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https://issues.apache.org/jira/browse/DRILL-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15240832#comment-15240832
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ASF GitHub Bot commented on DRILL-4539:
---------------------------------------
Github user vkorukanti commented on the pull request:
https://github.com/apache/drill/pull/462#issuecomment-209836956
Added few more tests:
```SELECT * FROM t1, t2, t3 WHERE t1.a = t2.a OR (t1.b is null and t3.b is
null)``` to test it throws CannotPlanException
```SELECT * FROM t1, t2 WHERE t1.a = t2.a OR (t1.a is null and t2.a is
null)``` to test null-equality filter is pushed into join condition. Had to
make some changes to ```DrillFilterJoinRules``` to handle this case.
Also few more tests around 3 table join that involve null-equality
condition in ```WHERE``` clause and ```JOIN ON```
4 tests from extended regression suite failed, because now we generate a
join condition that involves ```=`` and ```IS NOT DISTINCT FROM```.
```SELECT * FROM cp.`jsonInput/nullableOrdered1.json` t1 JOIN
cp.`jsonInput/nullableOrdered2.json` t2 ON t1.key = t2.key WHERE t1.data IS NOT
DISTINCT FROM t2.data```
It looks like HashJoin/MergeJoin operators are not handling mixed
comparator in join condition. Looking at the ```ChainedHashTable``` and
```MergeJoinBatch``` code briefly, it seems like we should be able to generate
code for handling mixed comparators case. @amansinha100: Let me know if I am
not correct.
> 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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