René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`RemoteOnlineStore.online_write_batch` hardcodes timestamp column names (`created`/`event_timestamp`), breaking remote `write_to_online_store` for feature views with a custom `created_timestamp_column`","articleBody":"## Expected Behavior\n\nRemote `write_to_online_store` should round-trip regardless of the feature view's\ntimestamp column names. Writing works for a local provider (the full dataframe is\nconverted in-process using the source's configured column names) and should behave the\nsame when the online store is remote (`online_store: { type: remote }` / the feature\nserver `/write-to-online-store` endpoint).\n\n## Current Behavior\n\nWriting to the online store through the remote path fails on the server with:\n\n```\nKeyError: 'Field \"created_at\" does not exist in schema'\n```\n\nwhenever the feature view's batch source sets `created_timestamp_column` (or\n`timestamp_field`) to anything other than the literals `\"created\"` /\n`\"event_timestamp\"`.\n\nRoot cause — `RemoteOnlineStore.online_write_batch` serializes the timestamps into\n**hardcoded** column names when building the request body:\n\n```python\n# sdk/python/feast/infra/online_stores/remote.py  (online_write_batch)\ncolumnar_data[\"event_timestamp\"].append(_to_naive_utc(event_ts).isoformat())\ncolumnar_data[\"created\"].append(\n    _to_naive_utc(created_ts).isoformat() if created_ts else None\n)\nreq_body = {\"feature_view_name\": table.name, \"df\": columnar_data, ...}\npost_remote_online_write(config=config, req_body=req_body)\n```\n\nThe server rebuilds the dataframe verbatim and runs the standard conversion:\n\n```python\n# sdk/python/feast/feature_server.py\ndf = pd.DataFrame(request.df)     # columns: entities, features, event_timestamp, created\nstore.write_to_online_store(..., df=df)\n# -\u003e _prep_rows_to_write_for_ingestion -\u003e _convert_arrow_to_proto\n```\n\nbut `_convert_arrow_fv_to_proto` (in `utils.py`) resolves the created-timestamp column\nby the **feature-view-configured name**, not the hardcoded `\"created\"`:\n\n```python\nif feature_view.batch_source.created_timestamp_column:\n    created_timestamps = [\n        ... table.column(\n            feature_view.batch_source.created_timestamp_column   # e.g. \"created_at\"\n        ) ...\n    ]\n```\n\nSo the client emits the column as `created` and the server looks it up as `created_at`\n→ `KeyError`. The timestamp **value is not lost** — it is on the wire under `created`;\nit is simply **labeled with a name the server does not look up**. The client write and\nthe server-side conversion disagree on the timestamp column names.\n\nServer-side traceback:\n\n```\nFile \".../feast/feature_server.py\", in write_to_online_store\nFile \".../feast/feature_store.py\", in write_to_online_store\nFile \".../feast/infra/passthrough_provider.py\", in _prep_rows_to_write_for_ingestion\nFile \".../feast/utils.py\", in _convert_arrow_fv_to_proto\nKeyError: 'Field \"created_at\" does not exist in schema'\n```\n\n## Steps to reproduce\n\n1. Define a feature view whose batch source uses non-default timestamp column names,\n   e.g. `PostgreSQLSource(timestamp_field=\"event_timestamp\",\n   created_timestamp_column=\"created_at\", ...)`.\n2. Point a client at a remote online store: `online_store: { type: remote, path:\n   \u003cfeature-server-url\u003e }` (or call the feature server `/write-to-online-store`).\n3. `store.write_to_online_store(fv_name, df=df)` where `df` includes the `created_at`\n   column. The client-side conversion succeeds; the server returns HTTP 500 with the\n   `KeyError` above. The same write against a local provider succeeds.\n\n### Specifications\n\n- Version: 0.64.0 (client and feature server)\n- Platform: Linux, Python 3.13\n- Subsystem: remote online store (`feast/infra/online_stores/remote.py`) /\n  Python feature server `/write-to-online-store` (`feast/feature_server.py`) /\n  `_convert_arrow_fv_to_proto` (`feast/utils.py`)\n\n## Possible Solution\n\nIn `RemoteOnlineStore.online_write_batch`, label the timestamp columns using the\nfeature view's configured fields instead of hardcoded literals:\n\n```python\nevent_col   = table.batch_source.timestamp_field or \"event_timestamp\"\ncreated_col = table.batch_source.created_timestamp_column or \"created\"\ncolumnar_data[event_col].append(...)\nif created_col:\n    columnar_data[created_col].append(...)\n```\n\nAlternatively, have the server map the well-known `event_timestamp` / `created`\nrequest columns onto the FV's configured names before conversion. Fixing the client to\nemit the configured names is the smaller change and keeps the request self-describing.\n","author":{"url":"https://github.com/BigyaPradhan","@type":"Person","name":"BigyaPradhan"},"datePublished":"2026-07-09T17:36:13.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/6595/feast/issues/6595"}