Export: It just queries the data and writes it to a file. In terms of the database interaction, this is just like any query of the data.
Import: Depending on the type of import, this will either be:
- Exactly the same as regular row-by-row inserts if using conventional path loading. - Exactly the same as direct path loads, building an entire block and inserting it beyond the high watermark in the table.
Data pump doesn't do anything miraculous. It is just a client tool that is interacting with the database.
When using conventional path, then everything comes through the buffer cache. When doing direct path, whole blocks are built up and written to the datafile, rather than doing a row-by-row insert. It is like the difference between: