Lint: Raise exceptions if cursor returned no columns or rows

Add log statement

Lint: Fix _to_arrow_internal

Lint: Fix _get_entity_df_event_timestamp_range

Update exception

Use ZeroColumnQueryResult

Signed-off-by: Job Almekinders <job.almekinders@teampicnic.com>

Author: job-almekinders

sdk/python/feast/errors.py

@@ -401,3 +401,13 @@ def __init__(self, input_dict: dict):
         super().__init__(
             f"Failed to serialize the provided dictionary into a pandas DataFrame: {input_dict.keys()}"
         )
+
+
+class ZeroRowsQueryResult(Exception):
+    def __init__(self, query: str):
+        super().__init__(f"This query returned zero rows:\n{query}")
+
+
+class ZeroColumnQueryResult(Exception):
+    def __init__(self, query: str):
+        super().__init__(f"This query returned zero columns:\n{query}")

sdk/python/feast/infra/offline_stores/contrib/postgres_offline_store/postgres.py

@@ -1,4 +1,5 @@
 import contextlib
+import logging
 from dataclasses import asdict
 from datetime import datetime
 from typing import (
@@ -23,7 +24,7 @@
 from pytz import utc
 
 from feast.data_source import DataSource
-from feast.errors import InvalidEntityType
+from feast.errors import InvalidEntityType, ZeroColumnQueryResult, ZeroRowsQueryResult
 from feast.feature_view import DUMMY_ENTITY_ID, DUMMY_ENTITY_VAL, FeatureView
 from feast.infra.offline_stores import offline_utils
 from feast.infra.offline_stores.contrib.postgres_offline_store.postgres_source import (
@@ -276,6 +277,8 @@ def _to_arrow_internal(self, timeout: Optional[int] = None) -> pa.Table:
             with _get_conn(self.config.offline_store) as conn, conn.cursor() as cur:
                 conn.read_only = True
                 cur.execute(query)
+                if not cur.description:
+                    raise ZeroColumnQueryResult(query)
                 fields = [
                     (c.name, pg_type_code_to_arrow(c.type_code))
                     for c in cur.description
@@ -331,16 +334,19 @@ def _get_entity_df_event_timestamp_range(
             entity_df_event_timestamp.max().to_pydatetime(),
         )
     elif isinstance(entity_df, str):
-        # If the entity_df is a string (SQL query), determine range
-        # from table
+        # If the entity_df is a string (SQL query), determine range from table
         with _get_conn(config.offline_store) as conn, conn.cursor() as cur:
-            (
-                cur.execute(
-                    f"SELECT MIN({entity_df_event_timestamp_col}) AS min, MAX({entity_df_event_timestamp_col}) AS max FROM ({entity_df}) as tmp_alias"
-                ),
-            )
+            query = f"""
+                SELECT
+                    MIN({entity_df_event_timestamp_col}) AS min,
+                    MAX({entity_df_event_timestamp_col}) AS max
+                FROM ({entity_df}) AS tmp_alias
+                """
+            cur.execute(query)
             res = cur.fetchone()
-        entity_df_event_timestamp_range = (res[0], res[1])
+            if not res:
+                raise ZeroRowsQueryResult(query)
+            entity_df_event_timestamp_range = (res[0], res[1])
     else:
         raise InvalidEntityType(type(entity_df))
 

sdk/python/feast/infra/offline_stores/contrib/postgres_offline_store/postgres_source.py

@@ -1,10 +1,11 @@
 import json
+import logging
 from typing import Callable, Dict, Iterable, Optional, Tuple
 
 from typeguard import typechecked
 
 from feast.data_source import DataSource
-from feast.errors import DataSourceNoNameException
+from feast.errors import DataSourceNoNameException, ZeroColumnQueryResult
 from feast.infra.utils.postgres.connection_utils import _get_conn
 from feast.protos.feast.core.DataSource_pb2 import DataSource as DataSourceProto
 from feast.protos.feast.core.SavedDataset_pb2 import (
@@ -111,7 +112,11 @@ def get_table_column_names_and_types(
         self, config: RepoConfig
     ) -> Iterable[Tuple[str, str]]:
         with _get_conn(config.offline_store) as conn, conn.cursor() as cur:
-            cur.execute(f"SELECT * FROM {self.get_table_query_string()} AS sub LIMIT 0")
+            query = f"SELECT * FROM {self.get_table_query_string()} AS sub LIMIT 0"
+            cur.execute(query)
+            if not cur.description:
+                raise ZeroColumnQueryResult(query)
+
             return (
                 (c.name, pg_type_code_to_pg_type(c.type_code)) for c in cur.description
             )