Class LabelView

sdk/python/feast/labeling/label_view.py:28–446

A LabelView manages mutable labels decoupled from immutable feature data. A LabelView defines a mutable set of labels or annotations that are kept separate from the immutable feature data stored in regular FeatureViews. It supports multi-labeler workflows where different sources (human

@typechecked
class LabelView(BaseFeatureView):
    """A LabelView manages mutable labels decoupled from immutable feature data.

    A LabelView defines a mutable set of labels or annotations that are kept
    separate from the immutable feature data stored in regular FeatureViews.
    It supports multi-labeler workflows where different sources (human reviewers,
    automated safety scanners, reward models) can independently write labels for
    the same entity keys.

    .. note::

        **Enforcement scope:**

        - ``conflict_policy`` is enforced for **offline store reads** (training
          data generation, UI browse/quality endpoints, batch pipelines). The
          online store always uses LAST_WRITE_WINS for low-latency serving.
        - The offline store always retains full write history (all writes are
          appended). The online store keeps only the latest value per entity key.

    Attributes:
        name: The unique name of the label view.
        entities: The list of entity names associated with this label view.
        ttl: How long labels are valid for online serving. ``timedelta(0)``
            means labels never expire.
        source: The data source (typically a ``PushSource``) feeding label data.
        entity_columns: The entity key columns in the schema.
        features: The label columns (non-entity fields in the schema).
        online: Whether labels are served from the online store.
        description: A human-readable description.
        tags: Arbitrary key-value metadata.
        owner: Owner email or identifier.
        labeler_field: Name of the schema field that identifies who wrote the
            label (default ``"labeler"``).
        conflict_policy: How conflicting labels from different labelers are
            resolved (default ``ConflictPolicy.LAST_WRITE_WINS``). Enforced for
            offline store reads (training, UI). Online store uses LAST_WRITE_WINS.
        reference_feature_view: Optional name of the ``FeatureView`` whose
            entities this label view annotates.
    """

    name: str
    entities: List[str]
    ttl: Optional[timedelta]
    source: Optional[DataSource]
    entity_columns: List[Field]
    features: List[Field]
    online: bool
    description: str
    tags: Dict[str, str]
    owner: str

    labeler_field: str
    conflict_policy: ConflictPolicy
    reference_feature_view: Optional[str]

    def __init__(
        self,
        *,