Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Feb 19, 2010 at 11:33 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> We can also fetch that tuple's
>> relfilenode and pass it to the subplan, which we do by setting the $0
>> Param value before invoking the subplan.
> Are the same tuples in scope when evaluating the expression that sets
> $0 as were in scope when evaluating ((b.oid)::integer + 1)?
Yes, exactly the same. The parameter-value expression is just like any
other scalar expression that could appear where the SubPlan reference
is. It doesn't know anything about the subplan, really.
regards, tom lane