Re: Rollback Segments

Answers embedded.

Hth,

Sybrand Bakker, Oracle DBA

"Will C." <whc2u_at_hotmail.com> wrote in message news:84c3d20c.0106101213.2b7f2c45_at_posting.google.com...
> Hi,
>
> I have a couple of questions about rollback segments. Any help is
> appricated. So, my System: Oracle 8.1.6 on Linux
>
> Question 1:
> According to Technet, if I don't specify rollback segments
> in my init.ora file, the Oracle instance will automatically aquire the
> rollback segments it needs (from those that are avaiable). At the
> moment, I'm refering to PUBLIC rollback segments. Technet also
> states that the SYSTEM rollback segment is aquired automaticaly
> as well and that if there are too many transactions for the
> non-SYSTEM rollback segments, Oracle will use the SYSTEM
> segment. So, if this occurs, and I create and bring online additional
> rollback segments, will they automatically be utilized by the
> instance, or will I have to shutdown and restart the instance?
>

If you bring them online (alter rollback segment <segment_name> online) they will be used and you will not need to restart the instance.

BTW personally I don't use PUBLIC rollback segments when not running Oracle Parallel Server.

> Question 2:
> If I specify the rollback segments I want the instance
> to use in init.ora, do I need to specify system segments as well,
> or only just the public/private rollback segments? (ie, are
> SYSTEM rollback segments always automatically aquired?)
>

By design there is only *one* SYSTEM rollback segment (ie a rollback segment with the name SYSTEM, handling DDL only, and in the SYSTEM tablespace), and this is automatically brought online.
For additional rollback segments in the SYSTEM tablespace: - they are normal rollback segments (ie they are *NOT* SYSTEM rollback segments, of which you can have only one), and normal rules apply - Prefereably you shouldn't have only one extra spare rollback segment in the SYSTEM tablespace, OFFLINE, which you can bring ONLINE, when your other rollback segments *OUTSIDE* the SYSTEM tablespace go bananas.

> Question 3:
> If I added an additional SYSTEM rollback segment and bring it
> online, its it utilized automatically?

As explained above, there is only *ONE* SYSTEM rollback segment.

>
> Much Thanks,
>
> Will C.
Received on Sun Jun 10 2001 - 15:38:33 CDT