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HBase, mail # dev - Re: How to replace MetaUtils.ScannerListener?


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Re: How to replace MetaUtils.ScannerListener?
Nick Dimiduk 2013-03-22, 23:34
Err, "an *empty* source file".

On Fri, Mar 22, 2013 at 4:33 PM, Nick Dimiduk <[EMAIL PROTECTED]> wrote:

> On Fri, Mar 22, 2013 at 8:19 AM, Jonathan Hsieh <[EMAIL PROTECTED]> 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?
>>
>
> Somewhat tangential to this thread, I think we shouldn't be shy about
> deleting old/stale/deprecated code. This should be done on a case-by-case
> basis, of course. For example, in this case, maybe the snapshot
> functionality will evolve such that the CopyTable interface and semantics
> become a pure subset of snapshots. At that point, we should absolutely
> delete CopyTable as an independent code-path.
>
> As they say, "an source file ships no bugs".
>
> Just my 2¢
> -n
>
>  On Thu, Mar 21, 2013 at 7:07 PM, Jean-Marc Spaggiari <
>> [EMAIL PROTECTED]> wrote:
>>
>> > Hi Enis,
>> >
>> > I totaly agree. But even if online merge are available, maybe offline
>> > merges can still usefull in case the cluster is down for maintenance,
>> > or because there is any issue to start it, or anything else? We have
>> > it, so we should maybe try to keep it?
>> >
>> > JM
>> >
>> > 2013/3/21 Enis Söztutar <[EMAIL PROTECTED]>:
>> > > 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, there
>> should
>> > > not be a need to merge offline tables.
>> > >
>> > > Enis
>> > >
>> > >
>> > > On Thu, Mar 21, 2013 at 3:16 PM, Jean-Marc Spaggiari <
>> > > [EMAIL PROTECTED]> wrote:
>> > >
>> > >> Offline merge is already there and working fine.
>> > >>
>> > >> The usecase here was to retreive all the regions for a given table 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 the
>> > >> code in the offline merge since it will disapear soon, but in the
>> > >> meantime, at least, we will have the offline one.
>> > >>
>> > >> JM
>> > >>
>> > >> 2013/3/21 Enis Söztutar <[EMAIL PROTECTED]>:
>> > >> > 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 <
>> > [EMAIL PROTECTED]
>> > >> >wrote:
>> > >> >
>> > >> >> As far as I can tell, only the merge code uses MetaUtils to do
>> > 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
>> > >> >> <[EMAIL PROTECTED]> wrote:
>> > >> >> > Vector is because of a very old bad habit ;) I will change that
>> to
>> > >> >> ArrayList.
>> > >> >> >
>> > >> >> > So far I have inlined the scanMetaRegion feature into the Merge,
>> > but
>> > >> >> > maybe it should be cleaner to put it back in?
>> > >> >> >
>> > >> >> > Anyway, I will keep the inlined one until everything is cleaned.
>> > >> >> >
>> > >> >> > 2013/3/21 Enis Söztutar <[EMAIL PROTECTED]>:
>> > >> >> >> The problem around current META scanning is that there is more
>> > than
>> > >> one
>> > >> >> way
>> > >> >> >> to do these, and the META layout is exposed. We should refrain
>> > from
>> > >> >> >> exposing the META details.
>> > >> >> >> AFAIK, these do the same thing:
>> > >> >> >>  MetaReader.Visitor
>>