Why do the Export and Import utilities exist, and why should you bother using them?
With so many other utilities becoming available and the changes to Oracle Enterprise Manager, you would think that these utilities would slowly disappear. Perhaps in time they will, but it is much more likely that they will be fully incorporated in other products.
For the time being, these utilities do exist, are free, and are part of the Oracle Oracle Certified Professional (OCP) backup and recovery exam.
Let us review some basic information. You can perform two types of backups:
Logical backups copy information from your database to a file with no regard to the physical location of data.
Physical backups copy information from your database to a file with physical block location information of the database stored as part of the backup file.
Export will perform a logical backup of database objects and/or data to a physical binary file in a special Oracle format.
Import will then read the file created by Export and insert database objects and/or data into an Oracle database.
The following diagram explains the use of Export and Import utilities:
You can also use both the Export and the Import utility to provide backward support for earlier versions of Oracle.
Many sites have Oracle and Oracle7 versions running concurrently, and Export/Import will allow you to move data from an Oracle database to an Oracle7 database (and even Oracle6). Keep in mind that certain database objects are not compatible with different versions of the Oracle database.
In the next lesson, you will continue learning to use Export as part of a backup and recovery strategy.