Re: Why export is not a good archiving tool

From: Mladen Gogala <>
Date: Tue, 18 May 2010 01:48:18 +0000 (UTC)
Message-ID: <hssrl2$rbd$>

On Mon, 17 May 2010 15:43:31 -0700, wrote:

> I need to know why exporting a database periodically is not a suitable
> method for preserve access to historical data. A customer with 10-20
> year retentions is using this to "preserve access" for compliance
> reasons. I would like to push them towards IBM Optim, Outerbay, Solix,
> etc. but I don't know how to explain the shortcomings of their method.
> Apparently the existing records don't have a nice date field to identify
> old data and leaving it in place doesn't protect it from damage or loss.

As other people will undoubtedly tell you, export is a snapshot tool, not a backup tool. The difference between a snapshot and a backup is that backup makes it possible to do a complete recovery of all committed transactions, up to the point of failure. Snapshot, on the other hand, allows you to restore the state of the database at the moment that the snapshot was taken. You can not do recovery from export. That means that export makes it possible for you to store a logical state of your database at some important moment, like the end of the financial year. To recover from a backup, you need the backup itself plus all of the archived logs from the moment of the backup to the moment of the recovery. No archive logs means that there is no recovery. You can also do cold backups, which are taken while the database is shut down, and which can serve both as a snapshot and a basis for recovery but you still need all of the archives.
Export, being a logical snapshot tool, allows you to export a single table or schema, which backup does not. Backup knows nothing of tables, indexes or schemas. Backup does data files, it's a physical tool. It's 9:45 PM, I am getting ready to go to bed, this is as much as I can type this late. There are several good books about Oracle backup, all of them written by Robert Freeman. Please, check them out, they are very instructive.

Received on Mon May 17 2010 - 20:48:18 CDT

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