fix: Fix materialization with ttl=0 bug

sdk/python/feast/feature_store.py

@@ -16,7 +16,7 @@
 import os
 import warnings
 from collections import Counter, defaultdict
-from datetime import datetime
+from datetime import datetime, timedelta
 from pathlib import Path
 from typing import (
     TYPE_CHECKING,
@@ -1080,7 +1080,16 @@ def materialize_incremental(
                         f"No start time found for feature view {feature_view.name}. materialize_incremental() requires"
                         f" either a ttl to be set or for materialize() to have been run at least once."
                     )
-                start_date = datetime.utcnow() - feature_view.ttl
+                elif feature_view.ttl.total_seconds() > 0:
+                    start_date = datetime.utcnow() - feature_view.ttl
+                else:
+                    # TODO(felixwang9817): Find the earliest timestamp for this specific feature
+                    # view from the offline store, and set the start date to that timestamp.
+                    print(
+                        f"Since the ttl is 0 for feature view {Style.BRIGHT + Fore.GREEN}{feature_view.name}{Style.RESET_ALL}, "
+                        "the start date will be set to 1 year before the current time."
+                    )
+                    start_date = datetime.utcnow() - timedelta(weeks=52)
             provider = self._get_provider()
             print(
                 f"{Style.BRIGHT + Fore.GREEN}{feature_view.name}{Style.RESET_ALL}"

sdk/python/tests/example_repos/example_feature_repo_with_ttl_0.py

@@ -0,0 +1,48 @@
+from datetime import timedelta
+
+from feast import Entity, FeatureView, Field, FileSource, ValueType
+from feast.types import Float32, Int32, Int64
+
+driver_hourly_stats = FileSource(
+    path="%PARQUET_PATH%",  # placeholder to be replaced by the test
+    timestamp_field="event_timestamp",
+    created_timestamp_column="created",
+)
+
+driver = Entity(name="driver_id", value_type=ValueType.INT64, description="driver id")
+
+
+driver_hourly_stats_view = FeatureView(
+    name="driver_hourly_stats",
+    entities=[driver],
+    ttl=timedelta(days=0),
+    schema=[
+        Field(name="conv_rate", dtype=Float32),
+        Field(name="acc_rate", dtype=Float32),
+        Field(name="avg_daily_trips", dtype=Int64),
+    ],
+    online=True,
+    source=driver_hourly_stats,
+    tags={},
+)
+
+
+global_daily_stats = FileSource(
+    path="%PARQUET_PATH_GLOBAL%",  # placeholder to be replaced by the test
+    timestamp_field="event_timestamp",
+    created_timestamp_column="created",
+)
+
+
+global_stats_feature_view = FeatureView(
+    name="global_daily_stats",
+    entities=[],
+    ttl=timedelta(days=0),
+    schema=[
+        Field(name="num_rides", dtype=Int32),
+        Field(name="avg_ride_length", dtype=Float32),
+    ],
+    online=True,
+    source=global_daily_stats,
+    tags={},
+)

sdk/python/tests/integration/online_store/test_e2e_local.py

@@ -101,12 +101,12 @@ def _test_materialize_and_online_retrieval(
 
 def test_e2e_local() -> None:
     """
-    A more comprehensive than "basic" test, using local provider.
+    Tests the end-to-end workflow of apply, materialize, and online retrieval.
 
-    1. Create a repo.
-    2. Apply
-    3. Ingest some data to online store from parquet
-    4. Read from the online store to make sure it made it there.
+    This test runs against several different types of repos:
+    1. A repo with a normal FV and an entity-less FV.
+    2. A repo using the SDK from version 0.19.0.
+    3. A repo with a FV with a ttl of 0.
     """
     runner = CliRunner()
     with tempfile.TemporaryDirectory() as data_dir:
@@ -143,6 +143,16 @@ def test_e2e_local() -> None:
                 runner, store, start_date, end_date, driver_df
             )
 
+        with runner.local_repo(
+            get_example_repo("example_feature_repo_with_ttl_0.py")
+            .replace("%PARQUET_PATH%", driver_stats_path)
+            .replace("%PARQUET_PATH_GLOBAL%", global_stats_path),
+            "file",
+        ) as store:
+            _test_materialize_and_online_retrieval(
+                runner, store, start_date, end_date, driver_df
+            )
+
         # Test a failure case when the parquet file doesn't include a join key
         with runner.local_repo(
             get_example_repo("example_feature_repo_with_entity_join_key.py").replace(