Remove field id constraint on add files

mkdocs/docs/api.md

@@ -1006,9 +1006,11 @@ Expert Iceberg users may choose to commit existing parquet files to the Iceberg
 
 <!-- prettier-ignore-start -->
 
-!!! note "Name Mapping"
-    Because `add_files` uses existing files without writing new parquet files that are aware of the Iceberg's schema, it requires the Iceberg's table to have a [Name Mapping](https://iceberg.apache.org/spec/?h=name+mapping#name-mapping-serialization) (The Name mapping maps the field names within the parquet files to the Iceberg field IDs). Hence, `add_files` requires that there are no field IDs in the parquet file's metadata, and creates a new Name Mapping based on the table's current schema if the table doesn't already have one.
-
+!!! note "Name Mapping and Field IDs"
+    `add_files` can work with Parquet files both with and without field IDs in their metadata:
+    - **Files with field IDs**: When field IDs are present in the Parquet metadata, they must match the corresponding field IDs in the Iceberg table schema. This is common for files generated by tools like Spark or when using or other libraries with explicit field ID metadata.
+    - **Files without field IDs**: When field IDs are absent, the table must have a [Name Mapping](https://iceberg.apache.org/spec/?h=name+mapping#name-mapping-serialization) to map field names to Iceberg field IDs. `add_files` will automatically create a Name Mapping based on the table's current schema if one doesn't already exist.
+    In both cases, a Name Mapping is created if the table doesn't have one, ensuring compatibility with various readers.
 !!! note "Partitions"
     `add_files` only requires the client to read the existing parquet files' metadata footer to infer the partition value of each file. This implementation also supports adding files to Iceberg tables with partition transforms like `MonthTransform`, and `TruncateTransform` which preserve the order of the values after the transformation (Any Transform that has the `preserves_order` property set to True is supported). Please note that if the column statistics of the `PartitionField`'s source column are not present in the parquet metadata, the partition value is inferred as `None`.
 

pyiceberg/io/pyarrow.py

@@ -2610,7 +2610,10 @@ def _check_pyarrow_schema_compatible(
     Raises:
         ValueError: If the schemas are not compatible.
     """
+    # Check if the PyArrow schema has explicit field IDs
+    has_field_ids = visit_pyarrow(provided_schema, _HasIds())
     name_mapping = requested_schema.name_mapping
+
     try:
         provided_schema = pyarrow_to_schema(
             provided_schema,
@@ -2624,8 +2627,41 @@ def _check_pyarrow_schema_compatible(
         )
         additional_names = set(provided_schema._name_to_id.keys()) - set(requested_schema._name_to_id.keys())
         raise ValueError(
-            f"PyArrow table contains more columns: {', '.join(sorted(additional_names))}. Update the schema first (hint, use union_by_name)."
+            f"PyArrow table contains more columns: {', '.join(sorted(additional_names))}. "
+            "Update the schema first (hint, use union_by_name)."
         ) from e
+
+    # If the file has explicit field IDs, validate they match the table schema exactly
+    if has_field_ids:
+        # Build mappings for both schemas (including nested fields)
+        requested_id_to_name = requested_schema._lazy_id_to_name
+        provided_id_to_name = provided_schema._lazy_id_to_name
+
+        # Also build reverse mapping: path -> field_id for the table
+        requested_name_to_id = {path: field_id for field_id, path in requested_id_to_name.items()}
+
+        # Check that all field paths in the file have matching field IDs in the table
+        mismatched_fields = []
+        for field_id, provided_path in provided_id_to_name.items():
+            # Check if this path exists in the table schema
+            expected_field_id = requested_name_to_id.get(provided_path)
+            if expected_field_id is None:
+                # The file has a field path that doesn't exist in the table at all
+                # This will be caught by _check_schema_compatible later, so skip it here
+                continue
+            elif expected_field_id != field_id:
+                # Same path, different field ID - this is the critical error
+                mismatched_fields.append(
+                    f"'{provided_path}': table expects field_id={expected_field_id}, file has field_id={field_id}"
+                )
+
+        if mismatched_fields:
+            raise ValueError(
+                "Field IDs in Parquet file do not match table schema. When field IDs are explicitly set in the "
+                "Parquet metadata, they must match the Iceberg table schema.\nMismatched fields:\n"
+                + "\n".join(f"  - {field}" for field in mismatched_fields)
+            )
+
     _check_schema_compatible(requested_schema, provided_schema)
 
