Re: Oracle8 performance problem

Little Prince <milan1810_at_geocities.com> wrote:
>When I query v$waitstat, the following appears:
 [snip]
> The above statistics shows a lot of waits in data block,
> segment header, undo header and undo block. What do they mean? How can
> I reduce the waits?

These are subclasses of the "buffer busy wait" event. Before you even bother attempting to tune these, ask yourself if "buffer busy wait" is a significant proportion of the total wait events on your system. Unless it is, there's no point. The raw numbers you posted aren't useful without more context (such as the time frame over which the data was collected).

Assuming that they are a significant wait event, for tuning advice see: http://www.ixora.com.au/q+a/cache.htm

I most often see buffer busy waits on tables with heavy insert activity and insufficient numbers of freelists, your mileage may vary.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/