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From Dean Wampler <dean.wamp...@thinkbiganalytics.com>
Subject Re: Execution of udf
Date Fri, 18 Jan 2013 14:58:45 GMT
That should be an identity pass through or NOOP that does nothing, but
MapReduce requires "something".

On Fri, Jan 18, 2013 at 8:57 AM, nagarjuna kanamarlapudi <
nagarjuna.kanamarlapudi@gmail.com> wrote:

> No but the query execution shows a reducer running .. And infant I feel
> that reduce phase can be there
>
>
> On Friday, January 18, 2013, Dean Wampler wrote:
>
>> There is no reduce phase needed in this query.
>>
>> On Fri, Jan 18, 2013 at 6:59 AM, nagarjuna kanamarlapudi <
>> nagarjuna.kanamarlapudi@gmail.com> wrote:
>>
>>> Hi,
>>>
>>> Select col1,myudf(col2,col3) from table1;
>>>
>>>
>>> In what phase if map reduce an udf is executed.
>>>
>>> In the very beginning, I assumed that hive will be joining two tables.,
>>> getting the required columns and then applies udf on columns specified
>>> I.e., essentially on reducer phase . But later on I realised that I was
>>> wrong.
>>>
>>> Is there any specific parameter which suggests hive to call udf at
>>> reducer phase rather than at Mapper phase.
>>>
>>>
>>> Regards,
>>> Nagarjuna
>>>
>>>
>>> --
>>> Sent from iPhone
>>>
>>
>>
>>
>> --
>> *Dean Wampler, Ph.D.*
>> thinkbiganalytics.com
>> +1-312-339-1330
>>
>>
>
> --
> Sent from iPhone
>



-- 
*Dean Wampler, Ph.D.*
thinkbiganalytics.com
+1-312-339-1330

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