Monitoring - Databricks ML Professional¶
Overview¶
This section covers model and data monitoring, representing 10% of the exam. You need to understand drift detection, performance monitoring, Lakehouse Monitoring, and retraining triggers.
π Lakehouse Monitoring - Data and model monitoring π Inference Tables - Prediction logging
Key Topics¶
1. Types of Drift¶
| Drift Type | What Changes | Example |
|---|---|---|
| Data drift | Input feature distributions | Customer demographics shift over time |
| Concept drift | Relationship between features and target | User preferences change due to market trends |
| Prediction drift | Model output distributions | Predictions become more extreme or clustered |
| Label drift | Target variable distribution | Fraud rate increases seasonally |
Key Concepts: - Data drift means the model receives different inputs than it was trained on - Concept drift means the underlying patterns have changed - Data drift does not always cause model degradation (features may still be predictive) - Concept drift usually requires retraining because the learned patterns are outdated
2. Statistical Tests for Drift¶
| Test | What It Measures | Use Case |
|---|---|---|
| KS test (Kolmogorov-Smirnov) | Distribution difference for continuous features | Numerical feature drift |
| Chi-squared test | Distribution difference for categorical features | Categorical feature drift |
| PSI (Population Stability Index) | Overall distribution shift magnitude | Production monitoring dashboards |
| Jensen-Shannon divergence | Symmetric distribution difference | Comparing probability distributions |
PSI Interpretation: | PSI Value | Interpretation | |-----------|---------------| | < 0.1 | No significant drift | | 0.1 - 0.25 | Moderate drift - investigate | | > 0.25 | Significant drift - action needed |
3. Lakehouse Monitoring¶
π Lakehouse Monitoring - Monitoring setup
from databricks.sdk import WorkspaceClient
w = WorkspaceClient()
# Create a monitor on a table
monitor = w.quality_monitors.create(
table_name="catalog.schema.predictions",
output_schema_name="catalog.schema",
time_series={
"timestamp_col": "prediction_timestamp",
"granularities": ["1 day"]
}
)
Key Concepts: - Automated profiling of table statistics over time - Tracks column-level statistics: mean, stddev, null counts, distinct counts - Time-series analysis shows how distributions change over time - Custom metrics for domain-specific monitoring - Drift detection with configurable alerting thresholds - Profile tables store monitoring results for querying and dashboarding
4. Model Performance Monitoring¶
Key Concepts: - Inference table logging captures all requests and responses - Ground truth joins: match predictions with actual outcomes when available - Delayed labels: some outcomes are known hours or days after prediction - Performance dashboards track accuracy, latency, and throughput over time - Alert thresholds trigger notifications when performance degrades
Monitoring Pipeline:
Inference Tables -> Ground Truth Join -> Metric Calculation -> Dashboard -> Alerts
5. Retraining Triggers¶
| Trigger Type | Condition | Response |
|---|---|---|
| Scheduled | Fixed interval (weekly, monthly) | Retrain on latest data |
| Performance-based | Accuracy drops below threshold | Retrain immediately |
| Drift-based | PSI exceeds threshold | Investigate and retrain |
| Data-based | New labeled data available | Retrain to incorporate new data |
Key Concepts: - Combine scheduled and triggered retraining for robust monitoring - Validation gates ensure retrained models pass quality checks before deployment - Track retraining history: which data, model version, and performance metrics - Automated retraining pipelines as Databricks Workflows
6. Feature Importance Monitoring¶
Key Concepts: - Track feature importance over time to detect shifts in model behavior - Sudden changes in feature importance may indicate data quality issues - SHAP values provide interpretable feature contribution scores - Compare feature importance between training and production data - Missing or degraded features can cause silent model degradation
7. Cost and Operational Monitoring¶
Key Concepts: - Track serving endpoint compute costs per model - Monitor request volume and latency percentiles (p50, p95, p99) - Set up alerts for error rate spikes or latency budget violations - Optimize endpoint sizing based on actual traffic patterns - Scale-to-zero for low-traffic endpoints to reduce costs
Exam Tips for This Domain¶
- Data drift vs concept drift - Know the difference and how to detect each
- PSI thresholds - < 0.1 (no drift), 0.1-0.25 (investigate), > 0.25 (action needed)
- Lakehouse Monitoring - Automated profiling and drift detection on tables
- Inference tables - Automatic request/response logging from serving endpoints
- Retraining triggers - Scheduled, performance-based, drift-based, data-based
- Ground truth joins - Required for accurate performance monitoring
Documentation Links Summary¶
| Topic | Link |
|---|---|
| Lakehouse Monitoring | docs.databricks.com/en/lakehouse-monitoring/index.html |
| Inference Tables | docs.databricks.com/en/machine-learning/model-serving/inference-tables.html |