Deleted Subject is still detected on registerSchema while absent from getSubjects

[zaghdous]

Hi, I have a weird behaviour using the schema registry v7.2.0. Some context: We use the abraham-leal/ccloud-schema-exporter to perform backup/restore of schema registry. On restore, the subjects are hard deleted before importing the backup. As result we have a message in the _schema topic with a field deleted=true. After a restart of SR, when we call GET /subjects, the subject is absent which is the expected behaviour.

Bug description:

A client with empty cache tries to register a new schema (for the deleted subject) POST /subjects/mySubject/versions, we expect then that the schema is registered and a new ID is returned. BUT in place, the ID of the deleted schema for mySubject is resolved and we get the error : "i.c.k.s.c.r.e.RestClientException: Overwrite new schema with id 23 is not permitted.; error code: 42205"

The registerSchema operation conflicts between the deleted schema and an existing schema on another subject (same ID 23).

Workaround:

We deleted from the _schemas topic the first schema (deleted=true) by setting the cleanup.policy to "delete" and running kafka-delete-records. After a SR restart, the conflict disapeared and the new schema and we were able to register the new schema with a different ID. => Schema registry still keep a track of deleted schema !

Please let me know if this bug has been resolved in a newer version.

Best regards

[OneCricketeer]

Can you please share your command to reproduce the problem? For example, there's a -syncHardDeletes flag

[AishD3]

Is this issue still present

[shqear93]

We had an issue related and maybe same root cause, we had to change the compatibility of the subject to None, then change the mode to READWRITE then create the schema