Hi, I have a index create like this: CREATE INDEX idx_tab ON tab (column1 ASC, 1); I used the the collect statistics command like this: BEGIN dbms_stats.gather_table_stats( ownname => user, tabname => 'TAB', estimate_percent => 100, cascade => TRUE, method_opt => 'FOR ALL HIDDEN COLUMNS SIZE 1'); END; / BEGIN dbms_stats.gather_table_stats ( ownname => USER, tabname => 'TAB', estimate_percent => 100, cascade => TRUE, method_opt => 'for all columns size skewonly for columns (nvl(COLUMN1,1))' ); END; / But the index is not used in the query. Is this resource (index based on function) released for Oracle Standard ? Regards Eriovaldo