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Ashutosh Chauhan commented on HIVE-17493: ----------------------------------------- This can also be extended for full outer and inner joins. For full, pick min selectivity among 2 sides and for inner joins pick max selectivity. > 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 > Attachments: HIVE-17493.1.patch > > > 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. -- This message was sent by Atlassian JIRA (v6.4.14#64029)