Some Basic Qs on materialized views

Folks

1. Is creating constraint a mandatory pre-requisite/requirement for materialized view to do a refresh of the respective Table? NOTE Our application does NOT contain any constraints.
2. What Commands/setup is needed to fire an automated refresh at a certain frequency? NOTE - We have used 2 Commands DBMS_REFRESH.MAKE to create a refresh group & DBMS_REFRESH.ADD to add a materialized view the refresh group. What is being missed / additional commands needed to fire automated refresh?
3. For automated refresh what amount of time (15 minutes) is usually a Good frequency for a 600 GB Database?

Thanks indeed

• CAUTION - Disclaimer ***************** This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify the sender by e-mail and delete the original message. Further, you are not to copy, disclose, or distribute this e-mail or its contents to any other person and any such actions are unlawful. This e-mail may contain viruses. Infosys has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachment. Infosys reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infosys e-mail system. ***INFOSYS******** End of Disclaimer ********INFOSYS*** -- http://www.freelists.org/webpage/oracle-l