Re: rollback segment too old

From: Howard J. Rogers <dba_at_hjrdba.com>
Date: Fri, 21 Jun 2002 21:39:10 +1000
Message-ID: <aev3ab$593$1@lust.ihug.co.nz>

"Knut Talman" <knut.talman_at_mytoys.de> wrote in message news:3D130468.826B5A8A_at_mytoys.de...
> Pinto wrote:
>
> > if you can see, the wraps have more than doubled. and as expected i am
still
> > getting ora-1555
>
> Not only the size of a rollback segment can become a bottleneck also the
number
> of rbs is important. Every transaction has to use the header of the rbs to
enter
> its information. If there are no slots left (in the header) you'll get
> ORA-01555, even if there are a lot of free rollback segment blocks.
>

Er, no... you'd end up with horrendous amounts of buffer busy waits, but that's about it. The 1555s you are thinking of is because of the delayed block cleanout mechanism. It's when the transaction slot on a *normal data block* is re-used, thus preventing retrieval of rollback information needed for a consistent read, and hence producing a 1555.

Regards
HJR
> Regards,
>
> Knut
Received on Fri Jun 21 2002 - 06:39:10 CDT