Function describe_row_shape 

fn describe_row_shape(row: &Row, table_desc: &MySqlTableDesc) -> String

Describes the structural shape of a row without revealing any data values. Iterates every wire column. For each, emits the wire name, the binlog wire type, the character-set id (or binary), a classification relative to table_desc (expected=<scalar> for active columns, ignored for columns excluded from the source, extra for upstream columns with no descriptor entry), and a value disposition (null or bytes(len=N) / primitive kind). Intended for diagnostic logging on decode errors: MySQL serializes CHAR, VARCHAR, TEXT, JSON, BLOB, etc. all as Value::Bytes, so the wire type tag and the expected scalar type are what distinguish them.