"MapReduce-MPI WWW Site"_mws - "MapReduce-MPI Documentation"_md :c

:link(mws,http://www.cs.sandia.gov/~sjplimp/mapreduce.html)
:link(md,Manual.html)

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MapReduce broadcast() method :h3

uint64_t MapReduce::broadcast(int root) :pre

This calls the broadcast() method of a MapReduce object, which delete
the key/value pairs of a KeyValue object on all processors except
root, and then broadcasts the key/value pairs owned by the root
processor to all the other processors.  The end result is
that all processors have a copy of the key/value pairs initially
owned by the root processor.

The resulting set of distributed key/value pairs will have P copies of
each entry, where P = the # of processors.  This will in general not
be useful for further MapReduce operations, but it can be useful after
a "gather()"_gather.html before doing a final "reduce()"_reduce.html
where you want to give each processor access to the entire gathered
result and let it make a local copy of the datums.

This method requires parallel communication as processors send their
key/value pairs to other processors.

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[Related methods]: "gather()"_gather.html
