Re: Missing MaterialPath support in reparameterize_path_by_child
| От | Richard Guo |
|---|---|
| Тема | Re: Missing MaterialPath support in reparameterize_path_by_child |
| Дата | |
| Msg-id | CAMbWs48SHeBxcDBgJ5mCENvyzrZbs6qnotkJiSvLcesbHutfew@mail.gmail.com обсуждение исходный текст |
| Ответ на | Missing MaterialPath support in reparameterize_path_by_child (Tom Lane <tgl@sss.pgh.pa.us>) |
| Список | pgsql-hackers |
On Fri, Dec 2, 2022 at 10:55 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
I traced that to the fact that reparameterize_path_by_child()
omits support for MaterialPath, so that if the only surviving
path(s) for a child join include materialization steps, we'll
fail outright to produce a plan for the parent join.
Yeah, that's true. It's weird we neglect MaterialPath here.
Unfortunately, I don't have an example that produces such a
failure against HEAD. It seems certain to me that such cases
exist, though, so I'd like to apply and back-patch the attached.
I tried on HEAD and got one, which leverages sampled rel to generate the
MaterialPath and lateral reference to make it the only available path.
SET enable_partitionwise_join to true;
CREATE TABLE prt (a int, b int) PARTITION BY RANGE(a);
CREATE TABLE prt_p1 PARTITION OF prt FOR VALUES FROM (0) TO (10);
CREATE EXTENSION tsm_system_time;
explain (costs off)
select * from prt t1 left join lateral (select t1.a as t1a, t2.a as t2a from prt t2 TABLESAMPLE system_time (10)) ss on ss.t1a = ss.t2a;
ERROR: could not devise a query plan for the given query
Thanks
Richard
MaterialPath and lateral reference to make it the only available path.
SET enable_partitionwise_join to true;
CREATE TABLE prt (a int, b int) PARTITION BY RANGE(a);
CREATE TABLE prt_p1 PARTITION OF prt FOR VALUES FROM (0) TO (10);
CREATE EXTENSION tsm_system_time;
explain (costs off)
select * from prt t1 left join lateral (select t1.a as t1a, t2.a as t2a from prt t2 TABLESAMPLE system_time (10)) ss on ss.t1a = ss.t2a;
ERROR: could not devise a query plan for the given query
Thanks
Richard
В списке pgsql-hackers по дате отправления: