Re: [Q] Rollback segments; Small vs. large extents.

Dana Stockler wrote:
>
> Seasons greeting to all,
>
> I have been having some problems with the rollback segments on
> the database we use for software development. The transactions
> here vary in size from 'petit' to 'humongous'.
>
> I have implemented what I consider to be a good mix of small and
> large segments. The small segments have an extent size of 100K
> and the large segments have an extent size of 1M.
>
> I have been tempted to increase the extent sizes to 1M and 5M,
> but I'm not sure of the tradeoffs involved and I don't want to
> find out the hard way.
>
> I have read a number of books and articles, and the subject of
> optimal rollback segment extent size is still rather murky for me.
>
> Question 1.
> What are the advantages of using small rollback segment extents?
>
> Question 2.
> What are the advantages of using large rollback segment extents?
>
> Question 3.
> Is there any reason why I shouldn't just create all rollback
> segments with the same large (say 5M) extent size?
>
> Thank you in advance for any and all input.
>
> Regards,
> Dana

Oracle uses a round robin scheme to choose the roll back segments. So, if you have a large jobs that does frequent updates and infrequent commits, the job can possibly land on the small rollback segment.

If most of the processes are similar in nature, then using rollback segments of equal size makes sense. How many you use, however is a separate issue. Received on Fri Dec 20 1996 - 00:00:00 CST