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From unmesha sreeveni <unmeshab...@gmail.com>
Subject Re: what all can be done using MR
Date Sat, 11 Jan 2014 16:20:48 GMT
For that do we have to write a custom class for value inorder to pass all
the columns as value.
ie in the example 2 values. Or jst do a concatenation and emit values.


On Sat, Jan 11, 2014 at 9:46 PM, Chris Mawata <chris.mawata@gmail.com>wrote:

> Results will be sorted by key so make A the key and put the rest in the
> value
> Chris
> On Jan 11, 2014 10:11 AM, "unmesha sreeveni" <unmeshabiju@gmail.com>
> wrote:
>
>> What about sorting .
>> Acutually it is done by MapReduce itself.
>>  But if we are giving a csv file as input and trying to sort one/multiple
>> column...Whether the corresponting columns also get reflectted??
>>
>> eg: foo.csv
>>  B,2,3
>> A,4,6
>>
>> When we apply sorting to first column:whether the resultent will be
>> A,4,6
>> B,2,3
>> A will be mapped to its correct values right?
>> If so what will be context.write() of mapper?
>>
>>
>> On Wed, Jan 8, 2014 at 8:18 PM, Chris Mawata <chris.mawata@gmail.com>wrote:
>>
>>>  Yes.
>>> Check out, for example,
>>> http://packtlib.packtpub.com/library/hadoop-mapreduce-cookbook/ch06lvl1sec66#
>>>
>>>
>>>
>>> On 1/8/2014 2:41 AM, unmesha sreeveni wrote:
>>>
>>>  Can we do aggregation with in Hadoop MR
>>> like find min,max,sum,avg of a column in a csv file.
>>>
>>>  --
>>> *Thanks & Regards*
>>>
>>>  Unmesha Sreeveni U.B
>>>  Junior Developer
>>>
>>>  http://www.unmeshasreeveni.blogspot.in/
>>>
>>>
>>>
>>>
>>
>>
>> --
>> *Thanks & Regards*
>>
>> Unmesha Sreeveni U.B
>> Junior Developer
>>
>> http://www.unmeshasreeveni.blogspot.in/
>>
>>
>>


-- 
*Thanks & Regards*

Unmesha Sreeveni U.B
Junior Developer

http://www.unmeshasreeveni.blogspot.in/

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