Function map_cdf_to_changelog 

pub fn map_cdf_to_changelog(
    batch: &RecordBatch,
) -> Result<Option<RecordBatch>, ConnectorError>

Maps CDF _change_type → _op (I/U/D), drops update_preimage rows and CDF metadata columns (_change_type, _commit_version, _commit_timestamp). Returns None if all rows were preimages.

Errors

Returns ConnectorError::ReadError on Arrow operation failure.