At 10:28 PM 8/03/2004 +0000, you wrote:

>Can anyone give me a definitive answer to this one: is it possible to
>'over-sweep' a database? Will there be a performance penalty from sweeping
>(say) each night?? Obviously it will slow the system while sweep takes
>place. But at 3am I don't care about this.
>
>My position is that sweeping can't do any harm, provided the system is
>quiet at the time. However, someone had suggested to me that *any*
>sweeping is a bad idea,

Regular sweeping - especially at 3 a.m. - is a very, very good idea.

>and can degrade server performance, even when the sweep is completed.

Not a word of truth in it. If you don't sweep, then there are some
garbages around the database that won't get cleared at all. After the
sweep, all is sweet, nothing left.

>(he recommends regular backup/restore, which I think is a bit excessive!

Not to replace sweeping - you're right. Sweep releases page space but it
doesn't compress pages, so regular backup/restore *as a separate
housekeeping issue* is good practice because you can start over with page
space fully utilised and indexes all fresh and balanced.

>I usually do this once per year on my FB databases).

The frequency of restores is determined by the conditions. An annual
restore might be OK for a db where data changes are low volume.

>
>The concept of 'over-sweeping' doesn't make sense to me. I can't see a
>downside, if you ignore the obvious slow-down while sweeping itself takes
>place.

Your assessment sounds about right to me.

/heLen