and { only { filter_eq { all_rows ; engine ; ford cosworth dfr v8 } } ; eq { hop { filter_eq { all_rows ; engine ; ford cosworth dfr v8 } ; year } ; 1989 } } = true
select the rows whose engine record fuzzily matches to ford cosworth dfr v8 . there is only one such row in the table . the year record of this unqiue row is 1989 .