Incremental exports are possible. The first thing you need to do is to perform a baseline backup. This is a full backup of your database. Use the FULL=Y parameter in the export utility to obtain a full backup.
There are three types of exports to be concerned with here. They are the FULL export, the CUMULATIVE export, and the INCREMENTAL export. The CUMULATIVE export will export the changes since the last CUMULATIVE or FULL export. THe INCREMENTAL export will export the changes since the last INCREMENTAL, CUMULATIVE, or FULL export.
To specify a CUMULATIVE export, use the INCTYPE=CUMULATIVE parameter instead of FULL=Y. To specify an INCREMENTAL export, use the INCTYPE=INCREMENTAL parameter instead of FULL=Y.
This was first published in November 2004