Hello all,

I tried to follow the steps in the documentation to back up the database;

On Windows: Click Start, point to Programs, point to Oracle Database 10g Express Edition, and then select Backup Database

but I dont see Backup Database under Oracle database 10g express, here is what I have there:

Get Help >
Get Started
Go To Database Home Page
Run SQL Command Line
Start Database
Stop Database

Thats all.
What I am trying to check is, if I can change the location for backups to avoid the 2 backup limitation. Is it possible to do that?

The doc is a little ahead of the beta product in this regard. We had to pull the backup/recover scripts and icons as we discovered a slight problem. These will be back in time for production

Sorry - I also missed you second question. It's not that there is a two backup limitation. It's just that out of the box we want the default backup capability to support two generations of backup, instead of one. It's a safety thing. You are of course free to change the default scripts we provide to keep as many generations of backup as you want.

Well - this is the area we are having a lot of internal discussions on - so this is not final yet, but feedback would be a good thing.

Lets say you shut the machine down mid transaction one night while there are still users connected. This would not cause disk corruption, but you had inflight transactions at the time. On restart, the database would automatically roll forward the committed transactions, and automatically rollback uncommited transactions. So your database would be consistent. You would of course lose the transactions that were uncommited. This is what we call instance recovery.

Lets say you take a backup on Monday, using the techniques we are proposing. On Tuesday the disk crashes and dies. You are not using Raid 5 etc, so you have no disk based mirror of your data. So you go and buy a new disk, add it to the machine, re-install the database software, and then restore from Monday nights backup. This is what we call media recovery.

Using the techniques we propose for Oracle Database XE, you will lose ALL transactions from the time of the backup (i.e Tuesday) - both committed and uncommited until you complete the restore.

If you did not want to run the risk of losing transactions in the event of a disk crash, then you should look at one of the licensable versions, which uses a technique called archive logging to allow you to roll forward all transactions since your last (or any given backup).

Note that for all versions however, backup is online.

Thoughts ?

That's part of the internal discussion - "Should we prohibit this for production ?"

Thanks for the answer.

If it has any weight at all - I'd want the product to have online backup facilities. Dumps of data and backups are not the same thing.

Niall

Niall - I take this as a vote for both online backup and roll forward from archive logs.

Or are you saying that an online backup is OK, however roll forward from an archive log is not required (which is what I believe SQLServer Express does, at least in the default setup).

For a production system, I'd vote for both online backup and roll forward from archive logs.

I can't count the number of times I've told classes how important archive log and roll forward are to their enterprise, except possibly in DW. And with DW features like bit-map indexes turned off ...
/Hans