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Home -> Community -> Usenet -> c.d.o.server -> Re: Why Backup Temp and Rollback segs?
A copy of this was sent to Graham Thornton
<graham.thornton_at_ln.ssw.abbott.com.nospam>
(if that email address didn't require changing)
On Mon, 19 Oct 1998 07:58:20 -0500, you wrote:
>Hello,
>
>Reading through the Oracle DBA handbook, I noticed that the section on
>on-line backups includes examples of backing up the TEMPORARY and
>ROLLBACK datafiles.
>
>Why would you want to do this? - If you need to recover from a crash you
>can only recover committed transactions so why would you need the
>TEMPORARY and ROLLBACK datafiles? - Wouldn't it be easier to just
>recreate them?
>
>Maybe I'm missing something here.
>
>Thanks
>
>Graham.
Lets say you are doing online (HOT) backups.
Then rollback is *definitely* *absolutely* needed (no questions, no if and or buts -- you *need* it). Rollback is very important to the database in this case. We need it to do a point in time recovery (which is what a restore of a hot backup will do). We roll forward from the archived redo log and then must be able to rollback uncommitted transactions from rollback. Rollback is an integral part of the recovery mechanism and *must* be preserved.
Temp space (true TEMPORARY TABLESPACES that contain no permanent objects, created with the 'TEMPORARY' clause) is also needed to make the recovery go *smoothly*. It would be HARDER and more confusing during the recovery process (when you want, no NEED, things to go smoothly - you are already in panic mode, why complicate it?) to recreate these segments. It would make recovery harder for you to do and add more manual steps.
Temp space (normal tablespace assigned to users as TEMP space where permanent objects may or may not exist) should be backed up as normal since to the database it appears to be just another tablespace. Prior to the 'temporary' clause on tablespaces -- there was no such thing as a true temporary tablespace.
Thomas Kyte
tkyte_at_us.oracle.com
Oracle Government
Herndon VA
--
http://govt.us.oracle.com/ -- downloadable utilities
Anti-Anti Spam Msg: if you want an answer emailed to you, you have to make it easy to get email to you. Any bounced email will be treated the same way i treat SPAM-- I delete it. Received on Mon Oct 19 1998 - 08:28:08 CDT
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