So, I was playing with an 11g new feature one day, trying to figure out how to make it work. The documentation was unclear until I remembered a little salient point that I'd forgotten. Let me share with you what I discovered and at the same time talk about Oracle Data Pump and point out a feature or two you might have forgotten or not realized had existed.
So, did you know that Oracle Data Pump can use one of two methods when exporting and importing objects? One is direct path mode and the other is by using external tables. (There is actually a third, using a direct network link, but let's forget that one for a moment).
Data Pump will try to use the direct path method if possible. There are a number of cases where it will have to use external tables. Which leads me to a hidden feature in Data Pump, the access_method=external_table switch. There are some cases (bugs) where Oracle Data Pump won't be able to load your data unless you have used the external_table method to import the data (I'd bet there are some export bugs too, but I'm not aware of them). The access_method=external_table switch can be used to force Data Pump to use the external table method of loading or unloading data.
THIS leads to an 11g NEW FEATURE which I will discuss in my next 11g related blog posting very very soon. Poll results are coming up in the next couple of days, stay tuned!