 
@@ -2641,10 +2677,6 @@ def parquet_file_to_data_file(io: FileIO, table_metadata: TableMetadata, file_pa
         parquet_metadata = pq.read_metadata(input_stream)
 
     arrow_schema = parquet_metadata.schema.to_arrow_schema()
-    if visit_pyarrow(arrow_schema, _HasIds()):
-        raise NotImplementedError(
-            f"Cannot add file {file_path} because it has field IDs. `add_files` only supports addition of files without field_ids"
-        )
 
     schema = table_metadata.schema()
     _check_pyarrow_schema_compatible(schema, arrow_schema, format_version=table_metadata.format_version)

tests/integration/test_add_files.py

@@ -47,6 +47,7 @@
     LongType,
     NestedField,
     StringType,
+    StructType,
     TimestampType,
     TimestamptzType,
 )
@@ -216,23 +217,150 @@ def test_add_files_to_unpartitioned_table_raises_file_not_found(
 
 
 @pytest.mark.integration
-def test_add_files_to_unpartitioned_table_raises_has_field_ids(
+def test_add_files_to_unpartitioned_table_with_field_ids(
     spark: SparkSession, session_catalog: Catalog, format_version: int
 ) -> None:
-    identifier = f"default.unpartitioned_raises_field_ids_v{format_version}"
+    identifier = f"default.unpartitioned_with_field_ids_v{format_version}"
     tbl = _create_table(session_catalog, identifier, format_version)
 
-    file_paths = [f"s3://warehouse/default/unpartitioned_raises_field_ids/v{format_version}/test-{i}.parquet" for i in range(5)]
-    # write parquet files
+    file_paths = [f"s3://warehouse/default/unpartitioned_with_field_ids/v{format_version}/test-{i}.parquet" for i in range(5)]
+    # write parquet files with field IDs matching the table schema
     for file_path in file_paths:
         fo = tbl.io.new_output(file_path)
         with fo.create(overwrite=True) as fos:
             with pq.ParquetWriter(fos, schema=ARROW_SCHEMA_WITH_IDS) as writer:
                 writer.write_table(ARROW_TABLE_WITH_IDS)
 
