> As for what I think we *should* do near-term, I'm pretty strongly
> tempted to suggest that we just throw an error if a subtransaction
tries
> to upgrade an upper transaction's shared lock to exclusive.
So when a RI check locks a parent, you would not be able to update the
parent
in a later subtrans.
I can imagine, that the error would be a problem in a select for update
loop,
because there you usually want to update the row.
Andreas