Re: Do I need backup rollback segement tablespace and temporary table ?

> Jeremiah Wilton wrote:
> >
> > The poster stated that a hot backup is the the backup method. It seems
> > to me there is no way to have a valid backup of the database withouut
> > rollback segments.
 

Frank van Bortel wrote:
>
> This would mean the sequence of backup matters as well... rollback should then
> always be backed up last? But what about committed transactions into the
> first backed up TS?
>
> I was under the impression, that recovery was done via redo (on and offline
> redo log files), and rollback was regenerated from that. After a roll forward,
> the (regenerated!) rollback is applied, after which the db is consistent.
> So yes, you need a rollback segment (but there's allways the system rollback)
> but I believe you do not need to backup rollback.

If you didn't back up all the tablespaces containing active rollback segments, to what datafiles would you apply recovery to get current rollback segments that you can use for rolling back uncommitted transactions once media recovery is complete? When you restore from a backup, you have to have something to apply recovery to. This means if you recover a database, you have to recover the data tablespaces and the rollback tablespaces, so that the rollback tablespace will be there when the time comes around to roll back uncommitted transactions. If you didn't restore and recover the rollback tablespaces, what are you going to use to roll back uncommitted transactions once media recovery is complete?

There is no need to back up tablespaces in any particular order, because you apply redo to restored tablespaces bringing them all current to the same point in time. Whenever a tablespace started getting backed up, that's the time forward from which the redo will be applied during recovery.

For hot backups, you need the rollback segments backed up, or there will be nothing to use to roll back uncommitted transaction once media recover is complete.

> Met vriendelijke groet/kind regards,

Tot schrijfs!
--
Jeremiah Received on Fri Oct 29 1999 - 14:44:01 CDT