[GitHub] [spark] cloud-fan commented on a change in pull request #30999: [SPARK-33971][SQL] Eliminate distinct from more aggregates

[GitBox <gi...@apache.org>]

cloud-fan commented on a change in pull request #30999:
URL: https://github.com/apache/spark/pull/30999#discussion_r556263075



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -349,11 +349,19 @@ abstract class Optimizer(catalogManager: CatalogManager)
  */
 object EliminateDistinct extends Rule[LogicalPlan] {
   override def apply(plan: LogicalPlan): LogicalPlan = plan transformExpressions  {
-    case ae: AggregateExpression if ae.isDistinct =>
-      ae.aggregateFunction match {
-        case _: Max | _: Min => ae.copy(isDistinct = false)
-        case _ => ae
-      }
+    case ae: AggregateExpression if ae.isDistinct && isDuplicateAgnostic(ae.aggregateFunction) =>
+      ae.copy(isDistinct = false)
+  }
+
+  private def isDuplicateAgnostic(af: AggregateFunction): Boolean = af match {
+    case _: Max => true
+    case _: Min => true
+    case _: BitAndAgg => true
+    case _: BitOrAgg => true
+    case _: First => true

Review comment:
       Let's exclude First/Last here before #29810 is merged




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