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MapReduce >> mail # user >> Multiple Aggregate functions in map reduce program

iwannaplay games 2012-10-05, 07:02
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Re: Multiple Aggregate functions in map reduce program

It is definitely possible. In your map make the dept name as the output key and salary as the value.

In the reducer for every key you can initialize a counter and a sum. Add on to the sum for all values and increment the counter by 1 for each value. Output the dept key and the new aggregated sum and count for each key.
Bejoy KS

Sent from handheld, please excuse typos.

-----Original Message-----
From: iwannaplay games <[EMAIL PROTECTED]>
Date: Fri, 5 Oct 2012 12:32:28
Subject: Multiple Aggregate functions in map reduce program

Hi All,

I have to get the count and sum of data
for eg if my  table is
*employeename   salary   department*
A                       1000     testing
B                       2000     testing
C                       3000     development
D                       4000     testing
E                       1000     development
F                       5000     management

I want result like

Department       TotalSalary      count(employees)

testing                    7000                 3
development           4000                  2
management           5000                  1
Please let me know whether it is possible to write a java map reduce for
this.I tried this on hive.It takes time for big data.I heard map reduce
java code will b faster.IS it true???Or i should go for pig programming??

Please guide..

Bertrand Dechoux 2012-10-05, 08:13