Re: backup without archivelog mode

"Howard J. Rogers" wrote:
>
> True enough, though there isn't a nologging transaction in existence which
> cannot be recovered by some other means (index rebuilds, for example). The
> database simply ignores the nologging keyword for anything which couldn't
> possibly be recovered (such as regular DML). So even a nologging
> transaction *is* recoverable.

Now who's nitpicking (are not unrecoverable transactions, by definition, unrecoverable?)? But fine, I'll play along. If "by some other means" you're referring to repeating the original operation (direct SQL*Loader jobs, direct load inserts, etc.), then I agree, you can "recover" it. But that's true of *any* transaction, logging or not. Any transaction is "recoverable" under your definition by simply doing it over again. The trick is knowing/remebering what you did.

> > > But: You can never, ever make a copy of any database file whilst the
> > > database is running, without that copy being internally inconsistent.

You're not trying to defend this statement, are you?

> > > If you want to take hot backups (which your use of the 'alter tablespace
> > > Florence begin backup' command suggests you want to do) then you will
> > > absolutely, positively have to be in archivelog mode. There is no
> exception
> > > to the rule that hot files cannot simply be copied.
> >
> > Except for datafiles belonging to read-only tablespaces.
> >
>
> Be definition, read-only tablespaces are not hot.

By whose definition? The files are part of a running database. The files are available to users queries. Arguing semantics at this stage is bit late. Fine, though, we can uses Oracle's definition of a "hot backup" from the Backup and Recovery Guide: "You can perform a hot backup, that is, a backup made while the database is open and available for use." Read-only datafiles are available to the users in a running database. And yet, one can simply copy them.

Offline-normal, I'll grant you, is a bit more of a grey area. The database is still running (i.e. "hot"), the backups are still good by simply copying the files, but the particular files are not "available for use."

I wouldn't "nitpick" if you hadn't used such strongly absolute language "never, ever," "any database file," and "there is no exception." Maybe not the best words when you're trying to give "generic" advice.

Regards,
Sean Received on Sat Mar 23 2002 - 17:19:08 CST