On Tue, Jun 14, 2016 at 2:16 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > > Robert Haas <robertmhaas@gmail.com> writes: > > In practice, we don't yet have the ability for > > parallel-safe paths from subqueries to affect planning at higher query > > levels, but that's because the pathification stuff landed too late in > > the cycle for me to fully react to it. > > I wonder if that's not just from confusion between subplans and > subqueries.
>
Won't the patch as written will allow parallel-restricted things to be pushed to workers for UNION ALL kind of queries?
Explain verbose Select * from (SELECT c1+1 FROM t1 UNION ALL SELECT c1+1 FROM t2 where c1 < 10) ss(a);
In above kind of queries, set_rel_consider_parallel() might set consider_parallel as true for rel, but later in set_append_rel_size(), it might pull some unsafe clauses in target of childrel. Basically, I am wondering about the same problem as we discussed here [1].