A Theoretical Situation

Hi,

Assuming an instance of this configuration:
- 5 redo logs of 10K each.

Assume this situation:
- A single transaction (say an UPDATE) produces more than 50K of redo
information, filling the redo logs, and then wraps around.
- There is plenty of rollback space for the transaction.

• The transaction is not committed.

In this situation, some redo information concerning the transaction is being overwritten or written off to offline archive logs. I would assume that at least some of the modified blocks for this offlined/overwritten information has been getting written out to the datafiles by DBWR.

Now, my question is, if the instance crashes (or shutdown aborts), how is Oracle going to roll back all the blocks changes in the transaction if they are no longer in the redo logs?

As I understand Oracle's mechanism for recovery, it cannot roll back the transaction. Is this correct? If so, what does the server do in this case? I imagine that if it's in archive mode, it could demand media recovery, but what a surprise that would be! And what about non-archive mode?

Thanks!

Alan. Received on Fri Aug 01 1997 - 00:00:00 CDT