[VL] Fixed iceberg table properties config logic

backends-velox/src-iceberg/main/scala/org/apache/gluten/execution/AbstractIcebergWriteExec.scala

@@ -51,7 +51,7 @@ abstract class AbstractIcebergWriteExec extends IcebergWriteExec {
       MAX_TARGET_FILE_SIZE_SESSION.key -> getTargetFileSizeBytes
     ).foreach {
       case (key, value) =>
-        if (SQLConf.get.getConfString(key, null) != null) {
+        if (SQLConf.get.getConfString(key, null) == null) {
           icebergProperties.put(key, value)
         }
     }

backends-velox/src-iceberg/test/scala/org/apache/gluten/execution/enhanced/VeloxIcebergSuite.scala

@@ -18,7 +18,6 @@ package org.apache.gluten.execution.enhanced
 
 import org.apache.gluten.execution._
 import org.apache.gluten.tags.EnhancedFeaturesTest
-
 import org.apache.spark.sql.{DataFrame, Row}
 import org.apache.spark.sql.execution.CommandResultExec
 import org.apache.spark.sql.execution.GlutenImplicits._
@@ -465,4 +464,68 @@ class VeloxIcebergSuite extends IcebergSuite {
       )
     }
   }
+  test("iceberg native write respects target file size bytes") {
+    withTable("iceberg_small_target_tbl") {
+      spark.sql("""
+                  |CREATE TABLE iceberg_small_target_tbl (
+                  |  id INT,
+                  |  payload STRING
+                  |) USING iceberg
+                  |TBLPROPERTIES (
+                  |  'write.format.default' = 'parquet',
+                  |  'write.parquet.compression-codec' = 'uncompressed',
+                  |  'write.parquet.row-group-size-bytes' = '4096',
+                  |  'write.parquet.page-size-bytes' = '1024B',
+                  |  'write.target-file-size-bytes' = '8192'
+                  |)
+                  |""".stripMargin)
+
+      checkAnswer(
+        spark.sql("""
+                    |SHOW TBLPROPERTIES iceberg_small_target_tbl
+                    |('write.target-file-size-bytes')
+                    |""".stripMargin),
+        Seq(Row("write.target-file-size-bytes", "8192")))
+
+      val df = spark.sql("""
+                           |INSERT INTO iceberg_small_target_tbl
+                           |SELECT /*+ COALESCE(1) */
+                           |  CAST(id AS INT),
+                           |  concat(
+                           |    CAST(id AS STRING),
+                           |    '-',
+                           |    sha2(CAST(id AS STRING), 256),
+                           |    '-',
+                           |    sha2(CAST(id + 1000 AS STRING), 256)
+                           |  )
+                           |FROM range(1000)
+                           |""".stripMargin)
+
+      val commandPlan =
+        df.queryExecution.executedPlan.asInstanceOf[CommandResultExec].commandPhysicalPlan
+
+      assert(commandPlan.isInstanceOf[VeloxIcebergAppendDataExec])
+
+      checkAnswer(
+        spark.sql("SELECT COUNT(*) FROM iceberg_small_target_tbl"),
+        Seq(Row(1000L)))
+
+      val files = spark.sql("""
+                              |SELECT file_size_in_bytes
+                              |FROM default.iceberg_small_target_tbl.files
+                              |""".stripMargin).collect().map(_.getLong(0))
+
+      assert(files.nonEmpty)
+
+      assert(
+        files.length > 1,
+        s"Expected write.target-file-size-bytes=8192 to create multiple files, " +
+          s"but got files=${files.mkString("[", ", ", "]")}")
+
+      assert(
+        files.max < 64L * 1024L,
+        s"Expected small target file size to keep max file size reasonably small, " +
+          s"but got files=${files.mkString("[", ", ", "]")}")
+    }
+  }
 }

gluten-iceberg/src/main/scala/org/apache/gluten/execution/IcebergWriteExec.scala

@@ -19,7 +19,7 @@ package org.apache.gluten.execution
 import org.apache.gluten.backendsapi.BackendsApiManager
 
 import org.apache.iceberg.{FileFormat, PartitionField, PartitionSpec, Schema, TableProperties}
-import org.apache.iceberg.TableProperties.{ORC_COMPRESSION, ORC_COMPRESSION_DEFAULT, PARQUET_COMPRESSION, PARQUET_COMPRESSION_DEFAULT, PARQUET_PAGE_SIZE_BYTES, PARQUET_PAGE_SIZE_BYTES_DEFAULT, WRITE_TARGET_FILE_SIZE_BYTES, WRITE_TARGET_FILE_SIZE_BYTES_DEFAULT}
+import org.apache.iceberg.TableProperties.{ORC_COMPRESSION, ORC_COMPRESSION_DEFAULT, PARQUET_COMPRESSION, PARQUET_COMPRESSION_DEFAULT, PARQUET_PAGE_SIZE_BYTES, PARQUET_PAGE_SIZE_BYTES_DEFAULT}
 import org.apache.iceberg.avro.AvroSchemaUtil
 import org.apache.iceberg.spark.source.IcebergWriteUtil
 import org.apache.iceberg.types.Type.TypeID
@@ -50,15 +50,14 @@ trait IcebergWriteExec extends ColumnarV2TableWriteExec {
   }
 
   protected def getParquetPageSizeBytes: String = {
-    val config = IcebergWriteUtil.getWriteProperty(write)
-    config.getOrDefault(
+    val tableProps = IcebergWriteUtil.getTable(write).properties()
+    tableProps.getOrDefault(
       normalizeCapacityString(PARQUET_PAGE_SIZE_BYTES),
       normalizeCapacityString(PARQUET_PAGE_SIZE_BYTES_DEFAULT.toString))
   }
 
   protected def getTargetFileSizeBytes: String = {
-    val config = IcebergWriteUtil.getWriteProperty(write)
-    config.getOrDefault(WRITE_TARGET_FILE_SIZE_BYTES, WRITE_TARGET_FILE_SIZE_BYTES_DEFAULT.toString)
+    IcebergWriteUtil.getWriteConf(write).targetDataFileSize().toString
   }
 
   protected def getPartitionSpec: PartitionSpec = {