Transferring data into and out of your database may be necessary in several situations. For example:
Importing an initial set of data into a new database.
Building new copies of a database, perhaps with a modified structure.
Exporting data from your database for use with other applications, such as spreadsheets.
Creating extractions of a database for replication or synchronization.
Repairing a corrupt database.
Rebuilding a database to improve its performance.
Obtaining a newer version of database software and completing software upgrades.
These tasks are often grouped together as bulk operations. They are carried out by a user with DBA authority and are not part of typical end-user applications. Bulk operations may put particular demands on concurrency and transaction logs and are often best performed when no other users are connected to the database.
Performance aspects of bulk operations
Data recovery issues for bulk operations