Github user dilipbiswal commented on a diff in the pull request:
https://github.com/apache/spark/pull/22326#discussion_r214828964
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -1208,9 +1208,26 @@ object PushPredicateThroughJoin extends
Rule[LogicalPlan] with PredicateHelper {
reduceLeftOption(And).map(Filter(_, left)).getOrElse(left)
val newRight = rightJoinConditions.
reduceLeftOption(And).map(Filter(_, right)).getOrElse(right)
- val newJoinCond = commonJoinCondition.reduceLeftOption(And)
-
- Join(newLeft, newRight, joinType, newJoinCond)
+ val (newJoinConditions, others) =
+ commonJoinCondition.partition(canEvaluateWithinJoin)
+ val newJoinCond = newJoinConditions.reduceLeftOption(And)
+ // if condition expression is unevaluable, it will be removed
from
+ // the new join conditions, if all conditions is unevaluable, we
should
+ // change the join type to CrossJoin.
+ val newJoinType =
+ if (commonJoinCondition.nonEmpty && newJoinCond.isEmpty) {
+ logWarning(s"The whole
commonJoinCondition:$commonJoinCondition of the join " +
+ s"plan:\n $j is unevaluable, it will be ignored and the
join plan will be " +
--- End diff --
@xuanyuanking @mgaido91 In the above example, the UDF's refer to attributes
from distinct legs of the join. Can we not plan this better than a cross join
in this case ? I am wondering why we can't do -
```
Join Inner, leftAlias1 = rightAlias1
Project dummyUDF(a, b) as leftAlias1
LocalRelation(a, b)
Project dummyUDF(c, d) as rightAlias1
LocalRelation(c, d)
```
Perhaps i am missing something ..
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