Oracle Database 11g The Complete Reference

CHAPTER 28Using External Tables

You can use the external table feature to access external files as if they were tables inside the database. When you create an external table, you define its structure and location within Oracle. When you query the table, Oracle reads the external table and returns the results just as if the data had been stored within the database. But because the data is outside the database, you do not have to be concerned about the process for loading it into the database—a potentially significant benefit for data warehouses and large databases.

External tables have limits—you cannot update or delete their rows from within Oracle, and you cannot index them. Because they are part of the database application, you will have to ...