Hi, please can some body share some rules about running this dbms_stats procedures. In documentation says, you have to run.... but I still don't got, how frequently, or if some background process does it periodically so the only thing you have to do is for example ste statistics level to typical or all. Thank you -- Oracle Certified Profesional 9i 10g Orace Certified Professional Developer 6i 8 years of experience in Oracle 7,8i,9i,10g and developer 6i -- //www.freelists.org/webpage/oracle-l