Jeff Davis <pgsql@j-davis.com> writes:
> The design is that one backend needs to be able to see values being
> inserted by other backends before commit.
I don't understand why this isn't handled exactly the way unique
constraints are done now. Frankly, the amount of added complexity you
propose below is enough to make me want to reject the patch forthwith;
given that it's going to be a relatively little-used feature, the bugs
are never going to be out of it completely if we do it like this.
regards, tom lane