Quoting amit poddar <amit.poddar@xxxxxxxx>: > Hi, > > "You say you can't change the query, so if you want to fake this query, > you probably need to use dbms_stats.set_table_stats > to tell Oracle that the table has a very small number of rows - > but don't change the block count - so that a properly calculated > selectivity is fooled into getting the right cardinality." > > Sorry for being dense, but how does changing num_rows change the > selectivity ? > It doesn't. Note that Jonathan said "so that a properly calculated selectivity is fooled into getting the right cardinality" i.e. the selectivity calculation (5% or 5% of 5%) isn't changed but the resulting cardinality estimate (num_rows * selectivity) is. -- regards Wolfgang Breitling Oracle 7,8,8i,9i OCP DBA Centrex Consulting Corporation www.centrexcc.com -- //www.freelists.org/webpage/oracle-l