[GitHub] viirya commented on a change in pull request #23701: [SPARK-26741][SQL] Allow using aggregate expressions in ORDER BY clause

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viirya commented on a change in pull request #23701: [SPARK-26741][SQL] Allow using aggregate expressions in ORDER BY clause
URL: https://github.com/apache/spark/pull/23701#discussion_r253005531
 
 

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 File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
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 @@ -1679,7 +1694,31 @@ class Analyzer(
     }
 
     def containsAggregate(condition: Expression): Boolean = {
-      condition.find(_.isInstanceOf[AggregateExpression]).isDefined
+      condition.find(e =>
+        e.isInstanceOf[AggregateExpression] ||
+          e.isInstanceOf[GroupingID] || e.isInstanceOf[Grouping]).isDefined
+    }
+
+    private def pushDownMissingAttrs(
+        missingAttrs: Seq[NamedExpression], plan: LogicalPlan): LogicalPlan = {
+      // Missing attributes can be unresolved attributes or resolved attributes which are not in
+      // the output attributes of the plan.
+      plan match {
+        case p: Project =>
+          // Recursively pushing down expressions on the child of current plan.
+          val newChild = pushDownMissingAttrs(missingAttrs, p.child)
+          Project(p.projectList ++ missingAttrs.map(_.toAttribute), newChild)
+
+        case a @ Aggregate(_, aggExprs, _) =>
+          a.copy(aggregateExpressions = aggExprs ++ missingAttrs)
+
+        // For other operators (eg. Filter), push down recursively
+        case n: UnaryNode =>
 
 Review comment:
   Are there other operators than `Filter` can be here? If no, should we just reduce the case to `Filter`?

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