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HBase, mail # user - HBase table - distinct values


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RE: HBase table - distinct values
Anoop Sam John 2012-10-11, 04:01
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-
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From: [EMAIL PROTECTED] [[EMAIL PROTECTED]]
Sent: Wednesday, October 10, 2012 7:51 PM
To: [EMAIL PROTECTED]
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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 <[EMAIL PROTECTED]> wrote: -----
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
From: Anoop Sam John <[EMAIL PROTECTED]>
Date: 10/10/2012 06:18PM
Subject: RE: HBase table - distinct values

Hi
Your schema? 'deptno'  is a cf:qualifier?

-Anoop-
________________________________________
From: [EMAIL PROTECTED] [[EMAIL PROTECTED]]
Sent: Wednesday, October 10, 2012 4:29 PM
To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
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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