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https://issues.apache.org/jira/browse/DRILL-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15228646#comment-15228646
]
ASF GitHub Bot commented on DRILL-4539:
---------------------------------------
Github user vkorukanti commented on a diff in the pull request:
https://github.com/apache/drill/pull/462#discussion_r58742546
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/common/DrillRelOptUtil.java
---
@@ -169,4 +176,223 @@ private static boolean containIdentity(List<? extends
RexNode> exps,
}
return true;
}
+
+ /**
+ * Copied from {@link RelOptUtil#splitJoinCondition(RelNode, RelNode,
RexNode, List, List)}. Modified to rewrite
--- End diff --
I will followup with a JIRA on Calcite project to see if we can push this
change to Calcite.
The function ```RelOptUtil#splitJoinCondition``` in the current form itself
seems to have a problem/limitation. Currently it just returns the left and
right join key indices, but doesn't return whether the condition is ```EQUAL```
or ```IS NOT DISTINCT FROM``` (it adds the key pair if they have either of
these function in comparison).
> 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.
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