Thomas,
I looked at Jeff MacDonald's gripe:
Jeff MacDonald <jeff@pgsql.com> writes:
> 2: Have any of y'all ever seeen this error
> ""transformExpr: does not know how to transform node 501 (internal error)"
> from statement:
> "SELECT DISTINCT ss.stateID, ss.stateValue FROM State ss INNER JOIN Standard
> st ON ss.stateID = st.stateID"
(which behavior is in fact duplicated in the join regress test!) and
find that it looks like it would work, except that there is confusion in
the parser about whether pstate->p_join_quals is a list of expressions
or just an expression.
As far as I can see, there is no need for it to be a list, so we have
a choice of fixing it either by consistently making it be a list, or
consistently making it *not* be a list. I'd lean to the latter on
grounds of simplicity, but I wonder whether you intended it to be
a list because you were looking forward to some currently-unimplemented
feature that does need it to be a list.
Comments?
regards, tom lane