     # add the parquet files as data files
-    with pytest.raises(NotImplementedError):
-        tbl.add_files(file_paths=file_paths)
+    tbl.add_files(file_paths=file_paths)
+
+    # NameMapping should still be set even though files have field IDs
+    assert tbl.name_mapping() is not None
+
+    # Verify files were added successfully
+    rows = spark.sql(
+        f"""
+        SELECT added_data_files_count, existing_data_files_count, deleted_data_files_count
+        FROM {identifier}.all_manifests
+    """
+    ).collect()
+
+    assert [row.added_data_files_count for row in rows] == [5]
+    assert [row.existing_data_files_count for row in rows] == [0]
+    assert [row.deleted_data_files_count for row in rows] == [0]
+
+    # Verify data can be read back correctly
+    df = spark.table(identifier).toPandas()
+    assert len(df) == 5
+    assert all(df["foo"] == True)  # noqa: E712
+    assert all(df["bar"] == "bar_string")
+    assert all(df["baz"] == 123)
+    assert all(df["qux"] == date(2024, 3, 7))
+
+
+@pytest.mark.integration
+def test_add_files_with_mismatched_field_ids(spark: SparkSession, session_catalog: Catalog, format_version: int) -> None:
+    identifier = f"default.unpartitioned_mismatched_field_ids_v{format_version}"
+    tbl = _create_table(session_catalog, identifier, format_version)
+
+    # Create schema with field IDs that don't match the table schema
+    # Table has: 1=foo, 2=bar, 3=baz, 4=qux (assigned by catalog)
+    # This file has: 1=foo, 2=bar, 5=baz, 6=qux (wrong IDs for baz and qux)
+    mismatched_schema = pa.schema(
+        [
+            pa.field("foo", pa.bool_(), nullable=False, metadata={"PARQUET:field_id": "1"}),
+            pa.field("bar", pa.string(), nullable=False, metadata={"PARQUET:field_id": "2"}),
+            pa.field("baz", pa.int32(), nullable=False, metadata={"PARQUET:field_id": "5"}),  # Wrong: should be 3
+            pa.field("qux", pa.date32(), nullable=False, metadata={"PARQUET:field_id": "6"}),  # Wrong: should be 4
+        ]
+    )
+
+    file_path = f"s3://warehouse/default/unpartitioned_mismatched_field_ids/v{format_version}/test.parquet"
+    fo = tbl.io.new_output(file_path)
+    with fo.create(overwrite=True) as fos:
+        with pq.ParquetWriter(fos, schema=mismatched_schema) as writer:
+            writer.write_table(ARROW_TABLE_WITH_IDS)
+
+    # Adding files with mismatched field IDs should fail
+    with pytest.raises(ValueError, match="Field IDs in Parquet file do not match table schema"):
+        tbl.add_files(file_paths=[file_path])
+
+
+@pytest.mark.integration
+def test_add_files_with_mismatched_nested_field_ids(spark: SparkSession, session_catalog: Catalog, format_version: int) -> None:
+    """Test that files with mismatched nested (struct) field IDs are rejected."""
+    identifier = f"default.nested_mismatched_field_ids_v{format_version}"
+
+    # Create a table with a nested struct field
+    try:
+        session_catalog.drop_table(identifier=identifier)
+    except NoSuchTableError:
+        pass
+
+    nested_schema = Schema(
+        NestedField(1, "id", IntegerType(), required=False),
+        NestedField(
+            2,
+            "user",
+            StructType(
+                NestedField(3, "name", StringType(), required=False),
+                NestedField(4, "age", IntegerType(), required=False),
+            ),
+            required=False,
+        ),
+        schema_id=0,
+    )
+
+    tbl = session_catalog.create_table(
+        identifier=identifier,
+        schema=nested_schema,
+        properties={"format-version": str(format_version)},
+    )
+
+    # Create PyArrow schema with MISMATCHED nested field IDs
+    # The table expects: id=1, user=2, user.name=3, user.age=4
+    # This file has: id=1, user=2, user.name=99, user.age=100 (wrong nested IDs)
+    pa_schema_mismatched = pa.schema(
+        [
+            pa.field("id", pa.int32(), nullable=True, metadata={b"PARQUET:field_id": b"1"}),
+            pa.field(
+                "user",
+                pa.struct(
+                    [
+                        pa.field("name", pa.string(), nullable=True, metadata={b"PARQUET:field_id": b"99"}),  # Wrong!
+                        pa.field("age", pa.int32(), nullable=True, metadata={b"PARQUET:field_id": b"100"}),  # Wrong!
+                    ]
+                ),
+                nullable=True,
+                metadata={b"PARQUET:field_id": b"2"},
+            ),
+        ]
+    )
+
+    pa_table = pa.table(
+        {
+            "id": pa.array([1, 2, 3], type=pa.int32()),
+            "user": pa.array(
+                [
+                    {"name": "Alice", "age": 30},
+                    {"name": "Bob", "age": 25},
+                    {"name": "Charlie", "age": 35},
+                ],
+                type=pa_schema_mismatched.field("user").type,
+            ),
+        },
+        schema=pa_schema_mismatched,
+    )
+
+    file_path = f"s3://warehouse/default/nested_mismatched_field_ids/v{format_version}/test.parquet"
+    fo = tbl.io.new_output(file_path)
+    with fo.create(overwrite=True) as fos:
+        with pq.ParquetWriter(fos, schema=pa_schema_mismatched) as writer:
+            writer.write_table(pa_table)
+
+    # Adding files with mismatched nested field IDs should fail
+    with pytest.raises(ValueError, match="Field IDs in Parquet file do not match table schema"):
+        tbl.add_files(file_paths=[file_path])
 
 
 @pytest.mark.integration