To use incremental or cumulative exports, you must start with a complete export. After that you can do incremental exports -- these will export any TABLE that has been modified since the last complete, incremental or cumulative export. It exports the entire table -- not just changed rows.

A cumulative export will export all tables that have been modified since the last complete or cumulative export -- you can now discard all intervening incremental backups you have done.

Lets say you do the following:

o a complete database export (should use consistent=y). That will generate an export with everything in it.

o you add a row to tables T1, T2 and T3.

o you do an incremental export. That will export T1, T2, and T3 only.

o you add a row to T3, T4 and T5

o you do an incremental export. That will export T3, T4, and T5.

Now, you can take that full complete export and apply it to an empty database -- then apply the first incremental. That will drop and recreate (and populate) T1..T3. Apply the next incremental and it'll do the same for T3..T5.

It is important to note that, since importing an incremental export file imports new versions of existing objects, existing objects are dropped before new ones are imported. This behavior differs from a normal import. During a normal import, objects are not dropped and an error is generated if the object already exists.

You may find that taking a HOT backup of the source database and restoring that and doing a point in time recovery may be faster if the volumne of changed data is high in the source database. Rather then dropping and recreating the table (and all indexes) -- just copy the datafiles after putting the database into hot backup mode and apply some logs to the copy to get it going.