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From "Jesus Camacho Rodriguez (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-13069) Enable cartesian product merging
Date Wed, 17 Feb 2016 08:56:18 GMT
Jesus Camacho Rodriguez created HIVE-13069:
----------------------------------------------

             Summary: Enable cartesian product merging
                 Key: HIVE-13069
                 URL: https://issues.apache.org/jira/browse/HIVE-13069
             Project: Hive
          Issue Type: Bug
          Components: Parser
            Reporter: Jesus Camacho Rodriguez
            Assignee: Jesus Camacho Rodriguez


Currently we can merge 2-way joins into n-way joins when the joins are executed over the same
column.

In turn, CBO might produce plans containing cartesian products if the join columns are constant
values; after HIVE-12543 went in, this is rather common, as those constant columns are correctly
pruned. However, currently we do not merge a cartesian product with two inputs into a cartesian
product with multiple inputs, which could result in performance loss.



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