I don't believe you can...however one of the pieces of code I'm quite proud of was using a combination of c# reflection and postgres built in types to convert a

I don't believe you can...however one of the pieces of code I'm quite proud of was using a combination of c# reflection and postgres built in types to convert and arbitray list of objects into a postgres binary representation and then insert that in bulk. In our situation we are able to "reserve" primary keys by incrementing the sequencer directly by the number of objects we are inserting (separate statement beforehand) and assign the ID before we insert it...so whilst you can't get the IDe from using "returning" you can work around it. Hope that helps someone :-)