Rod Taylor <rbt@rbt.ca> writes:
> It would seem a new primnode (change InsertDef into SetDefault or
> similar) will be required with some executor logic.
It is not the executor's business to know about defaults. The rewriter
is the place where defaults get inserted - see rewriteTargetList().
Note that default NULL will have to be treated a little differently from
what we do for INSERT, since the, um, default behavior of UPDATE is to
preserve columns rather than replace 'em with nulls.
regards, tom lane