Re: setting timed_statistics = true

"Cookie Monster" <cookie.monster_at_somewhere.com> wrote in message news:c1v38r$1n78pt$1_at_ID-82797.news.uni-berlin.de...
> Hi,
>
> Packages like perfstats require timed_statistics to be set to true for
> calculating wait times. I'm think of setting this value to true at the
> instance level. But does it make sense to have this value set true all
the
> time?

Yes. if you want to reduce the time spent by processes, you need to measure the time spent by the processes. If you want to use the wait interface then again you need the timing info.

> Does this have an impact on performance??

Yes. it is impossible to monitor a process without adding overhead. The real question is does this have an *unacceptable* overhead. For most systems the answer to this is no, the figure 10% that you were given is at the high end of figures that I have seen (but there have been port-specific bugs so checking metalink for your platform and version would be advisable).

> Should I only use this at
> the session level when required?

I'd always have it set. I don't know ahead of time where my problems will be...

-- 
Niall Litchfield
Oracle DBA
Audit Commission UK