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From Harsh J <ha...@cloudera.com>
Subject Re: TableReducer keyout
Date Tue, 19 Jun 2012 06:00:02 GMT
Hey Kevin,

(Moved this to the HBase user lists as it is more appropriate there -
cause of the libs you are using per your question. BCC'd
mapreduce-user and CC'd you in case you aren't subscribed to HBase
user lists).

The TableOutputFormat ignores keys. So it is safe to pass a null
object. This is also documented at

On Mon, Jun 18, 2012 at 6:17 PM, Kevin <kevin.macksamie@gmail.com> wrote:
> Hi,
> I am going through some samples of using MapReduce with HBase. My question
> is concerning the importance of the KEYOUT type of a TableReducer. Does the
> output key really matter if the output value must always be a Put or a
> Delete instance, in which the row key for the sink table is always
> specified? Can I just use null when writing the output key in the reducer
> class (e.g., context.write(null, MyPut))? It seems like in this usage of
> MapReduce the keyout would be only used when chaining jobs.
> -Kevin

Harsh J

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