[
https://issues.apache.org/jira/browse/DRILL-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15228628#comment-15228628
]
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_r58741416
--- Diff:
exec/java-exec/src/main/codegen/templates/ComparisonFunctions.java ---
@@ -215,6 +192,36 @@ public void eval() {
}
}
+ <#-- IS_DISTINCT_FROM function -->
+ @FunctionTemplate(names = {"is_distinct_from", "is distinct from" },
--- End diff --
I am not sure if there is way to differentiate between the function in join
condition vs. function in project expr. I don't see any context info in
DrillConvertletTable.get() method call. Also the generated code in rewritten
case is too much. For following query:
```SELECT INT_col is not distinct from BIGINT_col as col,
int_distinct_result FROM cp.`functions/distinct_from.json```
Without rewrite:
https://gist.github.com/vkorukanti/e981058f985ed24e6c4ef6b47d670e0f
With rewrite:
https://gist.github.com/vkorukanti/d80aa2ba40c65c9215c38ed18b20a685
Sizes may differ after scalar replacement is done, but it is still too much
code to simple ```is not distinct from``` function.
> 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)
