How To Gather Table Stats Effectively
Greg Rahn wrote a pretty good article back in 2008 - it still applies today. (16 August 2010)
Update 3 November 2026: The link works, but you might get intercepted by a bot guard. I can no longer get through as just clicking the link, activates a rejection. As I’m no longer doing Oracle (I retired) I haven’t bothered to complain as advised.
Cheers.