Re: Rollback segment doesn't shrink back to optimal

Here's the way I understand it:

If a segment extends beyond OPTIMAL AND the transaction that caused this commits. The segment will not shrink until another transaction or set of transactions start at the beginning of the segment and work their way either back to OPTIMAL OR to the last allocated extent beyond OPTIMAL in the long segment. At that time the next extent would be the first extent ( a wrap ) and anything beyond OPTIMAL would be cleared away ( shrunk ).

At any rate, the thing will not shrink immediately. If it did, and you had a lot of concurrent activity, you'd end up getting SNAPSHOT TOO OLD errors all the time because the long transaction isn't always the only one using those undo blocks.

-Kevin

<fsiegel_at_my-deja.com> wrote in message news:8s73fr$ij2$1_at_nnrp1.deja.com...
> In Oracle 8.0.5 has anyone experienced rollback segments that do not
> shrink back to optimal size after a transaction ends?
>
> The rollback segment AND it's associated tablespace both have
> min extents = 20
>
> The rollback segment has pctincrease 0
> The rollback segment TABLESPACE has pctincrease 50
>
> thank for your time!
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Fri Oct 13 2000 - 11:03:09 CDT