February 21, 2005 at 11:55 pm
hi,
I have two doubts..
1. Differential backups will capture the changes made subsequently to the full backup of database objects..
How it will treat the changes made to the existing objects (other than tables and indexes like sps,functions,etc) ?
And on most dynamic tables how online backups were made possible? Any documentation about this mechanism ?
Thanks
Nsrao
February 22, 2005 at 6:02 am
There is a lot in BOL but basically don't think of it as the objects and data changing it is the pages that are backed up. When a page has a change occurr to any data on it whether it be table data or object definition (which is data to sql sys tables) a change bit is flagged. When a differential runs it collects all the pages with a change flag into the backup. The change bit is not unflagged until the next full backup, this is why you will see major growth in your differential backups over time between full backups. So changes to the data on any page will be backed up.
February 22, 2005 at 9:36 am
Online backups are possible because as a database is being backed up, uncommitted transactions are saved to the transaction log. When the backup is completed, the transactions then are committed into the database. For this reason, if you have a long performing backup during high activity, your transaction log may grow out of control. Also, for this reason, you cannot perform a transaction log backup while the full backup is running.
Viewing 3 posts - 1 through 2 (of 2 total)
You must be logged in to reply to this topic. Login to reply