fix(redis): Preserve millisecond timestamp precision for Redis online store (#5807)

* Update redis.py

Add millisecond-precision timestamp support to Redis online store

Signed-off-by: Jatin Kumar <jatink.5251@gmail.com>

* Update redis.py

sub-second precision when returning timestamps to client

Signed-off-by: Jatin Kumar <jatink.5251@gmail.com>

* Update redis.py

fix(redis): preserve millisecond timestamp precision

Signed-off-by: Jatin Kumar <jatink.5251@gmail.com>

* Update redis.py

fix: Remove whitespace on blank lines (W293)

Signed-off-by: Jatin Kumar <jatink.5251@gmail.com>

---------

Signed-off-by: Jatin Kumar <jatink.5251@gmail.com>

Author: jatin5251

sdk/python/feast/infra/online_stores/redis.py

@@ -304,22 +304,25 @@ def online_write_batch(
             for redis_key_bin, prev_event_time, (_, values, timestamp, _) in zip(
                 keys, prev_event_timestamps, data
             ):
-                event_time_seconds = int(utils.make_tzaware(timestamp).timestamp())
-
-                # ignore if event_timestamp is before the event features that are currently in the feature store
+                # Convert incoming timestamp to millisecond-aware datetime
+                aware_ts = utils.make_tzaware(timestamp)
+                # Build protobuf timestamp with nanos
+                ts = Timestamp()
+                ts.FromDatetime(aware_ts)
+                # New timestamp in nanoseconds
+                new_total_nanos = ts.seconds * 1_000_000_000 + ts.nanos
+                # Compare against existing timestamp (nanosecond precision)
                 if prev_event_time:
                     prev_ts = Timestamp()
                     prev_ts.ParseFromString(prev_event_time)
-                    if prev_ts.seconds and event_time_seconds <= prev_ts.seconds:
-                        # TODO: somehow signal that it's not overwriting the current record?
+                    prev_total_nanos = prev_ts.seconds * 1_000_000_000 + prev_ts.nanos
+                    # Skip only if older OR exact same instant
+                    if prev_total_nanos and new_total_nanos <= prev_total_nanos:
                         if progress:
                             progress(1)
                         continue
-
-                ts = Timestamp()
-                ts.seconds = event_time_seconds
-                entity_hset = dict()
-                entity_hset[ts_key] = ts.SerializeToString()
+                # Store full timestamp (seconds + nanos)
+                entity_hset = {ts_key: ts.SerializeToString()}
 
                 for feature_name, val in values.items():
                     f_key = _mmh3(f"{feature_view}:{feature_name}")
@@ -456,5 +459,7 @@ def _get_features_for_entity(
         if not res:
             return None, None
         else:
-            timestamp = datetime.fromtimestamp(res_ts.seconds, tz=timezone.utc)
+            # reconstruct full timestamp including nanos
+            total_seconds = res_ts.seconds + res_ts.nanos / 1_000_000_000.0
+            timestamp = datetime.fromtimestamp(total_seconds, tz=timezone.utc)
             return timestamp, res