Hi Lars
Sorry for the delay in reply. I tested this out with 50000 rows each having a size of 10000, and it worked fine in that case. How many rows do you have in the DB? Does the OOM happen in the DdlUtils command, or on the server side?
If there are too many entries I think the better option for you will be to use the embedded driver that will allow batch updates with FK rewrite.
thanks
sumedh