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

On Fri, May 13, 2016 at 9:43 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
>
> On Thu, May 12, 2016 at 11:37 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > Robert Haas <robertmhaas(at)gmail(dot)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:
>

Here I want to ask base rels which are plain rels?

It might be that I am missing something, but if we debug the serial plan
for original query [1] for which this issue is reported, we have noticed
that PlaceHolderVars that contain subplans are added to base rels for which
RTE kind is (RTE_RELATION).

[1] - select ref_68.is_trigger_deletable as c0, (select d from
public.renamecolumnchild limit 1 offset 15) as c1,
ref_68.is_trigger_insertable_into as c2, 3 as c3 from
information_schema.role_udt_grants as ref_67 left join
information_schema.views as ref_68 on (ref_67.grantee =
ref_68.table_catalog ) where true limit 138;

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com