Feature Quality Monitoring

Overview

Feast's data quality monitoring system computes, stores, and serves statistical metrics for every registered feature. It gives you visibility into feature health — distributions, null rates, percentiles, histograms — across batch data and feature serving logs.

This guide covers:

1. Prerequisites
2. Auto-baseline on registration
3. Scheduled monitoring with the CLI
4. Monitoring feature serving logs
5. Reading metrics via REST API
6. On-demand exploration (transient compute)
7. Integrating with orchestrators
8. Supported backends
9. Monitoring in the Feast UI

1. Prerequisites

Monitoring works with any supported offline store backend. No additional infrastructure or configuration is needed — monitoring tables are created automatically on first use.

Minimum setup:

• A Feast project with at least one feature view and a configured offline store
• Feast SDK installed (pip install feast)

For serving log monitoring:

• At least one feature service with logging_config set (see step 4)

2. Auto-baseline on registration

When you run feast apply to register new features, Feast automatically queues baseline metric computation:

$ feast apply
Applying changes...
Created feature view 'driver_stats' with 3 features
  → Queued baseline metrics computation (DQM job: abc-123)
Done!

The baseline reads all available source data and stores the resulting statistics with is_baseline=TRUE. This serves as the reference distribution for future drift detection.

Baseline computation is:

• Threaded — runs in a background thread but completes before feast apply exits
• Idempotent — only features without existing baselines are computed; re-running feast apply won't recompute existing baselines

Enabling auto-baseline

To enable automatic baseline computation on feast apply, set the DQM config in feature_store.yaml:

data_quality_monitoring:
  auto_baseline: true

When using the Feast operator, set this in the FeatureStore CR:

apiVersion: feast.dev/v1
kind: FeatureStore
spec:
  feastProject: my_project
  dataQualityMonitoring:
    autoBaseline: true

To disable it, set auto_baseline: false (or autoBaseline: false in the CR).

3. Scheduled monitoring with the CLI

Auto mode (recommended for production)

Schedule a single daily job that computes all granularities automatically:

feast monitor run

This detects the latest event timestamp in the source data and computes metrics for 5 time windows:

Granularity	Window
daily	Last 1 day
weekly	Last 7 days
biweekly	Last 14 days
monthly	Last 30 days
quarterly	Last 90 days

No date arguments needed. One scheduled job produces all granularities.

Targeting a specific feature view

feast monitor run --feature-view driver_stats

Explicit date range and granularity

feast monitor run \
  --feature-view driver_stats \
  --start-date 2025-01-01 \
  --end-date 2025-01-07 \
  --granularity weekly

Setting a manual baseline

feast monitor run \
  --feature-view driver_stats \
  --start-date 2025-01-01 \
  --end-date 2025-03-31 \
  --granularity daily \
  --set-baseline

CLI reference

Usage: feast monitor run [OPTIONS]

Options:
  -p, --project TEXT         Feast project name (defaults to feature_store.yaml)
  -v, --feature-view TEXT    Feature view name (omit for all)
  -f, --feature-name TEXT    Feature name(s), repeatable (omit for all)
  --start-date TEXT          Start date YYYY-MM-DD (omit for auto-detect)
  --end-date TEXT            End date YYYY-MM-DD (omit for auto-detect)
  -g, --granularity          One of: daily, weekly, biweekly, monthly, quarterly
  --set-baseline             Mark this computation as baseline
  --source-type              One of: batch, log, all (default: batch)
  --help                     Show this message and exit.

4. Monitoring feature serving logs

If your feature services have logging configured, you can compute metrics from the actual features served to models in production.

Setting up feature service logging

In your feature definitions:

from feast import FeatureService, LoggingConfig
from feast.infra.offline_stores.contrib.postgres_offline_store.postgres_source import (
    PostgreSQLLoggingDestination,
)

driver_service = FeatureService(
    name="driver_service",
    features=[driver_stats_fv],
    logging_config=LoggingConfig(
        destination=PostgreSQLLoggingDestination(table_name="feast_driver_logs"),
        sample_rate=1.0,
    ),
)

Computing log metrics

Auto mode (all feature services with logging):

feast monitor run --source-type log

Specific feature service:

feast monitor run --source-type log --feature-view driver_service

Both batch and log in one run:

feast monitor run --source-type all

Log metrics are stored with data_source_type="log" alongside batch metrics in the same monitoring tables. Feature names from the log schema (e.g., driver_stats__conv_rate) are automatically normalized back to their original names (conv_rate) and associated with the correct feature view — enabling batch-vs-log comparison and drift detection.

