fix: Preserve ordering of features in _get_column_names (#2457)

* Preserve ordering of features in _get_column_names

* Correction + unit test

Signed-off-by: David Y Liu <davidyliuliu@gmail.com>

* lint corrections

Signed-off-by: David Y Liu <davidyliuliu@gmail.com>

* correction

Signed-off-by: David Y Liu <davidyliuliu@gmail.com>

* my 'make lint' seems to work differently than the ones in the PR tests. Reverting lint changes

Signed-off-by: David Y Liu <davidyliuliu@gmail.com>

sdk/python/feast/infra/provider.py

@@ -290,9 +290,13 @@ def _get_column_names(
 
     # We need to exclude join keys and timestamp columns from the list of features, after they are mapped to
     # their final column names via the `field_mapping` field of the source.
-    _feature_names = set(feature_names) - set(join_keys)
-    _feature_names = _feature_names - {event_timestamp_column, created_timestamp_column}
-    feature_names = list(_feature_names)
+    feature_names = [
+        name
+        for name in feature_names
+        if name not in join_keys
+        and name != event_timestamp_column
+        and name != created_timestamp_column
+    ]
     return (
         join_keys,
         feature_names,

sdk/python/tests/unit/infra/test_provider.py

@@ -0,0 +1,47 @@
+# Copyright 2020 The Feast Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from datetime import timedelta
+
+from feast import BigQuerySource
+from feast.entity import Entity
+from feast.feature import Feature
+from feast.feature_view import FeatureView
+from feast.infra.provider import _get_column_names
+from feast.value_type import ValueType
+
+
+def test_get_column_names_preserves_feature_ordering():
+    entity = Entity("my-entity", description="My entity", value_type=ValueType.STRING)
+    fv = FeatureView(
+        name="my-fv",
+        entities=["my-entity"],
+        ttl=timedelta(days=1),
+        batch_source=BigQuerySource(table="non-existent-mock"),
+        features=[
+            Feature(name="a", dtype=ValueType.STRING),
+            Feature(name="b", dtype=ValueType.STRING),
+            Feature(name="c", dtype=ValueType.STRING),
+            Feature(name="d", dtype=ValueType.STRING),
+            Feature(name="e", dtype=ValueType.STRING),
+            Feature(name="f", dtype=ValueType.STRING),
+            Feature(name="g", dtype=ValueType.STRING),
+            Feature(name="h", dtype=ValueType.STRING),
+            Feature(name="i", dtype=ValueType.STRING),
+            Feature(name="j", dtype=ValueType.STRING),
+        ],
+    )
+
+    _, feature_list, _, _ = _get_column_names(fv, [entity])
+    assert feature_list == ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]