To show that an attribute has no value, a null bitmap is used in the variable-length record format. Of many cases, the values in a tuple are empty. It is possible to minimize the cost of a null...

To show that an attribute has no value, a null bitmap is used in the variable-length record format. Of many cases, the values in a tuple are empty. It is possible to minimize the cost of a null attribute to a single bit by altering the record representation.