Re: Undo retention and tablespace size

On Thu, 27 Oct 2005 01:12:50 +0200, Keysan amused us by writing:

> Situation:
>
> Oracle 9.2.0.1 with undo_retention=10800 but with a 2GB size limit for the
> undo tablespace with no autoextend.
>
> As far as i know, with 10800 the undo tablespace could grown to around 10GB
> but i'm not sure. I need to know if this is clearly a wrong setup (imho it
> is) or could be an acceptable situation in some scenarios.
>

You are asking for an undo retention of 3 hours. And you say based on your transaction rate you apparently need 10GB storage.

Seems reasonable for a moderately busy DB.

10GB, at current storage costs, is (IMO) not be a terribly expensive way to avoid some types of database point-in-time recoveries. However, if that 10GB spills you to a new SAN frame it might be prohibitive (although I personally find that difficult to picture when the typical SAN drive is 100+GB).

How did you arrive at this 10GB number? Did you use the 'formula' or Enterprise Manager's guess? Why is this a concern?

(I assume you are aware you can add more data files to the UNDO tablespace.)

-- 
Hans Forbrich                           
Canada-wide Oracle training and consulting
mailto: Fuzzy.GreyBeard_at_gmail.com   
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