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From Viral Bajaria <>
Subject hive : question about reducers
Date Thu, 10 Feb 2011 21:57:51 GMT

In my Hive cluster, I have setup the mapred.reduce.tasks to be -1 i.e. I am
allowing HIVE to figure out the # of reducers that it would need from the

When I run a query, it determines that it will need 4 reducers but when I
look at the MAPRED logs, I see that all the work is done by a single reducer
while the other 3 reducers forward 0 rows. Is this just bad planning on HIVE
side or am I missing something.


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