Re: Inconsistent nullingrels due to oversight in deconstruct_distribute_oj_quals

On Thu, Feb 9, 2023 at 11:55 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > This query would trigger the Assert() in search_indexed_tlist_for_var.
> > So I wonder that we should use othersj->syn_righthand here.
>
> There are two such calls in deconstruct_distribute_oj_quals ...
> don't they both need this change?

Yeah, I wondered about that too, but didn't manage to devise a query
that can show the problem caused by the call for 'above_sjinfo' case.
After a night of sleep I came up with one this morning. :-)

create table t (a int, b int);

insert into t select i, i from generate_series(1,10)i;
analyze t;

select * from t t1 left join t t2 left join t t3 on t2.b = t3.b left join t
t4 on t2.a > t3.a on t2.a > t1.a;

In this query, for the qual 't2.a > t3.a', when we try to push t3/t4
join to above t1/t2 join, we fail to add t1/t2 ojrelid to
nullingrels of t3.a, because t3 is not in t1/t2 join's min_righthand
(but in its syn_righthand). We really should have done that because
after the commutation t1/t2 join can null not only t2 but also t3 in
this case.

Thanks
Richard