Question: if a stream has a pre-defined schema and one of the columns/fields is no longer returned by the source (eg column deleted in the source database, REST api no longer returns the field, etc.) and the stream's schema is not updated, what happens?

Record doesn't have that key sent as it's missing

Got it, would an error be thrown or no?

If the schema says it's a required field, it will fail validation (in targets that perform schema validation), otherwise the column will be created but no data will be loaded to it.

great, thanks guys!