grundprinzip commented on code in PR #38468:
URL: https://github.com/apache/spark/pull/38468#discussion_r1013643400


##########
sql/core/src/main/scala/org/apache/spark/sql/execution/arrow/ArrowConverters.scala:
##########
@@ -128,6 +128,65 @@ private[sql] object ArrowConverters extends Logging {
     }
   }
 
+  private[sql] def toArrowBatchIterator(
+      rowIter: Iterator[InternalRow],
+      schema: StructType,
+      maxRecordsPerBatch: Int,
+      timeZoneId: String,
+      context: TaskContext): Iterator[(Array[Byte], Long, Long)] = {
+    val arrowSchema = ArrowUtils.toArrowSchema(schema, timeZoneId)
+    val allocator = ArrowUtils.rootAllocator.newChildAllocator(
+      "toArrowBatchIterator", 0, Long.MaxValue)
+
+    val root = VectorSchemaRoot.create(arrowSchema, allocator)
+    val unloader = new VectorUnloader(root)
+    val arrowWriter = ArrowWriter.create(root)
+
+    if (context != null) { // for test at driver
+      context.addTaskCompletionListener[Unit] { _ =>
+        root.close()
+        allocator.close()
+      }
+    }
+
+    new Iterator[(Array[Byte], Long, Long)] {
+
+      override def hasNext: Boolean = rowIter.hasNext || {
+        root.close()
+        allocator.close()
+        false
+      }
+
+      override def next(): (Array[Byte], Long, Long) = {

Review Comment:
   did you check what happens if you do a `select * from table limit 0` I have 
previously had some challenges where the query returned 0 partitions and 
because of that we would not send a schema.



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