Re: Rules: passing new/old to functions

Gunter Diehl <gdid(at)gmx(dot)de> writes:
> create funtion f1(v, v) returns void as '...'
> create rule vupt as on update to v do instead select f1(new, old)
> While accepting this definitions, pg says it can not handle "whole-tuple
> references" at runtime.

FWIW, the "old" case works fine. "new" doesn't work so well because the
new row hasn't been formed into a tuple at the point where the rule
runs; it only exists as a list of variables. (This is a rather handwavy
explanation, but I think it captures the key point.) While this could
probably be fixed with some effort, I doubt it's going to happen soon.
Is there any chance of doing what you want with a trigger instead of a
rule?

regards, tom lane