Re: why need to backup undo tablespace?

From: Howard J. Rogers <hjr_at_dizwell.com>
Date: Fri, 10 Dec 2004 14:35:31 +1100
Message-ID: <41b91981$0$1289$afc38c87@news.optusnet.com.au>

Denis Do wrote:
> On 2004-12-09, niy38_at_hotmail.com <niy38_at_hotmail.com> wrote:
>

>>as subject.
>>

>
>
> As you know, in Oracle recovery process there are 2 stages:
> - rolling database forward
> - rolling uncommited transactions back
>
> Second step is impossible without RBS, and they are in UNDO
> tablespace.

Actually, the first step is impossible, too. As a transaction is re-performed, we must re-generate the undo that was generated when the transaction was first performed. You need an undo segment for that, too, therefore.

The whole thing is a major distraction in any case. The documented, supported, well-established rules are: you back up your control files and ALL data files, except for ones associated with temporary tablespaces, and you are permitted not to backup read-only tablespaces very often (though commonsense dictates you do it more than just once, which is the theoretical minimum).

I have never even heard of anyone ever suggesting UNDO is somehow an exception to the rule before. I guess you just live and learn and should never be surprised at the levels of danger that some people are prepared to live with.

Regards
HJR Received on Thu Dec 09 2004 - 21:35:31 CST