Via REST API

# Compute log metrics
POST /monitoring/compute/log
{
  "project": "my_project",
  "feature_service_name": "driver_service",
  "granularity": "daily"
}

# Auto-compute all log metrics
POST /monitoring/auto_compute/log
{
  "project": "my_project"
}

5. Reading metrics via REST API

All read endpoints support cascading filters: project → feature_service_name → feature_view_name → feature_name → granularity → data_source_type.

Per-feature metrics

GET /monitoring/metrics/features?project=my_project&feature_view_name=driver_stats&granularity=daily

Response:

[
  {
    "project_id": "my_project",
    "feature_view_name": "driver_stats",
    "feature_name": "conv_rate",
    "feature_type": "numeric",
    "metric_date": "2025-03-26",
    "granularity": "daily",
    "data_source_type": "batch",
    "row_count": 15000,
    "null_count": 12,
    "null_rate": 0.0008,
    "mean": 0.523,
    "stddev": 0.189,
    "min_val": 0.001,
    "max_val": 0.998,
    "p50": 0.51,
    "p75": 0.68,
    "p90": 0.82,
    "p95": 0.89,
    "p99": 0.96,
    "histogram": {
      "bins": [0.0, 0.05, 0.1, "..."],
      "counts": [120, 340, 560, "..."],
      "bin_width": 0.05
    }
  }
]

Per-feature-view aggregates

GET /monitoring/metrics/feature_views?project=my_project&feature_view_name=driver_stats

Per-feature-service aggregates

GET /monitoring/metrics/feature_services?project=my_project&feature_service_name=driver_service

Baseline

GET /monitoring/metrics/baseline?project=my_project&feature_view_name=driver_stats

Time-series (for trend charts)

GET /monitoring/metrics/timeseries?project=my_project&feature_name=conv_rate&granularity=daily&start_date=2025-01-01&end_date=2025-03-31

Filtering batch vs. log metrics

Add data_source_type=batch or data_source_type=log to any read endpoint:

GET /monitoring/metrics/features?project=my_project&data_source_type=log

Full endpoint reference

Method	Endpoint	Description
POST	/monitoring/compute	Submit batch DQM job
POST	/monitoring/auto_compute	Auto-detect dates, all granularities
POST	/monitoring/compute/transient	On-demand compute (not stored)
POST	/monitoring/compute/log	Compute from serving logs
POST	/monitoring/auto_compute/log	Auto-detect log dates, all granularities
GET	/monitoring/jobs/{job_id}	DQM job status
GET	/monitoring/metrics/features	Per-feature metrics
GET	/monitoring/metrics/feature_views	Per-view aggregates
GET	/monitoring/metrics/feature_services	Per-service aggregates
GET	/monitoring/metrics/baseline	Baseline metrics
GET	/monitoring/metrics/timeseries	Time-series data

6. On-demand exploration

When you need metrics for an arbitrary date range (e.g., "show me the distribution for Jan 5 to Jan 20"), use the transient compute endpoint. It reads source data for the exact range, computes fresh statistics, and returns them directly without storing.

POST /monitoring/compute/transient
{
  "project": "my_project",
  "feature_view_name": "driver_stats",
  "feature_names": ["conv_rate"],
  "start_date": "2025-01-05",
  "end_date": "2025-01-20"
}

This is necessary because pre-computed histograms from different date ranges have different bin edges and cannot be merged losslessly.

