Feast: materialize features and retrieve them online

Steps

1. Initialize a Feast feature repository with feast init and configure feature_store.yaml with your offline store (e.g., file or BigQuery), online store (e.g., Redis or SQLite), and registry location.
2. Define FeatureView objects in Python files within the repository, specifying the data source, entity, and feature columns with their types.
3. Apply the feature definitions to the registry with feast apply run from the repository directory.
4. Materialize features from the offline store to the online store for a time range: feast materialize START_DATETIME END_DATETIME, or use feast materialize-incremental END_DATETIME for ongoing pipelines.
5. In your application, instantiate a FeatureStore, then call store.get_online_features(features=['VIEW_NAME:FEATURE'], entity_rows=[{'ENTITY_KEY': value}]) to retrieve low-latency features.
6. Verify retrieved feature values and timestamps to ensure materialization completed successfully and the online store is not serving stale data.