question: private void calculateUniqueValue ( Object [ ] minValue , Object [ ] uniqueValue ) { for ( int i = 0 ; i < measureCount ; i ++ ) { if ( type [ i ] == CarbonCommonConstants . BIG_INT_MEASURE ) { uniqueValue [ i ] = ( long ) minValue [ i ] - 1 ; } else if ( type [ i ] == CarbonCommonConstants . BIG_DECIMAL_MEASURE ) { BigDecimal val = ( BigDecimal ) minValue [ i ] ; uniqueValue [ i ] = ( val . subtract ( new BigDecimal ( 1.0 ) ) ) ; } else { uniqueValue [ i ] = ( double ) minValue [ i ] - 1 ; } } }
target:  This method will calculate the unique value which will be used as storage key for null values of measures