I maintain a spreadsheet of questions sent by users and from that I single out a topic to write and share my knowledge and opinion. Unless and until I find an issue appealing, I do not prefer to write about it, till the issue crosses the threshold. Today the question that crossed the threshold is – what is the difference between NORECOVERY and RECOVERY when restoring database and what is the restore sequence.
The fact is that one can easily go to MSDN and learn the difference, so I had myself to MSDN and read the difference. This is what the Book On Line suggests here.
NORECOVERY specifies that roll back not occur. This allows roll forward to continue with the next statement in the sequence.
In this case, the restore sequence can restore other backups and roll them forward.
RECOVERY (the default) indicates that roll back should be performed after roll forward is completed for the current backup.
Recovering the database requires that the entire set of data being restored (the roll forward set) is consistent with the database. If the roll forward set has not been rolled forward far enough to be consistent with the database and RECOVERY is specified, the Database Engine issues an error.
Book On Line has very clearly explained the same subject and provides a succinct explanation of the difference.
In other words-
While doing a RESTORE Operation if you restoring database files, always use NORECOVER option as that will keep the database in a state where more backup file is restored. This will also keep database offline also to prevent any changes, which can create integrity issues. Once all backup file is restored run RESTORE command with a RECOVERY option to get database online and operational.
It is also important to be acquainted with the restore sequence of how full database backup is restored.
First, restore full database backup, differential database backup and all transaction log backups WITH NORECOVERY Option. After that, bring back database online using WITH RECOVERY option.
Following is the sample Restore Sequence
RESTORE DATABASE DATABASE FROM full_database_backup WITH NORECOVERY; RESTORE DATABASE DATABASE FROM differential_backup WITH NORECOVERY; RESTORE LOG DATABASE FROM log_backup WITH NORECOVERY; -- Repeat this till you restore last log backup RESTORE DATABASE DATABASE WITH RECOVERY;
I hope now it is very clear to you all what is restore sequence and the difference between recovery options.
Reference: Pinal Dave (http://blog.SQLAuthority.com)