Subject RE: [firebird-support] over-sweeping??
Author Alan McDonald
> 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, and can degrade server
> performance, even when the sweep is completed. (he recommends
> regular backup/restore, which I think is a bit excessive! I
> usually do this once per year on my FB databases). 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. Can anyone help? John

I didn't say *ANY* sweeping - I said *TOO MUCH* sweeping is not required and according to the Interbase Operations Guide p128,
On the other hand, frequent database sweeps can reduce application performance.
Raising the sweep interval could help improve overall performance. The DBA should
weigh the issues for the affected applications and decide whether the sweep interval provides the desired database performance.
Tip: Unless the database contains many rolled back transactions, changing the sweep interval has little effect on database size. As a result, it is more common for a DBA to tune the database by disabling sweeping and performing it at specific times. These activities are described in the next two sections.
definitely, since the sweeping bug in IB5.5 was fixed, sweeping will not damage your data, but frequent sweeping will only deliver overall improvement on only a limited set of circumstances. It's not a belts-n-braces approach to be taken on all ditributions. All too often, the backup/restore cycle at the interval you are currently using will deliver, to your application, the optimum performance available.