Wednesday, March 31, 2010

Backup Databases

Backing up database is tricky. Database evolution is incremental; you will need another database to log every user action, and another, and another... Database development is progressive. There is hardly a subversion control. But there are two practical approaches. First, physical backups which are backups of the physical files used in storing and recovering your database. Ultimately, every physical backup is a copy of files storing database information to some other location, whether on disk or some offline storage such as tape. Second, logical backups that contain logical data (for example, tables schema or stored procedures) exported from a database, for later re-importing into a database using the corresponding import utility.

If a structural backup of the database (without any data) is needed, get the logical backups. If a full database backup (both schema and data) is needed, get the physical backups.

In SQL server, there are utilities for backup and restore. Essentially, it creates mirror image of the database file system, and loads it back when required. Occasionally, you may want to create another standalone database that mirrors the existing one. In this case, you need to
1. Create a database and give a proper name;
2. Specify the new mdb and log file location;
3. Find and load the backup file.
and done.

Doing both backup is essential.

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