select from pg_inherits inner join information_schema.element_types right join (select from pg_constraint as sample_2) on true on false, lateral (select scope_catalog, inhdetachpending from pg_publication_namespace limit 3); ERROR: could not devise a query plan for the given query
Thanks for the report! I've looked at it a little bit and traced down to function have_unsafe_outer_join_ref(). The comment there says
* In practice, this test never finds a problem ... * ... * It still seems worth checking * as a backstop, but we don't go to a lot of trouble: just reject if the * unsatisfied part includes any outer-join relids at all.
This seems not correct as showed by the counterexample. ISTM that we need to do the check honestly as what the other comment says
* If the parameterization is only partly satisfied by the outer rel, * the unsatisfied part can't include any outer-join relids that could * null rels of the satisfied part.
The NOT_USED part of code is doing this check. But I think we need a little tweak. We should check the nullable side of related outer joins against the satisfied part, rather than inner_paramrels. Maybe something like attached.
However, this test seems to cost some cycles after the change. So I wonder if it's worthwhile to perform it, considering that join order restrictions should be able to guarantee there is no problem here.
BTW, here is a simplified query that can trigger this issue on HEAD.
select * from t1 inner join t2 left join (select null as c from t3 left join t4 on true) as sub on true on true, lateral (select c, t1.a from t5 offset 0 ) ss;
