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From Takahiko Kawasaki <takahiko.kawas...@jibemobile.jp>
Subject Re: Restrictions during compactions
Date Fri, 25 May 2012 05:17:32 GMT
Dear Dave,

My lack of knowledge about HBase made me anxious unnecessarily, but your
answer blew my worries away. Thank you very much!

Best regards,
Takahiko Kawasaki

2012/5/24 Dave Revell <dave@urbanairship.com>

> On Wed, May 23, 2012 at 6:15 AM, Takahiko Kawasaki <
> takahiko.kawasaki@jibemobile.jp> wrote:
>
> > Hello,
> >
> > I'm a newbie and wondering whether or not there is any restriction during
> > HBase minor/major compactions. I read the online document but could not
> > find any explicit mention about restrictions. What I'm mostly worrying
> > about is whether read/write operations are blocked during compactions.
> >
> > The description about 'hbase.hstore.blockingWaitTime':
> >
> > ---
> > The time an HRegion will block updates for after hitting the StoreFile
> > limit defined by hbase.hstore.blockingStoreFiles. After this time has
> > elapsed, the HRegion will stop blocking updates even if a compaction has
> > not been completed. Default: 90 seconds.
> > ---
> >
> > implies that updates are blocked during compactions, but at the same time
> > it says that there are cases where blocking updates is stopped even if a
> > compaction has not been completed. However, does it mean that the
> > compaction is aborted or that the compaction continues and updates are
> > performed successfully? And if the latter case is true, what is the
> reason
> > to block updates during compactions? I'm confused.
> >
>
> That's not quite true. No operations are blocked during compactions. The
> config value you're referring to is a kind of safety valve to prevent high
> write throughput from overwhelming HBase's ability to compact. In the
> normal case, you shouldn't have to worry about that config value until you
> have very high write traffic.
>
> So, short answer: clients can operate normally during compactions.
>
> Best,
> Dave
>

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