Doug Chamberlin schrieb am 07.06.2012 um 14:07 (-0400):

> I think I would challenge whether adding a necessary entity (to
> satisfy the FK requirement) needs to be in the same transaction
> as the overall dataset processing.

Another possibility might be to screen the dataset (which apparently
has to be processed in one fell swoop) to detect any missing entities
and then to quickly create them, or rather, assert their existence,
creating them as necessary.

Or maybe make all such screening go through one supervisor that each
ETL process is required to get clearance from. Voilà, another way to
serialize.

I think it boils down to create some serialization / synchronization
point to avoid races and hence duplication.

Michael