The better question is why would you need a reducer?

That's a bit cryptic, I understand, but you have to ask yourself when do you 
need to use a reducer when you are writing to a database... ;-)


Sent from my iPhone

On Feb 28, 2012, at 10:14 AM, "T Vinod Gupta" <[email protected]> wrote:

> Mike,
> I didn't understand - why would I not need reducer in hbase m/r? there can
> be cases right.
> My use case is very similar to Sujee's blog on frequency counting -
> http://sujee.net/tech/articles/hadoop/hbase-map-reduce-freq-counter/
> So in the reducer, I can do all the aggregations. Is there a better way? I
> can think of another way - to use increments in the map job itself. i have
> to figure out if thats possible though.
> 
> thanks
> 
> On Tue, Feb 28, 2012 at 7:44 AM, Michel Segel 
> <[email protected]>wrote:
> 
>> Yes you can do it.
>> But why do you have a reducer when running a m/r job against HBase?
>> 
>> The trick in writing multiple rows... You do it independently of the
>> output from the map() method.
>> 
>> 
>> Sent from a remote device. Please excuse any typos...
>> 
>> Mike Segel
>> 
>> On Feb 28, 2012, at 8:34 AM, T Vinod Gupta <[email protected]> wrote:
>> 
>>> while doing map reduce on hbase tables, is it possible to do multiple
>> puts
>>> in the reducer? what i want is a way to be able to write multiple rows.
>> if
>>> its not possible, then what are the other alternatives? i mean like
>>> creating a wider table in that case.
>>> 
>>> thanks
>> 

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