Re: Performance penalty when turn on timed_statistics

TFM (Oracle Reference) warns "Normally, TIMED_STATISTICS should be FALSE"

They say so because timed statistics mainly serves the database tuning process - and normally you dont tune so often, so it's better to turn timed statistics off to avoid possible overhead.

On the other hand you need timed statistics when you monitor the database thru dynamic performance views, so in this case times statistics should be always on.

The performance impact of timed statistics depends on the hardware, platform and database activity. The best thing is to enable it (so you have this info available always and dont bother with ALTER SYSTEM or ALTER SESSION). If you experience constant performance degradation then turn it off (turn it on only when it's absolutely necessary, e.g. when you tune).

Regards,
Giorgos

"Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message news:thbutcg89d8e52_at_beta-news.demon.nl...
>
> "Ken Chung" <chungcck_at_netvigator.com> wrote in message
> news:9f4plf$9bq99_at_imsp212.netvigator.com...
> > Have anyone test/know the performance impact of setting timed_statistics
> > to true. One told me that it does affect the performance too much.
> > However, some books said that never turn on timed_statistics to true
> > on production environments. It will slow down the database.
> >
> >
> > Regards,
> > Ken
> >
> >
> >
> >
>
> I have never seen any noticeable impact. Keep in mind, most of these
> statistics are gathered anyway, and the only difference you now keep track
> of the time.
> I have also read several times you should enable it always, and I have
 never
> seen warnings against it.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
>
>
Received on Thu May 31 2001 - 06:05:15 CDT