fix add columnar to row

Author: wForget

spark/src/main/scala/org/apache/comet/rules/CometExecRule.scala

@@ -608,18 +608,20 @@ case class CometExecRule(session: SparkSession) extends Rule[SparkPlan] {
         }
     }
 
-    plan.transformUp { case op =>
-      val newOp = convertNode(op)
-      // if newOp is not columnar and newOp.children has columnar, we need to add columnar to row
-      if (!newOp.supportsColumnar && !newOp.isInstanceOf[ColumnarToRowTransition]) {
-        val newChildren = newOp.children.map {
+    val newPlan = plan.transformUp { case op =>
+      convertNode(op)
+    }
+
+    // insert CometColumnarToRowExec if necessary
+    newPlan.transformUp {
+      case c2r: ColumnarToRowTransition => c2r
+      case op if !op.supportsColumnar =>
+        val newChildren = op.children.map {
           case c if c.supportsColumnar => CometColumnarToRowExec(c)
           case other => other
         }
-        newOp.withNewChildren(newChildren)
-      } else {
-        newOp
-      }
+        op.withNewChildren(newChildren)
+      case o => o
     }
   }