The WriteAheadProvenanceRepository can use the Provenance data stored by the PersistentProvenanceRepository. However, the PersistentProvenanceRepository may not be able to read the data written by the WriteAheadProvenanceRepository. Therefore, once the Provenance Repository is changed to use the WriteAheadProvenanceRepository, it cannot be changed back to the PersistentProvenanceRepository without first deleting the data in the Provenance Repository. It is therefore recommended that before changing the implementation to Write Ahead, ensure your version of NiFi is stable, in case an issue arises that requires the need to roll back to a previous version of NiFi that did not support the WriteAheadProvenanceRepository.