1. A method for generating a clustering statistic for an attribute of a relation to be used in optimizing execution of a query directed to one or more attributes of said relation, comprising determining clustered storage locations of records in said relation, said clustered storage locations being locations where said records would be found in the event that said records were clustered relative to said attribute, computing a correlation between actual storage locations of records in said relation and said clustered storage locations of said records, and generating said clustering statistic based upon said correlation.