To show that an attribute has no value, the variable-length record format uses a null bitmap. The bulk of a tuple's properties are null in a few unusual instances. By altering the way records are...

To show that an attribute has no value, the variable-length record format uses a null bitmap. The bulk of a tuple's properties are null in a few unusual instances. By altering the way records are represented, it is feasible to reduce the cost of a null attribute to only one bit.