less { hop { filter_eq { all_rows ; location ; ullswater } ; date } ; hop { filter_eq { all_rows ; location ; lake dumbleyung } ; date } } = true
select the rows whose location record fuzzily matches to ullswater . take the date record of this row . select the rows whose location record fuzzily matches to lake dumbleyung . take the date record of this row . the first record is less than the second record .