Re: strange behaviour of "CHECK ... IN (SELECT ...)" as constraint

Helge Bahmann <bahmann@math.tu-freiberg.de> writes:
>   CREATE TABLE ex2(name text, CHECK (name in (SELECT name FROM ex1)));

>   ERROR:  ExecEvalExpr: unknown expression type 108

I don't believe the constraint code knows how to cope with constraint
expressions that require planning :-(.

If you want to become a backend programming guru, a good path to
enlightenment would be to figure out how to fix that without
unacceptable performance penalties.

If you don't, I'd suggest embedding the SELECT in a plpgsql function.

            regards, tom lane