1. A method that is implemented on a computer, the method comprising: receiving a request to create a constant filtered set definition to select a set of members in a crosstab, the crosstab including data retrieved from a data source; creating, with an expression based filter that depends on data in the data source, the constant filtered set definition; selecting, after the creation of the constant filtered set definition, the set of members in the crosstab based on the constant filtered set definition; and updating the set of members in the crosstab based on the constant filtered set definition and a change to the data in the data source without updating the set of members in the cross tab based on a change to a global definition corresponding to the crosstab such that the constant filtered set definition overrides the global definition.