Re: BUG #19412: Wrong query result with not null constraint

On Wed, Feb 18, 2026 at 10:51 AM Richard Guo <guofenglinux(at)gmail(dot)com> wrote:
> Exactly. I think this is because when adjust_appendrel_attrs_mutator
> propagates the nullingrel bits from the parent rel's Var into the
> translated Var, it loses the translated Var's original bits. Instead
> of overwriting the translated Var's nullingrels, I think we should
> merge them.
>
> --- a/src/backend/optimizer/util/appendinfo.c
> +++ b/src/backend/optimizer/util/appendinfo.c
> @@ -291,8 +291,11 @@ adjust_appendrel_attrs_mutator(Node *node,
> var->varattno, get_rel_name(appinfo->parent_reloid));
> if (IsA(newnode, Var))
> {
> - ((Var *) newnode)->varreturningtype = var->varreturningtype;
> - ((Var *) newnode)->varnullingrels = var->varnullingrels;
> + Var *newvar = (Var *) newnode;
> +
> + newvar->varreturningtype = var->varreturningtype;
> + newvar->varnullingrels = bms_add_members(newvar->varnullingrels,
> + var->varnullingrels);
> }

Here is a more readable version of the patch.

- Richard