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From Hef <hef.onl...@gmail.com>
Subject Re: HBase scan returns inconsistent results on multiple runs for same dataset
Date Fri, 03 Mar 2017 03:59:55 GMT
Thanks for the hint, which led me to investigate from the client side and
finally had this problem resolved.

I reviewed the code and found that 1.0.0-cdh5.6.1, an old version of
hbase-client was used in my project. After updated to 1.2.0-cdh5.9.0,
 consistent with the one server is running,  my tasks work correctly.

I looked into the source of HBase 1.2.0-cdh5.9.0, HBASE-15378 is not
patched. And I also went through all release notes from CDH HBase 5.6 to
5.9, nothing about this inconsistent scan behavior had been mentioned.
Though the problem has been resolved for now , I have no idea what the root
cause  actually is, and whether it will come out again if my dataset grows
larger, without HBASE-15378.



On Thu, Mar 2, 2017 at 12:09 AM, Sean Busbey <busbey@apache.org> wrote:

> The place to check for include JIRAs on top of those in the ASF release is
> here:
>
> http://archive.cloudera.com/cdh5/cdh/5/hbase-1.2.0-cdh5.9.
> 1.releasenotes.html
>
> HBASE-15378 is not in CDH5.9.1.
>
> On Wed, Mar 1, 2017 at 9:58 AM, Ted Yu <yuzhihong@gmail.com> wrote:
> > I don't see it here:
> >
> > http://archive.cloudera.com/cdh5/cdh/5/hbase-1.2.0-cdh5.9.
> 1.CHANGES.txt?_ga=1.10311413.1914112506.1454459553
> >
> > On Wed, Mar 1, 2017 at 5:46 AM, Hef <hef.online@gmail.com> wrote:
> >
> >> I'm using CDH 5.9, the document show its HBase version is
> >> hbase-1.2.0+cdh5.9.1+222.  (
> >> https://www.cloudera.com/documentation/enterprise/
> >> release-notes/topics/cdh_vd_cdh_package_tarball_59.html
> >> )
> >> I have no idea if  HBASE-15378  is included.
> >>
> >> On Wed, Mar 1, 2017 at 9:33 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> >>
> >> > Which hbase version are you using ?
> >> >
> >> > Does it include HBASE-15378 ?
> >> >
> >> > > On Mar 1, 2017, at 5:02 AM, Hef <hef.online@gmail.com> wrote:
> >> > >
> >> > > Hi,
> >> > > I'm encountering a strange behavior on MapReduce when using HBase
as
> >> > input
> >> > > format. I run my MR tasks on a same table, same dataset, with a same
> >> > > pattern of Fuzzy Row Filter, multiple times. The Input Records
> counters
> >> > > shown are not consistent, the smallest number can be 40% less than
> the
> >> > > largest one.
> >> > >
> >> > > More specifically,
> >> > > - the table is split into 18 regions, distributed on 3 region
> server.
> >> The
> >> > > TTL is set to 10 days for the record, though the dataset for MR only
> >> > > includes those inserted in 7days.
> >> > >
> >> > > - The row key is defined as:
> >> > > sault(1byte) + time_of_hour(4bytes) + uuid(36bytes)
> >> > >
> >> > >
> >> > > - The scan is created as below:
> >> > >
> >> > > Scan scan = new Scan();
> >> > > scan.setBatch(100);
> >> > > scan.setCaching(10000);
> >> > > scan.setCacheBlocks(false);
> >> > > scan.setMaxVersions(1);
> >> > >
> >> > >
> >> > > And the row filter for the scan is a FuzzyRowFilter that filters
> only
> >> > > events of a given time_of_hour.
> >> > >
> >> > > Everything looks fine while the result is out of expect.
> >> > > A same task runs 10 times, the Input Records counters  show 6
> different
> >> > > numbers, and the final output shows 6 different results.
> >> > >
> >> > > Does anyone has every faced this problem before?
> >> > > What could be the cause of this inconsistency of HBase scan result?
> >> > >
> >> > > Thanks
> >> >
> >>
>

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