cocoindex-io/cocoindex · error · ValueError

Iggy does not support Kafka-style tombstones. Provide deleti

Error message

Iggy does not support Kafka-style tombstones. Provide deletion_value_fn or encode deletes in the payload.

What it means

Unlike Kafka, Iggy has no native tombstone records for deletes. When a reconciliation sees a desired state of non-existence and the connector has no deletion_value_fn configured, it raises ValueError rather than emitting an ambiguous delete.

Source

Thrown at python/cocoindex/connectors/iggy/_target.py:128

            partitioning=self._partition,
            messages=messages,
        )

    def reconcile(
        self,
        key: coco.StableKey,
        desired_target_state: bytes | str | coco.NonExistenceType,
        prev_possible_records: Collection[_MessageFingerprint],
        prev_may_be_missing: bool,
        /,
    ) -> coco.TargetReconcileOutput[_MessageAction, _MessageFingerprint] | None:
        assert isinstance(key, (bytes, str))

        if coco.is_non_existence(desired_target_state):
            if not prev_possible_records and not prev_may_be_missing:
                return None
            if self._deletion_value_fn is None:
                raise ValueError(
                    "Iggy does not support Kafka-style tombstones. "
                    "Provide deletion_value_fn or encode deletes in the payload."
                )
            deletion_value = self._deletion_value_fn(key)
            return coco.TargetReconcileOutput(
                action=_MessageAction(key=key, value=deletion_value),
                sink=self._sink,
                tracking_record=coco.NON_EXISTENCE,
            )

        # Upsert case
        if isinstance(desired_target_state, bytes):
            target_fp = fingerprint_bytes(desired_target_state)
        else:
            target_fp = fingerprint_str(desired_target_state)

        if not prev_may_be_missing and all(
            prev == target_fp for prev in prev_possible_records

View on GitHub (pinned to e84aa99b32)

Solutions

Provide deletion_value_fn when constructing the Iggy target so deletes can be encoded as a message value
Encode deletes inside the normal payload (e.g. a flag in the message value) and handle them downstream
If deletes are impossible/unnecessary, ensure prev records and prev_may_be_missing are handled so no delete action is generated

Example fix

// before
target = iggy.TableTarget(client, stream="s", topic="t", ...)
// after
target = iggy.TableTarget(client, stream="s", topic="t", deletion_value_fn=lambda key: encode_tombstone(key), ...)

Defensive patterns

Strategy: validation

Validate before calling

if deletion_value_fn is None:
    raise ValueError("Iggy target requires deletion_value_fn to handle deletes")

Try / catch

try:
    await app.update()
except ValueError as e:
    if "tombstones" in str(e):
        reconfigure_target_with_deletion_value_fn()

Prevention

Always configure deletion_value_fn for Iggy targets that can see deletions
Model deletes explicitly in the payload schema and document downstream handling
Test delete scenarios (source record removed) against the Iggy target before production

When it happens

Trigger: Reconcile output for a key with coco.is_non_existence(desired_target_state) (a delete) on an Iggy target constructed without deletion_value_fn — e.g. during update when a source record disappears.

Common situations: Source rows/files deleted between runs causing target deletes; switching a target from Kafka (tombstones supported) to Iggy without adapting delete handling.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of cocoindex-io/cocoindex@e84aa99b32 (2026-09-08). Data as JSON: /api/errors/c52aa82023b0435c. Report an issue: GitHub.