Sql to gcs with exclude columns

airflow/providers/google/cloud/transfers/sql_to_gcs.py

@@ -71,6 +71,7 @@ class BaseSQLToGCSOperator(BaseOperator):
         If set as a sequence, the identities from the list must grant
         Service Account Token Creator IAM role to the directly preceding identity, with first
         account from the list granting this role to the originating account (templated).
+    :param exclude_columns: set of columns to exclude from transmission
     """
 
     template_fields: Sequence[str] = (
@@ -103,9 +104,13 @@ def __init__(
         gcp_conn_id: str = 'google_cloud_default',
         delegate_to: Optional[str] = None,
         impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
+        exclude_columns=None,
         **kwargs,
     ) -> None:
         super().__init__(**kwargs)
+        if exclude_columns is None:
+            exclude_columns = set()
+
         self.sql = sql
         self.bucket = bucket
         self.filename = filename
@@ -120,6 +125,7 @@ def __init__(
         self.gcp_conn_id = gcp_conn_id
         self.delegate_to = delegate_to
         self.impersonation_chain = impersonation_chain
+        self.exclude_columns = exclude_columns
 
     def execute(self, context: 'Context'):
         self.log.info("Executing query")
@@ -165,7 +171,9 @@ def _write_local_data_files(self, cursor):
             names in GCS, and values are file handles to local files that
             contain the data for the GCS objects.
         """
-        schema = list(map(lambda schema_tuple: schema_tuple[0], cursor.description))
+        org_schema = list(map(lambda schema_tuple: schema_tuple[0], cursor.description))
+        schema = [column for column in org_schema if column not in self.exclude_columns]
+
         col_type_dict = self._get_col_type_dict()
         file_no = 0
 
@@ -314,7 +322,11 @@ def _write_local_schema_file(self, cursor):
             schema = self.schema
         else:
             self.log.info("Starts generating schema")
-            schema = [self.field_to_bigquery(field) for field in cursor.description]
+            schema = [
+                self.field_to_bigquery(field)
+                for field in cursor.description
+                if field[0] not in self.exclude_columns
+            ]
 
         if isinstance(schema, list):
             schema = json.dumps(schema, sort_keys=True)

tests/providers/google/cloud/transfers/test_sql_to_gcs.py

@@ -61,6 +61,12 @@
 
 OUTPUT_DF = pd.DataFrame([['convert_type_return_value'] * 3] * 3, columns=COLUMNS)
 
+EXCLUDE_COLUMNS = set('column_c')
+NEW_COLUMNS = [c for c in COLUMNS if c not in EXCLUDE_COLUMNS]
+OUTPUT_DF_WITH_EXCLUDE_COLUMNS = pd.DataFrame(
+    [['convert_type_return_value'] * len(NEW_COLUMNS)] * 3, columns=NEW_COLUMNS
+)
+
 
 class DummySQLToGCSOperator(BaseSQLToGCSOperator):
     def field_to_bigquery(self, field) -> Dict[str, str]:
@@ -287,3 +293,26 @@ def test__write_local_data_files_parquet(self):
         file.flush()
         df = pd.read_parquet(file.name)
         assert df.equals(OUTPUT_DF)
+
+    def test__write_local_data_files_json_with_exclude_columns(self):
+        op = DummySQLToGCSOperator(
+            sql=SQL,
+            bucket=BUCKET,
+            filename=FILENAME,
+            task_id=TASK_ID,
+            schema_filename=SCHEMA_FILE,
+            export_format="json",
+            gzip=False,
+            schema=SCHEMA,
+            gcp_conn_id='google_cloud_default',
+            exclude_columns=EXCLUDE_COLUMNS,
+        )
+        cursor = MagicMock()
+        cursor.__iter__.return_value = INPUT_DATA
+        cursor.description = CURSOR_DESCRIPTION
+
+        files = op._write_local_data_files(cursor)
+        file = next(files)['file_handle']
+        file.flush()
+        df = pd.read_json(file.name, orient='records', lines=True)
+        assert df.equals(OUTPUT_DF_WITH_EXCLUDE_COLUMNS)