How often should statistics be generated?

Hi:

        I read about the phasing out of rule-based optiization. I would like to know how often statistics need to be generated so that we can use cost-based optimiation by default.

        We are using rule-based optimization currently and it seems fine. When we do use cost-based optimization, things get extremely slow. The obvious explanation is that the statistics that we have are not "recent". Well, how often should I generate statistics to get the optimizer to perform at its best?

        We have a lot of interactive users during the day and some nightly batch jobs. If we generate statistics during the day, it will not only slow down users, but also give wrong information for the optimizer since the activity is not typical. If we generate statistics during the night, users will be hit since the optimizer is again based not on user's queries.

What is the necessary action? Please help,

-Badri Received on Wed Dec 27 1995 - 00:00:00 CET