This chapter describes how to use the Export utility to write data from an Oracle database into an operating system file in binary format. This file is stored outside the database, and it can be read into another Oracle database using the Import utility. What Is the Export Utility?
Export provides a simple way for you to transfer data objects between Oracle databases, even if they reside on platforms with different hardware and software configurations. Export extracts the object definitions and table data from an Oracle database and stores them in an Oracle binary-format Export dump file located typically on disk or tape.
Such files can then be transferred using FTP or physically transported (in the case of tape) to a different site. The files can then be used with the Import utility to transfer data between databases that are on machines not connected through a network. The files can also be used as backups in addition to normal backup procedures. The Export and Import utilities can also facilitate certain aspects of Oracle
Advanced Replication functionality such as offline instantiation.
Export dump files can only be read by the Oracle utility, Import.
When you run Export against an Oracle database, objects (such as tables) are extracted, followed by their related objects (such as indexes, comments, and grants) if any, and then written to the Export file.
Figure : Exporting a Database
Reading the Contents of an Export File
Export files are stored in Oracle-binary format. Export files generated by Export cannot be read by utilities other than Import. Export files created by Export cannot be read by earlier versions of the Import utility. However, Import can read files written by the current and previous releases of Export, but cannot read files in other formats.
You can, however, display the contents of an export file by using the Import SHOW parameter.
To use Export, you must have the CREATE SESSION privilege on an Oracle database. To export tables owned by another user, you must have the EXP_FULL_ DATABASE role enabled. This role is granted to all DBAs.
If you do not have the system privileges contained in the EXP_FULL_DATABASE role, you cannot export objects contained in another user’s schema. For example, you cannot export a table in another user’s schema, even if you created a synonym for it.
Note also that the following schema names are reserved and will not be processed by Export: