[WIP] feat: Prefer to columnar

common/src/main/scala/org/apache/comet/CometConf.scala

@@ -601,6 +601,13 @@ object CometConf extends ShimCometConf {
       .toSequence
       .createWithDefault(Seq("Range,InMemoryTableScan,RDDScan"))
 
+  val COMET_PREFER_TO_ARROW_ENABLED: ConfigEntry[Boolean] =
+    conf("spark.comet.preferToColumnar.enabled")
+      .internal()
+      .doc("TODO: doc")
+      .booleanConf
+      .createWithDefault(true)
+
   val COMET_CASE_CONVERSION_ENABLED: ConfigEntry[Boolean] =
     conf("spark.comet.caseConversion.enabled")
       .doc(

common/src/main/scala/org/apache/spark/sql/comet/util/Utils.scala

@@ -154,7 +154,13 @@ object Utils extends CometTypeShim {
           name,
           fieldType,
           Seq(toArrowField("element", elementType, containsNull, timeZoneId)).asJava)
-      case StructType(fields) =>
+      case st @ StructType(fields) =>
+        if (st.names.toSet.size != fields.length) {
+          throw new SparkException(
+            "Duplicated field names in Arrow Struct are not allowed," +
+              s" got ${st.names.mkString("[", ", ", "]")}.")
+        }
+
         val fieldType = new FieldType(nullable, ArrowType.Struct.INSTANCE, null)
         new Field(
           name,

spark/src/main/scala/org/apache/comet/ExtendedExplainInfo.scala

@@ -25,6 +25,7 @@ import org.apache.spark.sql.ExtendedExplainGenerator
 import org.apache.spark.sql.catalyst.trees.{TreeNode, TreeNodeTag}
 import org.apache.spark.sql.execution.{InputAdapter, SparkPlan, WholeStageCodegenExec}
 import org.apache.spark.sql.execution.adaptive.{AdaptiveSparkPlanExec, QueryStageExec}
+import org.apache.spark.sql.execution.exchange.ReusedExchangeExec
 
 import org.apache.comet.CometExplainInfo.getActualPlan
 
@@ -158,6 +159,7 @@ object CometExplainInfo {
       case p: InputAdapter => getActualPlan(p.child)
       case p: QueryStageExec => getActualPlan(p.plan)
       case p: WholeStageCodegenExec => getActualPlan(p.child)
+      case p: ReusedExchangeExec => getActualPlan(p.child)
       case p => p
     }
   }