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From Martin Fiala <fial...@gmail.com>
Subject Re: Regions assigned multiple times after disabling table
Date Fri, 09 Apr 2010 06:19:48 GMT
Stack napsal(a):
> On Thu, Apr 8, 2010 at 6:38 AM, Martin Fiala <fialama@gmail.com> wrote:
>   
>> Now, the table is disabled, but the region is online on
>> "fernet1-v49.ng.seznam.cz"!! Is there some race condition?
>>
>>     
>
> Enabling/disabling largish tables has always been problematic.  We
> intend fixing it properly in the next major hbase but meantime we're
> patching what is currently in place, effectively the sending of a
> mesage across the cluster and then hoping rather than guaranteeing its
> received by all regionservers and that there are no issues during the
> enable/disable.
>
> You could try being extra careful.  On disable, ensure all are offline
> before proceeding.This probably requires manual inspection of meta
> region (region gets status=offline feature when disabled successfully)
> for now.  0.20.4 which has improvements that particularly address this
> issue should be out soon also.
>
> Meantime, its probably best to do as little enable/disable as possible.
>
> St.Ack
>   

Yes, that's exactly what we do now :). After disabling the table, we
manually check that no region from the disabled table is online on any
of the RegionServers. Then alter table works fine. Next we'll try
checking the meta region, as you advise.

Thank you, stack, we are looking forward to next releases!

Martin Fiala


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