7. Integrating with orchestrators

Airflow

from airflow.operators.bash import BashOperator

monitor_task = BashOperator(
    task_id="feast_monitor",
    bash_command="feast monitor run",
    cwd="/path/to/feast/repo",
)

Kubeflow Pipelines (KFP)

from kfp import dsl

@dsl.component(base_image="feast-image:latest")
def monitor_features():
    import subprocess
    subprocess.run(["feast", "monitor", "run"], check=True, cwd="/feast/repo")

Cron

# Daily at 2:00 AM UTC
0 2 * * * cd /path/to/feast/repo && feast monitor run >> /var/log/feast-monitor.log 2>&1

Monitoring both batch and log in one job

feast monitor run --source-type all

8. Supported backends

Monitoring works natively with all offline stores that serve as compute engines for Feast materialization:

Backend	Compute	Storage
PostgreSQL	SQL push-down	INSERT ON CONFLICT
Snowflake	SQL push-down	MERGE with VARIANT JSON
BigQuery	SQL push-down	MERGE into BQ tables
Redshift	SQL push-down	MERGE via Data API
Spark	SparkSQL push-down	Parquet tables
Oracle	SQL via Ibis	MERGE from DUAL
DuckDB	In-memory SQL	Parquet files
Dask	PyArrow compute	Parquet files

Backends not listed above fall back to Python-based computation — the offline store's pull_all_from_table_or_query() returns a PyArrow Table, and metrics are computed using pyarrow.compute and numpy.

What metrics are computed

Per-feature (full profile):

Metric	Numeric	Categorical
row_count, null_count, null_rate	Yes	Yes
mean, stddev, min, max	Yes	—
p50, p75, p90, p95, p99	Yes	—
histogram (JSONB)	Binned distribution	Top-N values with counts

Per-feature-view and per-feature-service (aggregate summaries):

Metric	Description
total_row_count	Total rows in the view
total_features	Number of features
features_with_nulls	Count of features with any nulls
avg_null_rate, max_null_rate	Aggregate null rate statistics

RBAC

Monitoring respects Feast's existing RBAC:

• Compute operations (POST /monitoring/compute, /auto_compute, /compute/log, /auto_compute/log) require AuthzedAction.UPDATE
• Transient compute (POST /monitoring/compute/transient) requires AuthzedAction.DESCRIBE
• Read operations (GET /monitoring/metrics/*) require AuthzedAction.DESCRIBE

9. Monitoring in the Feast UI

The Feast web UI includes a built-in monitoring dashboard accessible from the Monitoring item in the sidebar navigation.

What you see

The monitoring page has three tabs:

Tab	Shows
Features	Per-feature metrics table with null rate, row count, freshness, and health status
Feature Views	Aggregated data quality per feature view
Feature Services	Aggregated metrics per feature service

Filters

At the top of the monitoring page you can filter by:

• Feature View — scope to a specific feature view or view all
• Granularity — select Baseline, Daily, Weekly, Biweekly, Monthly, or Quarterly
• Source — filter by batch or log data source
• Start/End Date — filter metrics to a specific date range (disabled for Baseline since baseline uses all data)

Feature detail page

Clicking any feature row navigates to a detail page showing:

• Distribution histogram — expandable/zoomable chart of the feature's value distribution
• Statistics panel — null rate, mean, stddev, min/max, percentiles (p50–p99)
• Granularity dropdown — switch between computed granularities and baseline
• Time Series Analysis — trend charts for aggregate metrics drift (Mean/P50/P95) and null rate evolution over time

Computing metrics from the UI

Click the Compute Metrics button in the page header to trigger an auto_compute job. This computes all granularities for all feature views (or the selected feature view if filtered). Results appear after the table refreshes.

The Refresh button re-fetches already computed metrics from the backend without triggering new computation.

When no data is available

If no metrics have been computed yet, the page shows a prompt:

No monitoring data has been computed for this project. Click "Compute Metrics" to run data quality analysis on your feature views.

If the monitoring backend is unreachable, a warning banner appears:

Could not connect to the monitoring API. Make sure the Feast registry server is running with monitoring enabled.

Enabling monitoring for the UI

The monitoring page is always accessible in the sidebar. To see actual data:

1. Add data_quality_monitoring to your feature_store.yaml:

   data_quality_monitoring:
     auto_baseline: true

   Or, when using the Feast operator, set this in the FeatureStore CR:

   apiVersion: feast.dev/v1
   kind: FeatureStore
   spec:
     feastProject: my_project
     dataQualityMonitoring:
       autoBaseline: true

2. Run feast apply — this computes baseline metrics automatically
3. Schedule feast monitor run (or click "Compute Metrics" in the UI) to generate daily/weekly/monthly metrics