merge main

pyiceberg/io/pyarrow.py

@@ -2034,7 +2034,7 @@ def bin_pack_arrow_table(tbl: pa.Table, target_file_size: int) -> Iterator[List[
 
 def _check_schema_compatible(table_schema: Schema, other_schema: pa.Schema, downcast_ns_timestamp_to_us: bool = False) -> None:
     """
-    Check if the `table_schema` is compatible with `other_schema`.
+    Check if the `table_schema` is compatible with `other_schema` in terms of the Iceberg Schema representation.
 
     The schemas are compatible if:
     - All fields in `other_schema` are present in `table_schema`. (other_schema <= table_schema)
@@ -2043,22 +2043,22 @@ def _check_schema_compatible(table_schema: Schema, other_schema: pa.Schema, down
     Raises:
         ValueError: If the schemas are not compatible.
     """
-    from pyiceberg.io.pyarrow import _pyarrow_to_schema_without_ids, pyarrow_to_schema
-
     name_mapping = table_schema.name_mapping
     try:
-        other_schema = pyarrow_to_schema(other_schema, name_mapping=name_mapping)
+        other_schema = pyarrow_to_schema(
+            other_schema, name_mapping=name_mapping, downcast_ns_timestamp_to_us=downcast_ns_timestamp_to_us
+        )
     except ValueError as e:
-        other_schema = _pyarrow_to_schema_without_ids(other_schema)
+        other_schema = _pyarrow_to_schema_without_ids(other_schema, downcast_ns_timestamp_to_us=downcast_ns_timestamp_to_us)
         additional_names = set(other_schema.column_names) - set(table_schema.column_names)
         raise ValueError(
             f"PyArrow table contains more columns: {', '.join(sorted(additional_names))}. Update the schema first (hint, use union_by_name)."
         ) from e
 
-    missing_table_schema_fields = {field for field in other_schema.fields if field not in table_schema.fields}
-    required_table_schema_fields = {field for field in table_schema.fields if field.required}
-    missing_required_fields = {field for field in required_table_schema_fields if field not in other_schema.fields}
-    if missing_table_schema_fields or missing_required_fields:
+    fields_missing_from_table = {field for field in other_schema.fields if field not in table_schema.fields}
+    required_fields_in_table = {field for field in table_schema.fields if field.required}
+    missing_required_fields_in_other = {field for field in required_fields_in_table if field not in other_schema.fields}
+    if fields_missing_from_table or missing_required_fields_in_other:
         from rich.console import Console
         from rich.table import Table as RichTable
 
@@ -2182,17 +2182,20 @@ def _dataframe_to_data_files(
         default=TableProperties.WRITE_TARGET_FILE_SIZE_BYTES_DEFAULT,
     )
 
+    # projects schema to match the pyarrow table
+    write_schema = pyarrow_to_schema(df.schema, name_mapping=table_metadata.schema().name_mapping)
+
     if table_metadata.spec().is_unpartitioned():
         yield from write_file(
             io=io,
             table_metadata=table_metadata,
             tasks=iter([
-                WriteTask(write_uuid=write_uuid, task_id=next(counter), record_batches=batches, schema=table_metadata.schema())
+                WriteTask(write_uuid=write_uuid, task_id=next(counter), record_batches=batches, schema=write_schema)
                 for batches in bin_pack_arrow_table(df, target_file_size)
             ]),
         )
     else:
-        partitions = _determine_partitions(spec=table_metadata.spec(), schema=table_metadata.schema(), arrow_table=df)
+        partitions = _determine_partitions(spec=table_metadata.spec(), schema=write_schema, arrow_table=df)
         yield from write_file(
             io=io,
             table_metadata=table_metadata,

tests/io/test_pyarrow.py

@@ -1832,20 +1832,6 @@ def test_schema_downcast(table_schema_simple: Schema) -> None:
         pytest.fail("Unexpected Exception raised when calling `_check_schema_compatible`")
 
 
-def test_schema_downcast(table_schema_simple: Schema) -> None:
-    # large_string type is compatible with string type
-    other_schema = pa.schema((
-        pa.field("foo", pa.large_string(), nullable=True),
-        pa.field("bar", pa.int32(), nullable=False),
-        pa.field("baz", pa.bool_(), nullable=True),
-    ))
-
-    try:
-        _check_schema_compatible(table_schema_simple, other_schema)
-    except Exception:
-        pytest.fail("Unexpected Exception raised when calling `_check_schema`")
-
-
 def test_partition_for_demo() -> None:
     test_pa_schema = pa.schema([("year", pa.int64()), ("n_legs", pa.int64()), ("animal", pa.string())])
     test_schema = Schema(