On Thu, Jun 9, 2016 at 11:38 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > > Robert Haas <robertmhaas@gmail.com> writes: > > > Could you answer my question about whether adjust_appendrel_attrs() > > might translate Vars into non-Vars? > > Yes, absolutely.
Isn't this true only for UNION ALL cases and not for inheritance child relations (at least that is what seems to be mentioned in comments for translated_vars in AppendRelInfo)? If that is right, then I think there shouldn't be a problem w.r.t parallel plans even if adjust_appendrel_attrs() translate Vars into non-Vars, because for UNION ALL it seems parent rels rtekind is RTE_SUBQUERY and we consider such rels as parallel unsafe (see set_rel_consider_parallel()). So it doesn't matter even if child rels target list contains any parallel unsafe expression, as we are not going to create parallel paths for such relations.
