Re: [sqlsmith] Failed assertion in parallel worker (ExecInitSubPlan)

On Thu, May 12, 2016 at 11:37 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Robert Haas <robertmhaas@gmail.com> writes:
> >> Target list for a relation, you mean?  See relation.h:
> >>
> >> *      reltarget - Default Path output tlist for this rel; normally contains
> >> *                  Var and PlaceHolderVar nodes for the values we need to
> >> *                  output from this relation.
> >> *                  List is in no particular order, but all rels of an
> >> *                  appendrel set must use corresponding orders.
> >> *                  NOTE: in an appendrel child relation, may contain
> >> *                  arbitrary expressions pulled up from a subquery!
>
> > Err, wow.  That makes my head hurt.  Can you explain why this case
> > only arises for appendrel children, and not for plain rels?
>
> Well, plain rels only output Vars ;-)
>

Does this mean that base rels can't contain PlaceHolderVars?  Isn't it possible in below code:

..

}