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From "Kevin Wilfong (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-3467) BucketMapJoinOptimizer should optimize joins on partition columns
Date Fri, 14 Sep 2012 17:28:08 GMT
Kevin Wilfong created HIVE-3467:
-----------------------------------

             Summary: BucketMapJoinOptimizer should optimize joins on partition columns
                 Key: HIVE-3467
                 URL: https://issues.apache.org/jira/browse/HIVE-3467
             Project: Hive
          Issue Type: Bug
          Components: Query Processor
    Affects Versions: 0.10.0
            Reporter: Kevin Wilfong


Consider the query:

SELECT * FROM t1 JOIN t2 on t1.part = t2.part and t1.key = t2.key;

Where t1 and t2 are partitioned by part and bucketed by key.
Suppose part take values 1 and 2 and t1 and t2 are bucketed into 2 buckets.

The bucket map join optimizer will put the first bucket of part=1 and part=2 partitions of
t2 into the same mapper as that of part=1 partition of t1.  It will do the same for the part=2
partition of t1.

It could take advantage of the partition values and send the first bucket of only the part=1
partitions of t1 and t2 into one mapper and the first bucket of only the part=2 partitions
into another.

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