Re: assertion failure with unique index + partitioning + join

On Wed, Jun 17, 2026 at 11:00 AM Tender Wang <tndrwang(at)gmail(dot)com> wrote:
> In remove_rel_from_eclass(), we have
> ...
> if (!IsA(em->em_expr, Var))
> em->em_expr = (Expr *)
> remove_rel_from_phvs((Node *) em->em_expr, relid, ojrelid);
> ...
> "where s.id = 1" in the test case, the Const node seems to be able to skip, too.

Good point. Patch updated.

> I have another question, although it's unrelated to this bug.
> The logic in remove_rel_from_query() makes me a bit uneasy. It
> currently has to handle both self-join and outer-join cases,
> and it seems possible that inner-join-specific handling could end up
> being added there in the future as well.
> The function appears to be taking on multiple distinct
> responsibilities, which makes the overall design feel somewhat
> awkward.

Yeah. remove_rel_from_query() was originally written for left-join
removal only. The self-join elimination (SJE) commit grafted
self-join removal onto it, which made it do more than one thing within
one function. Commit 20efbdffe cleaned it up, clarifying the
separation between the left-join removal and self-join elimination
code paths within it. That cleanup was also meant to make it better
structured for adding new types of join removal, such as inner-join
removal, in the future.

That said, I agree that the current shape is not ideal. A better
structure might be to make remove_rel_from_query() handle only the
bookkeeping that is common to all removal types, and push the
type-specific work into the per-type callers. I think that is worth
pursuing as separate future work, kept apart from the current bug fix.

- Richard