Re: explain and PARAM_EXEC

Robert Haas <robertmhaas@gmail.com> writes:
> So I guess there are two issues here: (1) somehow I feel like we
> should be telling the user what expression is being used to initialize
> $0, $1, etc. when they are PARAM_EXEC parameters;

Maybe, but the only reasonable place to put it would be within the
(SubPlan N) reference, which is not a place where verboseness would be
appreciated, I think.  In principle it could look something like
(SubPlan N ($0 := b.oid))

but with a few parameters and a bunch of other stuff on the same line
that would get out of hand.

> and (2) where does
> the output list for the sequential scan "go" when there's only one
> table involved?

The (SubPlan N) reference is meant to be understood as an expression
element yielding the output of the subplan.  One of us is confused,
because I don't see any material difference between your examples;
they're all calling the subplan in the same way.
        regards, tom lane