Re: ERROR: ORDER/GROUP BY expression not found in targetlist
| От | Amit Kapila |
|---|---|
| Тема | Re: ERROR: ORDER/GROUP BY expression not found in targetlist |
| Дата | |
| Msg-id | CAA4eK1+yGs-onuJDy+TTqnrnT0hty_QQPC1GipS+ce-W3872QQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: ERROR: ORDER/GROUP BY expression not found in targetlist (Tom Lane <tgl@sss.pgh.pa.us>) |
| Список | pgsql-hackers |
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.
>
> 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].
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