Re: backup versus export of db

In article <4884rs$65r_at_earth.alpha.net>, metco_at_earth.execpc.com (Milwaukee Tool) says:

>
>
>I've been told by a Value-Added-Resaler of Oracle that if i want to backup
>an oracle 7 db, i should first do a full export, and then backup up the
>exported file.
>They said that a simple backup of the files used by oracle isn't good enough.
>The reason given went something like this,
>
> "while oracle is running, it leaves certain files open. Consequently,
> if you do a simple backup of the filesystem on which oracle resides,
> even if no db transactions are pending, you aren't guaranteed to
> capture the complete, latest state of the data."
>

A normal file-system backup will only work if you shutdown your database. If your database is running, and you also run a backup, you are risking the referential integrity of the database. Picture the following scenario:

Start a backup.
Backup table a
Backup table b
Transaction begins that inserts into table a, updates table c, then commits Backup table c

Your backup now contains only the update to table c, not the insert into table a. If you have to restore this backup, you'll be missing the insert into table a.

Hope this helps.

Blair. Received on Fri Nov 17 1995 - 00:00:00 CET