Re: Disabling rollback. Is it possible?

darryl snedeker <darryl.snedeker_at_amd.com> wrote:

>You cannot disable rollback segments.
 

>Before Image read-consistency functionality is a fundamental and necessary component to any
>fully relational database. While it's true that Oracle v7.2 will introduce 'operations' that
>will allow you to turn off logging (UNRECOVERABLE), this will not provide any benefit to your
>rollback segment problems.
 

>I agree that this area of database management may be one of the most frustrating because it
>provides you, the DBA with the least control. However, it light of the frequency of your
>problems, it seems the Rollback Segment strategy you currently have employed is ineffective.
>It may be due to having too few segments, inadequate segment size(s), default OPTIMAL settings,
>etc.

The problem here is the sheer size of the transactions. We're implementing a distributed data warehouse using snapshots and the snapshots are H-U-G-E! In some cases millions of rows containing gigbytes of data. How are you supposed to manage that in a rollback segment? If I want to use Oracle's snapshots which treat the initial creation and refreshes as a single transaction, I'm going to need gigabytes of RBS no matter how you look at it. That's just the nature of using transactions this large.

The only other alternatives I can think of are to

(A) Wait for 7.2 and disable recovery.
(B) Don't use snapshots. Just try and manage everything manually through export/import and ship out tapes to each slave database (which will be spread out all over the U.S.)
(C) Rewrite the snapshot packages to COMMIT every couple of hundred rows.

None of these are very good alternatives.

--
Chuck Hamilton
chuckh_at_ix.netcom.com

Incoming fire has the right of way!