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Date: Thu, 11 Oct 2012 13:07:35 +0330
Message-ID: 
 <CAONjveOTDkAkL8+9=2ucTk6D8ONRbzExHBFNREPh3Xds3n8kJQ@mail.gmail.com>
Subject: Re: HBase table - distinct values
From: yutoo yanio <yutoo.yanio@gmail.com>
To: user@hbase.apache.org
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you can create a table with key=deptno or every value that you need
distinct value of it.
scan of this table shows the distinct values.

On Thu, Oct 11, 2012 at 8:22 AM, Ramkrishna.S.Vasudevan <
ramkrishna.vasudevan@huawei.com> wrote:

> Are you planning to use region splits? Can the rowkey have the deptno?
>
> Having dept no in another table, may be having a reverse mapping of deptno
> to empno may be helpful too if such queries are frequent.
>
> Regards
> Ram
> > -----Original Message-----
> > From: Anoop Sam John [mailto:anoopsj@huawei.com]
> > Sent: Thursday, October 11, 2012 9:32 AM
> > To: user@hbase.apache.org
> > Cc: hbase-user@hadoop.apache.org
> > Subject: RE: HBase table - distinct values
> >
> > Hi Ravi
> >          If dept_no is a CF:qualifier, to know all the dept numbers
> > (distinct or not) you need a full table scan. As Doug said if it is a
> > frequent online query don't think MR is a good choice..  If the data in
> > your emp table is huge a full table scan also wont be that good I
> > feel....  Can you guys think about storing dept number in another
> > table?  If you people need query like select <empdetails> from emp
> > where dept_no=?  (this query also)  you can think about creating
> > secondary index implementation and indexing dept_no... You can use
> > index table for above query as well as the 1st one you asked about.  :)
> >
> > -Anoop-
> > ________________________________________
> > From: raviprasad.t@polarisFT.com [raviprasad.t@polarisFT.com]
> > Sent: Wednesday, October 10, 2012 7:51 PM
> > To: user@hbase.apache.org
> > Cc: hbase-user@hadoop.apache.org; user@hbase.apache.org
> > Subject: RE: HBase table - distinct values
> >
> > Hi,
> >   Hbase table name  :- emp
> >   Column family :- cf
> >     Under the column family cf  we will be having the field name
> > deptno
> >
> >
> > Regards
> > Raviprasad. T
> > Mobile :-  91- 9894769541
> >
> >
> > -----Anoop Sam John <anoopsj@huawei.com> wrote: -----
> > To: "user@hbase.apache.org" <user@hbase.apache.org>, "hbase-
> > user@hadoop.apache.org" <hbase-user@hadoop.apache.org>
> > From: Anoop Sam John <anoopsj@huawei.com>
> > Date: 10/10/2012 06:18PM
> > Subject: RE: HBase table - distinct values
> >
> > Hi
> > Your schema? 'deptno'  is a cf:qualifier?
> >
> > -Anoop-
> > ________________________________________
> > From: raviprasad.t@polarisFT.com [raviprasad.t@polarisFT.com]
> > Sent: Wednesday, October 10, 2012 4:29 PM
> > To: user@hbase.apache.org; hbase-user@hadoop.apache.org
> > Subject: HBase table - distinct values
> >
> > Hi all,
> >   Is it possible to select distinct value from Hbase table.
> >
> > Example :-
> >    what is the equivalant code for the below Oracle code  in Hbase  ?
> >
> >   Select count (distinct deptno) from emp ;
> >
> > Regards
> > Raviprasad. T
> >
> >
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