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From Enis Söztutar <enis....@gmail.com>
Subject Re: How to replace MetaUtils.ScannerListener?
Date Thu, 21 Mar 2013 23:17:07 GMT
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 <
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 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 <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 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
> >> <jean-marc@spaggiari.org> 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 <enis.soz@gmail.com>:
> >> >> 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
> >> >>  MetaScanner.MetaScannerVisitor, and
> >> >>  MetaUtils.ScannerListener
> >> >>
> >> >> More concerning is that the code for managing META is spread over
> >> >> MetaEditor, MetaReader, MetaScanner, MetaUtils, HRegionInfo (and
> maybe
> >> >> more). There are a couple of issues to rework these interfaces, but
I
> >> did
> >> >> not get the chance to work on those.
> >> >>
> >> >>
> >> >> Enis
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >>
> >> >> On Thu, Mar 21, 2013 at 2:18 PM, Jean-Daniel Cryans <
> >> jdcryans@apache.org>wrote:
> >> >>
> >> >>> Mmmm I may have been trigger happy. You could pull back the
> >> >>> ScannerListener and scanMetaRegion.
> >> >>>
> >> >>> BTW, why are you using a Vector instead of ArrayList?
> >> >>>
> >> >>> J-D
> >> >>>
> >> >>> On Thu, Mar 21, 2013 at 2:05 PM, Jean-Marc Spaggiari
> >> >>> <jean-marc@spaggiari.org> wrote:
> >> >>> > Hi,
> >> >>> >
> >> >>> > In trunk, since HBASE-3171 (Drop ROOT and instead store META
> >> >>> > location(s) directly in ZooKeeper ) there is no more
> >> >>> > MetaUtils.ScannerListener.
> >> >>> >
> >> >>> > In the merge, I used it to retreive all the regions belonging
to a
> >> >>> > specific table, from the META. kind of scan.
> >> >>> >
> >> >>> >           // Retrieve the list of regions for this table.
> >> >>> >           final List<HRegionInfo> regions = new
> >> Vector<HRegionInfo>();
> >> >>> >           utils.scanMetaRegion(HRegionInfo.FIRST_META_REGIONINFO,
> new
> >> >>> > MetaUtils.ScannerListener() {
> >> >>> >             public boolean processRow(HRegionInfo info) {
> >> >>> >               if ((info != null) &&
> >> >>> > (Bytes.compareTo(info.getTableName(), tableName) == 0)) {
> >> >>> >                 regions.add(info);
> >> >>> >               }
> >> >>> >               return true;
> >> >>> >             }
> >> >>> >           });
> >> >>> >
> >> >>> >
> >> >>> > Is there a recommanded way to replace that? The Merge is running
> >> >>> > offline, so I can't do a scan.
> >> >>> >
> >> >>> > Thanks,
> >> >>> >
> >> >>> > JM
> >> >>>
> >>
>

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