On Sep 21, 2008, at 9:33 PM, Sandy wrote:
Is there a way to get the total number of keys emitted by particular
mapper
in the beginning of the combiner function?
The short answer is no. As I said in my previous email, the combiner
will get called when the first spill is being dumped. This can happen
while the map is still running in a different thread. Therefore, the
number wouldn't make much sense. Also note that the combiner may be
called a second (or third or forth) time on a given record as the
spills are merged.
-- Owen
