We all know the difference between RMAN full backup and Incremental Level 0 backup. Only incremental Level 0 backup can be the base for other incremental level 1 (cumulative and differential) backups.
I have been wondering so much about this. Why not a full backup as the base? I finally came up with my own imaginary behind-story. This is purely my own guess. So ignore if you don't like my notion.
We know Oracle DBMS has been evolved a lot. I think there have been a lot of changes and add-on to the backup part of Oracle DBMS.
1) There might not have been "incremental backup" with the earlier version of Oracle(like Oracle 7 for example).
2) they introduced incremental type of backup with later version to allow more flexible backup strategies*: probably level 1 differential only at that time)
3) they found people's need for more, more flexible backup strategies, so Oracle further introduced 'Cumulative incremental' and 'Level 0 incremental'
But, things got a bit complicated in the technical side. The developers couldn't find a way to integrate all the new types of backup functions with their original full backup codes. Or they found it too expensive to change the codes(it might end up being 'spaghetti code'). So they probably decided to keep the original Full backup and Level 0 incremental backup as well.
Again. this is just an idea. Peace!!!
No comments:
Post a Comment