"Joolz" <joolz@arbodienst-limburg.nl> writes:
> Is there a bug in the UNIQUE behaviour?
No known bugs, anyway. I'm inclined to guess that your target table has
slightly different datatypes than the source, and that results in equal
values for some reason (such as fractional values being rounded to
integer, or char vs varchar having different ideas about significance of
trailing blanks).
> Is there any way I can DEFER the unique clause, or remove it and put
> it back later?
You can always drop and re-add the constraint ... but I'll be pretty
surprised if that gets around the problem (ie, I bet re-adding the
constraint will fail).
regards, tom lane