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Aman Sinha commented on DRILL-4539: ----------------------------------- Interesting that Calcite's default behavior is to do the conversion of IS_NOT_DISTINCT_FROM to CASE if it was specified in the original query considering that Calcite itself internally generates the HashJoin plan with IS_NOT_DISTINCT_FROM join condition (see DRILL-2092 for an example). > Add support for Null Equality Joins > ----------------------------------- > > Key: DRILL-4539 > URL: https://issues.apache.org/jira/browse/DRILL-4539 > Project: Apache Drill > Issue Type: Improvement > Reporter: Jacques Nadeau > Assignee: Venki Korukanti > > Tableau frequently generates queries similar to this: > {code} > SELECT `t0`.`city` AS `city`, > `t2`.`X_measure__B` AS `max_Calculation_DFIDBHHAIIECCJFDAG_ok`, > `t0`.`state` AS `state`, > `t0`.`sum_stars_ok` AS `sum_stars_ok` > FROM ( > SELECT `business`.`city` AS `city`, > `business`.`state` AS `state`, > SUM(`business`.`stars`) AS `sum_stars_ok` > FROM `mongo.academic`.`business` `business` > GROUP BY `business`.`city`, > `business`.`state` > ) `t0` > INNER JOIN ( > SELECT MAX(`t1`.`X_measure__A`) AS `X_measure__B`, > `t1`.`city` AS `city`, > `t1`.`state` AS `state` > FROM ( > SELECT `business`.`city` AS `city`, > `business`.`state` AS `state`, > `business`.`business_id` AS `business_id`, > SUM(`business`.`stars`) AS `X_measure__A` > FROM `mongo.academic`.`business` `business` > GROUP BY `business`.`city`, > `business`.`state`, > `business`.`business_id` > ) `t1` > GROUP BY `t1`.`city`, > `t1`.`state` > ) `t2` ON (((`t0`.`city` = `t2`.`city`) OR ((`t0`.`city` IS NULL) AND > (`t2`.`city` IS NULL))) AND ((`t0`.`state` = `t2`.`state`) OR ((`t0`.`state` > IS NULL) AND (`t2`.`state` IS NULL)))) > {code} > If you look at the join condition, you'll note that the join condition is an > equality condition which also allows null=null. We should add a planning > rewrite rule and execution join option to allow null equality so that we > don't treat this as a cartesian join. -- This message was sent by Atlassian JIRA (v6.3.4#6332)