Re: V$ROLLSTAT - Waits

John Higgins wrote:

> I cut the following from the Oracle 8 Concepts Manual:
>
> Each rollback segment can handle a fixed number of transactions from
> one
> instance. Oracle distributes active transactions across available
> rollback
> segments so that all rollback segments are assigned approximately the
> same
> number of active transactions. Distribution does not depend on the
> size of
> the available rollback segments. Therefore, in environments where all
> transactions generate the same amount of rollback information, all
> rollback
> segments can be the same size. The number of transactions that a
> rollback
> segment can handle is an operating system-specific function of the
> data
> block size. See your Oracle operating system-specific documentation
> for more
> information.
> ___________________________________
>
> If all the rollback segments are handling their maximum number of
> active
> transactions, the next transaction must wait for a rollback to free
> up.
>
> Simmo wrote:
>
> > Howdy,
> >
> > I am monitoring V$ROLLSTAT to check the number of waits that occur
> in
> > the rollback segment, but.
> >
> > What is the actual event that makes the number of waits increase? I
> can
> > find no clear definition for why and what makes them occur.
> >
> > Thanx in advance
> > --
> > Regards
> >
> > Paul Simmons

   waits occur when user processes are contending for rollback segments excessively, ie no of time a user process had to wait for rollback segments. to reduce this rollback segs have to be added.

Hope this helps. Received on Tue May 04 1999 - 11:36:58 CDT