Re: remove_useless_joins vs. bug #19560

Richard Guo <guofenglinux(at)gmail(dot)com> 于2026年9月1日周二 10:08写道：
> Agreed. Before 2ebf25e7d, there were quite a few cases where an
> expression was removed logically but still present in the parse tree
> physically, and nothing ever walked the tree afterwards expecting
> consistency. Now the new Asserts are shaking out all these cases, and
> in the end we'll get a much neater parse tree.
>

I tested v2 and reviewed the changes. LGTM.

One minor comment: the header comment for reduce_outer_joins() still says:
...
Attempt to reduce outer joins to plain inner joins.
...

But the function can also reduce a LEFT JOIN to an ANTI JOIN (and perform
other join-type reductions), so perhaps this could be updated to something
more general, for example:
...
Attempt to reduce outer joins to simpler join types.
...

--
Thanks,
Tender Wang