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From: Avrilia Floratou <floratou@cs.wisc.edu>
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Subject: Question on bucketed map join
Date: Thu, 19 Jan 2012 09:53:28 -0600
Message-Id: <67B1A444-AF6A-45B9-A978-58293180CB69@cs.wisc.edu>
To: user@hive.apache.org
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Hi,

I have two tables with 8 buckets each on the same key and want to join =
them.
I ran "explain extended" and get the plan produced by HIVE which shows =
that a map-side join is a possible plan.

I then set in my script the hive.optimize.bucketmapjoin option to true =
and reran the "explain extended" query. I get the exact same plans as =
output.

I ran the query with and without the bucketmapjoin optimization and saw =
no difference in the running time.

I have the following questions:

1. Should I see sth different in the explain extended output if I set =
and unset the hive.optimize.bucketmapjoin option?

2. Should I see something different in the output of hive while running =
the query if again I set and unset the hive.optimize.bucketmapjoin?

3. Is it possible that even though I set bucketmapjoin to true, Hive =
will still perform a normal map-side join for some reason? How can I =
check if this has actually happened?

Thanks,
Avrilia=20=