I would first go about finding out whats the longest
query time in the db using v$undostat.maxquerylen .
Based on that, set the undo_retention. Then also
ensure that undo tablespace is big enough, otherwise,
the server will ignore the undo_retention value and
take extents from that undo segments.

Thanks,
-Sudhi.

--- Amith Uppal <amithuppal@...> wrote:

>
> All ,
> Have gone thru several docs on how to avoid
> snapshot too old
> error in 9i while using automatic undo management .
> basically we need
> to set proper value of undo_retention . And we can
> check the stats in
> v$undostat to get some approximation on that.
>
> Still if someone can put more light on this ...with
> some examples or
> some queries to calculate the right value of
> undo_retention ...would
> be great .
>
> Also ...how about shrinking the undo segements
> ...dosent look like
> SMON does it very often ...I read somewhere that
> Oracle was trying to
> build that into later releases ...not sure ...any
> ideas here ...lemme
> know .
>
> Amith
>
>
>
>




__________________________________
Do you Yahoo!?
Yahoo! Mail - Helps protect you from nasty viruses.
http://promotions.yahoo.com/new_mail