19. The system as recited in claim 18 , further comprising a selectivity tester to run the query against the database to test the selectivity of the filter of the captured query, to develop a selectivity estimate for the captured query and to compare the selectivity estimate to selectivity estimates for other queries.
19. The system as recited in claim 18 , further comprising a selectivity tester to run the query against the database to test the selectivity of the filter of the captured query, to develop a selectivity estimate for the captured query and to compare the selectivity estimate to selectivity estimates for other queries. 20. The system as recited in claim 19 , wherein the selectivity tester first runs the query against only a portion of the database.