Re: ARCHIVELOG mode : Do I really need TEMP and RBS. Can't just recreate ?

Hi Sybrand,

I agree that having a backup that doesn't include the RBS tablespace is a little like having lifejackets on a ship but no lifeboats. Hopefully we've all seen the movie ;)

However, I disagree with the requirement to "really need" (as asked by the OP) to backup the TEMP tablespace for a number of reasons.

Firstly, the assumption here is that this is a "true" temporary tablespace (with temp files and the such) or at the very least a "temporary" temporary tablespace. If a permanent tablespace were being used as someone's default tablespace (as sadly happens) then that's somewhat different.

A temp tablespace by definition only contains a temp segment. If something unfortunate were to happen to this tablespace, then you can only lose temp data. And this temp data is of no use whatsoever as any application using the stuffed temp tablespace would likewise be stuffed. In summary, there's nothing worth recovering.

Oracle understands this and hence has incorporated some significant differences in how it handles datafiles vs. tempfiles. The keys ones are:

• RMAN doesn't bother to backup tempfiles
• Oracle doesn't prevent the database opening upon detecting a stuffed temp data file
• Oracle doesn't allow you to issue any recovery commands against a temp tablespace or tempfile. If will simply not recognise the temp tablespace or datafile you are vain, trying to recover.

The solution to "fixing" a stuffed temporary tablespace is simply to drop the bugger and recreate it. If the tablespace is the database default tablespace (9i) then this needs to be changed first before it can be dropped.

So in summary, no you don't really need to backup the temp tablespace.

Cheers

Richard
"Sybrand Bakker" <gooiditweg_at_sybrandb.demon.nl> wrote in message news:ogl2tusuqh19oa7led7jac7mj1ou8219ka_at_4ax.com...
> On Tue, 12 Nov 2002 19:14:08 -0000, "Jorge Meirim"
> <jorge.meirim_at_tmn.pt.remove> wrote:
>
> >Do I have to backup these files?
> >Can't just recreate ? I'am starting to clone my main DB. Will it be
> >inconsistent without these datafiles?
> >If possible, can I apply the same logic to index datafiles and just
recreate
> >them?. (TAPE to slow)
> >Where can I read some about?(This specific issue, I mean avoiding
recovery -
> >recreate the thing)
> >Regards,
> >Jorge Meirim
>
>
> RBS definitely has to backupped. You will be toast without it.
>
> I don't see much advantage in going to screw around and not have a
> backup of TEMP. This will result in 'penny wise/pound foolish
> scenarios' as you will have to ascertain TEMP was empty at the start
> of the backup and will stay empty during backup. TEMP is not being
> archivelogged by default, so if something was going on during backup
> you will be toast again.
>
> But then your audacity level might be greater than mine.
>
>
> Regards
>
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address
Received on Tue Nov 12 2002 - 17:15:08 CST