When i was with my previous employer we actually wanted this feature.  The reason was tables
was dropped and created on a daily basis.  So because of this problem, the developers had
written a client code which creates the table by adding directly into META and then tries
to enable those regions. I think that was in 0.90 code.  
The later version of hbase made the creation more reliable but often in our integration tests
and Functional testing we end up with the tables getting half created and we end up in problems.
That is why it prompted us to work on this.
bq.s it simpler to disable the table and let the user create the table again in such a case
Yes this is possible.  But involves the following changes that i can think of immediately
-> Even if the table znode is in ENABLING we  should still disable the table.
-> If we mark the table disabled, user should be very clear that the table he created is
partial and that is what is DISABLED now. I think the better way is to use a new state- say
UNUSABLE (or something like this) which will make the user to take a clear course of action.
I still feel the above steps are simpler.
But table creation is the basic step and handling the failure scenarios in this should be
more of automated rather than user interference is what i felt.  Hence decided to go on with
this way.
Thanks for going thro the patch.  I will make the necessary changes and upload it.  
Just waiting for more ideas and views on this.  

> Master restart on create table with splitkeys does not recreate table with all the splitkey
> ---------------------------------------------------------------------------------------------------
>                 Key: HBASE-5583
>                 URL: https://issues.apache.org/jira/browse/HBASE-5583
>             Project: HBase
>          Issue Type: Bug
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>             Fix For: 0.95.0
>         Attachments: HBASE-5583_new_1.patch, HBASE-5583_new_2.patch, HBASE-5583_new_4_WIP.patch,
> -> Create table using splitkeys
> -> MAster goes down before all regions are added to meta
> -> On master restart the table is again enabled but with less number of regions than
specified in splitkeys
> Anyway client will get an exception if i had called sync create table.  But table exists
or not check will say table exists. 
> Is this scenario to be handled by client only or can we have some mechanism on the master
side for this? Pls suggest.

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