12. The system of claim 11 wherein computer program instructions configured to determine a projected percentage of rows in the database table determined in dependence upon the subset of intersections further comprise computer program instructions configured to: determine a percentage of rows in the database table returned by each of the intersections of the subset; and sum the percentage of rows in the database table returned by each of the intersections of the subset; determine a scalar in dependence upon the selectivity ratings of the intersections of the subset; and scale the summed percentage in dependence upon the scalar.
11. The system of claim 7 wherein computer program instructions configured to select one or more of the intersections in dependence upon the selectivity rating further comprise computer program instructions configured to: select a subset of intersections, each subset of intersections including each predicate in the query; and wherein determining in dependence upon the intersections a percentage of rows in a database table returned by the query further comprises determining a projected percentage of rows in the database table determined in dependence upon the subset of intersections.