tanelk commented on a change in pull request #31045:
URL: https://github.com/apache/spark/pull/31045#discussion_r552866614
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -1612,9 +1612,12 @@ object ConvertToLocalRelation extends Rule[LogicalPlan] {
* {{{
* SELECT DISTINCT f1, f2 FROM t ==> SELECT f1, f2 FROM t GROUP BY f1, f2
* }}}
+ *
+ * The [[Distinct]] can be ignored if it is the right child of a left semi or
anti join.
*/
object ReplaceDistinctWithAggregate extends Rule[LogicalPlan] {
- def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transformDown {
+ case j @ Join(_, Distinct(right), LeftSemiOrAnti(_), _, _) => j.copy(right
= right)
Review comment:
I benchmarked a bit and you are right - this can cause a performance
regression. For example q87 took a 10% hit on sf100. I think it's best to close
this PR and issue.
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