How to refresh Statistics at the DB level

Hi,

I have come across this but I dont know how to refresh statistics at the DB level. Mind you I am not talking about Refresh DB stats for infocube in the infocube performance tab.

There seems to be a way of refreshing stats at the DB(Oracle DB) level for the whole BW system and this improves query performance greatly.

Does anybody know how this is done?

Thanks,

Reddy