Archive log confusion

Here's the question:

If the output of "ARCHIVE LOG LIST" is this at 12:00:00 am,

Database log mode                        ARCHIVELOG
Automatic archival                       ENABLED
Archive destination                      /oracle/log
Oldest online log sequence               30
Next log sequence to archive             31
Current log sequence number              33

and I start a hot backup at 12:00:01 am, what is the MINIMUM archive log sequence number I need to go with this backup?

Books I have read said you need the "Oldest online log sequence", but is that really true? It seems to me that you only need the archive log sequence that contains the changes that occurred at 12:00:01 (the start time of your hot backup) and beyond. So, wouldn't that be the "Current log sequence number 33"? - since that is the one that is being written to at 12:00:01 am, NOT the "Oldest online log sequence 30", which was written before 12:00:01. And 33 is the one that will become the archive log of the online redo log that was being written to at the time of the hot backup.

I've also read that you only need those archive logs that are older than the timestamp of the beginning of your last hot backup. But even this doesn't entirely make sense because 31 is the next sequence to be archived (the ARCH is slow), so 31 will be older than 12:00:01 by the time it is archived, but log 33 is first online redo log being written to at the time of the hot backup, not 31. 31 has changes in it that are older than the start of the hot backup, so that hot backup doesn't need those changes. It only needs changes in 33, right?

Somebody please clarify.

Thanks

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Tue Sep 26 2000 - 17:38:18 CDT