Richard Guo writes:
> On Tue, Feb 7, 2023 at 2:12 PM Tom Lane wrote:
>> I don't see any change in this query plan when I remove that code, so
>> I'm not sure you're explaining your point very well.
> To observe an obvious plan change, we can add unique constraint for 'a'
> and look how outer-joi
On Tue, Feb 7, 2023 at 2:12 PM Tom Lane wrote:
> Richard Guo writes:
> > I noticed this code because I came across a problem with a query as
> > below.
>
> > create table t (a int);
>
> > select t1.a from (t t1 left join t t2 on true) left join (t t3 left join
> t
> > t4 on t3.a = t4.a) on t2.a
Richard Guo writes:
> In deconstruct_distribute_oj_quals, when we've identified a commutable
> left join which provides join clause with flexible semantics, we try to
> generate multiple versions of the join clause. Here we have the logic
> that puts back any ojrelids that were removed from its m
