Re: rollback segments, why two extents?

No, many transactions can share a rollback extent. It is at the block level that no sharing occurs.

The two extents minimum has to do with the fact that Oracle needs at least two active extents whenever a wraparound occurs.

Andrew Babb wrote:

> Jonathan,
>
> I thought this was associated with allowing multiple sessions access.
> Under the old Oracle7 environments each transaction required it's own
> extent in the rollback segment, so if recursive SQL was required, then
> this would use the other extent.
>
> We are told this when we start DBA'ing and just accept it thereafter,
> Andrew
>
> Jonathan Gennick wrote:
>
> > Can anyone fill me in on exactly why rollback segments need
> > to have at least two extents? I thought that there was an
> > interested reason for this, related to the way Oracle uses
> > these segments. I remember reading something on that once,
> > but I can't find it now.
> >
> > thanks,
> >
> > Jonathan
Received on Sun May 02 1999 - 22:24:16 CDT