Export/Import

Export/Import

Export and Import are parameter-driven utilities used to make copies of Oracle objects. Based on the export mode used various levels of objects are moved to the export file and made available for import. Import can only read files created by the Export utility. The Export utility can only create an output from an Oracle database environment.
The group of objects retrieved from the database is controlled through an export mode parameter provided at the time the utility is executed. There are four modes: Table mode, User mode, Full-database mode and Tablespace mode. These modes determine what objects are exported from the source environment and thus what objects are available for import. For a table listing these modes and the objects exported see "Appendix A: Objects Exported In Each Mode".
The different modes permit export to be used for many different purposes. In Table mode a user may replicate a table or set of tables from one Oracle server to another or simply from one tablespace to another on the same server. In User mode, a DBA or privileged user may use export to replicate the complete enviornment of a user or list of users. In Tablespace mode, the underlying DDL of a tablespace may be copied to another tablespace. A tablespace can be copied to another database by exporting the source metadata in tablespace mode and copying the datafiles through standard operating system file utilities.

Opinion :

Finally, in Full database mode, export extracts all the object definitions and data (optionally) from a complete database. Import may then reload a complete database or selectively load objects or sets of objects from the full database export file.

The article was taken from :

http://www.indiana.edu/~dss/Services/DataWarehouse/Oracle/expimp.html