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fix: Remote Online Store Type Inference Error with All-NULL Columns#6063

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ntkathole merged 2 commits intofeast-dev:masterfrom
yuan1j:fix_remote_online_type_error_with_all_null_columns
Apr 12, 2026
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fix: Remote Online Store Type Inference Error with All-NULL Columns#6063
ntkathole merged 2 commits intofeast-dev:masterfrom
yuan1j:fix_remote_online_type_error_with_all_null_columns

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@yuan1j yuan1j commented Mar 4, 2026 •
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What this PR does / why we need it

📋 Problem Description

When reading features from a Feast Remote Online Store, a TypeError is raised if an entire feature column contains only NULL/NaN values. The error occurs in the python_values_to_proto_values() function when it cannot infer the value type from empty data.

🔍 Root Cause Analysis

Component Issue
Location feast/type_map.py - python_values_to_proto_values() function
Trigger Entire feature column contains NULL/NaN values
Reason Type inference fails when all values are empty, resulting in UNKNOWN value type
Current Behavior Raises TypeError: Couldn't infer value type from empty value
Impact Remote online feature reading fails completely

📊 Test Data Example

                   event_timestamp          driver_id  conv_rate  acc_rate  avg_daily_trips
0  2026-03-04 16:17:44+00:00       1001        NaN    1.000000           1000.0
1  2026-02-17 16:00:00+00:00       1005        NaN    0.708060            395.0
2  2026-02-17 17:00:00+00:00       1005        NaN    0.451616            145.0

⚠️ Note: The conv_rate column contains all NaN values.

💡 Solution

Modify the type inference logic to handle UNKNOWN value types gracefully:

Key Changes

  1. ✅ Do not raise error when value type is UNKNOWN
  2. ✅ Preserve schema-defined type from FeatureView definition
  3. ✅ Return proper NULL values in the response while maintaining type information

Code Change Summary

# Before
if value_type is UNKNOWN:
    raise TypeError("Couldn't infer value type from empty value")

# After
# Remove this part code, and use schema-defined type or skip type inference for NULL-only columns

✨ Expected Behavior

After this fix:

  • ✅ Remote online store can read columns with all-NULL values
  • ✅ Feature schema type is preserved from FeatureView definition
  • ✅ NULL values are returned correctly to the client
  • ✅ No breaking changes to existing functionality

Which issue(s) this PR fixes

Fixes: Remote Online Store Type Inference Error with All-NULL Columns

Related Error:

 Traceback (most recent call last):
  File "C:\svn\project\feature_store\feast\remote\test_workflow.py", line 130, in <module>
    run_demo()
  File "C:\svn\project\feature_store\feast\remote\test_workflow.py", line 25, in run_demo
    fetch_online_features(store)
  File "C:\svn\project\feature_store\feast\remote\test_workflow.py", line 121, in fetch_online_features
    returned_features = store.get_online_features(
  File "C:\Users\j\AppData\Local\Programs\Python\Python310\lib\site-packages\feast\feature_store.py", line 2445, in get_online_features
    response = provider.get_online_features(
  File "C:\Users\j\AppData\Local\Programs\Python\Python310\lib\site-packages\feast\infra\passthrough_provider.py", line 251, in get_online_features
    return self.online_store.get_online_features(
  File "C:\Users\j\AppData\Local\Programs\Python\Python310\lib\site-packages\feast\infra\online_stores\online_store.py", line 199, in get_online_features
    read_rows = self.online_read(
  File "C:\Users\j\AppData\Local\Programs\Python\Python310\lib\site-packages\feast\infra\online_stores\remote.py", line 169, in online_read
    message = python_values_to_proto_values(
  File "C:\Users\j\AppData\Local\Programs\Python\Python310\lib\site-packages\feast\type_map.py", line 838, in python_values_to_proto_values
    raise TypeError("Couldn't infer value type from empty value")
TypeError: Couldn't infer value type from empty value

Misc

🧪 Testing

Manual Test Steps

# 1. Start Feast services
cd C:\svn\project\feature_store\feast\test\feature_repo
feast ui
feast serve_registry
feast serve_offline
feast serve

# 2. Prepare test data with all-NULL column
# (conv_rate column contains only NaN values)

# 3. Run remote client
python remote/test_workflow.py

Configuration Used

project: test
registry: 
  registry_type: remote
  path: 127.0.0.1:6570
provider: local
online_store:
  type: remote
  path: http://127.0.0.1:6566
offline_store:
  type: remote
  host: 127.0.0.1
  port: 8815
entity_key_serialization_version: 3
auth:
  type: no_auth

📝 Additional Notes

Item Details
Breaking Changes None
API Changes None
Documentation May need update for NULL handling behavior
Unit Tests Should add test case for all-NULL column scenario
Affected Components feast/type_map.py, feast/infra/online_stores/remote.py

👥 Reviewers

  • @feast-maintainers
  • @feast-infra-team

✅ Checklist

  • Code follows Feast code conventions
  • Unit tests added/updated
  • Integration tests pass
  • Documentation updated (if needed)
  • Commits signed
  • PR title follows conventional commits format
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@yuan1j yuan1j requested a review from a team as a code owner March 4, 2026 15:30
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yuan1j commented Mar 4, 2026 via email

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yuan1j commented Mar 11, 2026
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Thank you for your helpful advice. This solution works for my case as well. Could you please review and approve the merge?

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yuan1j commented Apr 2, 2026 via email

@yuan1j yuan1j force-pushed the fix_remote_online_type_error_with_all_null_columns branch from 9eb84cd to cdcbc6a Compare April 2, 2026 14:50
@yuan1j yuan1j requested review from a team and sudohainguyen as code owners April 2, 2026 14:50
@yuan1j yuan1j requested review from lokeshrangineni, nquinn408 and redhatHameed and removed request for a team April 2, 2026 14:50
@yuan1j yuan1j force-pushed the fix_remote_online_type_error_with_all_null_columns branch 2 times, most recently from 75cc31c to e859233 Compare April 2, 2026 15:10
@yuan1j yuan1j requested a review from jyejare April 2, 2026 15:28
@yuan1j @ntkathole
fix_remote_online_type_error_with_all_null_columns
ec4282c 
Signed-off-by: yuanjun220 <1069645408@qq.com>
@ntkathole ntkathole force-pushed the fix_remote_online_type_error_with_all_null_columns branch from f45e8c0 to ec4282c Compare April 7, 2026 14:16
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yuan1j commented Apr 12, 2026

How can I merge these changes into the master branch?

@ntkathole ntkathole merged commit de67bdd into feast-dev:master Apr 12, 2026
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@devin-ai-integration devin-ai-integration[bot] devin-ai-integration[bot] left review comments

@ntkathole ntkathole ntkathole approved these changes

@sudohainguyen sudohainguyen Awaiting requested review from sudohainguyen

@lokeshrangineni lokeshrangineni Awaiting requested review from lokeshrangineni lokeshrangineni was automatically assigned from feast-dev/maintainers

@redhatHameed redhatHameed Awaiting requested review from redhatHameed redhatHameed was automatically assigned from feast-dev/maintainers

@nquinn408 nquinn408 Awaiting requested review from nquinn408 nquinn408 was automatically assigned from feast-dev/maintainers

+1 more reviewer

@jyejare jyejare jyejare approved these changes

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