Vineet Garg created HIVE-17493:
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Summary: Improve PKFK cardinality estimation in Physical planning
Key: HIVE-17493
URL: https://issues.apache.org/jira/browse/HIVE-17493
Project: Hive
Issue Type: Improvement
Components: Query Planning
Reporter: Vineet Garg
Assignee: Vineet Garg
Cardinality estimation of a join, after PK-FK relation has been ascertained,
could be improved if parent of the join operator is LEFT outer or RIGHT outer
join.
Currently estimation is done by estimating reduction of rows occurred on PK
side, then multiplying the reduction to FK side row count. This estimation of
reduction currently doesn't distinguish b/w INNER or OUTER joins. This could be
improved to handle outer joins better.
TPC-DS query45 is impacted by this.
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