Apache Kafka

Schema Registry Subject Count Growth Without Cleanup

info
configurationUpdated Mar 2, 2026

Unbounded growth of schema subjects and versions can lead to registry performance degradation, increased memory usage, and slower schema lookups.

Technologies:
How to detect:

Monitor kafka.schema_registry.subjects and kafka.schema_registry.versions for continuous growth without plateau. Alert when growth rate suggests lack of cleanup policy.

Recommended action:

1. Implement schema cleanup: Define retention policy for old schemas. 2. Review schema evolution: Use schema compatibility modes appropriately. 3. Delete unused schemas: Remove schemas for deprecated topics. 4. Monitor schema registry memory: Ensure sufficient memory for schema storage. 5. Configure schema caching: Optimize client-side caching to reduce lookups. 6. Review naming conventions: Avoid creating excessive schema subjects.