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Date: Fri, 22 Mar 2013 21:30:31 +0100
Message-ID: 
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Subject: Re: How to replace MetaUtils.ScannerListener?
From: Andrew Purtell <apurtell@apache.org>
To: "dev@hbase.apache.org" <dev@hbase.apache.org>
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I think we shouldn't remove the offline tools at this time (perhaps not
even at a future time - topic for another day) but a refactor that cleans
things up would be good.

On Friday, March 22, 2013, Enis S=F6ztutar wrote:

> CopyTable and Snapshots are very useful for backup, while merge and split
> are only relevant if the table is serving reads and writes. I can see
> having some tools for helping with cases where HBase cannot recover, but
> apart from that, normal Hbase operations should not need offline splits o=
r
> merges.
>
> I am not suggesting to remove it now, but if we get online merges rock
> solid, we can reevaluate.
>
> Enis
>
>
> On Fri, Mar 22, 2013 at 9:31 AM, Ted Yu <yuzhihong@gmail.com> wrote:
>
> > Point taken.
> >
> > But I don't think previous discussion was about removing offline merge.
> >
> > On Fri, Mar 22, 2013 at 8:19 AM, Jonathan Hsieh <jon@cloudera.com>
> wrote:
> >
> > > Let me offer a counter argument.  The offline splitting code is still
> > > present even though online splitting isn't the problem it used to be.
> We
> > > actually added an extenal wal replayer even though we have wal replay
> in
> > > our normal recovery path.  Copy table still exists even though
> snapshots
> > > and snapshot export exists.  Would we consider removing these?
> > >
> > > IMO, until online merge has been proven and hardened (gone through fe=
w
> > > releases and folk using) I don't feel comfortable removing it.
> > >
> > > Jon.
> > >
> > > On Thu, Mar 21, 2013 at 7:07 PM, Jean-Marc Spaggiari <
> > > jean-marc@spaggiari.org> wrote:
> > >
> > > > Hi Enis,
> > > >
> > > > I totaly agree. But even if online merge are available, maybe offli=
ne
> > > > merges can still usefull in case the cluster is down for maintenanc=
e,
> > > > or because there is any issue to start it, or anything else? We hav=
e
> > > > it, so we should maybe try to keep it?
> > > >
> > > > JM
> > > >
> > > > 2013/3/21 Enis S=F6ztutar <enis.soz@gmail.com>:
> > > > > Thanks J-M.
> > > > >
> > > > > What I am trying to understand is that whether we should cut the
> cord
> > > for
> > > > > offline merge once online is working. If you think about it, ther=
e
> > > should
> > > > > not be a need to merge offline tables.
> > > > >
> > > > > Enis
> > > > >
> > > > >
> > > > > On Thu, Mar 21, 2013 at 3:16 PM, Jean-Marc Spaggiari <
> > > > > jean-marc@spaggiari.org> wrote:
> > > > >
> > > > >> Offline merge is already there and working fine.
> > > > >>
> > > > >> The usecase here was to retreive all the regions for a given tab=
le
> > to
> > > > >> merge them 2 by 2, offline.
> > > > >>
> > > > >> It's working fine, but since the Meta rework it's not working
> > anymore
> > > > >> and I'm trying to rebase the patch.
> > > > >>
> > > > >> Like J-D is saying, yes, it's used only in the offline merge...
> And
> > > > >> since the online merge is coming, I think it's cleaner to keep t=
he
> > > > >> code in the offline merge since it will disapear soon, but in th=
e
> > > > >> meantime, at least, we will have the offline one.
> > > > >>
> > > > >> JM
> > > > >>
> > > > >> 2013/3/21 Enis S=F6ztutar <enis.soz@gmail.com>:
> > > > >> > What is the use case behind offline merge? Is it because we
> cannot
> > > do
> > > > >> > online merge yet? If we can get HBASE-7403 in, is there still
> need
> > > to
> > > > >> > support offline merge?
> > > > >> >
> > > > >> > Enis
> > > > >> >
> > > > >> >
> > > > >> > On Thu, Mar 21, 2013 at 2:56 PM, Jean-Daniel Cryans <
> > > > jdcryans@apache.org
> > > > >> >wrote:
> > > > >> >
> > > > >> >> As far as I can tell, only the merge code uses MetaUtils to d=
o
> > > > offline
> > > > >> >> work. If this is the code you are in then pull it back into
> > > MetaUtils
> > > > >> >> I think.
> > > > >> >>
> > > > >> >> J-D
> > > > >> >>
> > > > >> >> On Thu, Mar 21, 2013 at 2:44 PM, Jean-Marc Spaggiari
> > > > >


--=20
Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet Hein
(via Tom White)

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