Jason Dere created HIVE-16298:
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Summary: Add config to specify multi-column joins have correlated
columns
Key: HIVE-16298
URL: https://issues.apache.org/jira/browse/HIVE-16298
Project: Hive
Issue Type: Bug
Reporter: Jason Dere
Assignee: Jason Dere
The default row estimation for multi-key joins divides the row estimate by the
product of the NDVs for each join column, which can cause the row estimate to
be low. Try adding a config to assume the columns are correlated, where we only
divide the row estimate by the largest NDV.
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