FAQ
Hi,

In the hadoop documentation it says that all key-value classes need to
implement Writable to allow serialization and de-serialization of outputs
between mappers and reducers. Is this also necessary for key/value pairs
sent between the RecordReader and the Mapper (as well as the Reducer and the
RecordWriter)? I assume that each of these two cases, classes are
instantiated in the same VM. So is it safe to assume that key/value pairs
are sent by reference instead of serialization/deserialization? If so, my
specific application may get a performance boost. Please do let me know if
this so.

Thanks and best regards,
Dev

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groupcommon-user @
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postedJul 28, '09 at 6:24p
activeJul 29, '09 at 6:50p
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