fix: fall back on nested types for default values

docs/source/user-guide/compatibility.md

@@ -65,6 +65,7 @@ types (regardless of the logical type). This behavior can be disabled by setting
 - There is a known performance issue when pushing filters down to Parquet. See the [Comet Tuning Guide] for more
 information.
 - There are failures in the Spark SQL test suite when enabling these new scans (tracking issues: [#1542] and [#1545]).
+- No support for default values that are nested types (e.g., maps, arrays, structs). Literal default values are supported.
 
 [#1545]: https://github.com/apache/datafusion-comet/issues/1545
 [#1542]: https://github.com/apache/datafusion-comet/issues/1542

docs/templates/compatibility-template.md

@@ -65,6 +65,7 @@ The new scans currently have the following limitations:
 - There is a known performance issue when pushing filters down to Parquet. See the [Comet Tuning Guide] for more
   information.
 - There are failures in the Spark SQL test suite when enabling these new scans (tracking issues: [#1542] and [#1545]).
+- No support for default values that are nested types (e.g., maps, arrays, structs). Literal default values are supported.
 
 [#1545]: https://github.com/apache/datafusion-comet/issues/1545
 [#1542]: https://github.com/apache/datafusion-comet/issues/1542

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

@@ -22,16 +22,17 @@ package org.apache.comet.rules
 import scala.collection.mutable.ListBuffer
 
 import org.apache.spark.sql.SparkSession
-import org.apache.spark.sql.catalyst.expressions.{Attribute, Expression, PlanExpression}
+import org.apache.spark.sql.catalyst.expressions.{Attribute, Expression, GenericInternalRow, PlanExpression}
 import org.apache.spark.sql.catalyst.rules.Rule
-import org.apache.spark.sql.catalyst.util.MetadataColumnHelper
+import org.apache.spark.sql.catalyst.util.{ArrayBasedMapData, GenericArrayData, MetadataColumnHelper}
+import org.apache.spark.sql.catalyst.util.ResolveDefaultColumns.getExistenceDefaultValues
 import org.apache.spark.sql.comet.{CometBatchScanExec, CometScanExec}
 import org.apache.spark.sql.execution.{FileSourceScanExec, SparkPlan}
 import org.apache.spark.sql.execution.datasources.HadoopFsRelation
 import org.apache.spark.sql.execution.datasources.v2.BatchScanExec
 import org.apache.spark.sql.execution.datasources.v2.parquet.ParquetScan
 import org.apache.spark.sql.internal.SQLConf
-import org.apache.spark.sql.types.{ArrayType, ByteType, DataType, MapType, ShortType, StructType}
+import org.apache.spark.sql.types._
 
 import org.apache.comet.{CometConf, DataTypeSupport}
 import org.apache.comet.CometConf._
@@ -118,7 +119,20 @@ case class CometScanRule(session: SparkSession) extends Rule[SparkPlan] {
           return withInfos(scanExec, fallbackReasons.toSet)
         }
 
-        val typeChecker = new CometScanTypeChecker(scanImpl)
+        val possibleDefaultValues = getExistenceDefaultValues(scanExec.requiredSchema)
+        if (possibleDefaultValues.exists(d => {
+            d != null && (d.isInstanceOf[ArrayBasedMapData] || d
+              .isInstanceOf[GenericInternalRow] || d.isInstanceOf[GenericArrayData])
+          })) {
+          // Spark already converted these to Java-native types, so we can't check SQL types.
+          // ArrayBasedMapData, GenericInternalRow, GenericArrayData correspond to maps, structs,
+          // and arrays respectively.
+          fallbackReasons +=
+            "Full native scan disabled because nested types for default values are not supported"
+          return withInfos(scanExec, fallbackReasons.toSet)
+        }
+
+        val typeChecker = CometScanTypeChecker(scanImpl)
         val schemaSupported =
           typeChecker.isSchemaSupported(scanExec.requiredSchema, fallbackReasons)
         val partitionSchemaSupported =